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authorLinus Torvalds <torvalds@linux-foundation.org>2018-10-23 17:05:28 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-23 17:05:28 +0100
commit99792e0cea1ed733cdc8d0758677981e0cbebfed (patch)
treeacf6868f48f687dd8667ee4f99c156415ea8ff7b /arch
parent382d72a9aa525b56ab8453ce61751fa712414d3d (diff)
parent977e4be5eb714c48a67afc26a6c477f24130a1f2 (diff)
Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Ingo Molnar: "Lots of changes in this cycle: - Lots of CPA (change page attribute) optimizations and related cleanups (Thomas Gleixner, Peter Zijstra) - Make lazy TLB mode even lazier (Rik van Riel) - Fault handler cleanups and improvements (Dave Hansen) - kdump, vmcore: Enable kdumping encrypted memory with AMD SME enabled (Lianbo Jiang) - Clean up VM layout documentation (Baoquan He, Ingo Molnar) - ... plus misc other fixes and enhancements" * 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits) x86/stackprotector: Remove the call to boot_init_stack_canary() from cpu_startup_entry() x86/mm: Kill stray kernel fault handling comment x86/mm: Do not warn about PCI BIOS W+X mappings resource: Clean it up a bit resource: Fix find_next_iomem_res() iteration issue resource: Include resource end in walk_*() interfaces x86/kexec: Correct KEXEC_BACKUP_SRC_END off-by-one error x86/mm: Remove spurious fault pkey check x86/mm/vsyscall: Consider vsyscall page part of user address space x86/mm: Add vsyscall address helper x86/mm: Fix exception table comments x86/mm: Add clarifying comments for user addr space x86/mm: Break out user address space handling x86/mm: Break out kernel address space handling x86/mm: Clarify hardware vs. software "error_code" x86/mm/tlb: Make lazy TLB mode lazier x86/mm/tlb: Add freed_tables element to flush_tlb_info x86/mm/tlb: Add freed_tables argument to flush_tlb_mm_range smp,cpumask: introduce on_each_cpu_cond_mask smp: use __cpumask_set_cpu in on_each_cpu_cond ...
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Kconfig8
-rw-r--r--arch/x86/include/asm/io.h3
-rw-r--r--arch/x86/include/asm/kexec.h2
-rw-r--r--arch/x86/include/asm/page_64_types.h15
-rw-r--r--arch/x86/include/asm/tlb.h21
-rw-r--r--arch/x86/include/asm/tlbflush.h33
-rw-r--r--arch/x86/kernel/crash_dump_64.c60
-rw-r--r--arch/x86/kernel/ldt.c2
-rw-r--r--arch/x86/kernel/vm86_32.c2
-rw-r--r--arch/x86/mm/dump_pagetables.c35
-rw-r--r--arch/x86/mm/fault.c288
-rw-r--r--arch/x86/mm/init_32.c23
-rw-r--r--arch/x86/mm/ioremap.c24
-rw-r--r--arch/x86/mm/pageattr.c627
-rw-r--r--arch/x86/mm/tlb.c167
-rw-r--r--arch/x86/xen/smp_pv.c2
16 files changed, 854 insertions, 458 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8282985d438a..ff425a2d286c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1487,6 +1487,14 @@ config X86_DIRECT_GBPAGES
supports them), so don't confuse the user by printing
that we have them enabled.
+config X86_CPA_STATISTICS
+ bool "Enable statistic for Change Page Attribute"
+ depends on DEBUG_FS
+ ---help---
+ Expose statistics about the Change Page Attribute mechanims, which
+ helps to determine the effectivness of preserving large and huge
+ page mappings when mapping protections are changed.
+
config ARCH_HAS_MEM_ENCRYPT
def_bool y
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 9a92a3ac2ac5..832da8229cc7 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -187,11 +187,12 @@ extern void __iomem *ioremap_nocache(resource_size_t offset, unsigned long size)
#define ioremap_nocache ioremap_nocache
extern void __iomem *ioremap_uc(resource_size_t offset, unsigned long size);
#define ioremap_uc ioremap_uc
-
extern void __iomem *ioremap_cache(resource_size_t offset, unsigned long size);
#define ioremap_cache ioremap_cache
extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size, unsigned long prot_val);
#define ioremap_prot ioremap_prot
+extern void __iomem *ioremap_encrypted(resource_size_t phys_addr, unsigned long size);
+#define ioremap_encrypted ioremap_encrypted
/**
* ioremap - map bus memory into CPU space
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index f327236f0fa7..5125fca472bb 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -67,7 +67,7 @@ struct kimage;
/* Memory to backup during crash kdump */
#define KEXEC_BACKUP_SRC_START (0UL)
-#define KEXEC_BACKUP_SRC_END (640 * 1024UL) /* 640K */
+#define KEXEC_BACKUP_SRC_END (640 * 1024UL - 1) /* 640K */
/*
* CPU does not save ss and sp on stack if execution is already
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 6afac386a434..cd0cf1c568b4 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -59,13 +59,16 @@
#endif
/*
- * Kernel image size is limited to 1GiB due to the fixmap living in the
- * next 1GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S). Use
- * 512MiB by default, leaving 1.5GiB for modules once the page tables
- * are fully set up. If kernel ASLR is configured, it can extend the
- * kernel page table mapping, reducing the size of the modules area.
+ * Maximum kernel image size is limited to 1 GiB, due to the fixmap living
+ * in the next 1 GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S).
+ *
+ * On KASLR use 1 GiB by default, leaving 1 GiB for modules once the
+ * page tables are fully set up.
+ *
+ * If KASLR is disabled we can shrink it to 0.5 GiB and increase the size
+ * of the modules area to 1.5 GiB.
*/
-#if defined(CONFIG_RANDOMIZE_BASE)
+#ifdef CONFIG_RANDOMIZE_BASE
#define KERNEL_IMAGE_SIZE (1024 * 1024 * 1024)
#else
#define KERNEL_IMAGE_SIZE (512 * 1024 * 1024)
diff --git a/arch/x86/include/asm/tlb.h b/arch/x86/include/asm/tlb.h
index cb0a1f470980..404b8b1d44f5 100644
--- a/arch/x86/include/asm/tlb.h
+++ b/arch/x86/include/asm/tlb.h
@@ -6,16 +6,23 @@
#define tlb_end_vma(tlb, vma) do { } while (0)
#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
-#define tlb_flush(tlb) \
-{ \
- if (!tlb->fullmm && !tlb->need_flush_all) \
- flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end, 0UL); \
- else \
- flush_tlb_mm_range(tlb->mm, 0UL, TLB_FLUSH_ALL, 0UL); \
-}
+static inline void tlb_flush(struct mmu_gather *tlb);
#include <asm-generic/tlb.h>
+static inline void tlb_flush(struct mmu_gather *tlb)
+{
+ unsigned long start = 0UL, end = TLB_FLUSH_ALL;
+ unsigned int stride_shift = tlb_get_unmap_shift(tlb);
+
+ if (!tlb->fullmm && !tlb->need_flush_all) {
+ start = tlb->start;
+ end = tlb->end;
+ }
+
+ flush_tlb_mm_range(tlb->mm, start, end, stride_shift, tlb->freed_tables);
+}
+
/*
* While x86 architecture in general requires an IPI to perform TLB
* shootdown, enablement code for several hypervisors overrides
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 58ce5288878e..323a313947e0 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -148,22 +148,6 @@ static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
#define __flush_tlb_one_user(addr) __native_flush_tlb_one_user(addr)
#endif
-static inline bool tlb_defer_switch_to_init_mm(void)
-{
- /*
- * If we have PCID, then switching to init_mm is reasonably
- * fast. If we don't have PCID, then switching to init_mm is
- * quite slow, so we try to defer it in the hopes that we can
- * avoid it entirely. The latter approach runs the risk of
- * receiving otherwise unnecessary IPIs.
- *
- * This choice is just a heuristic. The tlb code can handle this
- * function returning true or false regardless of whether we have
- * PCID.
- */
- return !static_cpu_has(X86_FEATURE_PCID);
-}
-
struct tlb_context {
u64 ctx_id;
u64 tlb_gen;
@@ -547,23 +531,30 @@ struct flush_tlb_info {
unsigned long start;
unsigned long end;
u64 new_tlb_gen;
+ unsigned int stride_shift;
+ bool freed_tables;
};
#define local_flush_tlb() __flush_tlb()
-#define flush_tlb_mm(mm) flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL)
+#define flush_tlb_mm(mm) \
+ flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL, true)
-#define flush_tlb_range(vma, start, end) \
- flush_tlb_mm_range(vma->vm_mm, start, end, vma->vm_flags)
+#define flush_tlb_range(vma, start, end) \
+ flush_tlb_mm_range((vma)->vm_mm, start, end, \
+ ((vma)->vm_flags & VM_HUGETLB) \
+ ? huge_page_shift(hstate_vma(vma)) \
+ : PAGE_SHIFT, false)
extern void flush_tlb_all(void);
extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
- unsigned long end, unsigned long vmflag);
+ unsigned long end, unsigned int stride_shift,
+ bool freed_tables);
extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a)
{
- flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, VM_NONE);
+ flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, PAGE_SHIFT, false);
}
void native_flush_tlb_others(const struct cpumask *cpumask,
diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index 4f2e0778feac..eb8ab3915268 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -11,40 +11,62 @@
#include <linux/uaccess.h>
#include <linux/io.h>
-/**
- * copy_oldmem_page - copy one page from "oldmem"
- * @pfn: page frame number to be copied
- * @buf: target memory address for the copy; this can be in kernel address
- * space or user address space (see @userbuf)
- * @csize: number of bytes to copy
- * @offset: offset in bytes into the page (based on pfn) to begin the copy
- * @userbuf: if set, @buf is in user address space, use copy_to_user(),
- * otherwise @buf is in kernel address space, use memcpy().
- *
- * Copy a page from "oldmem". For this page, there is no pte mapped
- * in the current kernel. We stitch up a pte, similar to kmap_atomic.
- */
-ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
- size_t csize, unsigned long offset, int userbuf)
+static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
+ unsigned long offset, int userbuf,
+ bool encrypted)
{
void *vaddr;
if (!csize)
return 0;
- vaddr = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
+ if (encrypted)
+ vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE);
+ else
+ vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
+
if (!vaddr)
return -ENOMEM;
if (userbuf) {
- if (copy_to_user(buf, vaddr + offset, csize)) {
- iounmap(vaddr);
+ if (copy_to_user((void __user *)buf, vaddr + offset, csize)) {
+ iounmap((void __iomem *)vaddr);
return -EFAULT;
}
} else
memcpy(buf, vaddr + offset, csize);
set_iounmap_nonlazy();
- iounmap(vaddr);
+ iounmap((void __iomem *)vaddr);
return csize;
}
+
+/**
+ * copy_oldmem_page - copy one page of memory
+ * @pfn: page frame number to be copied
+ * @buf: target memory address for the copy; this can be in kernel address
+ * space or user address space (see @userbuf)
+ * @csize: number of bytes to copy
+ * @offset: offset in bytes into the page (based on pfn) to begin the copy
+ * @userbuf: if set, @buf is in user address space, use copy_to_user(),
+ * otherwise @buf is in kernel address space, use memcpy().
+ *
+ * Copy a page from the old kernel's memory. For this page, there is no pte
+ * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic.
+ */
+ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
+ unsigned long offset, int userbuf)
+{
+ return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false);
+}
+
+/**
+ * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the
+ * memory with the encryption mask set to accomodate kdump on SME-enabled
+ * machines.
+ */
+ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
+ unsigned long offset, int userbuf)
+{
+ return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
+}
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 733e6ace0fa4..ab18e0884dc6 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -273,7 +273,7 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot)
map_ldt_struct_to_user(mm);
va = (unsigned long)ldt_slot_va(slot);
- flush_tlb_mm_range(mm, va, va + LDT_SLOT_STRIDE, 0);
+ flush_tlb_mm_range(mm, va, va + LDT_SLOT_STRIDE, PAGE_SHIFT, false);
ldt->slot = slot;
return 0;
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 1c03e4aa6474..c2fd39752da8 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -199,7 +199,7 @@ static void mark_screen_rdonly(struct mm_struct *mm)
pte_unmap_unlock(pte, ptl);
out:
up_write(&mm->mmap_sem);
- flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL);
+ flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, PAGE_SHIFT, false);
}
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index a12afff146d1..fc37bbd23eb8 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -19,7 +19,9 @@
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/highmem.h>
+#include <linux/pci.h>
+#include <asm/e820/types.h>
#include <asm/pgtable.h>
/*
@@ -241,6 +243,29 @@ static unsigned long normalize_addr(unsigned long u)
return (signed long)(u << shift) >> shift;
}
+static void note_wx(struct pg_state *st)
+{
+ unsigned long npages;
+
+ npages = (st->current_address - st->start_address) / PAGE_SIZE;
+
+#ifdef CONFIG_PCI_BIOS
+ /*
+ * If PCI BIOS is enabled, the PCI BIOS area is forced to WX.
+ * Inform about it, but avoid the warning.
+ */
+ if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN &&
+ st->current_address <= PAGE_OFFSET + BIOS_END) {
+ pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages);
+ return;
+ }
+#endif
+ /* Account the WX pages */
+ st->wx_pages += npages;
+ WARN_ONCE(1, "x86/mm: Found insecure W+X mapping at address %pS\n",
+ (void *)st->start_address);
+}
+
/*
* This function gets called on a break in a continuous series
* of PTE entries; the next one is different so we need to
@@ -276,14 +301,8 @@ static void note_page(struct seq_file *m, struct pg_state *st,
unsigned long delta;
int width = sizeof(unsigned long) * 2;
- if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX)) {
- WARN_ONCE(1,
- "x86/mm: Found insecure W+X mapping at address %p/%pS\n",
- (void *)st->start_address,
- (void *)st->start_address);
- st->wx_pages += (st->current_address -
- st->start_address) / PAGE_SIZE;
- }
+ if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX))
+ note_wx(st);
/*
* Now print the actual finished series
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 0d45f6debb3a..2b1519bc5381 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -851,6 +851,15 @@ show_signal_msg(struct pt_regs *regs, unsigned long error_code,
show_opcodes(regs, loglvl);
}
+/*
+ * The (legacy) vsyscall page is the long page in the kernel portion
+ * of the address space that has user-accessible permissions.
+ */
+static bool is_vsyscall_vaddr(unsigned long vaddr)
+{
+ return unlikely((vaddr & PAGE_MASK) == VSYSCALL_ADDR);
+}
+
static void
__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
unsigned long address, u32 *pkey, int si_code)
@@ -874,18 +883,6 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
if (is_errata100(regs, address))
return;
-#ifdef CONFIG_X86_64
- /*
- * Instruction fetch faults in the vsyscall page might need
- * emulation.
- */
- if (unlikely((error_code & X86_PF_INSTR) &&
- ((address & ~0xfff) == VSYSCALL_ADDR))) {
- if (emulate_vsyscall(regs, address))
- return;
- }
-#endif
-
/*
* To avoid leaking information about the kernel page table
* layout, pretend that user-mode accesses to kernel addresses
@@ -1043,19 +1040,13 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
}
}
-static int spurious_fault_check(unsigned long error_code, pte_t *pte)
+static int spurious_kernel_fault_check(unsigned long error_code, pte_t *pte)
{
if ((error_code & X86_PF_WRITE) && !pte_write(*pte))
return 0;
if ((error_code & X86_PF_INSTR) && !pte_exec(*pte))
return 0;
- /*
- * Note: We do not do lazy flushing on protection key
- * changes, so no spurious fault will ever set X86_PF_PK.
- */
- if ((error_code & X86_PF_PK))
- return 1;
return 1;
}
@@ -1082,7 +1073,7 @@ static int spurious_fault_check(unsigned long error_code, pte_t *pte)
* (Optional Invalidation).
*/
static noinline int
-spurious_fault(unsigned long error_code, unsigned long address)
+spurious_kernel_fault(unsigned long error_code, unsigned long address)
{
pgd_t *pgd;
p4d_t *p4d;
@@ -1113,27 +1104,27 @@ spurious_fault(unsigned long error_code, unsigned long address)
return 0;
if (p4d_large(*p4d))
- return spurious_fault_check(error_code, (pte_t *) p4d);
+ return spurious_kernel_fault_check(error_code, (pte_t *) p4d);
pud = pud_offset(p4d, address);
if (!pud_present(*pud))
return 0;
if (pud_large(*pud))
- return spurious_fault_check(error_code, (pte_t *) pud);
+ return spurious_kernel_fault_check(error_code, (pte_t *) pud);
pmd = pmd_offset(pud, address);
if (!pmd_present(*pmd))
return 0;
if (pmd_large(*pmd))
- return spurious_fault_check(error_code, (pte_t *) pmd);
+ return spurious_kernel_fault_check(error_code, (pte_t *) pmd);
pte = pte_offset_kernel(pmd, address);
if (!pte_present(*pte))
return 0;
- ret = spurious_fault_check(error_code, pte);
+ ret = spurious_kernel_fault_check(error_code, pte);
if (!ret)
return 0;
@@ -1141,12 +1132,12 @@ spurious_fault(unsigned long error_code, unsigned long address)
* Make sure we have permissions in PMD.
* If not, then there's a bug in the page tables:
*/
- ret = spurious_fault_check(error_code, (pte_t *) pmd);
+ ret = spurious_kernel_fault_check(error_code, (pte_t *) pmd);
WARN_ONCE(!ret, "PMD has incorrect permission bits\n");
return ret;
}
-NOKPROBE_SYMBOL(spurious_fault);
+NOKPROBE_SYMBOL(spurious_kernel_fault);
int show_unhandled_signals = 1;
@@ -1193,6 +1184,14 @@ access_error(unsigned long error_code, struct vm_area_struct *vma)
static int fault_in_kernel_space(unsigned long address)
{
+ /*
+ * On 64-bit systems, the vsyscall page is at an address above
+ * TASK_SIZE_MAX, but is not considered part of the kernel
+ * address space.
+ */
+ if (IS_ENABLED(CONFIG_X86_64) && is_vsyscall_vaddr(address))
+ return false;
+
return address >= TASK_SIZE_MAX;
}
@@ -1214,31 +1213,23 @@ static inline bool smap_violation(int error_code, struct pt_regs *regs)
}
/*
- * This routine handles page faults. It determines the address,
- * and the problem, and then passes it off to one of the appropriate
- * routines.
+ * Called for all faults where 'address' is part of the kernel address
+ * space. Might get called for faults that originate from *code* that
+ * ran in userspace or the kernel.
*/
-static noinline void
-__do_page_fault(struct pt_regs *regs, unsigned long error_code,
- unsigned long address)
+static void
+do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code,
+ unsigned long address)
{
- struct vm_area_struct *vma;
- struct task_struct *tsk;
- struct mm_struct *mm;
- vm_fault_t fault, major = 0;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
- u32 pkey;
-
- tsk = current;
- mm = tsk->mm;
-
- prefetchw(&mm->mmap_sem);
-
- if (unlikely(kmmio_fault(regs, address)))
- return;
+ /*
+ * Protection keys exceptions only happen on user pages. We
+ * have no user pages in the kernel portion of the address
+ * space, so do not expect them here.
+ */
+ WARN_ON_ONCE(hw_error_code & X86_PF_PK);
/*
- * We fault-in kernel-space virtual memory on-demand. The
+ * We can fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
@@ -1246,41 +1237,74 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
* only copy the information from the master page table,
* nothing more.
*
- * This verifies that the fault happens in kernel space
- * (error_code & 4) == 0, and that the fault was not a
- * protection error (error_code & 9) == 0.
+ * Before doing this on-demand faulting, ensure that the
+ * fault is not any of the following:
+ * 1. A fault on a PTE with a reserved bit set.
+ * 2. A fault caused by a user-mode access. (Do not demand-
+ * fault kernel memory due to user-mode accesses).
+ * 3. A fault caused by a page-level protection violation.
+ * (A demand fault would be on a non-present page which
+ * would have X86_PF_PROT==0).
*/
- if (unlikely(fault_in_kernel_space(address))) {
- if (!(error_code & (X86_PF_RSVD | X86_PF_USER | X86_PF_PROT))) {
- if (vmalloc_fault(address) >= 0)
- return;
- }
-
- /* Can handle a stale RO->RW TLB: */
- if (spurious_fault(error_code, address))
+ if (!(hw_error_code & (X86_PF_RSVD | X86_PF_USER | X86_PF_PROT))) {
+ if (vmalloc_fault(address) >= 0)
return;
+ }
- /* kprobes don't want to hook the spurious faults: */
- if (kprobes_fault(regs))
- return;
- /*
- * Don't take the mm semaphore here. If we fixup a prefetch
- * fault we could otherwise deadlock:
- */
- bad_area_nosemaphore(regs, error_code, address, NULL);
+ /* Was the fault spurious, caused by lazy TLB invalidation? */
+ if (spurious_kernel_fault(hw_error_code, address))
+ return;
+ /* kprobes don't want to hook the spurious faults: */
+ if (kprobes_fault(regs))
return;
- }
+
+ /*
+ * Note, despite being a "bad area", there are quite a few
+ * acceptable reasons to get here, such as erratum fixups
+ * and handling kernel code that can fault, like get_user().
+ *
+ * Don't take the mm semaphore here. If we fixup a prefetch
+ * fault we could otherwise deadlock:
+ */
+ bad_area_nosemaphore(regs, hw_error_code, address, NULL);
+}
+NOKPROBE_SYMBOL(do_kern_addr_fault);
+
+/* Handle faults in the user portion of the address space */
+static inline
+void do_user_addr_fault(struct pt_regs *regs,
+ unsigned long hw_error_code,
+ unsigned long address)
+{
+ unsigned long sw_error_code;
+ struct vm_area_struct *vma;
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ vm_fault_t fault, major = 0;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+ u32 pkey;
+
+ tsk = current;
+ mm = tsk->mm;
/* kprobes don't want to hook the spurious faults: */
if (unlikely(kprobes_fault(regs)))
return;
- if (unlikely(error_code & X86_PF_RSVD))
- pgtable_bad(regs, error_code, address);
+ /*
+ * Reserved bits are never expected to be set on
+ * entries in the user portion of the page tables.
+ */
+ if (unlikely(hw_error_code & X86_PF_RSVD))
+ pgtable_bad(regs, hw_error_code, address);
- if (unlikely(smap_violation(error_code, regs))) {
- bad_area_nosemaphore(regs, error_code, address, NULL);
+ /*
+ * Check for invalid kernel (supervisor) access to user
+ * pages in the user address space.
+ */
+ if (unlikely(smap_violation(hw_error_code, regs))) {
+ bad_area_nosemaphore(regs, hw_error_code, address, NULL);
return;
}
@@ -1289,11 +1313,18 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
* in a region with pagefaults disabled then we must not take the fault
*/
if (unlikely(faulthandler_disabled() || !mm)) {
- bad_area_nosemaphore(regs, error_code, address, NULL);
+ bad_area_nosemaphore(regs, hw_error_code, address, NULL);
return;
}
/*
+ * hw_error_code is literally the "page fault error code" passed to
+ * the kernel directly from the hardware. But, we will shortly be
+ * modifying it in software, so give it a new name.
+ */
+ sw_error_code = hw_error_code;
+
+ /*
* It's safe to allow irq's after cr2 has been saved and the
* vmalloc fault has been handled.
*
@@ -1302,7 +1333,26 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
*/
if (user_mode(regs)) {
local_irq_enable();
- error_code |= X86_PF_USER;
+ /*
+ * Up to this point, X86_PF_USER set in hw_error_code
+ * indicated a user-mode access. But, after this,
+ * X86_PF_USER in sw_error_code will indicate either
+ * that, *or* an implicit kernel(supervisor)-mode access
+ * which originated from user mode.
+ */
+ if (!(hw_error_code & X86_PF_USER)) {
+ /*
+ * The CPU was in user mode, but the CPU says
+ * the fault was not a user-mode access.
+ * Must be an implicit kernel-mode access,
+ * which we do not expect to happen in the
+ * user address space.
+ */
+ pr_warn_once("kernel-mode error from user-mode: %lx\n",
+ hw_error_code);
+
+ sw_error_code |= X86_PF_USER;
+ }
flags |= FAULT_FLAG_USER;
} else {
if (regs->flags & X86_EFLAGS_IF)
@@ -1311,31 +1361,49 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
- if (error_code & X86_PF_WRITE)
+ if (sw_error_code & X86_PF_WRITE)
flags |= FAULT_FLAG_WRITE;
- if (error_code & X86_PF_INSTR)
+ if (sw_error_code & X86_PF_INSTR)
flags |= FAULT_FLAG_INSTRUCTION;
+#ifdef CONFIG_X86_64
/*
- * When running in the kernel we expect faults to occur only to
- * addresses in user space. All other faults represent errors in
- * the kernel and should generate an OOPS. Unfortunately, in the
- * case of an erroneous fault occurring in a code path which already
- * holds mmap_sem we will deadlock attempting to validate the fault
- * against the address space. Luckily the kernel only validly
- * references user space from well defined areas of code, which are
- * listed in the exceptions table.
+ * Instruction fetch faults in the vsyscall page might need
+ * emulation. The vsyscall page is at a high address
+ * (>PAGE_OFFSET), but is considered to be part of the user
+ * address space.
*
- * As the vast majority of faults will be valid we will only perform
- * the source reference check when there is a possibility of a
- * deadlock. Attempt to lock the address space, if we cannot we then
- * validate the source. If this is invalid we can skip the address
- * space check, thus avoiding the deadlock:
+ * The vsyscall page does not have a "real" VMA, so do this
+ * emulation before we go searching for VMAs.
+ */
+ if ((sw_error_code & X86_PF_INSTR) && is_vsyscall_vaddr(address)) {
+ if (emulate_vsyscall(regs, address))
+ return;
+ }
+#endif
+
+ /*
+ * Kernel-mode access to the user address space should only occur
+ * on well-defined single instructions listed in the exception
+ * tables. But, an erroneous kernel fault occurring outside one of
+ * those areas which also holds mmap_sem might deadlock attempting
+ * to validate the fault against the address space.
+ *
+ * Only do the expensive exception table search when we might be at
+ * risk of a deadlock. This happens if we
+ * 1. Failed to acquire mmap_sem, and
+ * 2. The access did not originate in userspace. Note: either the
+ * hardware or earlier page fault code may set X86_PF_USER
+ * in sw_error_code.
*/
if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
- if (!(error_code & X86_PF_USER) &&
+ if (!(sw_error_code & X86_PF_USER) &&
!search_exception_tables(regs->ip)) {
- bad_area_nosemaphore(regs, error_code, address, NULL);
+ /*
+ * Fault from code in kernel from
+ * which we do not expect faults.
+ */
+ bad_area_nosemaphore(regs, sw_error_code, address, NULL);
return;
}
retry:
@@ -1351,16 +1419,16 @@ retry:
vma = find_vma(mm, address);
if (unlikely(!vma)) {
- bad_area(regs, error_code, address);
+ bad_area(regs, sw_error_code, address);
return;
}
if (likely(vma->vm_start <= address))
goto good_area;
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
- bad_area(regs, error_code, address);
+ bad_area(regs, sw_error_code, address);
return;
}
- if (error_code & X86_PF_USER) {
+ if (sw_error_code & X86_PF_USER) {
/*
* Accessing the stack below %sp is always a bug.
* The large cushion allows instructions like enter
@@ -1368,12 +1436,12 @@ retry:
* 32 pointers and then decrements %sp by 65535.)
*/
if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) {
- bad_area(regs, error_code, address);
+ bad_area(regs, sw_error_code, address);
return;
}
}
if (unlikely(expand_stack(vma, address))) {
- bad_area(regs, error_code, address);
+ bad_area(regs, sw_error_code, address);
return;
}
@@ -1382,8 +1450,8 @@ retry:
* we can handle it..
*/
good_area:
- if (unlikely(access_error(error_code, vma))) {
- bad_area_access_error(regs, error_code, address, vma);
+ if (unlikely(access_error(sw_error_code, vma))) {
+ bad_area_access_error(regs, sw_error_code, address, vma);
return;
}
@@ -1425,13 +1493,13 @@ good_area:
return;
/* Not returning to user mode? Handle exceptions or die: */
- no_context(regs, error_code, address, SIGBUS, BUS_ADRERR);
+ no_context(regs, sw_error_code, address, SIGBUS, BUS_ADRERR);
return;
}
up_read(&mm->mmap_sem);
if (unlikely(fault & VM_FAULT_ERROR)) {
- mm_fault_error(regs, error_code, address, &pkey, fault);
+ mm_fault_error(regs, sw_error_code, address, &pkey, fault);
return;
}
@@ -1449,6 +1517,28 @@ good_area:
check_v8086_mode(regs, address, tsk);
}
+NOKPROBE_SYMBOL(do_user_addr_fault);
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+static noinline void
+__do_page_fault(struct pt_regs *regs, unsigned long hw_error_code,
+ unsigned long address)
+{
+ prefetchw(&current->mm->mmap_sem);
+
+ if (unlikely(kmmio_fault(regs, address)))
+ return;
+
+ /* Was the fault on kernel-controlled part of the address space? */
+ if (unlikely(fault_in_kernel_space(address)))
+ do_kern_addr_fault(regs, hw_error_code, address);
+ else
+ do_user_addr_fault(regs, hw_error_code, address);
+}
NOKPROBE_SYMBOL(__do_page_fault);
static nokprobe_inline void
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 979e0a02cbe1..142c7d9f89cc 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -923,34 +923,19 @@ static void mark_nxdata_nx(void)
void mark_rodata_ro(void)
{
unsigned long start = PFN_ALIGN(_text);
- unsigned long size = PFN_ALIGN(_etext) - start;
+ unsigned long size = (unsigned long)__end_rodata - start;
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
- printk(KERN_INFO "Write protecting the kernel text: %luk\n",
+ pr_info("Write protecting kernel text and read-only data: %luk\n",
size >> 10);
kernel_set_to_readonly = 1;
#ifdef CONFIG_CPA_DEBUG
- printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
- start, start+size);
- set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);
-
- printk(KERN_INFO "Testing CPA: write protecting again\n");
- set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
-#endif
-
- start += size;
- size = (unsigned long)__end_rodata - start;
- set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
- printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
- size >> 10);
-
-#ifdef CONFIG_CPA_DEBUG
- printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, start + size);
+ pr_info("Testing CPA: Reverting %lx-%lx\n", start, start + size);
set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
- printk(KERN_INFO "Testing CPA: write protecting again\n");
+ pr_info("Testing CPA: write protecting again\n");
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
#endif
mark_nxdata_nx();
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index c63a545ec199..24e0920a9b25 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -131,7 +131,8 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
* caller shouldn't need to know that small detail.
*/
static void __iomem *__ioremap_caller(resource_size_t phys_addr,
- unsigned long size, enum page_cache_mode pcm, void *caller)
+ unsigned long size, enum page_cache_mode pcm,
+ void *caller, bool encrypted)
{
unsigned long offset, vaddr;
resource_size_t last_addr;
@@ -199,7 +200,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
* resulting mapping.
*/
prot = PAGE_KERNEL_IO;
- if (sev_active() && mem_flags.desc_other)
+ if ((sev_active() && mem_flags.desc_other) || encrypted)
prot = pgprot_encrypted(prot);
switch (pcm) {
@@ -291,7 +292,7 @@ void __iomem *ioremap_nocache(resource_size_t phys_addr, unsigned long size)
enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC_MINUS;
return __ioremap_caller(phys_addr, size, pcm,
- __builtin_return_address(0));
+ __builtin_return_address(0), false);
}
EXPORT_SYMBOL(ioremap_nocache);
@@ -324,7 +325,7 @@ void __iomem *ioremap_uc(resource_size_t phys_addr, unsigned long size)
enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC;
return __ioremap_caller(phys_addr, size, pcm,
- __builtin_return_address(0));
+ __builtin_return_address(0), false);
}
EXPORT_SYMBOL_GPL(ioremap_uc);
@@ -341,7 +342,7 @@ EXPORT_SYMBOL_GPL(ioremap_uc);
void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WC,
- __builtin_return_address(0));
+ __builtin_return_address(0), false);
}
EXPORT_SYMBOL(ioremap_wc);
@@ -358,14 +359,21 @@ EXPORT_SYMBOL(ioremap_wc);
void __iomem *ioremap_wt(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WT,
- __builtin_return_address(0));
+ __builtin_return_address(0), false);
}
EXPORT_SYMBOL(ioremap_wt);
+void __iomem *ioremap_encrypted(resource_size_t phys_addr, unsigned long size)
+{
+ return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
+ __builtin_return_address(0), true);
+}
+EXPORT_SYMBOL(ioremap_encrypted);
+
void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
- __builtin_return_address(0));
+ __builtin_return_address(0), false);
}
EXPORT_SYMBOL(ioremap_cache);
@@ -374,7 +382,7 @@ void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size,
{
return __ioremap_caller(phys_addr, size,
pgprot2cachemode(__pgprot(prot_val)),
- __builtin_return_address(0));
+ __builtin_return_address(0), false);
}
EXPORT_SYMBOL(ioremap_prot);
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 51a5a69ecac9..62bb30b4bd2a 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -37,11 +37,20 @@ struct cpa_data {
unsigned long numpages;
int flags;
unsigned long pfn;
- unsigned force_split : 1;
+ unsigned force_split : 1,
+ force_static_prot : 1;
int curpage;
struct page **pages;
};
+enum cpa_warn {
+ CPA_CONFLICT,
+ CPA_PROTECT,
+ CPA_DETECT,
+};
+
+static const int cpa_warn_level = CPA_PROTECT;
+
/*
* Serialize cpa() (for !DEBUG_PAGEALLOC which uses large identity mappings)
* using cpa_lock. So that we don't allow any other cpu, with stale large tlb
@@ -94,6 +103,87 @@ void arch_report_meminfo(struct seq_file *m)
static inline void split_page_count(int level) { }
#endif
+#ifdef CONFIG_X86_CPA_STATISTICS
+
+static unsigned long cpa_1g_checked;
+static unsigned long cpa_1g_sameprot;
+static unsigned long cpa_1g_preserved;
+static unsigned long cpa_2m_checked;
+static unsigned long cpa_2m_sameprot;
+static unsigned long cpa_2m_preserved;
+static unsigned long cpa_4k_install;
+
+static inline void cpa_inc_1g_checked(void)
+{
+ cpa_1g_checked++;
+}
+
+static inline void cpa_inc_2m_checked(void)
+{
+ cpa_2m_checked++;
+}
+
+static inline void cpa_inc_4k_install(void)
+{
+ cpa_4k_install++;
+}
+
+static inline void cpa_inc_lp_sameprot(int level)
+{
+ if (level == PG_LEVEL_1G)
+ cpa_1g_sameprot++;
+ else
+ cpa_2m_sameprot++;
+}
+
+static inline void cpa_inc_lp_preserved(int level)
+{
+ if (level == PG_LEVEL_1G)
+ cpa_1g_preserved++;
+ else
+ cpa_2m_preserved++;
+}
+
+static int cpastats_show(struct seq_file *m, void *p)
+{
+ seq_printf(m, "1G pages checked: %16lu\n", cpa_1g_checked);
+ seq_printf(m, "1G pages sameprot: %16lu\n", cpa_1g_sameprot);
+ seq_printf(m, "1G pages preserved: %16lu\n", cpa_1g_preserved);
+ seq_printf(m, "2M pages checked: %16lu\n", cpa_2m_checked);
+ seq_printf(m, "2M pages sameprot: %16lu\n", cpa_2m_sameprot);
+ seq_printf(m, "2M pages preserved: %16lu\n", cpa_2m_preserved);
+ seq_printf(m, "4K pages set-checked: %16lu\n", cpa_4k_install);
+ return 0;
+}
+
+static int cpastats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, cpastats_show, NULL);
+}
+
+static const struct file_operations cpastats_fops = {
+ .open = cpastats_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init cpa_stats_init(void)
+{
+ debugfs_create_file("cpa_stats", S_IRUSR, arch_debugfs_dir, NULL,
+ &cpastats_fops);
+ return 0;
+}
+late_initcall(cpa_stats_init);
+#else
+static inline void cpa_inc_1g_checked(void) { }
+static inline void cpa_inc_2m_checked(void) { }
+static inline void cpa_inc_4k_install(void) { }
+static inline void cpa_inc_lp_sameprot(int level) { }
+static inline void cpa_inc_lp_preserved(int level) { }
+#endif
+
+
static inline int
within(unsigned long addr, unsigned long start, unsigned long end)
{
@@ -195,14 +285,20 @@ static void cpa_flush_all(unsigned long cache)
on_each_cpu(__cpa_flush_all, (void *) cache, 1);
}
-static void __cpa_flush_range(void *arg)
+static bool __cpa_flush_range(unsigned long start, int numpages, int cache)
{
- /*
- * We could optimize that further and do individual per page
- * tlb invalidates for a low number of pages. Caveat: we must
- * flush the high aliases on 64bit as well.
- */
- __flush_tlb_all();
+ BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
+
+ WARN_ON(PAGE_ALIGN(start) != start);
+
+ if (cache && !static_cpu_has(X86_FEATURE_CLFLUSH)) {
+ cpa_flush_all(cache);
+ return true;
+ }
+
+ flush_tlb_kernel_range(start, start + PAGE_SIZE * numpages);
+
+ return !cache;
}
static void cpa_flush_range(unsigned long start, int numpages, int cache)
@@ -210,12 +306,7 @@ static void cpa_flush_range(unsigned long start, int numpages, int cache)
unsigned int i, level;
unsigned long addr;
- BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
- WARN_ON(PAGE_ALIGN(start) != start);
-
- on_each_cpu(__cpa_flush_range, NULL, 1);
-
- if (!cache)
+ if (__cpa_flush_range(start, numpages, cache))
return;
/*
@@ -235,30 +326,13 @@ static void cpa_flush_range(unsigned long start, int numpages, int cache)
}
}
-static void cpa_flush_array(unsigned long *start, int numpages, int cache,
+static void cpa_flush_array(unsigned long baddr, unsigned long *start,
+ int numpages, int cache,
int in_flags, struct page **pages)
{
unsigned int i, level;
-#ifdef CONFIG_PREEMPT
- /*
- * Avoid wbinvd() because it causes latencies on all CPUs,
- * regardless of any CPU isolation that may be in effect.
- *
- * This should be extended for CAT enabled systems independent of
- * PREEMPT because wbinvd() does not respect the CAT partitions and
- * this is exposed to unpriviledged users through the graphics
- * subsystem.
- */
- unsigned long do_wbinvd = 0;
-#else
- unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */
-#endif
-
- BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
- on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1);
-
- if (!cache || do_wbinvd)
+ if (__cpa_flush_range(baddr, numpages, cache))
return;
/*
@@ -286,84 +360,179 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache,
}
}
-/*
- * Certain areas of memory on x86 require very specific protection flags,
- * for example the BIOS area or kernel text. Callers don't always get this
- * right (again, ioremap() on BIOS memory is not uncommon) so this function
- * checks and fixes these known static required protection bits.
- */
-static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
- unsigned long pfn)
+static bool overlaps(unsigned long r1_start, unsigned long r1_end,
+ unsigned long r2_start, unsigned long r2_end)
{
- pgprot_t forbidden = __pgprot(0);
+ return (r1_start <= r2_end && r1_end >= r2_start) ||
+ (r2_start <= r1_end && r2_end >= r1_start);
+}
- /*
- * The BIOS area between 640k and 1Mb needs to be executable for
- * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
- */
#ifdef CONFIG_PCI_BIOS
- if (pcibios_enabled && within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
- pgprot_val(forbidden) |= _PAGE_NX;
+/*
+ * The BIOS area between 640k and 1Mb needs to be executable for PCI BIOS
+ * based config access (CONFIG_PCI_GOBIOS) support.
+ */
+#define BIOS_PFN PFN_DOWN(BIOS_BEGIN)
+#define BIOS_PFN_END PFN_DOWN(BIOS_END - 1)
+
+static pgprotval_t protect_pci_bios(unsigned long spfn, unsigned long epfn)
+{
+ if (pcibios_enabled && overlaps(spfn, epfn, BIOS_PFN, BIOS_PFN_END))
+ return _PAGE_NX;
+ return 0;
+}
+#else
+static pgprotval_t protect_pci_bios(unsigned long spfn, unsigned long epfn)
+{
+ return 0;
+}
#endif
- /*
- * The kernel text needs to be executable for obvious reasons
- * Does not cover __inittext since that is gone later on. On
- * 64bit we do not enforce !NX on the low mapping
- */
- if (within(address, (unsigned long)_text, (unsigned long)_etext))
- pgprot_val(forbidden) |= _PAGE_NX;
+/*
+ * The .rodata section needs to be read-only. Using the pfn catches all
+ * aliases. This also includes __ro_after_init, so do not enforce until
+ * kernel_set_to_readonly is true.
+ */
+static pgprotval_t protect_rodata(unsigned long spfn, unsigned long epfn)
+{
+ unsigned long epfn_ro, spfn_ro = PFN_DOWN(__pa_symbol(__start_rodata));
/*
- * The .rodata section needs to be read-only. Using the pfn
- * catches all aliases. This also includes __ro_after_init,
- * so do not enforce until kernel_set_to_readonly is true.
+ * Note: __end_rodata is at page aligned and not inclusive, so
+ * subtract 1 to get the last enforced PFN in the rodata area.
*/
- if (kernel_set_to_readonly &&
- within(pfn, __pa_symbol(__start_rodata) >> PAGE_SHIFT,
- __pa_symbol(__end_rodata) >> PAGE_SHIFT))
- pgprot_val(forbidden) |= _PAGE_RW;
+ epfn_ro = PFN_DOWN(__pa_symbol(__end_rodata)) - 1;
+
+ if (kernel_set_to_readonly && overlaps(spfn, epfn, spfn_ro, epfn_ro))
+ return _PAGE_RW;
+ return 0;
+}
+
+/*
+ * Protect kernel text against becoming non executable by forbidding
+ * _PAGE_NX. This protects only the high kernel mapping (_text -> _etext)
+ * out of which the kernel actually executes. Do not protect the low
+ * mapping.
+ *
+ * This does not cover __inittext since that is gone after boot.
+ */
+static pgprotval_t protect_kernel_text(unsigned long start, unsigned long end)
+{
+ unsigned long t_end = (unsigned long)_etext - 1;
+ unsigned long t_start = (unsigned long)_text;
+
+ if (overlaps(start, end, t_start, t_end))
+ return _PAGE_NX;
+ return 0;
+}
#if defined(CONFIG_X86_64)
+/*
+ * Once the kernel maps the text as RO (kernel_set_to_readonly is set),
+ * kernel text mappings for the large page aligned text, rodata sections
+ * will be always read-only. For the kernel identity mappings covering the
+ * holes caused by this alignment can be anything that user asks.
+ *
+ * This will preserve the large page mappings for kernel text/data at no
+ * extra cost.
+ */
+static pgprotval_t protect_kernel_text_ro(unsigned long start,
+ unsigned long end)
+{
+ unsigned long t_end = (unsigned long)__end_rodata_hpage_align - 1;
+ unsigned long t_start = (unsigned long)_text;
+ unsigned int level;
+
+ if (!kernel_set_to_readonly || !overlaps(start, end, t_start, t_end))
+ return 0;
/*
- * Once the kernel maps the text as RO (kernel_set_to_readonly is set),
- * kernel text mappings for the large page aligned text, rodata sections
- * will be always read-only. For the kernel identity mappings covering
- * the holes caused by this alignment can be anything that user asks.
+ * Don't enforce the !RW mapping for the kernel text mapping, if
+ * the current mapping is already using small page mapping. No
+ * need to work hard to preserve large page mappings in this case.
*
- * This will preserve the large page mappings for kernel text/data
- * at no extra cost.
+ * This also fixes the Linux Xen paravirt guest boot failure caused
+ * by unexpected read-only mappings for kernel identity
+ * mappings. In this paravirt guest case, the kernel text mapping
+ * and the kernel identity mapping share the same page-table pages,
+ * so the protections for kernel text and identity mappings have to
+ * be the same.
*/
- if (kernel_set_to_readonly &&
- within(address, (unsigned long)_text,
- (unsigned long)__end_rodata_hpage_align)) {
- unsigned int level;
-
- /*
- * Don't enforce the !RW mapping for the kernel text mapping,
- * if the current mapping is already using small page mapping.
- * No need to work hard to preserve large page mappings in this
- * case.
- *
- * This also fixes the Linux Xen paravirt guest boot failure
- * (because of unexpected read-only mappings for kernel identity
- * mappings). In this paravirt guest case, the kernel text
- * mapping and the kernel identity mapping share the same
- * page-table pages. Thus we can't really use different
- * protections for the kernel text and identity mappings. Also,
- * these shared mappings are made of small page mappings.
- * Thus this don't enforce !RW mapping for small page kernel
- * text mapping logic will help Linux Xen parvirt guest boot
- * as well.
- */
- if (lookup_address(address, &level) && (level != PG_LEVEL_4K))
- pgprot_val(forbidden) |= _PAGE_RW;
- }
+ if (lookup_address(start, &level) && (level != PG_LEVEL_4K))
+ return _PAGE_RW;
+ return 0;
+}
+#else
+static pgprotval_t protect_kernel_text_ro(unsigned long start,
+ unsigned long end)
+{
+ return 0;
+}
#endif
- prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
+static inline bool conflicts(pgprot_t prot, pgprotval_t val)
+{
+ return (pgprot_val(prot) & ~val) != pgprot_val(prot);
+}
- return prot;
+static inline void check_conflict(int warnlvl, pgprot_t prot, pgprotval_t val,
+ unsigned long start, unsigned long end,
+ unsigned long pfn, const char *txt)
+{
+ static const char *lvltxt[] = {
+ [CPA_CONFLICT] = "conflict",
+ [CPA_PROTECT] = "protect",
+ [CPA_DETECT] = "detect",
+ };
+
+ if (warnlvl > cpa_warn_level || !conflicts(prot, val))
+ return;
+
+ pr_warn("CPA %8s %10s: 0x%016lx - 0x%016lx PFN %lx req %016llx prevent %016llx\n",
+ lvltxt[warnlvl], txt, start, end, pfn, (unsigned long long)pgprot_val(prot),
+ (unsigned long long)val);
+}
+
+/*
+ * Certain areas of memory on x86 require very specific protection flags,
+ * for example the BIOS area or kernel text. Callers don't always get this
+ * right (again, ioremap() on BIOS memory is not uncommon) so this function
+ * checks and fixes these known static required protection bits.
+ */
+static inline pgprot_t static_protections(pgprot_t prot, unsigned long start,
+ unsigned long pfn, unsigned long npg,
+ int warnlvl)
+{
+ pgprotval_t forbidden, res;
+ unsigned long end;
+
+ /*
+ * There is no point in checking RW/NX conflicts when the requested
+ * mapping is setting the page !PRESENT.
+ */
+ if (!(pgprot_val(prot) & _PAGE_PRESENT))
+ return prot;
+
+ /* Operate on the virtual address */
+ end = start + npg * PAGE_SIZE - 1;
+
+ res = protect_kernel_text(start, end);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "Text NX");
+ forbidden = res;
+
+ res = protect_kernel_text_ro(start, end);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "Text RO");
+ forbidden |= res;
+
+ /* Check the PFN directly */
+ res = protect_pci_bios(pfn, pfn + npg - 1);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "PCIBIOS NX");
+ forbidden |= res;
+
+ res = protect_rodata(pfn, pfn + npg - 1);
+ check_conflict(warnlvl, prot, res, start, end, pfn, "Rodata RO");
+ forbidden |= res;
+
+ return __pgprot(pgprot_val(prot) & ~forbidden);
}
/*
@@ -421,18 +590,18 @@ pte_t *lookup_address_in_pgd(pgd_t *pgd, unsigned long address,
*/
pte_t *lookup_address(unsigned long address, unsigned int *level)
{
- return lookup_address_in_pgd(pgd_offset_k(address), address, level);
+ return lookup_address_in_pgd(pgd_offset_k(address), address, level);
}
EXPORT_SYMBOL_GPL(lookup_address);
static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address,
unsigned int *level)
{
- if (cpa->pgd)
+ if (cpa->pgd)
return lookup_address_in_pgd(cpa->pgd + pgd_index(address),
address, level);
- return lookup_address(address, level);
+ return lookup_address(address, level);
}
/*
@@ -549,40 +718,35 @@ static pgprot_t pgprot_clear_protnone_bits(pgprot_t prot)
return prot;
}
-static int
-try_preserve_large_page(pte_t *kpte, unsigned long address,
- struct cpa_data *cpa)
+static int __should_split_large_page(pte_t *kpte, unsigned long address,
+ struct cpa_data *cpa)
{
- unsigned long nextpage_addr, numpages, pmask, psize, addr, pfn, old_pfn;
+ unsigned long numpages, pmask, psize, lpaddr, pfn, old_pfn;
+ pgprot_t old_prot, new_prot, req_prot, chk_prot;
pte_t new_pte, old_pte, *tmp;
- pgprot_t old_prot, new_prot, req_prot;
- int i, do_split = 1;
enum pg_level level;
- if (cpa->force_split)
- return 1;
-
- spin_lock(&pgd_lock);
/*
* Check for races, another CPU might have split this page
* up already:
*/
tmp = _lookup_address_cpa(cpa, address, &level);
if (tmp != kpte)
- goto out_unlock;
+ return 1;
switch (level) {
case PG_LEVEL_2M:
old_prot = pmd_pgprot(*(pmd_t *)kpte);
old_pfn = pmd_pfn(*(pmd_t *)kpte);
+ cpa_inc_2m_checked();
break;
case PG_LEVEL_1G:
old_prot = pud_pgprot(*(pud_t *)kpte);
old_pfn = pud_pfn(*(pud_t *)kpte);
+ cpa_inc_1g_checked();
break;
default:
- do_split = -EINVAL;
- goto out_unlock;
+ return -EINVAL;
}
psize = page_level_size(level);
@@ -592,8 +756,8 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
* Calculate the number of pages, which fit into this large
* page starting at address:
*/
- nextpage_addr = (address + psize) & pmask;
- numpages = (nextpage_addr - address) >> PAGE_SHIFT;
+ lpaddr = (address + psize) & pmask;
+ numpages = (lpaddr - address) >> PAGE_SHIFT;
if (numpages < cpa->numpages)
cpa->numpages = numpages;
@@ -620,71 +784,142 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
pgprot_val(req_prot) |= _PAGE_PSE;
/*
- * old_pfn points to the large page base pfn. So we need
- * to add the offset of the virtual address:
+ * old_pfn points to the large page base pfn. So we need to add the
+ * offset of the virtual address:
*/
pfn = old_pfn + ((address & (psize - 1)) >> PAGE_SHIFT);
cpa->pfn = pfn;
- new_prot = static_protections(req_prot, address, pfn);
+ /*
+ * Calculate the large page base address and the number of 4K pages
+ * in the large page
+ */
+ lpaddr = address & pmask;
+ numpages = psize >> PAGE_SHIFT;
/*
- * We need to check the full range, whether
- * static_protection() requires a different pgprot for one of
- * the pages in the range we try to preserve:
+ * Sanity check that the existing mapping is correct versus the static
+ * protections. static_protections() guards against !PRESENT, so no
+ * extra conditional required here.
*/
- addr = address & pmask;
- pfn = old_pfn;
- for (i = 0; i < (psize >> PAGE_SHIFT); i++, addr += PAGE_SIZE, pfn++) {
- pgprot_t chk_prot = static_protections(req_prot, addr, pfn);
+ chk_prot = static_protections(old_prot, lpaddr, old_pfn, numpages,
+ CPA_CONFLICT);
- if (pgprot_val(chk_prot) != pgprot_val(new_prot))
- goto out_unlock;
+ if (WARN_ON_ONCE(pgprot_val(chk_prot) != pgprot_val(old_prot))) {
+ /*
+ * Split the large page and tell the split code to
+ * enforce static protections.
+ */
+ cpa->force_static_prot = 1;
+ return 1;
}
/*
- * If there are no changes, return. maxpages has been updated
- * above:
+ * Optimization: If the requested pgprot is the same as the current
+ * pgprot, then the large page can be preserved and no updates are
+ * required independent of alignment and length of the requested
+ * range. The above already established that the current pgprot is
+ * correct, which in consequence makes the requested pgprot correct
+ * as well if it is the same. The static protection scan below will
+ * not come to a different conclusion.
*/
- if (pgprot_val(new_prot) == pgprot_val(old_prot)) {
- do_split = 0;
- goto out_unlock;
+ if (pgprot_val(req_prot) == pgprot_val(old_prot)) {
+ cpa_inc_lp_sameprot(level);
+ return 0;
}
/*
- * We need to change the attributes. Check, whether we can
- * change the large page in one go. We request a split, when
- * the address is not aligned and the number of pages is
- * smaller than the number of pages in the large page. Note
- * that we limited the number of possible pages already to
- * the number of pages in the large page.
+ * If the requested range does not cover the full page, split it up
*/
- if (address == (address & pmask) && cpa->numpages == (psize >> PAGE_SHIFT)) {
- /*
- * The address is aligned and the number of pages
- * covers the full page.
- */
- new_pte = pfn_pte(old_pfn, new_prot);
- __set_pmd_pte(kpte, address, new_pte);
- cpa->flags |= CPA_FLUSHTLB;
- do_split = 0;
- }
+ if (address != lpaddr || cpa->numpages != numpages)
+ return 1;
-out_unlock:
+ /*
+ * Check whether the requested pgprot is conflicting with a static
+ * protection requirement in the large page.
+ */
+ new_prot = static_protections(req_prot, lpaddr, old_pfn, numpages,
+ CPA_DETECT);
+
+ /*
+ * If there is a conflict, split the large page.
+ *
+ * There used to be a 4k wise evaluation trying really hard to
+ * preserve the large pages, but experimentation has shown, that this
+ * does not help at all. There might be corner cases which would
+ * preserve one large page occasionally, but it's really not worth the
+ * extra code and cycles for the common case.
+ */
+ if (pgprot_val(req_prot) != pgprot_val(new_prot))
+ return 1;
+
+ /* All checks passed. Update the large page mapping. */
+ new_pte = pfn_pte(old_pfn, new_prot);
+ __set_pmd_pte(kpte, address, new_pte);
+ cpa->flags |= CPA_FLUSHTLB;
+ cpa_inc_lp_preserved(level);
+ return 0;
+}
+
+static int should_split_large_page(pte_t *kpte, unsigned long address,
+ struct cpa_data *cpa)
+{
+ int do_split;
+
+ if (cpa->force_split)
+ return 1;
+
+ spin_lock(&pgd_lock);
+ do_split = __should_split_large_page(kpte, address, cpa);
spin_unlock(&pgd_lock);
return do_split;
}
+static void split_set_pte(struct cpa_data *cpa, pte_t *pte, unsigned long pfn,
+ pgprot_t ref_prot, unsigned long address,
+ unsigned long size)
+{
+ unsigned int npg = PFN_DOWN(size);
+ pgprot_t prot;
+
+ /*
+ * If should_split_large_page() discovered an inconsistent mapping,
+ * remove the invalid protection in the split mapping.
+ */
+ if (!cpa->force_static_prot)
+ goto set;
+
+ prot = static_protections(ref_prot, address, pfn, npg, CPA_PROTECT);
+
+ if (pgprot_val(prot) == pgprot_val(ref_prot))
+ goto set;
+
+ /*
+ * If this is splitting a PMD, fix it up. PUD splits cannot be
+ * fixed trivially as that would require to rescan the newly
+ * installed PMD mappings after returning from split_large_page()
+ * so an eventual further split can allocate the necessary PTE
+ * pages. Warn for now and revisit it in case this actually
+ * happens.
+ */
+ if (size == PAGE_SIZE)
+ ref_prot = prot;
+ else
+ pr_warn_once("CPA: Cannot fixup static protections for PUD split\n");
+set:
+ set_pte(pte, pfn_pte(pfn, ref_prot));
+}
+
static int
__split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
struct page *base)
{
+ unsigned long lpaddr, lpinc, ref_pfn, pfn, pfninc = 1;
pte_t *pbase = (pte_t *)page_address(base);
- unsigned long ref_pfn, pfn, pfninc = 1;
unsigned int i, level;
- pte_t *tmp;
pgprot_t ref_prot;
+ pte_t *tmp;
spin_lock(&pgd_lock);
/*
@@ -707,15 +942,17 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
* PAT bit to correct position.
*/
ref_prot = pgprot_large_2_4k(ref_prot);
-
ref_pfn = pmd_pfn(*(pmd_t *)kpte);
+ lpaddr = address & PMD_MASK;
+ lpinc = PAGE_SIZE;
break;
case PG_LEVEL_1G:
ref_prot = pud_pgprot(*(pud_t *)kpte);
ref_pfn = pud_pfn(*(pud_t *)kpte);
pfninc = PMD_PAGE_SIZE >> PAGE_SHIFT;
-
+ lpaddr = address & PUD_MASK;
+ lpinc = PMD_SIZE;
/*
* Clear the PSE flags if the PRESENT flag is not set
* otherwise pmd_present/pmd_huge will return true
@@ -736,8 +973,8 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
* Get the target pfn from the original entry:
*/
pfn = ref_pfn;
- for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
- set_pte(&pbase[i], pfn_pte(pfn, ref_prot));
+ for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc, lpaddr += lpinc)
+ split_set_pte(cpa, pbase + i, pfn, ref_prot, lpaddr, lpinc);
if (virt_addr_valid(address)) {
unsigned long pfn = PFN_DOWN(__pa(address));
@@ -756,14 +993,24 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
__set_pmd_pte(kpte, address, mk_pte(base, __pgprot(_KERNPG_TABLE)));
/*
- * Intel Atom errata AAH41 workaround.
+ * Do a global flush tlb after splitting the large page
+ * and before we do the actual change page attribute in the PTE.
+ *
+ * Without this, we violate the TLB application note, that says:
+ * "The TLBs may contain both ordinary and large-page
+ * translations for a 4-KByte range of linear addresses. This
+ * may occur if software modifies the paging structures so that
+ * the page size used for the address range changes. If the two
+ * translations differ with respect to page frame or attributes
+ * (e.g., permissions), processor behavior is undefined and may
+ * be implementation-specific."
*
- * The real fix should be in hw or in a microcode update, but
- * we also probabilistically try to reduce the window of having
- * a large TLB mixed with 4K TLBs while instruction fetches are
- * going on.
+ * We do this global tlb flush inside the cpa_lock, so that we
+ * don't allow any other cpu, with stale tlb entries change the
+ * page attribute in parallel, that also falls into the
+ * just split large page entry.
*/
- __flush_tlb_all();
+ flush_tlb_all();
spin_unlock(&pgd_lock);
return 0;
@@ -1247,7 +1494,9 @@ repeat:
pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
- new_prot = static_protections(new_prot, address, pfn);
+ cpa_inc_4k_install();
+ new_prot = static_protections(new_prot, address, pfn, 1,
+ CPA_PROTECT);
new_prot = pgprot_clear_protnone_bits(new_prot);
@@ -1273,7 +1522,7 @@ repeat:
* Check, whether we can keep the large page intact
* and just change the pte:
*/
- do_split = try_preserve_large_page(kpte, address, cpa);
+ do_split = should_split_large_page(kpte, address, cpa);
/*
* When the range fits into the existing large page,
* return. cp->numpages and cpa->tlbflush have been updated in
@@ -1286,28 +1535,8 @@ repeat:
* We have to split the large page:
*/
err = split_large_page(cpa, kpte, address);
- if (!err) {
- /*
- * Do a global flush tlb after splitting the large page
- * and before we do the actual change page attribute in the PTE.
- *
- * With out this, we violate the TLB application note, that says
- * "The TLBs may contain both ordinary and large-page
- * translations for a 4-KByte range of linear addresses. This
- * may occur if software modifies the paging structures so that
- * the page size used for the address range changes. If the two
- * translations differ with respect to page frame or attributes
- * (e.g., permissions), processor behavior is undefined and may
- * be implementation-specific."
- *
- * We do this global tlb flush inside the cpa_lock, so that we
- * don't allow any other cpu, with stale tlb entries change the
- * page attribute in parallel, that also falls into the
- * just split large page entry.
- */
- flush_tlb_all();
+ if (!err)
goto repeat;
- }
return err;
}
@@ -1529,19 +1758,19 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages,
cache = !!pgprot2cachemode(mask_set);
/*
- * On success we use CLFLUSH, when the CPU supports it to
- * avoid the WBINVD. If the CPU does not support it and in the
- * error case we fall back to cpa_flush_all (which uses
- * WBINVD):
+ * On error; flush everything to be sure.
*/
- if (!ret && boot_cpu_has(X86_FEATURE_CLFLUSH)) {
- if (cpa.flags & (CPA_PAGES_ARRAY | CPA_ARRAY)) {
- cpa_flush_array(addr, numpages, cache,
- cpa.flags, pages);
- } else
- cpa_flush_range(baddr, numpages, cache);
- } else
+ if (ret) {
cpa_flush_all(cache);
+ goto out;
+ }
+
+ if (cpa.flags & (CPA_PAGES_ARRAY | CPA_ARRAY)) {
+ cpa_flush_array(baddr, addr, numpages, cache,
+ cpa.flags, pages);
+ } else {
+ cpa_flush_range(baddr, numpages, cache);
+ }
out:
return ret;
@@ -1856,10 +2085,7 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
/*
* Before changing the encryption attribute, we need to flush caches.
*/
- if (static_cpu_has(X86_FEATURE_CLFLUSH))
- cpa_flush_range(start, numpages, 1);
- else
- cpa_flush_all(1);
+ cpa_flush_range(start, numpages, 1);
ret = __change_page_attr_set_clr(&cpa, 1);
@@ -1870,10 +2096,7 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
* in case TLB flushing gets optimized in the cpa_flush_range()
* path use the same logic as above.
*/
- if (static_cpu_has(X86_FEATURE_CLFLUSH))
- cpa_flush_range(start, numpages, 0);
- else
- cpa_flush_all(0);
+ cpa_flush_range(start, numpages, 0);
return ret;
}
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index e96b99eb800c..7d68489cfdb1 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -185,8 +185,11 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
{
struct mm_struct *real_prev = this_cpu_read(cpu_tlbstate.loaded_mm);
u16 prev_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid);
+ bool was_lazy = this_cpu_read(cpu_tlbstate.is_lazy);
unsigned cpu = smp_processor_id();
u64 next_tlb_gen;
+ bool need_flush;
+ u16 new_asid;
/*
* NB: The scheduler will call us with prev == next when switching
@@ -240,20 +243,41 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
next->context.ctx_id);
/*
- * We don't currently support having a real mm loaded without
- * our cpu set in mm_cpumask(). We have all the bookkeeping
- * in place to figure out whether we would need to flush
- * if our cpu were cleared in mm_cpumask(), but we don't
- * currently use it.
+ * Even in lazy TLB mode, the CPU should stay set in the
+ * mm_cpumask. The TLB shootdown code can figure out from
+ * from cpu_tlbstate.is_lazy whether or not to send an IPI.
*/
if (WARN_ON_ONCE(real_prev != &init_mm &&
!cpumask_test_cpu(cpu, mm_cpumask(next))))
cpumask_set_cpu(cpu, mm_cpumask(next));
- return;
+ /*
+ * If the CPU is not in lazy TLB mode, we are just switching
+ * from one thread in a process to another thread in the same
+ * process. No TLB flush required.
+ */
+ if (!was_lazy)
+ return;
+
+ /*
+ * Read the tlb_gen to check whether a flush is needed.
+ * If the TLB is up to date, just use it.
+ * The barrier synchronizes with the tlb_gen increment in
+ * the TLB shootdown code.
+ */
+ smp_mb();
+ next_tlb_gen = atomic64_read(&next->context.tlb_gen);
+ if (this_cpu_read(cpu_tlbstate.ctxs[prev_asid].tlb_gen) ==
+ next_tlb_gen)
+ return;
+
+ /*
+ * TLB contents went out of date while we were in lazy
+ * mode. Fall through to the TLB switching code below.
+ */
+ new_asid = prev_asid;
+ need_flush = true;
} else {
- u16 new_asid;
- bool need_flush;
u64 last_ctx_id = this_cpu_read(cpu_tlbstate.last_ctx_id);
/*
@@ -308,46 +332,48 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
/* Let nmi_uaccess_okay() know that we're changing CR3. */
this_cpu_write(cpu_tlbstate.loaded_mm, LOADED_MM_SWITCHING);
barrier();
+ }
- if (need_flush) {
- this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
- this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
- load_new_mm_cr3(next->pgd, new_asid, true);
-
- /*
- * NB: This gets called via leave_mm() in the idle path
- * where RCU functions differently. Tracing normally
- * uses RCU, so we need to use the _rcuidle variant.
- *
- * (There is no good reason for this. The idle code should
- * be rearranged to call this before rcu_idle_enter().)
- */
- trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
- } else {
- /* The new ASID is already up to date. */
- load_new_mm_cr3(next->pgd, new_asid, false);
-
- /* See above wrt _rcuidle. */
- trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);
- }
+ if (need_flush) {
+ this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
+ this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
+ load_new_mm_cr3(next->pgd, new_asid, true);
/*
- * Record last user mm's context id, so we can avoid
- * flushing branch buffer with IBPB if we switch back
- * to the same user.
+ * NB: This gets called via leave_mm() in the idle path
+ * where RCU functions differently. Tracing normally
+ * uses RCU, so we need to use the _rcuidle variant.
+ *
+ * (There is no good reason for this. The idle code should
+ * be rearranged to call this before rcu_idle_enter().)
*/
- if (next != &init_mm)
- this_cpu_write(cpu_tlbstate.last_ctx_id, next->context.ctx_id);
-
- /* Make sure we write CR3 before loaded_mm. */
- barrier();
+ trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
+ } else {
+ /* The new ASID is already up to date. */
+ load_new_mm_cr3(next->pgd, new_asid, false);
- this_cpu_write(cpu_tlbstate.loaded_mm, next);
- this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid);
+ /* See above wrt _rcuidle. */
+ trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);
}
- load_mm_cr4(next);
- switch_ldt(real_prev, next);
+ /*
+ * Record last user mm's context id, so we can avoid
+ * flushing branch buffer with IBPB if we switch back
+ * to the same user.
+ */
+ if (next != &init_mm)
+ this_cpu_write(cpu_tlbstate.last_ctx_id, next->context.ctx_id);
+
+ /* Make sure we write CR3 before loaded_mm. */
+ barrier();
+
+ this_cpu_write(cpu_tlbstate.loaded_mm, next);
+ this_cpu_write(cpu_tlbstate.loaded_mm_asid, new_asid);
+
+ if (next != real_prev) {
+ load_mm_cr4(next);
+ switch_ldt(real_prev, next);
+ }
}
/*
@@ -368,20 +394,7 @@ void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm)
return;
- if (tlb_defer_switch_to_init_mm()) {
- /*
- * There's a significant optimization that may be possible
- * here. We have accurate enough TLB flush tracking that we
- * don't need to maintain coherence of TLB per se when we're
- * lazy. We do, however, need to maintain coherence of
- * paging-structure caches. We could, in principle, leave our
- * old mm loaded and only switch to init_mm when
- * tlb_remove_page() happens.
- */
- this_cpu_write(cpu_tlbstate.is_lazy, true);
- } else {
- switch_mm(NULL, &init_mm, NULL);
- }
+ this_cpu_write(cpu_tlbstate.is_lazy, true);
}
/*
@@ -468,6 +481,9 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
* paging-structure cache to avoid speculatively reading
* garbage into our TLB. Since switching to init_mm is barely
* slower than a minimal flush, just switch to init_mm.
+ *
+ * This should be rare, with native_flush_tlb_others skipping
+ * IPIs to lazy TLB mode CPUs.
*/
switch_mm_irqs_off(NULL, &init_mm, NULL);
return;
@@ -528,17 +544,16 @@ static void flush_tlb_func_common(const struct flush_tlb_info *f,
f->new_tlb_gen == local_tlb_gen + 1 &&
f->new_tlb_gen == mm_tlb_gen) {
/* Partial flush */
- unsigned long addr;
- unsigned long nr_pages = (f->end - f->start) >> PAGE_SHIFT;
+ unsigned long nr_invalidate = (f->end - f->start) >> f->stride_shift;
+ unsigned long addr = f->start;
- addr = f->start;
while (addr < f->end) {
__flush_tlb_one_user(addr);
- addr += PAGE_SIZE;
+ addr += 1UL << f->stride_shift;
}
if (local)
- count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_pages);
- trace_tlb_flush(reason, nr_pages);
+ count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_invalidate);
+ trace_tlb_flush(reason, nr_invalidate);
} else {
/* Full flush. */
local_flush_tlb();
@@ -571,6 +586,11 @@ static void flush_tlb_func_remote(void *info)
flush_tlb_func_common(f, false, TLB_REMOTE_SHOOTDOWN);
}
+static bool tlb_is_not_lazy(int cpu, void *data)
+{
+ return !per_cpu(cpu_tlbstate.is_lazy, cpu);
+}
+
void native_flush_tlb_others(const struct cpumask *cpumask,
const struct flush_tlb_info *info)
{
@@ -606,8 +626,23 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
(void *)info, 1);
return;
}
- smp_call_function_many(cpumask, flush_tlb_func_remote,
+
+ /*
+ * If no page tables were freed, we can skip sending IPIs to
+ * CPUs in lazy TLB mode. They will flush the CPU themselves
+ * at the next context switch.
+ *
+ * However, if page tables are getting freed, we need to send the
+ * IPI everywhere, to prevent CPUs in lazy TLB mode from tripping
+ * up on the new contents of what used to be page tables, while
+ * doing a speculative memory access.
+ */
+ if (info->freed_tables)
+ smp_call_function_many(cpumask, flush_tlb_func_remote,
(void *)info, 1);
+ else
+ on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func_remote,
+ (void *)info, 1, GFP_ATOMIC, cpumask);
}
/*
@@ -623,12 +658,15 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
static unsigned long tlb_single_page_flush_ceiling __read_mostly = 33;
void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
- unsigned long end, unsigned long vmflag)
+ unsigned long end, unsigned int stride_shift,
+ bool freed_tables)
{
int cpu;
struct flush_tlb_info info __aligned(SMP_CACHE_BYTES) = {
.mm = mm,
+ .stride_shift = stride_shift,
+ .freed_tables = freed_tables,
};
cpu = get_cpu();
@@ -638,8 +676,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
/* Should we flush just the requested range? */
if ((end != TLB_FLUSH_ALL) &&
- !(vmflag & VM_HUGETLB) &&
- ((end - start) >> PAGE_SHIFT) <= tlb_single_page_flush_ceiling) {
+ ((end - start) >> stride_shift) <= tlb_single_page_flush_ceiling) {
info.start = start;
info.end = end;
} else {
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index e3b18ad49889..145506f9fdbe 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -22,6 +22,7 @@
#include <linux/tick.h>
#include <linux/nmi.h>
#include <linux/cpuhotplug.h>
+#include <linux/stackprotector.h>
#include <asm/paravirt.h>
#include <asm/desc.h>
@@ -88,6 +89,7 @@ static void cpu_bringup(void)
asmlinkage __visible void cpu_bringup_and_idle(void)
{
cpu_bringup();
+ boot_init_stack_canary();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}