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authorLinus Torvalds <torvalds@linux-foundation.org>2017-08-04 12:11:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-08-04 12:11:48 -0700
commitb3c6858fb172512f63838523ae7817ae8adec564 (patch)
tree4f2aff0bde6433a00f35e1685d97be68eda6404c /arch
parent0a23ea65ce9f10ec2ea392571006b781b150327f (diff)
parent82cd588052815eb4146f9f7c5347ca5e32c56360 (diff)
Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Will Deacon: "Here are some more arm64 fixes for 4.13. The main one is the PTE race with the hardware walker, but there are a couple of other things too. - Report correct timer frequency to userspace when trapping CNTFRQ_EL0 - Fix race with hardware page table updates when updating access flags - Silence clang overflow warning in VA_START and PAGE_OFFSET calculations" * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: avoid overflow in VA_START and PAGE_OFFSET arm64: Fix potential race with hardware DBM in ptep_set_access_flags() arm64: Use arch_timer_get_rate when trapping CNTFRQ_EL0
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/memory.h6
-rw-r--r--arch/arm64/kernel/traps.c2
-rw-r--r--arch/arm64/mm/fault.c15
3 files changed, 13 insertions, 10 deletions
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 32f82723338a..ef39dcb9ca6a 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -64,8 +64,10 @@
* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
*/
#define VA_BITS (CONFIG_ARM64_VA_BITS)
-#define VA_START (UL(0xffffffffffffffff) << VA_BITS)
-#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
+#define VA_START (UL(0xffffffffffffffff) - \
+ (UL(1) << VA_BITS) + 1)
+#define PAGE_OFFSET (UL(0xffffffffffffffff) - \
+ (UL(1) << (VA_BITS - 1)) + 1)
#define KIMAGE_VADDR (MODULES_END)
#define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
#define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index d48f47080213..8a62648848e5 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -523,7 +523,7 @@ static void cntfrq_read_handler(unsigned int esr, struct pt_regs *regs)
{
int rt = (esr & ESR_ELx_SYS64_ISS_RT_MASK) >> ESR_ELx_SYS64_ISS_RT_SHIFT;
- pt_regs_write_reg(regs, rt, read_sysreg(cntfrq_el0));
+ pt_regs_write_reg(regs, rt, arch_timer_get_rate());
regs->pc += 4;
}
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index c7861c9864e6..2509e4fe6992 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -163,26 +163,27 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
/* only preserve the access flags and write permission */
pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY;
- /*
- * PTE_RDONLY is cleared by default in the asm below, so set it in
- * back if necessary (read-only or clean PTE).
- */
+ /* set PTE_RDONLY if actual read-only or clean PTE */
if (!pte_write(entry) || !pte_sw_dirty(entry))
pte_val(entry) |= PTE_RDONLY;
/*
* Setting the flags must be done atomically to avoid racing with the
- * hardware update of the access/dirty state.
+ * hardware update of the access/dirty state. The PTE_RDONLY bit must
+ * be set to the most permissive (lowest value) of *ptep and entry
+ * (calculated as: a & b == ~(~a | ~b)).
*/
+ pte_val(entry) ^= PTE_RDONLY;
asm volatile("// ptep_set_access_flags\n"
" prfm pstl1strm, %2\n"
"1: ldxr %0, %2\n"
- " and %0, %0, %3 // clear PTE_RDONLY\n"
+ " eor %0, %0, %3 // negate PTE_RDONLY in *ptep\n"
" orr %0, %0, %4 // set flags\n"
+ " eor %0, %0, %3 // negate final PTE_RDONLY\n"
" stxr %w1, %0, %2\n"
" cbnz %w1, 1b\n"
: "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep))
- : "L" (~PTE_RDONLY), "r" (pte_val(entry)));
+ : "L" (PTE_RDONLY), "r" (pte_val(entry)));
flush_tlb_fix_spurious_fault(vma, address);
return 1;