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Diffstat (limited to 'arch/arm64/kernel/efi.c')
-rw-r--r--arch/arm64/kernel/efi.c101
1 files changed, 83 insertions, 18 deletions
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index e1be6c429810..fab05de2e12d 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -12,6 +12,14 @@
#include <asm/efi.h>
+static bool region_is_misaligned(const efi_memory_desc_t *md)
+{
+ if (PAGE_SIZE == EFI_PAGE_SIZE)
+ return false;
+ return !PAGE_ALIGNED(md->phys_addr) ||
+ !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT);
+}
+
/*
* Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
* executable, everything else can be mapped with the XN bits
@@ -25,14 +33,22 @@ static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
if (type == EFI_MEMORY_MAPPED_IO)
return PROT_DEVICE_nGnRE;
- if (WARN_ONCE(!PAGE_ALIGNED(md->phys_addr),
- "UEFI Runtime regions are not aligned to 64 KB -- buggy firmware?"))
+ if (region_is_misaligned(md)) {
+ static bool __initdata code_is_misaligned;
+
/*
- * If the region is not aligned to the page size of the OS, we
- * can not use strict permissions, since that would also affect
- * the mapping attributes of the adjacent regions.
+ * Regions that are not aligned to the OS page size cannot be
+ * mapped with strict permissions, as those might interfere
+ * with the permissions that are needed by the adjacent
+ * region's mapping. However, if we haven't encountered any
+ * misaligned runtime code regions so far, we can safely use
+ * non-executable permissions for non-code regions.
*/
- return pgprot_val(PAGE_KERNEL_EXEC);
+ code_is_misaligned |= (type == EFI_RUNTIME_SERVICES_CODE);
+
+ return code_is_misaligned ? pgprot_val(PAGE_KERNEL_EXEC)
+ : pgprot_val(PAGE_KERNEL);
+ }
/* R-- */
if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==
@@ -63,19 +79,16 @@ int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE ||
md->type == EFI_RUNTIME_SERVICES_DATA);
- if (!PAGE_ALIGNED(md->phys_addr) ||
- !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT)) {
- /*
- * If the end address of this region is not aligned to page
- * size, the mapping is rounded up, and may end up sharing a
- * page frame with the next UEFI memory region. If we create
- * a block entry now, we may need to split it again when mapping
- * the next region, and support for that is going to be removed
- * from the MMU routines. So avoid block mappings altogether in
- * that case.
- */
+ /*
+ * If this region is not aligned to the page size used by the OS, the
+ * mapping will be rounded outwards, and may end up sharing a page
+ * frame with an adjacent runtime memory region. Given that the page
+ * table descriptor covering the shared page will be rewritten when the
+ * adjacent region gets mapped, we must avoid block mappings here so we
+ * don't have to worry about splitting them when that happens.
+ */
+ if (region_is_misaligned(md))
page_mappings_only = true;
- }
create_pgd_mapping(mm, md->phys_addr, md->virt_addr,
md->num_pages << EFI_PAGE_SHIFT,
@@ -102,6 +115,9 @@ int __init efi_set_mapping_permissions(struct mm_struct *mm,
BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE &&
md->type != EFI_RUNTIME_SERVICES_DATA);
+ if (region_is_misaligned(md))
+ return 0;
+
/*
* Calling apply_to_page_range() is only safe on regions that are
* guaranteed to be mapped down to pages. Since we are only called
@@ -128,3 +144,52 @@ asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f)
pr_err_ratelimited(FW_BUG "register x18 corrupted by EFI %s\n", f);
return s;
}
+
+DEFINE_SPINLOCK(efi_rt_lock);
+
+asmlinkage u64 *efi_rt_stack_top __ro_after_init;
+
+asmlinkage efi_status_t __efi_rt_asm_recover(void);
+
+bool efi_runtime_fixup_exception(struct pt_regs *regs, const char *msg)
+{
+ /* Check whether the exception occurred while running the firmware */
+ if (current_work() != &efi_rts_work.work || regs->pc >= TASK_SIZE_64)
+ return false;
+
+ pr_err(FW_BUG "Unable to handle %s in EFI runtime service\n", msg);
+ add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+ clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+
+ regs->regs[0] = EFI_ABORTED;
+ regs->regs[30] = efi_rt_stack_top[-1];
+ regs->pc = (u64)__efi_rt_asm_recover;
+
+ if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK))
+ regs->regs[18] = efi_rt_stack_top[-2];
+
+ return true;
+}
+
+/* EFI requires 8 KiB of stack space for runtime services */
+static_assert(THREAD_SIZE >= SZ_8K);
+
+static int __init arm64_efi_rt_init(void)
+{
+ void *p;
+
+ if (!efi_enabled(EFI_RUNTIME_SERVICES))
+ return 0;
+
+ p = __vmalloc_node(THREAD_SIZE, THREAD_ALIGN, GFP_KERNEL,
+ NUMA_NO_NODE, &&l);
+l: if (!p) {
+ pr_warn("Failed to allocate EFI runtime stack\n");
+ clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+ return -ENOMEM;
+ }
+
+ efi_rt_stack_top = p + THREAD_SIZE;
+ return 0;
+}
+core_initcall(arm64_efi_rt_init);