The EFI page table is initially created as a copy of the kernel page table.
With VMAP_STACK enabled, kernel stacks are allocated in the vmalloc area:
if the stack is allocated in a new PGD (one that was not present at the
moment of the efi page table creation or not synced in a previous vmalloc
fault), the kernel will take a trap when switching to the efi page table
when the vmalloc kernel stack is accessed, resulting in a kernel panic.
Fix that by updating the efi kernel mappings before switching to the efi
page table.
Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
---
arch/riscv/include/asm/efi.h | 6 +++++-
arch/riscv/include/asm/pgalloc.h | 11 ++++++++---
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/include/asm/efi.h b/arch/riscv/include/asm/efi.h
index f74879a8f1ea..e229d7be4b66 100644
--- a/arch/riscv/include/asm/efi.h
+++ b/arch/riscv/include/asm/efi.h
@@ -10,6 +10,7 @@
#include <asm/mmu_context.h>
#include <asm/ptrace.h>
#include <asm/tlbflush.h>
+#include <asm/pgalloc.h>
#ifdef CONFIG_EFI
extern void efi_init(void);
@@ -20,7 +21,10 @@ extern void efi_init(void);
int efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md);
int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
-#define arch_efi_call_virt_setup() efi_virtmap_load()
+#define arch_efi_call_virt_setup() ({ \
+ sync_kernel_mappings(efi_mm.pgd); \
+ efi_virtmap_load(); \
+ })
#define arch_efi_call_virt_teardown() efi_virtmap_unload()
#define ARCH_EFI_IRQ_FLAGS_MASK (SR_IE | SR_SPIE)
diff --git a/arch/riscv/include/asm/pgalloc.h b/arch/riscv/include/asm/pgalloc.h
index 947f23d7b6af..59dc12b5b7e8 100644
--- a/arch/riscv/include/asm/pgalloc.h
+++ b/arch/riscv/include/asm/pgalloc.h
@@ -127,6 +127,13 @@ static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d)
#define __p4d_free_tlb(tlb, p4d, addr) p4d_free((tlb)->mm, p4d)
#endif /* __PAGETABLE_PMD_FOLDED */
+static inline void sync_kernel_mappings(pgd_t *pgd)
+{
+ memcpy(pgd + USER_PTRS_PER_PGD,
+ init_mm.pgd + USER_PTRS_PER_PGD,
+ (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+}
+
static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd;
@@ -135,9 +142,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
if (likely(pgd != NULL)) {
memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
/* Copy kernel mappings */
- memcpy(pgd + USER_PTRS_PER_PGD,
- init_mm.pgd + USER_PTRS_PER_PGD,
- (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+ sync_kernel_mappings(pgd);
}
return pgd;
}
--
2.37.2
