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riscv: Sync efi page table's kernel mappings before switching

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[ Upstream commit 3f105a742725a1b78766a55169f1d827732e62b8 ]

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@rivosinc.com>
Fixes: b91540d52a ("RISC-V: Add EFI runtime services")
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20221121133303.1782246-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Alexandre Ghiti
2022-11-21 14:33:03 +01:00
committed by Greg Kroah-Hartman
parent d86d698925
commit fa7a7d185e
2 changed files with 13 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/riscv/include/asm/efi.h
View File

@@ -10,6 +10,7 @@
#include <asm/mmu_context.h> #include <asm/mmu_context.h>
#include <asm/ptrace.h> #include <asm/ptrace.h>
#include <asm/tlbflush.h> #include <asm/tlbflush.h>
#include <asm/pgalloc.h>
#ifdef CONFIG_EFI #ifdef CONFIG_EFI
extern void efi_init(void); 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_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); 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_call_virt_teardown() efi_virtmap_unload()
#define arch_efi_call_virt(p, f, args...) p->f(args) #define arch_efi_call_virt(p, f, args...) p->f(args)

11
arch/riscv/include/asm/pgalloc.h
View File

@@ -38,6 +38,13 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
} }
#endif /* __PAGETABLE_PMD_FOLDED */ #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) static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{ {
pgd_t *pgd; pgd_t *pgd;
@@ -46,9 +53,7 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
if (likely(pgd != NULL)) { if (likely(pgd != NULL)) {
memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t)); memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
/* Copy kernel mappings */ /* Copy kernel mappings */
memcpy(pgd + USER_PTRS_PER_PGD, sync_kernel_mappings(pgd);
init_mm.pgd + USER_PTRS_PER_PGD,
(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
} }
return pgd; return pgd;
} }