From 91c1c092f27da4164d55ca81e0a483108f8a3235 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Mon, 7 Dec 2020 17:33:33 +0100 Subject: efi: capsule: use atomic kmap for transient sglist mappings Don't use the heavy-weight kmap() API to create short-lived mappings of the scatter-gather list entries that are released as soon as the entries are written. Instead, use kmap_atomic(), which is more suited to this purpose. Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/capsule.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/firmware/efi/capsule.c') diff --git a/drivers/firmware/efi/capsule.c b/drivers/firmware/efi/capsule.c index 598b7800d14e..43f6fe7bfe80 100644 --- a/drivers/firmware/efi/capsule.c +++ b/drivers/firmware/efi/capsule.c @@ -244,7 +244,7 @@ int efi_capsule_update(efi_capsule_header_t *capsule, phys_addr_t *pages) for (i = 0; i < sg_count; i++) { efi_capsule_block_desc_t *sglist; - sglist = kmap(sg_pages[i]); + sglist = kmap_atomic(sg_pages[i]); for (j = 0; j < SGLIST_PER_PAGE && count > 0; j++) { u64 sz = min_t(u64, imagesize, @@ -265,7 +265,7 @@ int efi_capsule_update(efi_capsule_header_t *capsule, phys_addr_t *pages) else sglist[j].data = page_to_phys(sg_pages[i + 1]); - kunmap(sg_pages[i]); + kunmap_atomic(sglist); } mutex_lock(&capsule_mutex); -- cgit v1.2.3 From 4dbe44fb538c59a4adae5abfa9ded2f310250315 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Mon, 7 Dec 2020 18:40:53 +0100 Subject: efi: capsule: clean scatter-gather entries from the D-cache Scatter-gather lists passed to UpdateCapsule() should be cleaned from the D-cache to ensure that they are visible to the CPU after a warm reboot before the MMU is enabled. On ARM and arm64 systems, this implies a D-cache clean by virtual address to the point of coherency. However, due to the fact that the firmware itself is not able to map physical addresses back to virtual addresses when running under the OS, this must be done by the caller. Signed-off-by: Ard Biesheuvel --- arch/arm/include/asm/efi.h | 5 +++++ arch/arm64/include/asm/efi.h | 5 +++++ drivers/firmware/efi/capsule.c | 12 ++++++++++++ 3 files changed, 22 insertions(+) (limited to 'drivers/firmware/efi/capsule.c') diff --git a/arch/arm/include/asm/efi.h b/arch/arm/include/asm/efi.h index 3ee4f4381985..e9a06e164e06 100644 --- a/arch/arm/include/asm/efi.h +++ b/arch/arm/include/asm/efi.h @@ -93,4 +93,9 @@ struct efi_arm_entry_state { u32 sctlr_after_ebs; }; +static inline void efi_capsule_flush_cache_range(void *addr, int size) +{ + __cpuc_flush_dcache_area(addr, size); +} + #endif /* _ASM_ARM_EFI_H */ diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h index 973b14415271..00bd1e179d36 100644 --- a/arch/arm64/include/asm/efi.h +++ b/arch/arm64/include/asm/efi.h @@ -141,4 +141,9 @@ static inline void efi_set_pgd(struct mm_struct *mm) void efi_virtmap_load(void); void efi_virtmap_unload(void); +static inline void efi_capsule_flush_cache_range(void *addr, int size) +{ + __flush_dcache_area(addr, size); +} + #endif /* _ASM_EFI_H */ diff --git a/drivers/firmware/efi/capsule.c b/drivers/firmware/efi/capsule.c index 43f6fe7bfe80..768430293669 100644 --- a/drivers/firmware/efi/capsule.c +++ b/drivers/firmware/efi/capsule.c @@ -12,6 +12,7 @@ #include #include #include +#include #include typedef struct { @@ -265,6 +266,17 @@ int efi_capsule_update(efi_capsule_header_t *capsule, phys_addr_t *pages) else sglist[j].data = page_to_phys(sg_pages[i + 1]); +#if defined(CONFIG_ARM) || defined(CONFIG_ARM64) + /* + * At runtime, the firmware has no way to find out where the + * sglist elements are mapped, if they are mapped in the first + * place. Therefore, on architectures that can only perform + * cache maintenance by virtual address, the firmware is unable + * to perform this maintenance, and so it is up to the OS to do + * it instead. + */ + efi_capsule_flush_cache_range(sglist, PAGE_SIZE); +#endif kunmap_atomic(sglist); } -- cgit v1.2.3