* [PATCH 0/2] efi capsule loader fixes
@ 2020-12-07 18:02 Ard Biesheuvel
2020-12-07 18:02 ` [PATCH 2/2] efi: capsule: clean scatter-gather entries from the D-cache Ard Biesheuvel
2020-12-07 18:02 ` [PATCH 1/2] efi: capsule: use atomic kmap for transient sglist mappings Ard Biesheuvel
0 siblings, 2 replies; 3+ messages in thread
From: Ard Biesheuvel @ 2020-12-07 18:02 UTC (permalink / raw)
To: linux-efi; +Cc: linux-arm-kernel, Ard Biesheuvel, Samer El-Haj-Mahmoud
A couple of fixes for the EFI capsule loader. Patch #1 switches from
kmap() to kmap_atomic(). Patch #2 adds cache maintenance of the scatter
gather list entries passed to UpdateCapsule.
Cc: Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@arm.com>
Ard Biesheuvel (2):
efi: capsule: use atomic kmap for transient sglist mappings
efi: capsule: clean scatter-gather entries from the D-cache
arch/arm/include/asm/efi.h | 5 +++++
arch/arm64/include/asm/efi.h | 5 +++++
drivers/firmware/efi/capsule.c | 16 ++++++++++++++--
3 files changed, 24 insertions(+), 2 deletions(-)
--
2.17.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH 2/2] efi: capsule: clean scatter-gather entries from the D-cache
2020-12-07 18:02 [PATCH 0/2] efi capsule loader fixes Ard Biesheuvel
@ 2020-12-07 18:02 ` Ard Biesheuvel
2020-12-07 18:02 ` [PATCH 1/2] efi: capsule: use atomic kmap for transient sglist mappings Ard Biesheuvel
1 sibling, 0 replies; 3+ messages in thread
From: Ard Biesheuvel @ 2020-12-07 18:02 UTC (permalink / raw)
To: linux-efi; +Cc: linux-arm-kernel, Ard Biesheuvel, Samer El-Haj-Mahmoud
The UEFI spec 2.9 has recently been updated to include a requirement
that 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 it enables the MMU. On ARM and arm64 systems, this
implies a D-cache clean by virtual address to the point of coherency.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
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(+)
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 <linux/highmem.h>
#include <linux/efi.h>
#include <linux/vmalloc.h>
+#include <asm/efi.h>
#include <asm/io.h>
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);
}
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 1/2] efi: capsule: use atomic kmap for transient sglist mappings
2020-12-07 18:02 [PATCH 0/2] efi capsule loader fixes Ard Biesheuvel
2020-12-07 18:02 ` [PATCH 2/2] efi: capsule: clean scatter-gather entries from the D-cache Ard Biesheuvel
@ 2020-12-07 18:02 ` Ard Biesheuvel
1 sibling, 0 replies; 3+ messages in thread
From: Ard Biesheuvel @ 2020-12-07 18:02 UTC (permalink / raw)
To: linux-efi; +Cc: linux-arm-kernel, Ard Biesheuvel, Samer El-Haj-Mahmoud
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 <ardb@kernel.org>
---
drivers/firmware/efi/capsule.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
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);
--
2.17.1
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