diff options
| -rw-r--r-- | arch/x86/boot/compressed/eboot.c | 2 | ||||
| -rw-r--r-- | drivers/firmware/efi/libstub/efi-stub-helper.c | 4 | ||||
| -rw-r--r-- | include/linux/efi.h | 22 |
3 files changed, 25 insertions, 3 deletions
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c index c3e869eaef0c..e007887a33b0 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -767,7 +767,7 @@ static efi_status_t setup_e820(struct boot_params *params, m |= (u64)efi->efi_memmap_hi << 32; #endif - d = (efi_memory_desc_t *)(m + (i * efi->efi_memdesc_size)); + d = efi_early_memdesc_ptr(m, efi->efi_memdesc_size, i); switch (d->type) { case EFI_RESERVED_TYPE: case EFI_RUNTIME_SERVICES_CODE: diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index b0184360efc6..50a9cab5a834 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -205,7 +205,7 @@ again: unsigned long m = (unsigned long)map; u64 start, end; - desc = (efi_memory_desc_t *)(m + (i * desc_size)); + desc = efi_early_memdesc_ptr(m, desc_size, i); if (desc->type != EFI_CONVENTIONAL_MEMORY) continue; @@ -298,7 +298,7 @@ efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg, unsigned long m = (unsigned long)map; u64 start, end; - desc = (efi_memory_desc_t *)(m + (i * desc_size)); + desc = efi_early_memdesc_ptr(m, desc_size, i); if (desc->type != EFI_CONVENTIONAL_MEMORY) continue; diff --git a/include/linux/efi.h b/include/linux/efi.h index 8269bcb8ccf7..a686ca9a7e5c 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1020,6 +1020,28 @@ extern int efi_memattr_init(void); extern int efi_memattr_apply_permissions(struct mm_struct *mm, efi_memattr_perm_setter fn); +/* + * efi_early_memdesc_ptr - get the n-th EFI memmap descriptor + * @map: the start of efi memmap + * @desc_size: the size of space for each EFI memmap descriptor + * @n: the index of efi memmap descriptor + * + * EFI boot service provides the GetMemoryMap() function to get a copy of the + * current memory map which is an array of memory descriptors, each of + * which describes a contiguous block of memory. It also gets the size of the + * map, and the size of each descriptor, etc. + * + * Note that per section 6.2 of UEFI Spec 2.6 Errata A, the returned size of + * each descriptor might not be equal to sizeof(efi_memory_memdesc_t), + * since efi_memory_memdesc_t may be extended in the future. Thus the OS + * MUST use the returned size of the descriptor to find the start of each + * efi_memory_memdesc_t in the memory map array. This should only be used + * during bootup since for_each_efi_memory_desc_xxx() is available after the + * kernel initializes the EFI subsystem to set up struct efi_memory_map. + */ +#define efi_early_memdesc_ptr(map, desc_size, n) \ + (efi_memory_desc_t *)((void *)(map) + ((n) * (desc_size))) + /* Iterate through an efi_memory_map */ #define for_each_efi_memory_desc_in_map(m, md) \ for ((md) = (m)->map; \ |