The existing map iteration helper for_each_efi_memory_desc_in_map can only be used after OS initializes EFI subsystem to fill data of struct efi_memory_map. Before that we also need iterate map descriptors which are stored in several intermediate structures, like struct efi_boot_memmap for arch independent usage and struct efi_info for x86 arch only.
Introduce efi_early_memdesc_ptr to get pointer to a map descriptor, and replace several places of open code with it. Signed-off-by: Baoquan He <[email protected]> --- v9->v10: Use the 'EFI subsystem' instead of EFI since EFI usually means firmware. Here we are talking about EFI subsystem inside kernel. arch/x86/boot/compressed/eboot.c | 2 +- drivers/firmware/efi/libstub/efi-stub-helper.c | 4 ++-- include/linux/efi.h | 21 +++++++++++++++++++++ 3 files changed, 24 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 @@ efi_status_t efi_high_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; @@ -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..ec296bc96bc5 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1020,6 +1020,27 @@ 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 function GetMemoryMap() 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. And also get the size of + * 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 in response to hardware innovation. Thus OS + * MUST use the returned size of 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 suggested after OS + * initializes EFI subsystem to fill data of 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; \ -- 2.5.5
