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efi: Introduce efi_early_memdesc_ptr to get pointer to memmap descriptor

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The existing map iteration helper for_each_efi_memory_desc_in_map can
only be used after the kernel initializes the EFI subsystem to set up
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 where that primitive is open coded.

Signed-off-by: Baoquan He <bhe@redhat.com>
[ Various improvements to the text. ]
Acked-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: ard.biesheuvel@linaro.org
Cc: fanc.fnst@cn.fujitsu.com
Cc: izumi.taku@jp.fujitsu.com
Cc: keescook@chromium.org
Cc: linux-efi@vger.kernel.org
Cc: n-horiguchi@ah.jp.nec.com
Cc: thgarnie@google.com
Link: http://lkml.kernel.org/r/20170816134651.GF21273@x1
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Baoquan He 2017-08-16 21:46:51 +08:00 committed by Ingo Molnar
parent 2257e268b1
commit 02e43c2dcd
3 changed files with 25 additions and 3 deletions
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2
arch/x86/boot/compressed/eboot.c
View File

@ -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:

4
drivers/firmware/efi/libstub/efi-stub-helper.c
View File

@ -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;

22
include/linux/efi.h
View File

@ -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; \