efi: Introduce efi_early_memdesc_ptr to get pointer to memmap descriptor
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>
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@ -767,7 +767,7 @@ static efi_status_t setup_e820(struct boot_params *params,
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m |= (u64)efi->efi_memmap_hi << 32;
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#endif
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d = (efi_memory_desc_t *)(m + (i * efi->efi_memdesc_size));
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d = efi_early_memdesc_ptr(m, efi->efi_memdesc_size, i);
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switch (d->type) {
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case EFI_RESERVED_TYPE:
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case EFI_RUNTIME_SERVICES_CODE:
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@ -205,7 +205,7 @@ again:
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unsigned long m = (unsigned long)map;
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u64 start, end;
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desc = (efi_memory_desc_t *)(m + (i * desc_size));
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desc = efi_early_memdesc_ptr(m, desc_size, i);
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if (desc->type != EFI_CONVENTIONAL_MEMORY)
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continue;
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@ -298,7 +298,7 @@ efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg,
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unsigned long m = (unsigned long)map;
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u64 start, end;
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desc = (efi_memory_desc_t *)(m + (i * desc_size));
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desc = efi_early_memdesc_ptr(m, desc_size, i);
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if (desc->type != EFI_CONVENTIONAL_MEMORY)
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continue;
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@ -1020,6 +1020,28 @@ extern int efi_memattr_init(void);
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extern int efi_memattr_apply_permissions(struct mm_struct *mm,
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efi_memattr_perm_setter fn);
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/*
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* efi_early_memdesc_ptr - get the n-th EFI memmap descriptor
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* @map: the start of efi memmap
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* @desc_size: the size of space for each EFI memmap descriptor
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* @n: the index of efi memmap descriptor
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*
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* EFI boot service provides the GetMemoryMap() function to get a copy of the
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* current memory map which is an array of memory descriptors, each of
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* which describes a contiguous block of memory. It also gets the size of the
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* map, and the size of each descriptor, etc.
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*
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* Note that per section 6.2 of UEFI Spec 2.6 Errata A, the returned size of
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* each descriptor might not be equal to sizeof(efi_memory_memdesc_t),
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* since efi_memory_memdesc_t may be extended in the future. Thus the OS
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* MUST use the returned size of the descriptor to find the start of each
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* efi_memory_memdesc_t in the memory map array. This should only be used
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* during bootup since for_each_efi_memory_desc_xxx() is available after the
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* kernel initializes the EFI subsystem to set up struct efi_memory_map.
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*/
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#define efi_early_memdesc_ptr(map, desc_size, n) \
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(efi_memory_desc_t *)((void *)(map) + ((n) * (desc_size)))
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/* Iterate through an efi_memory_map */
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#define for_each_efi_memory_desc_in_map(m, md) \
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for ((md) = (m)->map; \
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