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efi: Fix efi_memmap_alloc() leaks 

With efi_fake_memmap() and efi_arch_mem_reserve() the efi table may be
updated and replaced multiple times. When that happens a previous
dynamically allocated efi memory map can be garbage collected. Use the
new EFI_MEMMAP_{SLAB,MEMBLOCK} flags to detect when a dynamically
allocated memory map is being replaced.

Debug statements in efi_memmap_free() reveal:

  efi: __efi_memmap_free:37: phys: 0x23ffdd580 size: 2688 flags: 0x2
  efi: __efi_memmap_free:37: phys: 0x9db00 size: 2640 flags: 0x2
  efi: __efi_memmap_free:37: phys: 0x9e580 size: 2640 flags: 0x2

...a savings of 7968 bytes on a qemu boot with 2 entries specified to
efi_fake_mem=.

[ ardb: added a comment to clarify that efi_memmap_free() does nothing when
        called from efi_clean_memmap(), i.e., with data->flags == 0x0 ]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200113172245.27925-13-ardb@kernel.org
This commit is contained in:
Dan Williams 2020-01-13 18:22:44 +01:00 committed by Ingo Molnar
parent 1db91035d0
commit f0ef652347
1 changed files with 25 additions and 0 deletions
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25
drivers/firmware/efi/memmap.c
View File

@ -29,6 +29,28 @@ static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
return PFN_PHYS(page_to_pfn(p));
}
static void __init __efi_memmap_free(u64 phys, unsigned long size, unsigned long flags)
{
if (flags & EFI_MEMMAP_MEMBLOCK) {
if (slab_is_available())
memblock_free_late(phys, size);
else
memblock_free(phys, size);
} else if (flags & EFI_MEMMAP_SLAB) {
struct page *p = pfn_to_page(PHYS_PFN(phys));
unsigned int order = get_order(size);
free_pages((unsigned long) page_address(p), order);
}
}
static void __init efi_memmap_free(void)
{
__efi_memmap_free(efi.memmap.phys_map,
efi.memmap.desc_size * efi.memmap.nr_map,
efi.memmap.flags);
}
/**
* efi_memmap_alloc - Allocate memory for the EFI memory map
* @num_entries: Number of entries in the allocated map.
@ -100,6 +122,9 @@ static int __init __efi_memmap_init(struct efi_memory_map_data *data)
return -ENOMEM;
}
/* NOP if data->flags & (EFI_MEMMAP_MEMBLOCK | EFI_MEMMAP_SLAB) == 0 */
efi_memmap_free();
map.phys_map = data->phys_map;
map.nr_map = data->size / data->desc_size;
map.map_end = map.map + data->size;