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x86/efi: Map RAM into the identity page table for mixed mode

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We are relying on the pre-existing mappings in 'trampoline_pgd'
when accessing function arguments in the EFI mixed mode thunking
code.

Instead let's map memory explicitly so that things will continue
to work when we move to a separate page table in the future.

Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1448658575-17029-4-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Matt Fleming 2015-11-27 21:09:32 +00:00 committed by Ingo Molnar
parent edc3b9129c
commit b61a76f885
1 changed files with 20 additions and 0 deletions
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20
arch/x86/platform/efi/efi_64.c
View file

@ -144,6 +144,7 @@ void efi_sync_low_kernel_mappings(void)
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
unsigned long pfn, text;
efi_memory_desc_t *md;
struct page *page;
unsigned npages;
pgd_t *pgd;
@ -177,6 +178,25 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
if (!IS_ENABLED(CONFIG_EFI_MIXED))
return 0;
/*
* Map all of RAM so that we can access arguments in the 1:1
* mapping when making EFI runtime calls.
*/
for_each_efi_memory_desc(&memmap, md) {
if (md->type != EFI_CONVENTIONAL_MEMORY &&
md->type != EFI_LOADER_DATA &&
md->type != EFI_LOADER_CODE)
continue;
pfn = md->phys_addr >> PAGE_SHIFT;
npages = md->num_pages;
if (kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, npages, 0)) {
pr_err("Failed to map 1:1 memory\n");
return 1;
}
}
page = alloc_page(GFP_KERNEL|__GFP_DMA32);
if (!page)
panic("Unable to allocate EFI runtime stack < 4GB\n");