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

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>

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 5aa186db59e37000fc267f6c55d1006a1618bf1f..102976dda8c42043c0571a0f2a6e64d3a2f18fc4 100644 (file)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -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");