On Fri, 29 Jan, at 05:04:40PM, Sai Praneeth Prakhya wrote:
> From: Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx>
>
> Now that we have EFI memory region bits that indicate which regions do
> not need execute permission or read/write permission in the page tables,
> let's use them.
>
> We also check for EFI_NX_PE_DATA and only enforce the restrictive
> mappings if it's present (to allow us to ignore buggy firmware that sets
> bits it didn't mean to and to preserve backwards compatibility).
>
> Instead of assuming that firmware would set appropriate attributes in
> memory descriptor like EFI_MEMORY_RO for code and EFI_MEMORY_XP for
> data, we can expect some firmware out there which might only set *type*
> in memory descriptor to be EFI_RUNTIME_SERVICES_CODE or
> EFI_RUNTIME_SERVICES_DATA leaving away attribute. This will lead to
> improper mappings of EFI runtime regions. In order to avoid it, we check
> attribute and type of memory descriptor to update mappings and moreover
> Windows works this way.
>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Lee, Chun-Yi <jlee@xxxxxxxx>
> Cc: Ricardo Neri <ricardo.neri@xxxxxxxxx>
> Cc: Ravi Shankar <ravi.v.shankar@xxxxxxxxx>
> Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
> ---
> arch/x86/include/asm/efi.h | 2 +-
> arch/x86/platform/efi/efi.c | 9 +++++++--
> arch/x86/platform/efi/efi_64.c | 45 ++++++++++++++++++++++++++++++++++++++----
> 3 files changed, 49 insertions(+), 7 deletions(-)
I just hit the following build error,
arch/x86/built-in.o: In function `efi_enter_virtual_mode':
(.init.text+0x12ac0): undefined reference to `efi_runtime_update_mappings'
make[1]: *** [vmlinux] Error 1
I fixed it up like so,
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index 58d669bc8250..338402b91d2e 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -90,7 +90,7 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
__flush_tlb_all();
}
-void __init efi_runtime_mkexec(void)
+void __init efi_runtime_update_mappings(void)
{
if (__supported_pte_mask & _PAGE_NX)
runtime_code_page_mkexec();
--
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