diff options
| author | Matt Fleming <matt@codeblueprint.co.uk> | 2015-11-27 21:09:33 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-11-29 09:15:42 +0100 |
| commit | c9f2a9a65e4855b74d92cdad688f6ee4a1a323ff (patch) | |
| tree | 2042391b72cb2842b54b1170e5bfda2829adc104 /arch/x86/include/asm/efi.h | |
| parent | b61a76f8850d2979550abc42d7e09154ebb8d785 (diff) | |
| download | linux-c9f2a9a65e4855b74d92cdad688f6ee4a1a323ff.tar.bz2 | |
x86/efi: Hoist page table switching code into efi_call_virt()
This change is a prerequisite for pending patches that switch to
a dedicated EFI page table, instead of using 'trampoline_pgd'
which shares PGD entries with 'swapper_pg_dir'. The pending
patches make it impossible to dereference the runtime service
function pointer without first switching %cr3.
It's true that we now have duplicated switching code in
efi_call_virt() and efi_call_phys_{prolog,epilog}() but we are
sacrificing code duplication for a little more clarity and the
ease of writing the page table switching code in C instead of
asm.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
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: Stephen Smalley <sds@tycho.nsa.gov>
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/1448658575-17029-5-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/efi.h')
| -rw-r--r-- | arch/x86/include/asm/efi.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index 0010c78c4998..347eeacb06a8 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -3,6 +3,7 @@ #include <asm/fpu/api.h> #include <asm/pgtable.h> +#include <asm/tlb.h> /* * We map the EFI regions needed for runtime services non-contiguously, @@ -64,6 +65,17 @@ extern u64 asmlinkage efi_call(void *fp, ...); #define efi_call_phys(f, args...) efi_call((f), args) +/* + * Scratch space used for switching the pagetable in the EFI stub + */ +struct efi_scratch { + u64 r15; + u64 prev_cr3; + pgd_t *efi_pgt; + bool use_pgd; + u64 phys_stack; +} __packed; + #define efi_call_virt(f, ...) \ ({ \ efi_status_t __s; \ @@ -71,7 +83,20 @@ extern u64 asmlinkage efi_call(void *fp, ...); efi_sync_low_kernel_mappings(); \ preempt_disable(); \ __kernel_fpu_begin(); \ + \ + if (efi_scratch.use_pgd) { \ + efi_scratch.prev_cr3 = read_cr3(); \ + write_cr3((unsigned long)efi_scratch.efi_pgt); \ + __flush_tlb_all(); \ + } \ + \ __s = efi_call((void *)efi.systab->runtime->f, __VA_ARGS__); \ + \ + if (efi_scratch.use_pgd) { \ + write_cr3(efi_scratch.prev_cr3); \ + __flush_tlb_all(); \ + } \ + \ __kernel_fpu_end(); \ preempt_enable(); \ __s; \ |