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author | Matt Fleming <matt@codeblueprint.co.uk> | 2015-11-28 00:09:33 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2015-11-29 11:15:42 +0300 |
commit | c9f2a9a65e4855b74d92cdad688f6ee4a1a323ff (patch) | |
tree | 2042391b72cb2842b54b1170e5bfda2829adc104 /arch/x86/platform/efi | |
parent | b61a76f8850d2979550abc42d7e09154ebb8d785 (diff) | |
download | linux-c9f2a9a65e4855b74d92cdad688f6ee4a1a323ff.tar.xz |
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/platform/efi')
-rw-r--r-- | arch/x86/platform/efi/efi_64.c | 24 | ||||
-rw-r--r-- | arch/x86/platform/efi/efi_stub_64.S | 43 |
2 files changed, 11 insertions, 56 deletions
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 102976dda8c4..b19cdac959b2 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -47,16 +47,7 @@ */ static u64 efi_va = EFI_VA_START; -/* - * 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; +struct efi_scratch efi_scratch; static void __init early_code_mapping_set_exec(int executable) { @@ -83,8 +74,11 @@ pgd_t * __init efi_call_phys_prolog(void) int pgd; int n_pgds; - if (!efi_enabled(EFI_OLD_MEMMAP)) - return NULL; + if (!efi_enabled(EFI_OLD_MEMMAP)) { + save_pgd = (pgd_t *)read_cr3(); + write_cr3((unsigned long)efi_scratch.efi_pgt); + goto out; + } early_code_mapping_set_exec(1); @@ -96,6 +90,7 @@ pgd_t * __init efi_call_phys_prolog(void) vaddress = (unsigned long)__va(pgd * PGDIR_SIZE); set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress)); } +out: __flush_tlb_all(); return save_pgd; @@ -109,8 +104,11 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd) int pgd_idx; int nr_pgds; - if (!save_pgd) + if (!efi_enabled(EFI_OLD_MEMMAP)) { + write_cr3((unsigned long)save_pgd); + __flush_tlb_all(); return; + } nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE); diff --git a/arch/x86/platform/efi/efi_stub_64.S b/arch/x86/platform/efi/efi_stub_64.S index 86d0f9e08dd9..32020cb8bb08 100644 --- a/arch/x86/platform/efi/efi_stub_64.S +++ b/arch/x86/platform/efi/efi_stub_64.S @@ -38,41 +38,6 @@ mov %rsi, %cr0; \ mov (%rsp), %rsp - /* stolen from gcc */ - .macro FLUSH_TLB_ALL - movq %r15, efi_scratch(%rip) - movq %r14, efi_scratch+8(%rip) - movq %cr4, %r15 - movq %r15, %r14 - andb $0x7f, %r14b - movq %r14, %cr4 - movq %r15, %cr4 - movq efi_scratch+8(%rip), %r14 - movq efi_scratch(%rip), %r15 - .endm - - .macro SWITCH_PGT - cmpb $0, efi_scratch+24(%rip) - je 1f - movq %r15, efi_scratch(%rip) # r15 - # save previous CR3 - movq %cr3, %r15 - movq %r15, efi_scratch+8(%rip) # prev_cr3 - movq efi_scratch+16(%rip), %r15 # EFI pgt - movq %r15, %cr3 - 1: - .endm - - .macro RESTORE_PGT - cmpb $0, efi_scratch+24(%rip) - je 2f - movq efi_scratch+8(%rip), %r15 - movq %r15, %cr3 - movq efi_scratch(%rip), %r15 - FLUSH_TLB_ALL - 2: - .endm - ENTRY(efi_call) SAVE_XMM mov (%rsp), %rax @@ -83,16 +48,8 @@ ENTRY(efi_call) mov %r8, %r9 mov %rcx, %r8 mov %rsi, %rcx - SWITCH_PGT call *%rdi - RESTORE_PGT addq $48, %rsp RESTORE_XMM ret ENDPROC(efi_call) - - .data -ENTRY(efi_scratch) - .fill 3,8,0 - .byte 0 - .quad 0 |