Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752091AbbKNWBr (ORCPT ); Sat, 14 Nov 2015 17:01:47 -0500 Received: from mail-wm0-f53.google.com ([74.125.82.53]:32850 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751998AbbKNWA7 (ORCPT ); Sat, 14 Nov 2015 17:00:59 -0500 From: Matt Fleming To: Ingo Molnar , Thomas Gleixner , "H . Peter Anvin" Cc: Toshi Kani , Matt Fleming , linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, Sai Praneeth Prakhya , Linus Torvalds , Dave Jones , Andrew Morton , Andy Lutomirski , Denys Vlasenko , Stephen Smalley , Borislav Petkov Subject: [PATCH v2 3/5] x86/efi: Hoist page table switching code into efi_call_virt() Date: Sat, 14 Nov 2015 22:00:49 +0000 Message-Id: <1447538451-5793-4-git-send-email-matt@codeblueprint.co.uk> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1447538451-5793-1-git-send-email-matt@codeblueprint.co.uk> References: <1447538451-5793-1-git-send-email-matt@codeblueprint.co.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5729 Lines: 212 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. Reviewed-by: Borislav Petkov Cc: Sai Praneeth Prakhya Cc: Ingo Molnar Cc: Linus Torvalds Cc: Dave Jones Cc: Thomas Gleixner Cc: H. Peter Anvin Cc: Andrew Morton Cc: Andy Lutomirski Cc: Denys Vlasenko , Cc: Stephen Smalley Signed-off-by: Matt Fleming --- Changes in v2: - Fixed up some checkpatch warnings about mixing tabs and spaces. arch/x86/include/asm/efi.h | 25 +++++++++++++++++++++ arch/x86/platform/efi/efi_64.c | 24 ++++++++++----------- arch/x86/platform/efi/efi_stub_64.S | 43 ------------------------------------- 3 files changed, 36 insertions(+), 56 deletions(-) diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index cfee9d4b02af..0eb45a187339 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -3,6 +3,7 @@ #include #include +#include /* * 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; \ diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 634536034e32..ab5f14a886cc 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 -- 2.6.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/