From 03781e40890c18bdea40092355b61431d0073c1d Mon Sep 17 00:00:00 2001 From: Sai Praneeth Date: Mon, 12 Mar 2018 09:43:55 +0000 Subject: x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3 Use helper function efi_switch_mm() to switch to/from efi_mm when invoking any UEFI runtime services. Likewise, we need to switch back to previous mm (mm context stolen by efi_mm) after the above calls return successfully. We can use efi_switch_mm() helper function only with x86_64 kernel and "efi=old_map" disabled because, x86_32 and efi=old_map do not use efi_pgd, rather they use swapper_pg_dir. Tested-by: Bhupesh Sharma [ardb: add #include of sched/task.h for task_lock/_unlock] Signed-off-by: Sai Praneeth Prakhya Signed-off-by: Ard Biesheuvel Reviewed-by: Matt Fleming Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Lee, Chun-Yi Cc: Linus Torvalds Cc: Michael S. Tsirkin Cc: Peter Zijlstra Cc: Ravi Shankar Cc: Ricardo Neri Cc: Thomas Gleixner Cc: Tony Luck Cc: linux-efi@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/efi.h | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) (limited to 'arch/x86/include/asm/efi.h') diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index c62443fa7d0a..cec5fae23eb3 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -70,14 +70,13 @@ extern asmlinkage u64 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 - Scratch space used while switching to/from efi_mm + * @phys_stack: stack used during EFI Mixed Mode + * @prev_mm: store/restore stolen mm_struct while switching to/from efi_mm */ struct efi_scratch { - u64 r15; - u64 prev_cr3; - pgd_t *efi_pgt; - bool use_pgd; - u64 phys_stack; + u64 phys_stack; + struct mm_struct *prev_mm; } __packed; #define arch_efi_call_virt_setup() \ @@ -87,11 +86,8 @@ struct efi_scratch { __kernel_fpu_begin(); \ firmware_restrict_branch_speculation_start(); \ \ - if (efi_scratch.use_pgd) { \ - efi_scratch.prev_cr3 = __read_cr3(); \ - write_cr3((unsigned long)efi_scratch.efi_pgt); \ - __flush_tlb_all(); \ - } \ + if (!efi_enabled(EFI_OLD_MEMMAP)) \ + efi_switch_mm(&efi_mm); \ }) #define arch_efi_call_virt(p, f, args...) \ @@ -99,10 +95,8 @@ struct efi_scratch { #define arch_efi_call_virt_teardown() \ ({ \ - if (efi_scratch.use_pgd) { \ - write_cr3(efi_scratch.prev_cr3); \ - __flush_tlb_all(); \ - } \ + if (!efi_enabled(EFI_OLD_MEMMAP)) \ + efi_switch_mm(efi_scratch.prev_mm); \ \ firmware_restrict_branch_speculation_end(); \ __kernel_fpu_end(); \ @@ -145,6 +139,7 @@ extern void __init efi_dump_pagetable(void); extern void __init efi_apply_memmap_quirks(void); extern int __init efi_reuse_config(u64 tables, int nr_tables); extern void efi_delete_dummy_variable(void); +extern void efi_switch_mm(struct mm_struct *mm); struct efi_setup_data { u64 fw_vendor; -- cgit v1.2.3