From 7e904a91bf6049071ef9d605a52f863ae774081d Mon Sep 17 00:00:00 2001 From: Sai Praneeth Date: Mon, 12 Mar 2018 08:44:56 +0000 Subject: efi: Use efi_mm in x86 as well as ARM Presently, only ARM uses mm_struct to manage EFI page tables and EFI runtime region mappings. As this is the preferred approach, let's make this data structure common across architectures. Specially, for x86, using this data structure improves code maintainability and readability. Tested-by: Bhupesh Sharma [ardb: don't #include the world to get a declaration of struct mm_struct] 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 Link: http://lkml.kernel.org/r/20180312084500.10764-2-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/efi.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/include') diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index a399c1ebf6f0..c62443fa7d0a 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -7,6 +7,7 @@ #include #include #include +#include /* * We map the EFI regions needed for runtime services non-contiguously, -- cgit v1.2.3 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 +++++++++------------- arch/x86/platform/efi/efi_64.c | 41 +++++++++++++++++++----------------- arch/x86/platform/efi/efi_thunk_64.S | 2 +- 3 files changed, 33 insertions(+), 35 deletions(-) (limited to 'arch/x86/include') 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; diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 29b267b8cb63..4f8a9c963fbb 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include @@ -82,9 +83,8 @@ pgd_t * __init efi_call_phys_prolog(void) int n_pgds, i, j; if (!efi_enabled(EFI_OLD_MEMMAP)) { - save_pgd = (pgd_t *)__read_cr3(); - write_cr3((unsigned long)efi_scratch.efi_pgt); - goto out; + efi_switch_mm(&efi_mm); + return NULL; } early_code_mapping_set_exec(1); @@ -156,8 +156,7 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd) pud_t *pud; if (!efi_enabled(EFI_OLD_MEMMAP)) { - write_cr3((unsigned long)save_pgd); - __flush_tlb_all(); + efi_switch_mm(efi_scratch.prev_mm); return; } @@ -347,13 +346,6 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) if (efi_enabled(EFI_OLD_MEMMAP)) return 0; - /* - * Since the PGD is encrypted, set the encryption mask so that when - * this value is loaded into cr3 the PGD will be decrypted during - * the pagetable walk. - */ - efi_scratch.efi_pgt = (pgd_t *)__sme_pa(pgd); - /* * It can happen that the physical address of new_memmap lands in memory * which is not mapped in the EFI page table. Therefore we need to go @@ -367,8 +359,6 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) return 1; } - efi_scratch.use_pgd = true; - /* * Certain firmware versions are way too sentimential and still believe * they are exclusive and unquestionable owners of the first physical page, @@ -627,6 +617,22 @@ void __init efi_dump_pagetable(void) #endif } +/* + * Makes the calling thread switch to/from efi_mm context. Can be used + * for SetVirtualAddressMap() i.e. current->active_mm == init_mm as well + * as during efi runtime calls i.e current->active_mm == current_mm. + * We are not mm_dropping()/mm_grabbing() any mm, because we are not + * losing/creating any references. + */ +void efi_switch_mm(struct mm_struct *mm) +{ + task_lock(current); + efi_scratch.prev_mm = current->active_mm; + current->active_mm = mm; + switch_mm(efi_scratch.prev_mm, mm, NULL); + task_unlock(current); +} + #ifdef CONFIG_EFI_MIXED extern efi_status_t efi64_thunk(u32, ...); @@ -680,16 +686,13 @@ efi_status_t efi_thunk_set_virtual_address_map( efi_sync_low_kernel_mappings(); local_irq_save(flags); - efi_scratch.prev_cr3 = __read_cr3(); - write_cr3((unsigned long)efi_scratch.efi_pgt); - __flush_tlb_all(); + efi_switch_mm(&efi_mm); func = (u32)(unsigned long)phys_set_virtual_address_map; status = efi64_thunk(func, memory_map_size, descriptor_size, descriptor_version, virtual_map); - write_cr3(efi_scratch.prev_cr3); - __flush_tlb_all(); + efi_switch_mm(efi_scratch.prev_mm); local_irq_restore(flags); return status; diff --git a/arch/x86/platform/efi/efi_thunk_64.S b/arch/x86/platform/efi/efi_thunk_64.S index 189b218da87c..46c58b08739c 100644 --- a/arch/x86/platform/efi/efi_thunk_64.S +++ b/arch/x86/platform/efi/efi_thunk_64.S @@ -33,7 +33,7 @@ ENTRY(efi64_thunk) * Switch to 1:1 mapped 32-bit stack pointer. */ movq %rsp, efi_saved_sp(%rip) - movq efi_scratch+25(%rip), %rsp + movq efi_scratch(%rip), %rsp /* * Calculate the physical address of the kernel text. -- cgit v1.2.3