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authorSai Praneeth <sai.praneeth.prakhya@intel.com>2018-03-12 09:43:55 +0000
committerIngo Molnar <mingo@kernel.org>2018-03-12 11:05:05 +0100
commit03781e40890c18bdea40092355b61431d0073c1d (patch)
tree4a7c7b0f467cfb1cd6d4d94384350d3f66ee32d4
parent3ede3417f8d59fff5c07339b310b343468c81b07 (diff)
downloadop-kernel-dev-03781e40890c18bdea40092355b61431d0073c1d.zip
op-kernel-dev-03781e40890c18bdea40092355b61431d0073c1d.tar.gz
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 <bhsharma@redhat.com> [ardb: add #include of sched/task.h for task_lock/_unlock] Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Lee, Chun-Yi <jlee@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Shankar <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: linux-efi@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/include/asm/efi.h25
-rw-r--r--arch/x86/platform/efi/efi_64.c41
-rw-r--r--arch/x86/platform/efi/efi_thunk_64.S2
3 files changed, 33 insertions, 35 deletions
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index c62443f..cec5fae 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 29b267b..4f8a9c9 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -34,6 +34,7 @@
#include <linux/slab.h>
#include <linux/ucs2_string.h>
#include <linux/mem_encrypt.h>
+#include <linux/sched/task.h>
#include <asm/setup.h>
#include <asm/page.h>
@@ -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;
}
@@ -348,13 +347,6 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
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
* and ident-map those pages containing the map before calling
@@ -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 189b218..46c58b0 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.
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