The following commit has been merged into the efi/core branch of tip:
Commit-ID: 514b1a8477d25a157f65bf52a443f8ffcc2eb54e
Gitweb: https://git.kernel.org/tip/514b1a8477d25a157f65bf52a443f8ffcc2eb54e
Author: Ard Biesheuvel <ardb@xxxxxxxxxx>
AuthorDate: Tue, 19 Jan 2021 15:05:40 +01:00
Committer: Ard Biesheuvel <ardb@xxxxxxxxxx>
CommitterDate: Tue, 19 Jan 2021 17:57:15 +01:00
efi: x86: clean up previous struct mm switching
EFI on x86_64 keeps track of the process's MM pointer by storing it
in a global struct called 'efi_scratch', which also used to contain
the mixed mode stack pointer. Let's clean this up a little bit, by
getting rid of the struct, and pushing the mm handling into the
callees entirely.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
arch/x86/include/asm/efi.h | 17 +++++------------
arch/x86/platform/efi/efi_64.c | 27 +++++++++++++++------------
2 files changed, 20 insertions(+), 24 deletions(-)
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 5e37e6d..1328b79 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -95,20 +95,12 @@ extern asmlinkage u64 __efi_call(void *fp, ...);
__efi_call(__VA_ARGS__); \
})
-/*
- * struct efi_scratch - Scratch space used while switching to/from efi_mm
- * @prev_mm: store/restore stolen mm_struct while switching to/from efi_mm
- */
-struct efi_scratch {
- struct mm_struct *prev_mm;
-} __packed;
-
#define arch_efi_call_virt_setup() \
({ \
efi_sync_low_kernel_mappings(); \
kernel_fpu_begin(); \
firmware_restrict_branch_speculation_start(); \
- efi_switch_mm(&efi_mm); \
+ efi_enter_mm(); \
})
#define arch_efi_call_virt(p, f, args...) \
@@ -116,7 +108,7 @@ struct efi_scratch {
#define arch_efi_call_virt_teardown() \
({ \
- efi_switch_mm(efi_scratch.prev_mm); \
+ efi_leave_mm(); \
firmware_restrict_branch_speculation_end(); \
kernel_fpu_end(); \
})
@@ -135,7 +127,6 @@ struct efi_scratch {
#endif /* CONFIG_X86_32 */
-extern struct efi_scratch efi_scratch;
extern int __init efi_memblock_x86_reserve_range(void);
extern void __init efi_print_memmap(void);
extern void __init efi_map_region(efi_memory_desc_t *md);
@@ -148,10 +139,12 @@ 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);
extern void efi_recover_from_page_fault(unsigned long phys_addr);
extern void efi_free_boot_services(void);
+void efi_enter_mm(void);
+void efi_leave_mm(void);
+
/* kexec external ABI */
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 1d90418..62a6c86 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -54,10 +54,7 @@
* 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
*/
static u64 efi_va = EFI_VA_START;
-
-struct efi_scratch efi_scratch;
-
-EXPORT_SYMBOL_GPL(efi_mm);
+static struct mm_struct *efi_prev_mm;
/*
* We need our own copy of the higher levels of the page tables
@@ -481,11 +478,17 @@ void __init efi_dump_pagetable(void)
* can not change under us.
* It should be ensured that there are no concurent calls to this function.
*/
-void efi_switch_mm(struct mm_struct *mm)
+void efi_enter_mm(void)
+{
+ efi_prev_mm = current->active_mm;
+ current->active_mm = &efi_mm;
+ switch_mm(efi_prev_mm, &efi_mm, NULL);
+}
+
+void efi_leave_mm(void)
{
- efi_scratch.prev_mm = current->active_mm;
- current->active_mm = mm;
- switch_mm(efi_scratch.prev_mm, mm, NULL);
+ current->active_mm = efi_prev_mm;
+ switch_mm(&efi_mm, efi_prev_mm, NULL);
}
static DEFINE_SPINLOCK(efi_runtime_lock);
@@ -549,12 +552,12 @@ efi_thunk_set_virtual_address_map(unsigned long memory_map_size,
efi_sync_low_kernel_mappings();
local_irq_save(flags);
- efi_switch_mm(&efi_mm);
+ efi_enter_mm();
status = __efi_thunk(set_virtual_address_map, memory_map_size,
descriptor_size, descriptor_version, virtual_map);
- efi_switch_mm(efi_scratch.prev_mm);
+ efi_leave_mm();
local_irq_restore(flags);
return status;
@@ -848,7 +851,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size,
descriptor_size,
descriptor_version,
virtual_map);
- efi_switch_mm(&efi_mm);
+ efi_enter_mm();
kernel_fpu_begin();
@@ -864,7 +867,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size,
/* grab the virtually remapped EFI runtime services table pointer */
efi.runtime = READ_ONCE(systab->runtime);
- efi_switch_mm(efi_scratch.prev_mm);
+ efi_leave_mm();
return status;
}
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