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efi: x86: clean up previous struct mm switching

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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@kernel.org>
This commit is contained in:
Ard Biesheuvel 2021-01-19 15:05:40 +01:00
parent 3e1e00c00e
commit 514b1a8477
2 changed files with 20 additions and 24 deletions
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17
arch/x86/include/asm/efi.h
View File

@ -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;

27
arch/x86/platform/efi/efi_64.c
View File

@ -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_scratch.prev_mm = current->active_mm;
current->active_mm = mm;
switch_mm(efi_scratch.prev_mm, mm, NULL);
efi_prev_mm = current->active_mm;
current->active_mm = &efi_mm;
switch_mm(efi_prev_mm, &efi_mm, NULL);
}
void efi_leave_mm(void)
{
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;
}