Commit 514b1a84 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

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: default avatarArd Biesheuvel <ardb@kernel.org>
parent 3e1e00c0

arch/x86/include/asm/efi.h

+5 −12
Original line number Original line Diff line number Diff line
@@ -95,20 +95,12 @@ extern asmlinkage u64 __efi_call(void *fp, ...); 
	__efi_call(__VA_ARGS__);					\

	__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()					\

#define arch_efi_call_virt_setup()					\

({									\

({									\

	efi_sync_low_kernel_mappings();					\

	efi_sync_low_kernel_mappings();					\

	kernel_fpu_begin();						\

	kernel_fpu_begin();						\

	firmware_restrict_branch_speculation_start();			\

	firmware_restrict_branch_speculation_start();			\

	efi_switch_mm(&efi_mm);						\

	efi_enter_mm();							\

})

})





#define arch_efi_call_virt(p, f, args...)				\

#define arch_efi_call_virt(p, f, args...)				\
@@ -116,7 +108,7 @@ struct efi_scratch { 




#define arch_efi_call_virt_teardown()					\

#define arch_efi_call_virt_teardown()					\

({									\

({									\

	efi_switch_mm(efi_scratch.prev_mm);				\

	efi_leave_mm();							\

	firmware_restrict_branch_speculation_end();			\

	firmware_restrict_branch_speculation_end();			\

	kernel_fpu_end();						\

	kernel_fpu_end();						\

})

})
@@ -135,7 +127,6 @@ struct efi_scratch { 




#endif /* CONFIG_X86_32 */

#endif /* CONFIG_X86_32 */





extern struct efi_scratch efi_scratch;

extern int __init efi_memblock_x86_reserve_range(void);

extern int __init efi_memblock_x86_reserve_range(void);

extern void __init efi_print_memmap(void);

extern void __init efi_print_memmap(void);

extern void __init efi_map_region(efi_memory_desc_t *md);

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 void __init efi_apply_memmap_quirks(void);

extern int __init efi_reuse_config(u64 tables, int nr_tables);

extern int __init efi_reuse_config(u64 tables, int nr_tables);

extern void efi_delete_dummy_variable(void);

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_recover_from_page_fault(unsigned long phys_addr);

extern void efi_free_boot_services(void);

extern void efi_free_boot_services(void);





void efi_enter_mm(void);

void efi_leave_mm(void);



/* kexec external ABI */

/* kexec external ABI */

struct efi_setup_data {

struct efi_setup_data {

	u64 fw_vendor;

	u64 fw_vendor;

arch/x86/platform/efi/efi_64.c

+15 −12
Original line number Original line Diff line number Diff line
@@ -54,10 +54,7 @@ 
 * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.

 * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.

 */

 */

static u64 efi_va = EFI_VA_START;

static u64 efi_va = EFI_VA_START;



static struct mm_struct *efi_prev_mm;

struct efi_scratch efi_scratch;



EXPORT_SYMBOL_GPL(efi_mm);





/*

/*

 * We need our own copy of the higher levels of the page tables

 * 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.

 * can not change under us.

 * It should be ensured that there are no concurent calls to this function.

 * 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 = efi_prev_mm;

	current->active_mm = mm;

	switch_mm(&efi_mm, efi_prev_mm, NULL);

	switch_mm(efi_scratch.prev_mm, mm, NULL);

}

}





static DEFINE_SPINLOCK(efi_runtime_lock);

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();

	efi_sync_low_kernel_mappings();

	local_irq_save(flags);

	local_irq_save(flags);





	efi_switch_mm(&efi_mm);

	efi_enter_mm();





	status = __efi_thunk(set_virtual_address_map, memory_map_size,

	status = __efi_thunk(set_virtual_address_map, memory_map_size,

			     descriptor_size, descriptor_version, virtual_map);

			     descriptor_size, descriptor_version, virtual_map);





	efi_switch_mm(efi_scratch.prev_mm);

	efi_leave_mm();

	local_irq_restore(flags);

	local_irq_restore(flags);





	return status;

	return status;
@@ -848,7 +851,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size, 
							 descriptor_size,

							 descriptor_size,

							 descriptor_version,

							 descriptor_version,

							 virtual_map);

							 virtual_map);

	efi_switch_mm(&efi_mm);

	efi_enter_mm();





	kernel_fpu_begin();

	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 */

	/* grab the virtually remapped EFI runtime services table pointer */

	efi.runtime = READ_ONCE(systab->runtime);

	efi.runtime = READ_ONCE(systab->runtime);





	efi_switch_mm(efi_scratch.prev_mm);

	efi_leave_mm();





	return status;

	return status;

}
 
}