Commit 744937b0 authored by Ingo Molnar's avatar Ingo Molnar Committed by Matt Fleming
Browse files

efi: Clean up the efi_call_phys_[prolog|epilog]() save/restore interaction 



Currently x86-64 efi_call_phys_prolog() saves into a global variable (save_pgd),
and efi_call_phys_epilog() restores the kernel pagetables from that global
variable.

Change this to a cleaner save/restore pattern where the saving function returns
the saved object and the restore function restores that.

Apply the same concept to the 32-bit code as well.

Plus this approach, as an added bonus, allows us to express the
!efi_enabled(EFI_OLD_MEMMAP) situation in a clean fashion as well,
via a 'NULL' return value.

Cc: Tapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
parent 23a0d4e8

arch/x86/include/asm/efi.h

+4 −2
Original line number Diff line number Diff line
@@ -2,6 +2,8 @@ 
#define _ASM_X86_EFI_H



#include <asm/i387.h>

#include <asm/pgtable.h>



/*

 * We map the EFI regions needed for runtime services non-contiguously,

 * with preserved alignment on virtual addresses starting from -4G down
@@ -89,8 +91,8 @@ extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size, 
extern struct efi_scratch efi_scratch;

extern void __init efi_set_executable(efi_memory_desc_t *md, bool executable);

extern int __init efi_memblock_x86_reserve_range(void);

extern void __init efi_call_phys_prolog(void);

extern void __init efi_call_phys_epilog(void);

extern pgd_t * __init efi_call_phys_prolog(void);

extern void __init efi_call_phys_epilog(pgd_t *save_pgd);

extern void __init efi_unmap_memmap(void);

extern void __init efi_memory_uc(u64 addr, unsigned long size);

extern void __init efi_map_region(efi_memory_desc_t *md);

arch/x86/platform/efi/efi.c

+3 −2
Original line number Diff line number Diff line
@@ -86,8 +86,9 @@ static efi_status_t __init phys_efi_set_virtual_address_map( 
{

	efi_status_t status;

	unsigned long flags;

	pgd_t *save_pgd;



	efi_call_phys_prolog();

	save_pgd = efi_call_phys_prolog();



	/* Disable interrupts around EFI calls: */

	local_irq_save(flags);
@@ -96,7 +97,7 @@ static efi_status_t __init phys_efi_set_virtual_address_map( 
			       descriptor_version, virtual_map);

	local_irq_restore(flags);



	efi_call_phys_epilog();

	efi_call_phys_epilog(save_pgd);



	return status;

}

arch/x86/platform/efi/efi_32.c

+8 −3
Original line number Diff line number Diff line
@@ -56,19 +56,24 @@ void __init efi_map_region(efi_memory_desc_t *md) 
void __init efi_map_region_fixed(efi_memory_desc_t *md) {}

void __init parse_efi_setup(u64 phys_addr, u32 data_len) {}



void __init efi_call_phys_prolog(void)

pgd_t * __init efi_call_phys_prolog(void)

{

	struct desc_ptr gdt_descr;

	pgd_t *save_pgd;



	/* Current pgd is swapper_pg_dir, we'll restore it later: */

	save_pgd = swapper_pg_dir;

	load_cr3(initial_page_table);

	__flush_tlb_all();



	gdt_descr.address = __pa(get_cpu_gdt_table(0));

	gdt_descr.size = GDT_SIZE - 1;

	load_gdt(&gdt_descr);



	return save_pgd;

}



void __init efi_call_phys_epilog(void)

void __init efi_call_phys_epilog(pgd_t *save_pgd)

{

	struct desc_ptr gdt_descr;
@@ -76,7 +81,7 @@ void __init efi_call_phys_epilog(void) 
	gdt_descr.size = GDT_SIZE - 1;

	load_gdt(&gdt_descr);



	load_cr3(swapper_pg_dir);

	load_cr3(save_pgd);

	__flush_tlb_all();

}

arch/x86/platform/efi/efi_64.c

+16 −10
Original line number Diff line number Diff line
@@ -41,8 +41,6 @@ 
#include <asm/realmode.h>

#include <asm/time.h>



static pgd_t *save_pgd __initdata;



/*

 * We allocate runtime services regions bottom-up, starting from -4G, i.e.

 * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
@@ -77,14 +75,16 @@ static void __init early_code_mapping_set_exec(int executable) 
	}

}



void __init efi_call_phys_prolog(void)

pgd_t * __init efi_call_phys_prolog(void)

{

	unsigned long vaddress;

	pgd_t *save_pgd;



	int pgd;

	int n_pgds;



	if (!efi_enabled(EFI_OLD_MEMMAP))

		return;

		return NULL;



	early_code_mapping_set_exec(1);
@@ -97,22 +97,28 @@ void __init efi_call_phys_prolog(void) 
		set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress));

	}

	__flush_tlb_all();



	return save_pgd;

}



void __init efi_call_phys_epilog(void)

void __init efi_call_phys_epilog(pgd_t *save_pgd)

{

	/*

	 * After the lock is released, the original page table is restored.

	 */

	int pgd;

	int n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);

	int pgd_idx;

	int nr_pgds;



	if (!efi_enabled(EFI_OLD_MEMMAP))

	if (!save_pgd)

		return;



	for (pgd = 0; pgd < n_pgds; pgd++)

		set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), save_pgd[pgd]);

	nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);



	for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++)

		set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);



	kfree(save_pgd);



	__flush_tlb_all();

	early_code_mapping_set_exec(0);

}

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