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Commit 23a0d4e8 authored by Ingo Molnar's avatar Ingo Molnar Committed by Matt Fleming
Browse files

efi: Disable interrupts around EFI calls, not in the epilog/prolog calls 



Tapasweni Pathak reported that we do a kmalloc() in efi_call_phys_prolog()
on x86-64 while having interrupts disabled, which is a big no-no, as
kmalloc() can sleep.

Solve this by removing the irq disabling from the prolog/epilog calls
around EFI calls: it's unnecessary, as in this stage we are single
threaded in the boot thread, and we don't ever execute this from
interrupt contexts.

Reported-by: default avatarTapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
parent fed6cefe

arch/x86/platform/efi/efi.c

+7 −0
Original line number Diff line number Diff line
@@ -85,12 +85,19 @@ static efi_status_t __init phys_efi_set_virtual_address_map( 
	efi_memory_desc_t *virtual_map)

{

	efi_status_t status;

	unsigned long flags;



	efi_call_phys_prolog();



	/* Disable interrupts around EFI calls: */

	local_irq_save(flags);

	status = efi_call_phys(efi_phys.set_virtual_address_map,

			       memory_map_size, descriptor_size,

			       descriptor_version, virtual_map);

	local_irq_restore(flags);



	efi_call_phys_epilog();



	return status;

}

arch/x86/platform/efi/efi_32.c

+3 −8
Original line number Diff line number Diff line
@@ -33,11 +33,10 @@ 


/*

 * To make EFI call EFI runtime service in physical addressing mode we need

 * prolog/epilog before/after the invocation to disable interrupt, to

 * claim EFI runtime service handler exclusively and to duplicate a memory in

 * low memory space say 0 - 3G.

 * prolog/epilog before/after the invocation to claim the EFI runtime service

 * handler exclusively and to duplicate a memory mapping in low memory space,

 * say 0 - 3G.

 */

static unsigned long efi_rt_eflags;



void efi_sync_low_kernel_mappings(void) {}

void __init efi_dump_pagetable(void) {}
@@ -61,8 +60,6 @@ void __init efi_call_phys_prolog(void) 
{

	struct desc_ptr gdt_descr;



	local_irq_save(efi_rt_eflags);



	load_cr3(initial_page_table);

	__flush_tlb_all();
@@ -81,8 +78,6 @@ void __init efi_call_phys_epilog(void) 


	load_cr3(swapper_pg_dir);

	__flush_tlb_all();



	local_irq_restore(efi_rt_eflags);

}



void __init efi_runtime_mkexec(void)

arch/x86/platform/efi/efi_64.c

+0 −3
Original line number Diff line number Diff line
@@ -42,7 +42,6 @@ 
#include <asm/time.h>



static pgd_t *save_pgd __initdata;

static unsigned long efi_flags __initdata;



/*

 * We allocate runtime services regions bottom-up, starting from -4G, i.e.
@@ -88,7 +87,6 @@ void __init efi_call_phys_prolog(void) 
		return;



	early_code_mapping_set_exec(1);

	local_irq_save(efi_flags);



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

	save_pgd = kmalloc(n_pgds * sizeof(pgd_t), GFP_KERNEL);
@@ -116,7 +114,6 @@ void __init efi_call_phys_epilog(void) 
		set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), save_pgd[pgd]);

	kfree(save_pgd);

	__flush_tlb_all();

	local_irq_restore(efi_flags);

	early_code_mapping_set_exec(0);

}