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Commit 7bc90e01 authored by Josh Triplett's avatar Josh Triplett Committed by H. Peter Anvin
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efi: Add a function to look up existing IO memory mappings 



The EFI initialization creates virtual mappings for EFI boot services
memory, so if a driver wants to access EFI boot services memory, it
cannot call ioremap itself; doing so will trip the WARN about mapping
RAM twice.  Thus, a driver accessing EFI boot services memory must do so
via the existing mapping already created during EFI intiialization.
Since the EFI code already maintains a memory map for that memory, add a
function efi_lookup_mapped_addr to look up mappings in that memory map.

Signed-off-by: default avatarJosh Triplett <josh@joshtriplett.org>
Link: http://lkml.kernel.org/r/0eb48ae012797912874919110660ad420b90268b.1348876882.git.josh@joshtriplett.org


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 78510792

arch/x86/platform/efi/efi.c

+28 −0
Original line number Diff line number Diff line
@@ -776,6 +776,34 @@ static void __init runtime_code_page_mkexec(void) 
	}

}



/*

 * We can't ioremap data in EFI boot services RAM, because we've already mapped

 * it as RAM.  So, look it up in the existing EFI memory map instead.  Only

 * callable after efi_enter_virtual_mode and before efi_free_boot_services.

 */

void __iomem *efi_lookup_mapped_addr(u64 phys_addr)

{

	void *p;

	if (WARN_ON(!memmap.map))

		return NULL;

	for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {

		efi_memory_desc_t *md = p;

		u64 size = md->num_pages << EFI_PAGE_SHIFT;

		u64 end = md->phys_addr + size;

		if (!(md->attribute & EFI_MEMORY_RUNTIME) &&

		    md->type != EFI_BOOT_SERVICES_CODE &&

		    md->type != EFI_BOOT_SERVICES_DATA)

			continue;

		if (!md->virt_addr)

			continue;

		if (phys_addr >= md->phys_addr && phys_addr < end) {

			phys_addr += md->virt_addr - md->phys_addr;

			return (__force void __iomem *)(unsigned long)phys_addr;

		}

	}

	return NULL;

}



/*

 * This function will switch the EFI runtime services to virtual mode.

 * Essentially, look through the EFI memmap and map every region that

include/linux/efi.h

+1 −0
Original line number Diff line number Diff line
@@ -501,6 +501,7 @@ extern void efi_free_boot_services(void); 
#else

static inline void efi_free_boot_services(void) {}

#endif

extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);

extern u64 efi_get_iobase (void);

extern u32 efi_mem_type (unsigned long phys_addr);

extern u64 efi_mem_attributes (unsigned long phys_addr);