@@ -777,6 +777,34 @@ 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 *)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
* has the runtime attribute bit set in its memory descriptor and update
@@ -502,6 +502,7 @@ extern void efi_free_boot_services(void);
static void efi_enter_virtual_mode(void) {}
static 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);
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: Josh Triplett <josh@joshtriplett.org> --- arch/x86/platform/efi/efi.c | 28 ++++++++++++++++++++++++++++ include/linux/efi.h | 1 + 2 files changed, 29 insertions(+)