From 99a5603e2a1f146ac0c6414d8a3669aa749ccff8 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 4 Jul 2014 17:25:09 +0200 Subject: [PATCH] efi/arm64: Handle missing virtual mapping for UEFI System Table If we cannot resolve the virtual address of the UEFI System Table, its physical offset must be missing from the virtual memory map, and there is really no point in proceeding with installing the virtual memory map and the runtime services dispatch table. So back out gracefully. Signed-off-by: Ard Biesheuvel Acked-by: Mark Salter Acked-by: Catalin Marinas Signed-off-by: Matt Fleming --- arch/arm64/kernel/efi.c | 28 ++++++++++++++++++++++++---- 1 file changed, 24 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c index 56c3327bbf79..e72f3100958f 100644 --- a/arch/arm64/kernel/efi.c +++ b/arch/arm64/kernel/efi.c @@ -414,13 +414,24 @@ static int __init arm64_enter_virtual_mode(void) for_each_efi_memory_desc(&memmap, md) { if (!(md->attribute & EFI_MEMORY_RUNTIME)) continue; - if (remap_region(md, &virt_md)) - ++count; + if (!remap_region(md, &virt_md)) + goto err_unmap; + ++count; } efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table); - if (efi.systab) - set_bit(EFI_SYSTEM_TABLES, &efi.flags); + if (!efi.systab) { + /* + * If we have no virtual mapping for the System Table at this + * point, the memory map doesn't cover the physical offset where + * it resides. This means the System Table will be inaccessible + * to Runtime Services themselves once the virtual mapping is + * installed. + */ + pr_err("Failed to remap EFI System Table -- buggy firmware?\n"); + goto err_unmap; + } + set_bit(EFI_SYSTEM_TABLES, &efi.flags); local_irq_save(flags); cpu_switch_mm(idmap_pg_dir, &init_mm); @@ -453,5 +464,14 @@ static int __init arm64_enter_virtual_mode(void) set_bit(EFI_RUNTIME_SERVICES, &efi.flags); return 0; + +err_unmap: + /* unmap all mappings that succeeded: there are 'count' of those */ + for (virt_md = virtmap; count--; virt_md += memmap.desc_size) { + md = virt_md; + iounmap((__force void __iomem *)md->virt_addr); + } + kfree(virtmap); + return -1; } early_initcall(arm64_enter_virtual_mode); -- 2.11.0