From 5f0a4eba2a88480ce0e5d354768676086bae8f09 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 3 Jan 2020 12:39:46 +0100 Subject: [PATCH] efi/x86: Don't panic or BUG() on non-critical error conditions [ Upstream commit e2d68a955e49d61fd0384f23e92058dc9b79be5e ] The logic in __efi_enter_virtual_mode() does a number of steps in sequence, all of which may fail in one way or the other. In most cases, we simply print an error and disable EFI runtime services support, but in some cases, we BUG() or panic() and bring down the system when encountering conditions that we could easily handle in the same way. While at it, replace a pointless page-to-virt-phys conversion with one that goes straight from struct page to physical. Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arvind Sankar Cc: Matthew Garrett Cc: linux-efi@vger.kernel.org Link: https://lkml.kernel.org/r/20200103113953.9571-14-ardb@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- arch/x86/platform/efi/efi.c | 28 ++++++++++++++-------------- arch/x86/platform/efi/efi_64.c | 9 +++++---- 2 files changed, 19 insertions(+), 18 deletions(-) diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 8a4f389..01d7ca4 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -954,16 +954,14 @@ static void __init __efi_enter_virtual_mode(void) if (efi_alloc_page_tables()) { pr_err("Failed to allocate EFI page tables\n"); - clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); - return; + goto err; } efi_merge_regions(); new_memmap = efi_map_regions(&count, &pg_shift); if (!new_memmap) { pr_err("Error reallocating memory, EFI runtime non-functional!\n"); - clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); - return; + goto err; } pa = __pa(new_memmap); @@ -977,8 +975,7 @@ static void __init __efi_enter_virtual_mode(void) if (efi_memmap_init_late(pa, efi.memmap.desc_size * count)) { pr_err("Failed to remap late EFI memory map\n"); - clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); - return; + goto err; } if (efi_enabled(EFI_DBG)) { @@ -986,12 +983,11 @@ static void __init __efi_enter_virtual_mode(void) efi_print_memmap(); } - BUG_ON(!efi.systab); + if (WARN_ON(!efi.systab)) + goto err; - if (efi_setup_page_tables(pa, 1 << pg_shift)) { - clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); - return; - } + if (efi_setup_page_tables(pa, 1 << pg_shift)) + goto err; efi_sync_low_kernel_mappings(); @@ -1011,9 +1007,9 @@ static void __init __efi_enter_virtual_mode(void) } if (status != EFI_SUCCESS) { - pr_alert("Unable to switch EFI into virtual mode (status=%lx)!\n", - status); - panic("EFI call to SetVirtualAddressMap() failed!"); + pr_err("Unable to switch EFI into virtual mode (status=%lx)!\n", + status); + goto err; } efi_free_boot_services(); @@ -1042,6 +1038,10 @@ static void __init __efi_enter_virtual_mode(void) /* clean DUMMY object */ efi_delete_dummy_variable(); + return; + +err: + clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); } void __init efi_enter_virtual_mode(void) diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 08ce817..52a1e51 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -392,11 +392,12 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) return 0; page = alloc_page(GFP_KERNEL|__GFP_DMA32); - if (!page) - panic("Unable to allocate EFI runtime stack < 4GB\n"); + if (!page) { + pr_err("Unable to allocate EFI runtime stack < 4GB\n"); + return 1; + } - efi_scratch.phys_stack = virt_to_phys(page_address(page)); - efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */ + efi_scratch.phys_stack = page_to_phys(page + 1); /* stack grows down */ npages = (_etext - _text) >> PAGE_SHIFT; text = __pa(_text); -- 2.7.4