From 5bc653b7318217c54244a14f248f1f07abe0a865 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 10 Aug 2016 02:29:17 -0700 Subject: x86/efi: Allocate a trampoline if needed in efi_free_boot_services() On my Dell XPS 13 9350 with firmware 1.4.4 and SGX on, if I boot Fedora 24's grub2-efi off a hard disk, my first 1MB of RAM looks like: efi: mem00: [Runtime Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x0000000000000000-0x0000000000000fff] (0MB) efi: mem01: [Boot Data | | | | | | | | |WB|WT|WC|UC] range=[0x0000000000001000-0x0000000000027fff] (0MB) efi: mem02: [Loader Data | | | | | | | | |WB|WT|WC|UC] range=[0x0000000000028000-0x0000000000029fff] (0MB) efi: mem03: [Reserved | | | | | | | | |WB|WT|WC|UC] range=[0x000000000002a000-0x000000000002bfff] (0MB) efi: mem04: [Runtime Data |RUN| | | | | | | |WB|WT|WC|UC] range=[0x000000000002c000-0x000000000002cfff] (0MB) efi: mem05: [Loader Data | | | | | | | | |WB|WT|WC|UC] range=[0x000000000002d000-0x000000000002dfff] (0MB) efi: mem06: [Conventional Memory| | | | | | | | |WB|WT|WC|UC] range=[0x000000000002e000-0x0000000000057fff] (0MB) efi: mem07: [Reserved | | | | | | | | |WB|WT|WC|UC] range=[0x0000000000058000-0x0000000000058fff] (0MB) efi: mem08: [Conventional Memory| | | | | | | | |WB|WT|WC|UC] range=[0x0000000000059000-0x000000000009ffff] (0MB) My EBDA is at 0x2c000, which blocks off everything from 0x2c000 and up, and my trampoline is 0x6000 bytes (6 pages), so it doesn't fit in the loader data range at 0x28000. Without this patch, it panics due to a failure to allocate the trampoline. With this patch, it works: [ +0.001744] Base memory trampoline at [ffff880000001000] 1000 size 24576 Signed-off-by: Andy Lutomirski Reviewed-by: Matt Fleming Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Mario Limonciello Cc: Matt Fleming Cc: Matthew Garrett Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/998c77b3bf709f3dfed85cb30701ed1a5d8a438b.1470821230.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/platform/efi/quirks.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 4480c06cade7..89d1146f5a6f 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -254,6 +254,7 @@ void __init efi_free_boot_services(void) for_each_efi_memory_desc(md) { unsigned long long start = md->phys_addr; unsigned long long size = md->num_pages << EFI_PAGE_SHIFT; + size_t rm_size; if (md->type != EFI_BOOT_SERVICES_CODE && md->type != EFI_BOOT_SERVICES_DATA) @@ -263,6 +264,26 @@ void __init efi_free_boot_services(void) if (md->attribute & EFI_MEMORY_RUNTIME) continue; + /* + * Nasty quirk: if all sub-1MB memory is used for boot + * services, we can get here without having allocated the + * real mode trampoline. It's too late to hand boot services + * memory back to the memblock allocator, so instead + * try to manually allocate the trampoline if needed. + * + * I've seen this on a Dell XPS 13 9350 with firmware + * 1.4.4 with SGX enabled booting Linux via Fedora 24's + * grub2-efi on a hard disk. (And no, I don't know why + * this happened, but Linux should still try to boot rather + * panicing early.) + */ + rm_size = real_mode_size_needed(); + if (rm_size && (start + rm_size) < (1<<20) && size >= rm_size) { + set_real_mode_mem(start, rm_size); + start += rm_size; + size -= rm_size; + } + free_bootmem_late(start, size); } -- cgit v1.2.3-58-ga151