Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "This is bigger than usual - the reason is partly a pent-up stream of
  fixes after the merge window and partly accidental.  The fixes are:

   - five patches to fix a boot failure on Andy Lutomirsky's laptop
   - four SGI UV platform fixes
   - KASAN fix
   - warning fix
   - documentation update
   - swap entry definition fix
   - pkeys fix
   - irq stats fix"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/apic/x2apic, smp/hotplug: Don't use before alloc in x2apic_cluster_probe()
  x86/efi: Allocate a trampoline if needed in efi_free_boot_services()
  x86/boot: Rework reserve_real_mode() to allow multiple tries
  x86/boot: Defer setup_real_mode() to early_initcall time
  x86/boot: Synchronize trampoline_cr4_features and mmu_cr4_features directly
  x86/boot: Run reserve_bios_regions() after we initialize the memory map
  x86/irq: Do not substract irq_tlb_count from irq_call_count
  x86/mm: Fix swap entry comment and macro
  x86/mm/kaslr: Fix -Wformat-security warning
  x86/mm/pkeys: Fix compact mode by removing protection keys' XSAVE buffer manipulation
  x86/build: Reduce the W=1 warnings noise when compiling x86 syscall tables
  x86/platform/UV: Fix kernel panic running RHEL kdump kernel on UV systems
  x86/platform/UV: Fix problem with UV4 BIOS providing incorrect PXM values
  x86/platform/UV: Fix bug with iounmap() of the UV4 EFI System Table causing a crash
  x86/platform/UV: Fix problem with UV4 Socket IDs not being contiguous
  x86/entry: Clarify the RF saving/restoring situation with SYSCALL/SYSRET
  x86/mm: Disable preemption during CR3 read+write
  x86/mm/KASLR: Increase BRK pages for KASLR memory randomization
  x86/mm/KASLR: Fix physical memory calculation on KASLR memory randomization
  x86, kasan, ftrace: Put APIC interrupt handlers into .irqentry.text

1 files changed, 21 insertions, 0 deletions

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);
 	}