Merge tag 'efi-next' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi into efi/core

Pull EFI updates for v4.20 from Ard Biesheuvel:

- Add support for enlisting the help of the EFI firmware to create memory
  reservations that persist across kexec.
- Add page fault handling to the runtime services support code on x86 so
  we can gracefully recover from buggy EFI firmware.
- Fix command line handling on x86 for the boot path that omits the stub's
  PE/COFF entry point.
- Other assorted fixes.

arch/x86/mm/fault.c

@@ -16,6 +16,7 @@
 #include <linux/prefetch.h>		/* prefetchw			*/
 #include <linux/context_tracking.h>	/* exception_enter(), ...	*/
 #include <linux/uaccess.h>		/* faulthandler_disabled()	*/
+#include <linux/efi.h>			/* efi_recover_from_page_fault()*/
 #include <linux/mm_types.h>
 
 #include <asm/cpufeature.h>		/* boot_cpu_has, ...		*/
@@ -25,6 +26,7 @@
 #include <asm/vsyscall.h>		/* emulate_vsyscall		*/
 #include <asm/vm86.h>			/* struct vm86			*/
 #include <asm/mmu_context.h>		/* vma_pkey()			*/
+#include <asm/efi.h>			/* efi_recover_from_page_fault()*/
 
 #define CREATE_TRACE_POINTS
 #include <asm/trace/exceptions.h>
@@ -788,6 +790,13 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 	if (is_errata93(regs, address))
 		return;
 
+	/*
+	 * Buggy firmware could access regions which might page fault, try to
+	 * recover from such faults.
+	 */
+	if (IS_ENABLED(CONFIG_EFI))
+		efi_recover_from_page_fault(address);
+
 	/*
 	 * Oops. The kernel tried to access some bad page. We'll have to
 	 * terminate things with extreme prejudice: