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

Pull EFI updates from Ingo Molnar:
 "The main EFI changes in this cycle were:

   - Fix the apple-properties code (Andy Shevchenko)

   - Add WARN() on arm64 if UEFI Runtime Services corrupt the reserved
     x18 register (Ard Biesheuvel)

   - Use efi_switch_mm() on x86 instead of manipulating %cr3 directly
     (Sai Praneeth)

   - Fix early memremap leak in ESRT code (Ard Biesheuvel)

   - Switch to L"xxx" notation for wide string literals (Ard Biesheuvel)

   - ... plus misc other cleanups and bugfixes"

* 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3
  x86/efi: Replace efi_pgd with efi_mm.pgd
  efi: Use string literals for efi_char16_t variable initializers
  efi/esrt: Fix handling of early ESRT table mapping
  efi: Use efi_mm in x86 as well as ARM
  efi: Make const array 'apple' static
  efi/apple-properties: Use memremap() instead of ioremap()
  efi: Reorder pr_notice() with add_device_randomness() call
  x86/efi: Replace GFP_ATOMIC with GFP_KERNEL in efi_query_variable_store()
  efi/arm64: Check whether x18 is preserved by runtime services calls
  efi/arm*: Stop printing addresses of virtual mappings
  efi/apple-properties: Remove redundant attribute initialization from unmarshal_key_value_pairs()
  efi/arm*: Only register page tables when they exist

4 files changed, 52 insertions, 2 deletions

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 8389050328bb..192d791f1103 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -31,7 +31,7 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
 ({									\
 	efi_##f##_t *__f;						\
 	__f = p->f;							\
-	__f(args);							\
+	__efi_rt_asm_wrapper(__f, #f, args);				\
 })
 
 #define arch_efi_call_virt_teardown()					\
@@ -40,6 +40,8 @@ int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md);
 	efi_virtmap_unload();						\
 })
 
+efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...);
+
 #define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
 
 /* arch specific definitions used by the stub code */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index b87541360f43..6a4bd80c75bd 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -38,7 +38,8 @@ arm64-obj-$(CONFIG_CPU_PM)		+= sleep.o suspend.o
 arm64-obj-$(CONFIG_CPU_IDLE)		+= cpuidle.o
 arm64-obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
 arm64-obj-$(CONFIG_KGDB)		+= kgdb.o
-arm64-obj-$(CONFIG_EFI)			+= efi.o efi-entry.stub.o
+arm64-obj-$(CONFIG_EFI)			+= efi.o efi-entry.stub.o		\
+					   efi-rt-wrapper.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)		+= acpi.o
diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S
new file mode 100644
index 000000000000..05235ebb336d
--- /dev/null
+++ b/arch/arm64/kernel/efi-rt-wrapper.S
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2018 Linaro Ltd <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+
+ENTRY(__efi_rt_asm_wrapper)
+	stp	x29, x30, [sp, #-32]!
+	mov	x29, sp
+
+	/*
+	 * Register x18 is designated as the 'platform' register by the AAPCS,
+	 * which means firmware running at the same exception level as the OS
+	 * (such as UEFI) should never touch it.
+	 */
+	stp	x1, x18, [sp, #16]
+
+	/*
+	 * We are lucky enough that no EFI runtime services take more than
+	 * 5 arguments, so all are passed in registers rather than via the
+	 * stack.
+	 */
+	mov	x8, x0
+	mov	x0, x2
+	mov	x1, x3
+	mov	x2, x4
+	mov	x3, x5
+	mov	x4, x6
+	blr	x8
+
+	ldp	x1, x2, [sp, #16]
+	cmp	x2, x18
+	ldp	x29, x30, [sp], #32
+	b.ne	0f
+	ret
+0:	b	efi_handle_corrupted_x18	// tail call
+ENDPROC(__efi_rt_asm_wrapper)
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index a8bf1c892b90..4f9acb5fbe97 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -126,3 +126,9 @@ bool efi_poweroff_required(void)
 {
 	return efi_enabled(EFI_RUNTIME_SERVICES);
 }
+
+asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f)
+{
+	pr_err_ratelimited(FW_BUG "register x18 corrupted by EFI %s\n", f);
+	return s;
+}