Merge tag 'efi-next-for-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI updates from Ard Biesheuvel:
 "Another fairly sizable pull request, by EFI subsystem standards.

  Most of the work was done by me, some of it in collaboration with the
  distro and bootloader folks (GRUB, systemd-boot), where the main focus
  has been on removing pointless per-arch differences in the way EFI
  boots a Linux kernel.

   - Refactor the zboot code so that it incorporates all the EFI stub
     logic, rather than calling the decompressed kernel as a EFI app.

   - Add support for initrd= command line option to x86 mixed mode.

   - Allow initrd= to be used with arbitrary EFI accessible file systems
     instead of just the one the kernel itself was loaded from.

   - Move some x86-only handling and manipulation of the EFI memory map
     into arch/x86, as it is not used anywhere else.

   - More flexible handling of any random seeds provided by the boot
     environment (i.e., systemd-boot) so that it becomes available much
     earlier during the boot.

   - Allow improved arch-agnostic EFI support in loaders, by setting a
     uniform baseline of supported features, and adding a generic magic
     number to the DOS/PE header. This should allow loaders such as GRUB
     or systemd-boot to reduce the amount of arch-specific handling
     substantially.

   - (arm64) Run EFI runtime services from a dedicated stack, and use it
     to recover from synchronous exceptions that might occur in the
     firmware code.

   - (arm64) Ensure that we don't allocate memory outside of the 48-bit
     addressable physical range.

   - Make EFI pstore record size configurable

   - Add support for decoding CXL specific CPER records"

* tag 'efi-next-for-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi: (43 commits)
  arm64: efi: Recover from synchronous exceptions occurring in firmware
  arm64: efi: Execute runtime services from a dedicated stack
  arm64: efi: Limit allocations to 48-bit addressable physical region
  efi: Put Linux specific magic number in the DOS header
  efi: libstub: Always enable initrd command line loader and bump version
  efi: stub: use random seed from EFI variable
  efi: vars: prohibit reading random seed variables
  efi: random: combine bootloader provided RNG seed with RNG protocol output
  efi/cper, cxl: Decode CXL Error Log
  efi/cper, cxl: Decode CXL Protocol Error Section
  efi: libstub: fix efi_load_initrd_dev_path() kernel-doc comment
  efi: x86: Move EFI runtime map sysfs code to arch/x86
  efi: runtime-maps: Clarify purpose and enable by default for kexec
  efi: pstore: Add module parameter for setting the record size
  efi: xen: Set EFI_PARAVIRT for Xen dom0 boot on all architectures
  efi: memmap: Move manipulation routines into x86 arch tree
  efi: memmap: Move EFI fake memmap support into x86 arch tree
  efi: libstub: Undeprecate the command line initrd loader
  efi: libstub: Add mixed mode support to command line initrd loader
  efi: libstub: Permit mixed mode return types other than efi_status_t
  ...

1 files changed, 36 insertions, 3 deletions

diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S
index 75691a2641c1..a00886410537 100644
--- a/arch/arm64/kernel/efi-rt-wrapper.S
+++ b/arch/arm64/kernel/efi-rt-wrapper.S
@@ -6,7 +6,7 @@
 #include <linux/linkage.h>
 
 SYM_FUNC_START(__efi_rt_asm_wrapper)
-	stp	x29, x30, [sp, #-32]!
+	stp	x29, x30, [sp, #-112]!
 	mov	x29, sp
 
 	/*
@@ -17,6 +17,22 @@ SYM_FUNC_START(__efi_rt_asm_wrapper)
 	stp	x1, x18, [sp, #16]
 
 	/*
+	 * Preserve all callee saved registers and preserve the stack pointer
+	 * value at the base of the EFI runtime stack so we can recover from
+	 * synchronous exceptions occurring while executing the firmware
+	 * routines.
+	 */
+	stp	x19, x20, [sp, #32]
+	stp	x21, x22, [sp, #48]
+	stp	x23, x24, [sp, #64]
+	stp	x25, x26, [sp, #80]
+	stp	x27, x28, [sp, #96]
+
+	ldr_l	x16, efi_rt_stack_top
+	mov	sp, x16
+	stp	x18, x29, [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.
@@ -29,9 +45,10 @@ SYM_FUNC_START(__efi_rt_asm_wrapper)
 	mov	x4, x6
 	blr	x8
 
+	mov	sp, x29
 	ldp	x1, x2, [sp, #16]
 	cmp	x2, x18
-	ldp	x29, x30, [sp], #32
+	ldp	x29, x30, [sp], #112
 	b.ne	0f
 	ret
 0:
@@ -42,6 +59,22 @@ SYM_FUNC_START(__efi_rt_asm_wrapper)
 	 * called with preemption disabled and a separate shadow stack is used
 	 * for interrupts.
 	 */
-	mov	x18, x2
+#ifdef CONFIG_SHADOW_CALL_STACK
+	ldr_l	x18, efi_rt_stack_top
+	ldr	x18, [x18, #-16]
+#endif
+
 	b	efi_handle_corrupted_x18	// tail call
 SYM_FUNC_END(__efi_rt_asm_wrapper)
+
+SYM_CODE_START(__efi_rt_asm_recover)
+	mov	sp, x30
+
+	ldp	x19, x20, [sp, #32]
+	ldp	x21, x22, [sp, #48]
+	ldp	x23, x24, [sp, #64]
+	ldp	x25, x26, [sp, #80]
+	ldp	x27, x28, [sp, #96]
+	ldp	x29, x30, [sp], #112
+	ret
+SYM_CODE_END(__efi_rt_asm_recover)