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Subject[PATCH 14/18] arm64: efi: restore x18 if it was corrupted
From
If we detect a corrupted x18 and SCS is enabled, restore the register
before jumping back to instrumented code.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
arch/arm64/kernel/efi-rt-wrapper.S | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S
index 3fc71106cb2b..945744f16086 100644
--- a/arch/arm64/kernel/efi-rt-wrapper.S
+++ b/arch/arm64/kernel/efi-rt-wrapper.S
@@ -34,5 +34,10 @@ ENTRY(__efi_rt_asm_wrapper)
ldp x29, x30, [sp], #32
b.ne 0f
ret
-0: b efi_handle_corrupted_x18 // tail call
+0:
+#ifdef CONFIG_SHADOW_CALL_STACK
+ /* Restore x18 before returning to instrumented code. */
+ mov x18, x2
+#endif
+ b efi_handle_corrupted_x18 // tail call
ENDPROC(__efi_rt_asm_wrapper)
--
2.23.0.866.gb869b98d4c-goog
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