[PATCH 01/12] arm64/bti: Add BTI landing pad to __sdei_asm_handler()

[Josh Poimboeuf]

With CONFIG_UNMAP_KERNEL_AT_EL0, __sdei_asm_entry_trampoline() indirect
jumps to __sdei_asm_handler().  Add "bti j" to prevent a Branch Target
exception.

Discovered by code inspection.

Fixes: c50d32859e70 ("arm64: Add types to indirect called assembly functions")
Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org>
---
 arch/arm64/kernel/entry.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index e0db14e9c843a..16c21fcb41976 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -976,6 +976,7 @@ NOKPROBE(__sdei_asm_exit_trampoline)
  * want them.
  */
 SYM_CODE_START(__sdei_asm_handler)
+       bti     j
        stp     x2, x3, [x1, #SDEI_EVENT_INTREGS + S_PC]
        stp     x4, x5, [x1, #SDEI_EVENT_INTREGS + 16 * 2]
        stp     x6, x7, [x1, #SDEI_EVENT_INTREGS + 16 * 3]
-- 
2.55.0