[PATCH v5 30/33] arm64: entry: Align stack size for alternative
From: Chen Zhongjin <hidden>
Date: 2022-06-22 15:56:30
Also in:
linux-arch, linux-arm-kernel, linux-kbuild, live-patching, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
In kernel_exit there is a alternative branch for KPTI which causes stack size conflict for two instruction boundaries. To fix that, make both branch move the sp and then revert it in tramp_exit branch. Signed-off-by: Chen Zhongjin <redacted> --- arch/arm64/kernel/entry.S | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index d49bfbe81a0d..677e3be471bb 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S@@ -430,7 +430,11 @@ alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 ldr lr, [sp, #S_LR] add sp, sp, #PT_REGS_SIZE // restore sp eret -alternative_else_nop_endif +alternative_else + nop + add sp, sp, #PT_REGS_SIZE // restore sp + nop +alternative_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 bne 4f msr far_el1, x29
@@ -729,6 +733,7 @@ alternative_else_nop_endif .macro tramp_exit, regsize = 64 UNWIND_HINT_EMPTY + sub sp, sp, #PT_REGS_SIZE // revert sp tramp_data_read_var x30, this_cpu_vector get_this_cpu_offset x29 ldr x30, [x30, x29]
--
2.17.1