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Subject[PATCH v6 20/33] arm64: entry: Annotate unwind_hint for entry
Date
When taking an exception/interrupt, add UNWIND_HINT_REGS to indicate
from which point the pt_regs is on stack.

Whether returning to userland or creating a new task, sp is
pointing to a pt_regs frame, add UNWIND_HINT_REGS after that.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
---
arch/arm64/kernel/entry.S | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 3bd11101e79d..bbc440379304 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -120,6 +120,7 @@
alternative_cb spectre_v4_patch_fw_mitigation_enable
b .L__asm_ssbd_skip\@ // Patched to NOP
alternative_cb_end
+ UNWIND_HINT_REGS
ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1
cbz \tmp2, .L__asm_ssbd_skip\@
ldr \tmp2, [tsk, #TSK_TI_FLAGS]
@@ -218,6 +219,7 @@ alternative_cb_end
stp x24, x25, [sp, #16 * 12]
stp x26, x27, [sp, #16 * 13]
stp x28, x29, [sp, #16 * 14]
+ UNWIND_HINT_REGS

.if \el == 0
clear_gp_regs
@@ -601,6 +603,7 @@ SYM_CODE_START_LOCAL(ret_to_kernel)
SYM_CODE_END(ret_to_kernel)

SYM_CODE_START_LOCAL(ret_to_user)
+ UNWIND_HINT_REGS
ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step
enable_step_tsk x19, x2
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
@@ -872,6 +875,7 @@ NOKPROBE(cpu_switch_to)
* This is how we return from a fork.
*/
SYM_CODE_START(ret_from_fork)
+ UNWIND_HINT_REGS
bl schedule_tail
cbz x19, 1f // not a kernel thread
mov x0, x20
--
2.17.1
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