[RFC PATCH v4 35/37] arm64: entry: Annotate code switching to tasks

[Chen Zhongjin]

From: Julien Thierry <jthierry@xxxxxxxxxx>

Add UNWIND_HINT_REGS in kernel_entry after saving pt_regs.

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

Signed-off-by: Julien Thierry <jthierry@xxxxxxxxxx>
Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>
---
 arch/arm64/kernel/entry.S | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index eeb576ec97ba..c7ab5143949f 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -220,6 +220,7 @@ 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
@@ -602,6 +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
@@ -874,6 +876,7 @@ 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