[musl] [RFC PATCH 1/1] arm: Add CFA annotations to __syscall_cp_asm.

[musl] [RFC PATCH 1/1] arm: Add CFA annotations to __syscall_cp_asm.

[Ignacy Gawędzki]

When debugging a process that is currently in __syscall_cp_asm, GDB
loses track of the current frame once it passes __cp_begin.  At that
moment, the frame is at $sp + 16, and it seems GDB is unable to infer
that without proper support.

A remedy is to add CFI annotations to that part of code, to tell that
the frame starts at $ip, right after $sp has been saved to $ip.

Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr>
---
 src/thread/arm/syscall_cp.s | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/thread/arm/syscall_cp.s b/src/thread/arm/syscall_cp.s
index e607dd42..f5b9521e 100644
--- a/src/thread/arm/syscall_cp.s
+++ b/src/thread/arm/syscall_cp.s
@@ -10,7 +10,9 @@
 .hidden __syscall_cp_asm
 .type __syscall_cp_asm,%function
 __syscall_cp_asm:
+	.cfi_startproc
 	mov ip,sp
+	.cfi_def_cfa_register ip
 	stmfd sp!,{r4,r5,r6,r7}
 __cp_begin:
 	ldr r0,[r0]
@@ -27,3 +29,4 @@ __cp_end:
 __cp_cancel:
 	ldmfd sp!,{r4,r5,r6,r7}
 	b __cancel
+	.cfi_endproc
-- 
2.45.2