[musl] [PATCH 1/2] mipsel: Add debug information to __syscall_cp_asm

[Daniel Santos <daniel.santos@pobox.com>]

This is the function called for interruptable / repeatable syscalls like
nanosleep.  Without this patch, attaching a debugger to a program making
such a syscall results in the debugger being completely unable to
perform a backtrace.

Co-Authored-By: Daniele Tamino <dtamino@irobot.com>
Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
---
 src/thread/mips/syscall_cp.s | 41 +++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/thread/mips/syscall_cp.s b/src/thread/mips/syscall_cp.s
index d2846264..d39bff59 100644
--- a/src/thread/mips/syscall_cp.s
+++ b/src/thread/mips/syscall_cp.s
@@ -1,4 +1,14 @@
+.section	.mdebug.abi32
+.previous
 .set    noreorder
+.cfi_sections	.debug_frame
+.abicalls
+#ifdef __PIC__
+	.option	pic2
+#else
+	.option	pic0
+#endif
+.text
 
 .global __cp_begin
 .hidden __cp_begin
@@ -9,12 +19,32 @@
 .global __cp_cancel
 .hidden __cp_cancel
 .type   __cp_cancel,@function
-.hidden __cancel
+.hidden __cancel	/* long __cancel() in src/thread/pthread_cancel.c */
 .global __syscall_cp_asm
 .hidden __syscall_cp_asm
 .type   __syscall_cp_asm,@function
+
+/*
+long __syscall_cp_asm(
+	volatile int *cancel,
+	syscall_arg_t nr,
+	syscall_arg_t u,
+	syscall_arg_t v,
+	syscall_arg_t w,
+	syscall_arg_t x,
+	syscall_arg_t y,
+	syscall_arg_t z)
+*/
+
+	.ent	__syscall_cp_asm
+	.frame	$sp, 32, $ra
+	.mask	0x00000000, 0
+	.fmask	0x00000000, 0
+	.cfi_startproc
+	.cfi_return_column $ra
 __syscall_cp_asm:
 	subu    $sp, $sp, 32
+	.cfi_adjust_cfa_offset 32
 __cp_begin:
 	lw      $4, 0($4)
 	bne     $4, $0, __cp_cancel
@@ -35,14 +65,17 @@ __cp_begin:
 __cp_end:
 	beq     $7, $0, 1f
 	addu    $sp, $sp, 32
+	.cfi_adjust_cfa_offset -32
 	subu    $2, $0, $2
 1:	jr      $ra
 	nop
 
 __cp_cancel:
 	move    $2, $ra
+	.cfi_register $ra, $2
 	bal     1f
 	addu    $sp, $sp, 32
+	.cfi_adjust_cfa_offset -32
 	.gpword .
 	.gpword __cancel
 1:	lw      $3, ($ra)
@@ -51,3 +84,9 @@ __cp_cancel:
 	addu    $25, $25, $3
 	jr      $25
 	move    $ra, $2
+	.cfi_restore $ra
+#ifdef __ELF__
+	.size __syscall_cp_asm,.-__syscall_cp_asm
+#endif
+	.end	__syscall_cp_asm
+	.cfi_endproc
-- 
2.24.1