Fix dwarf2 unwinding through futex functions.

When profiling programs with lock problems with perf record -g dwarf,
libunwind can currently not backtrace through the futex and unlock
functions in pthread. This is because they use out of line sections,
and those are not correctly described in dwarf2 (I believe needs
dwarf3 or 4).

This patch first removes the out of line sections. They only save a
single jump, but cause a lot of pain. Then it converts the now inline
lock code to use the now standard gas .cfi_* commands.

With these changes libunwind/perf can backtrace through the futex
functions now.

Longer term it would be likely better to just use C futex() functions
on x86 like all the other architectures. This would clean the code up
even more.

1 files changed, 10 insertions, 157 deletions

diff --git a/nptl/sysdeps/unix/sysv/linux/i386/lowlevellock.h b/nptl/sysdeps/unix/sysv/linux/i386/lowlevellock.h
index 44ef4190b5..6903f92bd0 100644
--- a/nptl/sysdeps/unix/sysv/linux/i386/lowlevellock.h
+++ b/nptl/sysdeps/unix/sysv/linux/i386/lowlevellock.h
@@ -126,83 +126,6 @@
 /* Delay in spinlock loop.  */
 #define BUSY_WAIT_NOP	asm ("rep; nop")
 
-
-#define LLL_STUB_UNWIND_INFO_START \
-	".section	.eh_frame,\"a\",@progbits\n"		\
-"5:\t"	".long	7f-6f	# Length of Common Information Entry\n"	\
-"6:\t"	".long	0x0	# CIE Identifier Tag\n\t"		\
-	".byte	0x1	# CIE Version\n\t"			\
-	".ascii \"zR\\0\"	# CIE Augmentation\n\t"		\
-	".uleb128 0x1	# CIE Code Alignment Factor\n\t"	\
-	".sleb128 -4	# CIE Data Alignment Factor\n\t"	\
-	".byte	0x8	# CIE RA Column\n\t"			\
-	".uleb128 0x1	# Augmentation size\n\t"		\
-	".byte	0x1b	# FDE Encoding (pcrel sdata4)\n\t"	\
-	".byte	0xc	# DW_CFA_def_cfa\n\t"			\
-	".uleb128 0x4\n\t"					\
-	".uleb128 0x0\n\t"					\
-	".align 4\n"						\
-"7:\t"	".long	17f-8f	# FDE Length\n"				\
-"8:\t"	".long	8b-5b	# FDE CIE offset\n\t"			\
-	".long	1b-.	# FDE initial location\n\t"		\
-	".long	4b-1b	# FDE address range\n\t"		\
-	".uleb128 0x0	# Augmentation size\n\t"		\
-	".byte	0x16	# DW_CFA_val_expression\n\t"		\
-	".uleb128 0x8\n\t"					\
-	".uleb128 10f-9f\n"					\
-"9:\t"	".byte	0x78	# DW_OP_breg8\n\t"			\
-	".sleb128 3b-1b\n"
-#define LLL_STUB_UNWIND_INFO_END \
-	".byte	0x16	# DW_CFA_val_expression\n\t"		\
-	".uleb128 0x8\n\t"					\
-	".uleb128 12f-11f\n"					\
-"11:\t"	".byte	0x78	# DW_OP_breg8\n\t"			\
-	".sleb128 3b-2b\n"					\
-"12:\t"	".byte	0x40 + (3b-2b-1) # DW_CFA_advance_loc\n\t"	\
-	".byte	0x16	# DW_CFA_val_expression\n\t"		\
-	".uleb128 0x8\n\t"					\
-	".uleb128 16f-13f\n"					\
-"13:\t"	".byte	0x78	# DW_OP_breg8\n\t"			\
-	".sleb128 15f-14f\n\t"					\
-	".byte	0x0d	# DW_OP_const4s\n"			\
-"14:\t"	".4byte	3b-.\n\t"					\
-	".byte	0x1c	# DW_OP_minus\n\t"			\
-	".byte	0x0d	# DW_OP_const4s\n"			\
-"15:\t"	".4byte	18f-.\n\t"					\
-	".byte	0x22	# DW_OP_plus\n"				\
-"16:\t"	".align 4\n"						\
-"17:\t"	".previous\n"
-
-/* Unwind info for
-   1: lea ..., ...
-   2: call ...
-   3: jmp 18f
-   4:
-   snippet.  */
-#define LLL_STUB_UNWIND_INFO_3 \
-LLL_STUB_UNWIND_INFO_START					\
-"10:\t"	".byte	0x40 + (2b-1b) # DW_CFA_advance_loc\n\t"	\
-LLL_STUB_UNWIND_INFO_END
-
-/* Unwind info for
-   1: lea ..., ...
-   0: movl ..., ...
-   2: call ...
-   3: jmp 18f
-   4:
-   snippet.  */
-#define LLL_STUB_UNWIND_INFO_4 \
-LLL_STUB_UNWIND_INFO_START					\
-"10:\t"	".byte	0x40 + (0b-1b) # DW_CFA_advance_loc\n\t"	\
-	".byte	0x16	# DW_CFA_val_expression\n\t"		\
-	".uleb128 0x8\n\t"					\
-	".uleb128 20f-19f\n"					\
-"19:\t"	".byte	0x78	# DW_OP_breg8\n\t"			\
-	".sleb128 3b-0b\n"					\
-"20:\t"	".byte	0x40 + (2b-0b) # DW_CFA_advance_loc\n\t"	\
-LLL_STUB_UNWIND_INFO_END
-
-
 #define lll_futex_wait(futex, val, private) \
   lll_futex_timed_wait (futex, val, NULL, private)
 
@@ -298,16 +221,9 @@ LLL_STUB_UNWIND_INFO_END
     ({ int ignore1, ignore2;						      \
        if (__builtin_constant_p (private) && (private) == LLL_PRIVATE)	      \
 	 __asm __volatile (__lll_lock_asm_start				      \
-			   "jnz _L_lock_%=\n\t"				      \
-			   ".subsection 1\n\t"				      \
-			   ".type _L_lock_%=,@function\n"		      \
-			   "_L_lock_%=:\n"				      \
+			   "jz 18f\n\t"				      \
 			   "1:\tleal %2, %%ecx\n"			      \
 			   "2:\tcall __lll_lock_wait_private\n" 	      \
-			   "3:\tjmp 18f\n"				      \
-			   "4:\t.size _L_lock_%=, 4b-1b\n\t"		      \
-			   ".previous\n"				      \
-			   LLL_STUB_UNWIND_INFO_3			      \
 			   "18:"					      \
 			   : "=a" (ignore1), "=c" (ignore2), "=m" (futex)     \
 			   : "0" (0), "1" (1), "m" (futex),		      \
@@ -317,17 +233,10 @@ LLL_STUB_UNWIND_INFO_END
 	 {								      \
 	   int ignore3;							      \
 	   __asm __volatile (__lll_lock_asm_start			      \
-			     "jnz _L_lock_%=\n\t"			      \
-			     ".subsection 1\n\t"			      \
-			     ".type _L_lock_%=,@function\n"		      \
-			     "_L_lock_%=:\n"				      \
+			     "jz 18f\n\t"			 	      \
 			     "1:\tleal %2, %%edx\n"			      \
 			     "0:\tmovl %8, %%ecx\n"			      \
 			     "2:\tcall __lll_lock_wait\n"		      \
-			     "3:\tjmp 18f\n"				      \
-			     "4:\t.size _L_lock_%=, 4b-1b\n\t"		      \
-			     ".previous\n"				      \
-			     LLL_STUB_UNWIND_INFO_4			      \
 			     "18:"					      \
 			     : "=a" (ignore1), "=c" (ignore2),		      \
 			       "=m" (futex), "=&d" (ignore3) 		      \
@@ -341,17 +250,10 @@ LLL_STUB_UNWIND_INFO_END
 #define lll_robust_lock(futex, id, private) \
   ({ int result, ignore1, ignore2;					      \
      __asm __volatile (LOCK_INSTR "cmpxchgl %1, %2\n\t"			      \
-		       "jnz _L_robust_lock_%=\n\t"			      \
-		       ".subsection 1\n\t"				      \
-		       ".type _L_robust_lock_%=,@function\n"		      \
-		       "_L_robust_lock_%=:\n"				      \
+		       "jz 18f\n\t"					      \
 		       "1:\tleal %2, %%edx\n"				      \
 		       "0:\tmovl %7, %%ecx\n"				      \
 		       "2:\tcall __lll_robust_lock_wait\n"		      \
-		       "3:\tjmp 18f\n"					      \
-		       "4:\t.size _L_robust_lock_%=, 4b-1b\n\t"		      \
-		       ".previous\n"					      \
-		       LLL_STUB_UNWIND_INFO_4				      \
 		       "18:"						      \
 		       : "=a" (result), "=c" (ignore1), "=m" (futex),	      \
 			 "=&d" (ignore2)				      \
@@ -366,17 +268,10 @@ LLL_STUB_UNWIND_INFO_END
   (void)								      \
     ({ int ignore1, ignore2, ignore3;					      \
        __asm __volatile (LOCK_INSTR "cmpxchgl %1, %2\n\t"		      \
-			 "jnz _L_cond_lock_%=\n\t"			      \
-			 ".subsection 1\n\t"				      \
-			 ".type _L_cond_lock_%=,@function\n"		      \
-			 "_L_cond_lock_%=:\n"				      \
+			 "jz 18f\n\t"					      \
 			 "1:\tleal %2, %%edx\n"				      \
 			 "0:\tmovl %7, %%ecx\n"				      \
 			 "2:\tcall __lll_lock_wait\n"			      \
-			 "3:\tjmp 18f\n"				      \
-			 "4:\t.size _L_cond_lock_%=, 4b-1b\n\t"		      \
-			 ".previous\n"					      \
-			 LLL_STUB_UNWIND_INFO_4				      \
 			 "18:"						      \
 			 : "=a" (ignore1), "=c" (ignore2), "=m" (futex),      \
 			   "=&d" (ignore3)				      \
@@ -388,17 +283,10 @@ LLL_STUB_UNWIND_INFO_END
 #define lll_robust_cond_lock(futex, id, private) \
   ({ int result, ignore1, ignore2;					      \
      __asm __volatile (LOCK_INSTR "cmpxchgl %1, %2\n\t"			      \
-		       "jnz _L_robust_cond_lock_%=\n\t"			      \
-		       ".subsection 1\n\t"				      \
-		       ".type _L_robust_cond_lock_%=,@function\n"	      \
-		       "_L_robust_cond_lock_%=:\n"			      \
+		       "jz 18f\n\t"					      \
 		       "1:\tleal %2, %%edx\n"				      \
 		       "0:\tmovl %7, %%ecx\n"				      \
 		       "2:\tcall __lll_robust_lock_wait\n"		      \
-		       "3:\tjmp 18f\n"					      \
-		       "4:\t.size _L_robust_cond_lock_%=, 4b-1b\n\t"	      \
-		       ".previous\n"					      \
-		       LLL_STUB_UNWIND_INFO_4				      \
 		       "18:"						      \
 		       : "=a" (result), "=c" (ignore1), "=m" (futex),	      \
 			 "=&d" (ignore2)				      \
@@ -411,17 +299,10 @@ LLL_STUB_UNWIND_INFO_END
 #define lll_timedlock(futex, timeout, private) \
   ({ int result, ignore1, ignore2, ignore3;				      \
      __asm __volatile (LOCK_INSTR "cmpxchgl %1, %3\n\t"			      \
-		       "jnz _L_timedlock_%=\n\t"			      \
-		       ".subsection 1\n\t"				      \
-		       ".type _L_timedlock_%=,@function\n"		      \
-		       "_L_timedlock_%=:\n"				      \
+		       "jz 18f\n\t"					      \
 		       "1:\tleal %3, %%ecx\n"				      \
 		       "0:\tmovl %8, %%edx\n"				      \
 		       "2:\tcall __lll_timedlock_wait\n"		      \
-		       "3:\tjmp 18f\n"					      \
-		       "4:\t.size _L_timedlock_%=, 4b-1b\n\t"		      \
-		       ".previous\n"					      \
-		       LLL_STUB_UNWIND_INFO_4				      \
 		       "18:"						      \
 		       : "=a" (result), "=c" (ignore1), "=&d" (ignore2),      \
 			 "=m" (futex), "=S" (ignore3)			      \
@@ -440,17 +321,10 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
 #define lll_robust_timedlock(futex, timeout, id, private) \
   ({ int result, ignore1, ignore2, ignore3;				      \
      __asm __volatile (LOCK_INSTR "cmpxchgl %1, %3\n\t"			      \
-		       "jnz _L_robust_timedlock_%=\n\t"			      \
-		       ".subsection 1\n\t"				      \
-		       ".type _L_robust_timedlock_%=,@function\n"	      \
-		       "_L_robust_timedlock_%=:\n"			      \
+		       "jz 18f\n\t"			   		      \
 		       "1:\tleal %3, %%ecx\n"				      \
 		       "0:\tmovl %8, %%edx\n"				      \
 		       "2:\tcall __lll_robust_timedlock_wait\n"		      \
-		       "3:\tjmp 18f\n"					      \
-		       "4:\t.size _L_robust_timedlock_%=, 4b-1b\n\t"	      \
-		       ".previous\n"					      \
-		       LLL_STUB_UNWIND_INFO_4				      \
 		       "18:"						      \
 		       : "=a" (result), "=c" (ignore1), "=&d" (ignore2),      \
 			 "=m" (futex), "=S" (ignore3)			      \
@@ -473,16 +347,9 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
     ({ int ignore;							      \
        if (__builtin_constant_p (private) && (private) == LLL_PRIVATE)	      \
 	 __asm __volatile (__lll_unlock_asm				      \
-			   "jne _L_unlock_%=\n\t"			      \
-			   ".subsection 1\n\t"				      \
-			   ".type _L_unlock_%=,@function\n"		      \
-			   "_L_unlock_%=:\n"				      \
+			   "je 18f\n\t"					      \
 			   "1:\tleal %0, %%eax\n"			      \
 			   "2:\tcall __lll_unlock_wake_private\n"	      \
-			   "3:\tjmp 18f\n"				      \
-			   "4:\t.size _L_unlock_%=, 4b-1b\n\t"		      \
-			   ".previous\n"				      \
-			   LLL_STUB_UNWIND_INFO_3			      \
 			   "18:"					      \
 			   : "=m" (futex), "=&a" (ignore)		      \
 			   : "m" (futex), "i" (MULTIPLE_THREADS_OFFSET)	      \
@@ -491,17 +358,10 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
 	 {								      \
 	   int ignore2;							      \
 	   __asm __volatile (__lll_unlock_asm				      \
-			     "jne _L_unlock_%=\n\t"			      \
-			     ".subsection 1\n\t"			      \
-			     ".type _L_unlock_%=,@function\n"		      \
-			     "_L_unlock_%=:\n"				      \
+			     "je 18f\n\t"				      \
 			     "1:\tleal %0, %%eax\n"			      \
 			     "0:\tmovl %5, %%ecx\n"			      \
 			     "2:\tcall __lll_unlock_wake\n"		      \
-			     "3:\tjmp 18f\n"				      \
-			     "4:\t.size _L_unlock_%=, 4b-1b\n\t"	      \
-			     ".previous\n"				      \
-			     LLL_STUB_UNWIND_INFO_4			      \
 			     "18:"					      \
 			     : "=m" (futex), "=&a" (ignore), "=&c" (ignore2)  \
 			     : "i" (MULTIPLE_THREADS_OFFSET), "m" (futex),    \
@@ -514,17 +374,10 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
   (void)								      \
     ({ int ignore, ignore2;						      \
        __asm __volatile (LOCK_INSTR "andl %3, %0\n\t"			      \
-			 "jne _L_robust_unlock_%=\n\t"			      \
-			 ".subsection 1\n\t"				      \
-			 ".type _L_robust_unlock_%=,@function\n"	      \
-			 "_L_robust_unlock_%=:\n\t"			      \
+			 "je 18f\n\t"					      \
 			 "1:\tleal %0, %%eax\n"				      \
 			 "0:\tmovl %5, %%ecx\n"				      \
 			 "2:\tcall __lll_unlock_wake\n"			      \
-			 "3:\tjmp 18f\n"				      \
-			 "4:\t.size _L_robust_unlock_%=, 4b-1b\n\t"	      \
-			 ".previous\n"					      \
-			 LLL_STUB_UNWIND_INFO_4				      \
 			 "18:"						      \
 			 : "=m" (futex), "=&a" (ignore), "=&c" (ignore2)      \
 			 : "i" (FUTEX_WAITERS), "m" (futex),		      \