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, 30 insertions, 179 deletions

diff --git a/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h b/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h
index 0a2673974e..c13ca084df 100644
--- a/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h
+++ b/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h
@@ -106,105 +106,6 @@
 /* Delay in spinlock loop.  */
 #define BUSY_WAIT_NOP	  asm ("rep; nop")
 
-
-#define LLL_STUB_UNWIND_INFO_START \
-	".section	.eh_frame,\"a\",@progbits\n" 		\
-"7:\t"	".long	9f-8f	# Length of Common Information Entry\n" \
-"8:\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 -8	# CIE Data Alignment Factor\n\t" 	\
-	".byte	0x10	# CIE RA Column\n\t" 			\
-	".uleb128 0x1	# Augmentation size\n\t" 		\
-	".byte	0x1b	# FDE Encoding (pcrel sdata4)\n\t" 	\
-	".byte	0x12	# DW_CFA_def_cfa_sf\n\t" 		\
-	".uleb128 0x7\n\t" 					\
-	".sleb128 16\n\t" 					\
-	".align " LP_SIZE "\n" 					\
-"9:\t"	".long	23f-10f	# FDE Length\n" 			\
-"10:\t"	".long	10b-7b	# FDE CIE offset\n\t" 			\
-	".long	1b-.	# FDE initial location\n\t" 		\
-	".long	6b-1b	# FDE address range\n\t" 		\
-	".uleb128 0x0	# Augmentation size\n\t" 		\
-	".byte	0x16	# DW_CFA_val_expression\n\t" 		\
-	".uleb128 0x10\n\t" 					\
-	".uleb128 12f-11f\n" 					\
-"11:\t"	".byte	0x80	# DW_OP_breg16\n\t" 			\
-	".sleb128 4b-1b\n"
-#define LLL_STUB_UNWIND_INFO_END \
-	".byte	0x16	# DW_CFA_val_expression\n\t" 		\
-	".uleb128 0x10\n\t" 					\
-	".uleb128 14f-13f\n" 					\
-"13:\t"	".byte	0x80	# DW_OP_breg16\n\t" 			\
-	".sleb128 4b-2b\n" 					\
-"14:\t"	".byte	0x40 + (3b-2b) # DW_CFA_advance_loc\n\t" 	\
-	".byte	0x0e	# DW_CFA_def_cfa_offset\n\t" 		\
-	".uleb128 0\n\t" 					\
-	".byte	0x16	# DW_CFA_val_expression\n\t" 		\
-	".uleb128 0x10\n\t" 					\
-	".uleb128 16f-15f\n" 					\
-"15:\t"	".byte	0x80	# DW_OP_breg16\n\t" 			\
-	".sleb128 4b-3b\n" 					\
-"16:\t"	".byte	0x40 + (4b-3b-1) # DW_CFA_advance_loc\n\t" 	\
-	".byte	0x0e	# DW_CFA_def_cfa_offset\n\t" 		\
-	".uleb128 128\n\t" 					\
-	".byte	0x16	# DW_CFA_val_expression\n\t" 		\
-	".uleb128 0x10\n\t" 					\
-	".uleb128 20f-17f\n" 					\
-"17:\t"	".byte	0x80	# DW_OP_breg16\n\t" 			\
-	".sleb128 19f-18f\n\t" 					\
-	".byte	0x0d	# DW_OP_const4s\n" 			\
-"18:\t"	".4byte	4b-.\n\t" 					\
-	".byte	0x1c	# DW_OP_minus\n\t" 			\
-	".byte	0x0d	# DW_OP_const4s\n" 			\
-"19:\t"	".4byte	24f-.\n\t" 					\
-	".byte	0x22	# DW_OP_plus\n" 			\
-"20:\t"	".byte	0x40 + (5b-4b+1) # DW_CFA_advance_loc\n\t" 	\
-	".byte	0x13	# DW_CFA_def_cfa_offset_sf\n\t" 	\
-	".sleb128 16\n\t" 					\
-	".byte	0x16	# DW_CFA_val_expression\n\t" 		\
-	".uleb128 0x10\n\t" 					\
-	".uleb128 22f-21f\n" 					\
-"21:\t"	".byte	0x80	# DW_OP_breg16\n\t" 			\
-	".sleb128 4b-5b\n" 					\
-"22:\t"	".align " LP_SIZE "\n" 					\
-"23:\t"	".previous\n"
-
-/* Unwind info for
-   1: leaq ..., %rdi
-   2: subq $128, %rsp
-   3: callq ...
-   4: addq $128, %rsp
-   5: jmp 24f
-   6:
-   snippet.  */
-#define LLL_STUB_UNWIND_INFO_5 \
-LLL_STUB_UNWIND_INFO_START					\
-"12:\t"	".byte	0x40 + (2b-1b) # DW_CFA_advance_loc\n\t" 	\
-LLL_STUB_UNWIND_INFO_END
-
-/* Unwind info for
-   1: leaq ..., %rdi
-   0: movq ..., %rdx
-   2: subq $128, %rsp
-   3: callq ...
-   4: addq $128, %rsp
-   5: jmp 24f
-   6:
-   snippet.  */
-#define LLL_STUB_UNWIND_INFO_6 \
-LLL_STUB_UNWIND_INFO_START					\
-"12:\t"	".byte	0x40 + (0b-1b) # DW_CFA_advance_loc\n\t" 	\
-	".byte	0x16	# DW_CFA_val_expression\n\t" 		\
-	".uleb128 0x10\n\t" 					\
-	".uleb128 26f-25f\n" 					\
-"25:\t"	".byte	0x80	# DW_OP_breg16\n\t" 			\
-	".sleb128 4b-0b\n" 					\
-"26:\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)
 
@@ -283,7 +184,7 @@ LLL_STUB_UNWIND_INFO_END
 
 #if defined NOT_IN_libc || defined UP
 # define __lll_lock_asm_start LOCK_INSTR "cmpxchgl %4, %2\n\t"		      \
-			      "jnz 1f\n\t"
+			      "jz 24f\n\t"
 #else
 # define __lll_lock_asm_start "cmpl $0, __libc_multiple_threads(%%rip)\n\t"   \
 			      "je 0f\n\t"				      \
@@ -291,7 +192,7 @@ LLL_STUB_UNWIND_INFO_END
 			      "jnz 1f\n\t"				      \
 			      "jmp 24f\n"				      \
 			      "0:\tcmpxchgl %4, %2\n\t"			      \
-			      "jnz 1f\n\t"
+			      "jz 24f\n\t"
 #endif
 
 #define lll_lock(futex, private) \
@@ -299,17 +200,12 @@ LLL_STUB_UNWIND_INFO_END
     ({ int ignore1, ignore2, ignore3;					      \
        if (__builtin_constant_p (private) && (private) == LLL_PRIVATE)	      \
 	 __asm __volatile (__lll_lock_asm_start				      \
-			   ".subsection 1\n\t"				      \
-			   ".type _L_lock_%=, @function\n"		      \
-			   "_L_lock_%=:\n"				      \
 			   "1:\tlea %2, %%" RDI_LP "\n"			      \
 			   "2:\tsub $128, %%" RSP_LP "\n"		      \
+			   ".cfi_adjust_cfa_offset 128\n"		      \
 			   "3:\tcallq __lll_lock_wait_private\n"	      \
 			   "4:\tadd $128, %%" RSP_LP "\n"		      \
-			   "5:\tjmp 24f\n"				      \
-			   "6:\t.size _L_lock_%=, 6b-1b\n\t"		      \
-			   ".previous\n"				      \
-			   LLL_STUB_UNWIND_INFO_5			      \
+			   ".cfi_adjust_cfa_offset -128\n"		      \
 			   "24:"					      \
 			   : "=S" (ignore1), "=&D" (ignore2), "=m" (futex),   \
 			     "=a" (ignore3)				      \
@@ -317,17 +213,12 @@ LLL_STUB_UNWIND_INFO_END
 			   : "cx", "r11", "cc", "memory");		      \
        else								      \
 	 __asm __volatile (__lll_lock_asm_start				      \
-			   ".subsection 1\n\t"				      \
-			   ".type _L_lock_%=, @function\n"		      \
-			   "_L_lock_%=:\n"				      \
 			   "1:\tlea %2, %%" RDI_LP "\n"			      \
 			   "2:\tsub $128, %%" RSP_LP "\n"		      \
+			   ".cfi_adjust_cfa_offset 128\n"		      \
 			   "3:\tcallq __lll_lock_wait\n"		      \
 			   "4:\tadd $128, %%" RSP_LP "\n"		      \
-			   "5:\tjmp 24f\n"				      \
-			   "6:\t.size _L_lock_%=, 6b-1b\n\t"		      \
-			   ".previous\n"				      \
-			   LLL_STUB_UNWIND_INFO_5			      \
+			   ".cfi_adjust_cfa_offset -128\n"		      \
 			   "24:"					      \
 			   : "=S" (ignore1), "=D" (ignore2), "=m" (futex),    \
 			     "=a" (ignore3)				      \
@@ -338,18 +229,13 @@ LLL_STUB_UNWIND_INFO_END
 #define lll_robust_lock(futex, id, private) \
   ({ int result, ignore1, ignore2;					      \
     __asm __volatile (LOCK_INSTR "cmpxchgl %4, %2\n\t"			      \
-		      "jnz 1f\n\t"					      \
-		      ".subsection 1\n\t"				      \
-		      ".type _L_robust_lock_%=, @function\n"		      \
-		      "_L_robust_lock_%=:\n"				      \
+		      "jz 24f\n"					      \
 		      "1:\tlea %2, %%" RDI_LP "\n"			      \
 		      "2:\tsub $128, %%" RSP_LP "\n"			      \
+		      ".cfi_adjust_cfa_offset 128\n"			      \
 		      "3:\tcallq __lll_robust_lock_wait\n"		      \
 		      "4:\tadd $128, %%" RSP_LP "\n"			      \
-		      "5:\tjmp 24f\n"					      \
-		      "6:\t.size _L_robust_lock_%=, 6b-1b\n\t"		      \
-		      ".previous\n"					      \
-		      LLL_STUB_UNWIND_INFO_5				      \
+		      ".cfi_adjust_cfa_offset -128\n"			      \
 		      "24:"						      \
 		      : "=S" (ignore1), "=D" (ignore2), "=m" (futex),	      \
 			"=a" (result)					      \
@@ -361,18 +247,13 @@ LLL_STUB_UNWIND_INFO_END
   (void)								      \
     ({ int ignore1, ignore2, ignore3;					      \
        __asm __volatile (LOCK_INSTR "cmpxchgl %4, %2\n\t"		      \
-			 "jnz 1f\n\t"					      \
-			 ".subsection 1\n\t"				      \
-			 ".type _L_cond_lock_%=, @function\n"		      \
-			 "_L_cond_lock_%=:\n"				      \
+			 "jz 24f\n"					      \
 			 "1:\tlea %2, %%" RDI_LP "\n"			      \
 			 "2:\tsub $128, %%" RSP_LP "\n"			      \
+			 ".cfi_adjust_cfa_offset 128\n"			      \
 			 "3:\tcallq __lll_lock_wait\n"			      \
 			 "4:\tadd $128, %%" RSP_LP "\n"			      \
-			 "5:\tjmp 24f\n"				      \
-			 "6:\t.size _L_cond_lock_%=, 6b-1b\n\t"		      \
-			 ".previous\n"					      \
-			 LLL_STUB_UNWIND_INFO_5				      \
+			 ".cfi_adjust_cfa_offset -128\n"		      \
 			 "24:"						      \
 			 : "=S" (ignore1), "=D" (ignore2), "=m" (futex),      \
 			   "=a" (ignore3)				      \
@@ -383,18 +264,13 @@ LLL_STUB_UNWIND_INFO_END
 #define lll_robust_cond_lock(futex, id, private) \
   ({ int result, ignore1, ignore2;					      \
     __asm __volatile (LOCK_INSTR "cmpxchgl %4, %2\n\t"			      \
-		      "jnz 1f\n\t"					      \
-		      ".subsection 1\n\t"				      \
-		      ".type _L_robust_cond_lock_%=, @function\n"	      \
-		      "_L_robust_cond_lock_%=:\n"			      \
+		      "jz 24f\n"					      \
 		      "1:\tlea %2, %%" RDI_LP "\n"			      \
 		      "2:\tsub $128, %%" RSP_LP "\n"			      \
+		      ".cfi_adjust_cfa_offset 128\n"			      \
 		      "3:\tcallq __lll_robust_lock_wait\n"		      \
 		      "4:\tadd $128, %%" RSP_LP "\n"			      \
-		      "5:\tjmp 24f\n"					      \
-		      "6:\t.size _L_robust_cond_lock_%=, 6b-1b\n\t"	      \
-		      ".previous\n"					      \
-		      LLL_STUB_UNWIND_INFO_5				      \
+		      ".cfi_adjust_cfa_offset -128\n"			      \
 		      "24:"						      \
 		      : "=S" (ignore1), "=D" (ignore2), "=m" (futex),	      \
 			"=a" (result)					      \
@@ -406,19 +282,14 @@ LLL_STUB_UNWIND_INFO_END
 #define lll_timedlock(futex, timeout, private) \
   ({ int result, ignore1, ignore2, ignore3;				      \
      __asm __volatile (LOCK_INSTR "cmpxchgl %1, %4\n\t"			      \
-		       "jnz 1f\n\t"					      \
-		       ".subsection 1\n\t"				      \
-		       ".type _L_timedlock_%=, @function\n"		      \
-		       "_L_timedlock_%=:\n"				      \
+		       "jz 24f\n"					      \
 		       "1:\tlea %4, %%" RDI_LP "\n"			      \
 		       "0:\tmov %8, %%" RDX_LP "\n"			      \
 		       "2:\tsub $128, %%" RSP_LP "\n"			      \
+		       ".cfi_adjust_cfa_offset 128\n"			      \
 		       "3:\tcallq __lll_timedlock_wait\n"		      \
 		       "4:\tadd $128, %%" RSP_LP "\n"			      \
-		       "5:\tjmp 24f\n"					      \
-		       "6:\t.size _L_timedlock_%=, 6b-1b\n\t"		      \
-		       ".previous\n"					      \
-		       LLL_STUB_UNWIND_INFO_6				      \
+		       ".cfi_adjust_cfa_offset -128\n"			      \
 		       "24:"						      \
 		       : "=a" (result), "=D" (ignore1), "=S" (ignore2),	      \
 			 "=&d" (ignore3), "=m" (futex)			      \
@@ -437,19 +308,14 @@ 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, %4\n\t"			      \
-		       "jnz 1f\n\t"					      \
-		       ".subsection 1\n\t"				      \
-		       ".type _L_robust_timedlock_%=, @function\n"	      \
-		       "_L_robust_timedlock_%=:\n"			      \
+		       "jz 24f\n\t"					      \
 		       "1:\tlea %4, %%" RDI_LP "\n"			      \
 		       "0:\tmov %8, %%" RDX_LP "\n"			      \
 		       "2:\tsub $128, %%" RSP_LP "\n"			      \
+		       ".cfi_adjust_cfa_offset 128\n"			      \
 		       "3:\tcallq __lll_robust_timedlock_wait\n"	      \
 		       "4:\tadd $128, %%" RSP_LP "\n"			      \
-		       "5:\tjmp 24f\n"					      \
-		       "6:\t.size _L_robust_timedlock_%=, 6b-1b\n\t"	      \
-		       ".previous\n"					      \
-		       LLL_STUB_UNWIND_INFO_6				      \
+		       ".cfi_adjust_cfa_offset -128\n"			      \
 		       "24:"						      \
 		       : "=a" (result), "=D" (ignore1), "=S" (ignore2),       \
 			 "=&d" (ignore3), "=m" (futex)			      \
@@ -460,7 +326,7 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
 
 #if defined NOT_IN_libc || defined UP
 # define __lll_unlock_asm_start LOCK_INSTR "decl %0\n\t"		      \
-				"jne 1f\n\t"
+				"je 24f\n\t"
 #else
 # define __lll_unlock_asm_start "cmpl $0, __libc_multiple_threads(%%rip)\n\t" \
 				"je 0f\n\t"				      \
@@ -468,7 +334,7 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
 				"jne 1f\n\t"				      \
 				"jmp 24f\n\t"				      \
 				"0:\tdecl %0\n\t"			      \
-				"jne 1f\n\t"
+				"je 24f\n\t"
 #endif
 
 #define lll_unlock(futex, private) \
@@ -476,34 +342,24 @@ 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_start			      \
-			   ".subsection 1\n\t"				      \
-			   ".type _L_unlock_%=, @function\n"		      \
-			   "_L_unlock_%=:\n"				      \
 			   "1:\tlea %0, %%" RDI_LP "\n"			      \
 			   "2:\tsub $128, %%" RSP_LP "\n"		      \
+			   ".cfi_adjust_cfa_offset 128\n"		      \
 			   "3:\tcallq __lll_unlock_wake_private\n"	      \
 			   "4:\tadd $128, %%" RSP_LP "\n"		      \
-			   "5:\tjmp 24f\n"				      \
-			   "6:\t.size _L_unlock_%=, 6b-1b\n\t"		      \
-			   ".previous\n"				      \
-			   LLL_STUB_UNWIND_INFO_5			      \
+			   ".cfi_adjust_cfa_offset -128\n"		      \
 			   "24:"					      \
 			   : "=m" (futex), "=&D" (ignore)		      \
 			   : "m" (futex)				      \
 			   : "ax", "cx", "r11", "cc", "memory");	      \
        else								      \
 	 __asm __volatile (__lll_unlock_asm_start			      \
-			   ".subsection 1\n\t"				      \
-			   ".type _L_unlock_%=, @function\n"		      \
-			   "_L_unlock_%=:\n"				      \
 			   "1:\tlea %0, %%" RDI_LP "\n"			      \
 			   "2:\tsub $128, %%" RSP_LP "\n"		      \
+			   ".cfi_adjust_cfa_offset 128\n"		      \
 			   "3:\tcallq __lll_unlock_wake\n"		      \
 			   "4:\tadd $128, %%" RSP_LP "\n"		      \
-			   "5:\tjmp 24f\n"				      \
-			   "6:\t.size _L_unlock_%=, 6b-1b\n\t"		      \
-			   ".previous\n"				      \
-			   LLL_STUB_UNWIND_INFO_5			      \
+			   ".cfi_adjust_cfa_offset -128\n"		      \
 			   "24:"					      \
 			   : "=m" (futex), "=&D" (ignore)		      \
 			   : "m" (futex), "S" (private)			      \
@@ -515,18 +371,13 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
     {									      \
       int ignore;							      \
       __asm __volatile (LOCK_INSTR "andl %2, %0\n\t"			      \
-			"jne 1f\n\t"					      \
-			".subsection 1\n\t"				      \
-			".type _L_robust_unlock_%=, @function\n"	      \
-			"_L_robust_unlock_%=:\n"			      \
+			"je 24f\n\t"					      \
 			"1:\tlea %0, %%" RDI_LP "\n"			      \
 			"2:\tsub $128, %%" RSP_LP "\n"			      \
+			".cfi_adjust_cfa_offset 128\n"			      \
 			"3:\tcallq __lll_unlock_wake\n"			      \
 			"4:\tadd $128, %%" RSP_LP "\n"			      \
-			"5:\tjmp 24f\n"					      \
-			"6:\t.size _L_robust_unlock_%=, 6b-1b\n\t"	      \
-			".previous\n"					      \
-			LLL_STUB_UNWIND_INFO_5				      \
+			".cfi_adjust_cfa_offset -128\n"			      \
 			"24:"						      \
 			: "=m" (futex), "=&D" (ignore)			      \
 			: "i" (FUTEX_WAITERS), "m" (futex),		      \