arm: Introduce and use PC_OFS

Scour the source for raw "-8" adjustments that are related to the
offset created by reading the pc.

ports/ChangeLog.arm

@@ -11,6 +11,21 @@
 	* ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h: Likewise.
 	* sysdeps/unix/sysv/linux/arm/sysdep.h: Likewise.
 
+	* sysdeps/arm/sysdep.h (PC_OFS): New macros.
+	* sysdeps/arm/__longjmp.S (__longjmp): Use PC_OFS.
+	* sysdeps/arm/setjmp.S (__sigsetjmp): Likewise.
+	* sysdeps/unix/arm/sysdep.S (__syscall_error): Likewise.
+	* sysdeps/unix/sysv/linux/arm/getcontext.S (__getcontext): Likewise.
+	* sysdeps/unix/sysv/linux/arm/setcontext.S (__startcontext): Likewise.
+	* sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h
+	(SINGLE_THREAD_P): Likewise.
+	* sysdeps/unix/sysv/linux/arm/sysdep.h
+	(SYSCALL_ERROR_HANDLER): Likewise.
+	* sysdeps/unix/sysv/linux/arm/nptl/unwind-forcedunwind.c
+	(_Unwind_Resume): Use stringified PC_OFS.
+	* sysdeps/unix/sysv/linux/arm/nptl/unwind-resume.c
+	(_Unwind_Resume): Likewise.
+
 2013-02-27  Roland McGrath  <roland@hack.frob.com>
 
 	* sysdeps/arm/sysdep.h (CFI_SECTIONS): New macro.

ports/sysdeps/arm/__longjmp.S

@@ -105,12 +105,12 @@ ENTRY (__longjmp)
 
 #ifdef NEED_HWCAP
 # ifdef IS_IN_rtld
-1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - 8
+1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
 .Lrtld_local_ro:
 	.long	C_SYMBOL_NAME(_rtld_local_ro)(GOTOFF)
 # else
 #  ifdef PIC
-1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - 8
+1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
 .Lrtld_global_ro:
 	.long	C_SYMBOL_NAME(_rtld_global_ro)(GOT)
 #  else

ports/sysdeps/arm/setjmp.S

@@ -91,12 +91,12 @@ ENTRY (__sigsetjmp)
 
 #ifdef NEED_HWCAP
 # ifdef IS_IN_rtld
-1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - 8
+1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
 .Lrtld_local_ro:
 	.long	C_SYMBOL_NAME(_rtld_local_ro)(GOTOFF)
 # else
 #  ifdef PIC
-1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - 8
+1:	.long	_GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
 .Lrtld_global_ro:
 	.long	C_SYMBOL_NAME(_rtld_global_ro)(GOT)
 #  else

ports/sysdeps/arm/sysdep.h

@@ -118,3 +118,11 @@
 	.eabi_attribute 24, 1
 
 #endif	/* __ASSEMBLER__ */
+
+/* This number is the offset from the pc at the current location.  */
+/* ??? At the moment we're not turning on thumb mode in assembly.  */
+#if defined(__thumb__) && !defined(__ASSEMBLER__)
+# define PC_OFS  4
+#else
+# define PC_OFS  8
+#endif

ports/sysdeps/unix/arm/sysdep.S

@@ -50,14 +50,14 @@ __syscall_error:
 	mvn r0, #0
 	RETINSTR (, ip)
 
-1:	.word errno(gottpoff) + (. - 2b - 8)
+1:	.word errno(gottpoff) + (. - 2b - PC_OFS)
 #elif RTLD_PRIVATE_ERRNO
 	ldr r1, 1f
 0:	str r0, [pc, r1]
 	mvn r0, $0
 	DO_RET(r14)
 
-1:	.word C_SYMBOL_NAME(rtld_errno) - 0b - 8
+1:	.word C_SYMBOL_NAME(rtld_errno) - 0b - PC_OFS
 #else
 #error "Unsupported non-TLS case"
 #endif

ports/sysdeps/unix/sysv/linux/arm/getcontext.S

@@ -103,7 +103,7 @@ ENTRY(__getcontext)
 END(__getcontext)
 
 #ifdef PIC
-1:      .long   _GLOBAL_OFFSET_TABLE_ - 0b - 8
+1:      .long   _GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
 .Lrtld_global_ro:
 	.long   C_SYMBOL_NAME(_rtld_global_ro)(GOT)
 #else

ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h

@@ -208,7 +208,7 @@ extern int __local_multiple_threads attribute_hidden;
 	ldr ip, [pc, ip];						\
 	teq ip, #0;
 #   define PSEUDO_PROLOGUE						\
-  1:	.word	__local_multiple_threads - 2f - 8;
+  1:	.word	__local_multiple_threads - 2f - PC_OFS;
 #  endif
 # else
 /*  There is no __local_multiple_threads for librt, so use the TCB.  */

ports/sysdeps/unix/sysv/linux/arm/nptl/unwind-forcedunwind.c

@@ -84,6 +84,9 @@ __unwind_freeres (void)
    ARM unwinder relies on register state at entrance.  So we write this in
    assembly.  */
 
+#define STR1(S) #S
+#define STR(S)  STR1(S)
+
 asm (
 "	.globl	_Unwind_Resume\n"
 "	.type	_Unwind_Resume, %function\n"
@@ -118,11 +121,7 @@ asm (
 "	b	5b\n"
 "	" CFI_ENDPROC "\n"
 "	.align 2\n"
-#ifdef __thumb2__
+"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - " STR (PC_OFS) "\n"
-"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - 4\n"
-#else
-"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - 8\n"
-#endif
 "2:	.word	libgcc_s_resume(GOTOFF)\n"
 "	.size	_Unwind_Resume, .-_Unwind_Resume\n"
 );

ports/sysdeps/unix/sysv/linux/arm/nptl/unwind-resume.c

@@ -47,6 +47,9 @@ init (void)
    ARM unwinder relies on register state at entrance.  So we write this in
    assembly.  */
 
+#define STR1(S) #S
+#define STR(S)  STR1(S)
+
 asm (
 "	.globl	_Unwind_Resume\n"
 "	.type	_Unwind_Resume, %function\n"
@@ -81,11 +84,7 @@ asm (
 "	b	5b\n"
 "	" CFI_ENDPROC "\n"
 "	.align 2\n"
-#ifdef __thumb2__
+"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - " STR (PC_OFS) "\n"
-"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - 4\n"
-#else
-"1:	.word	_GLOBAL_OFFSET_TABLE_ - 3b - 8\n"
-#endif
 "2:	.word	libgcc_s_resume(GOTOFF)\n"
 "	.size	_Unwind_Resume, .-_Unwind_Resume\n"
 );

ports/sysdeps/unix/sysv/linux/arm/setcontext.S

@@ -93,7 +93,7 @@ ENTRY(__startcontext)
 END(__startcontext)
 
 #ifdef PIC
-1:      .long   _GLOBAL_OFFSET_TABLE_ - 0b - 8
+1:      .long   _GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
 .Lrtld_global_ro:
 	.long   C_SYMBOL_NAME(_rtld_global_ro)(GOT)
 #else

ports/sysdeps/unix/sysv/linux/arm/sysdep.h

@@ -114,7 +114,7 @@ __local_syscall_error:						\
 0:     str     r0, [pc, r1];					\
        mvn     r0, #0;						\
        DO_RET(lr);						\
-1:     .word C_SYMBOL_NAME(rtld_errno) - 0b - 8;
+1:     .word C_SYMBOL_NAME(rtld_errno) - 0b - PC_OFS;
 # else
 #  if defined(__ARM_ARCH_4T__) && defined(__THUMB_INTERWORK__)
 #   define POP_PC \