arm: Introduce and use NEGOFF series of macros

There are several places in which we access negative offsets from
the thread-pointer, but thumb2 only supports positive offsets in
memory references.

Avoid duplicating the rather large macros in which these references
are embedded by abstracting out the operation.

6 files changed, 43 insertions, 14 deletions

diff --git a/ports/ChangeLog.arm b/ports/ChangeLog.arm
index d3da2fbb10..b5c9ef3347 100644
--- a/ports/ChangeLog.arm
+++ b/ports/ChangeLog.arm
@@ -1,5 +1,13 @@
 2013-03-06  Richard Henderson <rth@redhat.com>
 
+	* sysdeps/arm/sysdep.h (NEGOFF_ADJ_BASE): New macro.
+	(NEGOFF_ADJ_BASE2, NEGOFF_OFF1, NEGOFF_OFF2): New macros.
+	* sysdeps/unix/sysv/linux/arm/clone.S (__clone): Use them.
+	* sysdeps/unix/sysv/linux/arm/nptl/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h (SINGLE_THREAD_P):
+	Likewise.
+
 	* sysdeps/arm/sysdep.h (LDST_PCREL): New macro.
 	* sysdeps/unix/arm/sysdep.S (__syscall_error): Use LDST_PCREL.
 	Fix up gottpoff load of errno for thumb2.
diff --git a/ports/sysdeps/arm/sysdep.h b/ports/sysdeps/arm/sysdep.h
index 29a78f043d..9230131c78 100644
--- a/ports/sysdeps/arm/sysdep.h
+++ b/ports/sysdeps/arm/sysdep.h
@@ -134,6 +134,22 @@
 	.previous;					\
 99:	OP	R, [pc, T]
 # endif
+
+/* Cope with negative memory offsets, which thumb can't encode.
+   Use NEGOFF_ADJ_BASE to (conditionally) alter the base register,
+   and then NEGOFF_OFF1 to use 0 for thumb and the offset for arm,
+   or NEGOFF_OFF2 to use A-B for thumb and A for arm.  */
+# ifdef __thumb2__
+#  define NEGOFF_ADJ_BASE(R, OFF)	add R, R, $OFF
+#  define NEGOFF_ADJ_BASE2(D, S, OFF)	add D, S, $OFF
+#  define NEGOFF_OFF1(R, OFF)		[R]
+#  define NEGOFF_OFF2(R, OFFA, OFFB)	[R, $((OFFA) - (OFFB))]
+# else
+#  define NEGOFF_ADJ_BASE(R, OFF)
+#  define NEGOFF_ADJ_BASE2(D, S, OFF)	mov D, S
+#  define NEGOFF_OFF1(R, OFF)		[R, $OFF]
+#  define NEGOFF_OFF2(R, OFFA, OFFB)	[R, $OFFA]
+# endif
 #endif	/* __ASSEMBLER__ */
 
 /* This number is the offset from the pc at the current location.  */
diff --git a/ports/sysdeps/unix/sysv/linux/arm/clone.S b/ports/sysdeps/unix/sysv/linux/arm/clone.S
index 732a3ffd01..653bd74102 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/clone.S
+++ b/ports/sysdeps/unix/sysv/linux/arm/clone.S
@@ -83,8 +83,9 @@ PSEUDO_END (__clone)
 	ite	ne
 	movne	r0, #-1
 	swieq	0x0
-	str	r0, [r1, #PID_OFFSET]
-	str	r0, [r1, #TID_OFFSET]
+	NEGOFF_ADJ_BASE (r1, TID_OFFSET)
+	str	r0, NEGOFF_OFF1 (r1, TID_OFFSET)
+	str	r0, NEGOFF_OFF2 (r1, PID_OFFSET, TID_OFFSET)
 3:
 #endif
 	@ pick the function arg and call address off the stack and execute
diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S b/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S
index a38d56419c..f79bb66f2b 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S
+++ b/ports/sysdeps/unix/sysv/linux/arm/nptl/pt-vfork.S
@@ -28,14 +28,15 @@
 	ldr	lr, [sp], #4;		/* Restore LR.  */		\
 	cfi_adjust_cfa_offset (-4);					\
 	cfi_restore (lr);						\
-	mov	r2, r0;			/* Save the TLS addr in r2.  */	\
-	ldr	r3, [r2, #PID_OFFSET];	/* Load the saved PID.  */	\
-	rsb	r0, r3, #0;		/* Negate it.  */		\
-	str	r0, [r2, #PID_OFFSET]	/* Store the temporary PID.  */
+	NEGOFF_ADJ_BASE2 (r2, r0, PID_OFFSET); /* Save the TLS addr in r2. */ \
+	ldr	r3, NEGOFF_OFF1 (r2, PID_OFFSET); /* Load the saved PID.  */  \
+	rsb	r0, r3, #0;		/* Negate it.  */		     \
+	str	r0, NEGOFF_OFF1 (r2, PID_OFFSET); /* Store the temp PID.  */
 
 /* Restore the old PID value in the parent.  */
 #define RESTORE_PID \
 	cmp	r0, #0;			/* If we are the parent... */	\
-	strne	r3, [r2, #PID_OFFSET]	/* ... restore the saved PID.  */
+	it	ne;							\
+	strne	r3, NEGOFF_OFF1 (r2, PID_OFFSET); /* restore the saved PID.  */
 
 #include "../vfork.S"
diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h b/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h
index 8889369ae3..9157d03270 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h
+++ b/ports/sysdeps/unix/sysv/linux/arm/nptl/sysdep-cancel.h
@@ -217,7 +217,8 @@ extern int __local_multiple_threads attribute_hidden;
 	cfi_adjust_cfa_offset (8);					\
 	cfi_rel_offset (lr, 4);						\
 	bl	__aeabi_read_tp;					\
-	ldr	ip, [r0, #MULTIPLE_THREADS_OFFSET];			\
+	NEGOFF_ADJ_BASE (r0, MULTIPLE_THREADS_OFFSET);			\
+	ldr	ip, NEGOFF_OFF1 (r0, MULTIPLE_THREADS_OFFSET);		\
 	ldmfd	sp!, {r0, lr};						\
 	cfi_adjust_cfa_offset (-8);					\
 	cfi_restore (lr);						\
diff --git a/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S b/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S
index 3fce2d1afa..1c6f3bb2bf 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S
+++ b/ports/sysdeps/unix/sysv/linux/arm/nptl/vfork.S
@@ -28,15 +28,17 @@
 	ldr	lr, [sp], #4;		/* Restore LR.  */		\
 	cfi_adjust_cfa_offset (-4);					\
 	cfi_restore (lr);						\
-	mov	r2, r0;			/* Save the TLS addr in r2.  */	\
-	ldr	r3, [r2, #PID_OFFSET];	/* Load the saved PID.  */	\
-	rsbs	r0, r3, #0;		/* Negate it.  */		\
-	moveq	r0, #0x80000000;	/* Use 0x80000000 if it was 0.  */ \
-	str	r0, [r2, #PID_OFFSET]	/* Store the temporary PID.  */
+	NEGOFF_ADJ_BASE2 (r2, r0, PID_OFFSET); /* Save the TLS addr in r2.  */ \
+	ldr	r3, NEGOFF_OFF1 (r2, PID_OFFSET); /* Load the saved PID.  */   \
+	rsbs	r0, r3, #0;		/* Negate it.  */		      \
+	it	eq;							      \
+	moveq	r0, #0x80000000;	/* Use 0x80000000 if it was 0.  */    \
+	str	r0, NEGOFF_OFF1 (r2, PID_OFFSET); /* Store the temp PID.  */
 
 /* Restore the old PID value in the parent.  */
 #define RESTORE_PID \
 	cmp	r0, #0;		/* If we are the parent... */		\
-	strne	r3, [r2, #PID_OFFSET]	/* ... restore the saved PID.  */
+	it	ne;							\
+	strne	r3, NEGOFF_OFF1 (r2, PID_OFFSET); /* restore the saved PID.  */
 
 #include "../vfork.S"