Patch UnixLib to build for armv4 when using EABI.

There are a few places where a decision is made at runtime as to
which atomic operations to perform. Modern gas objects to this
scheme if it isn't told about it, resulting in errors from the
assembler and failed builds. Tell gas what we're doing and make
the SWP-present logic depend on the architecture that UnixLib
is being built for (if you build for armv6 or later in EABI
mode, then no runtime decision or SWP instructions will be
emitted).

Additionally, there's a similar case where LDREX/STREX is used
from inline assembler in the __cmpxchg atomic built when
targetting EABI. Make this, too, conditional on building for
armv6 or later.

1 files changed, 80 insertions, 0 deletions

diff --git a/arm-riscos-gnueabihf/recipes/patches/gccsdk/unixlib-armv4.p b/arm-riscos-gnueabihf/recipes/patches/gccsdk/unixlib-armv4.p
new file mode 100644
index 0000000..1343d13
--- /dev/null
+++ b/arm-riscos-gnueabihf/recipes/patches/gccsdk/unixlib-armv4.p
@@ -0,0 +1,80 @@
+Index: libunixlib/gcccompat/atomics.c
+===================================================================
+--- libunixlib/gcccompat/atomics.c	(revision 7698)
++++ libunixlib/gcccompat/atomics.c	(working copy)
+@@ -378,7 +378,7 @@
+ ATOMIC_OP_FETCH(or,(*ptr) |= val,unsigned)
+ ATOMIC_OP_FETCH(nand,(*ptr) = ~((*ptr) & val),unsigned)
+ 
+-#ifdef __ARM_EABI__
++#if defined(__ARM_EABI__) && defined(__ARM_ARCH) && (__ARM_ARCH >= 6)
+ 
+ static int __cmpxchg (int oldval, int newval, volatile int *ptr)
+ {
+Index: libunixlib/pthread/_ints.s
+===================================================================
+--- libunixlib/pthread/_ints.s	(revision 7698)
++++ libunixlib/pthread/_ints.s	(working copy)
+@@ -14,6 +14,15 @@
+ 	.protected __pthread_enable_ints
+ 	.global	__pthread_protect_unsafe
+ 
++#if defined(__ARM_ARCH) && (__ARM_ARCH__ < 6)
++	/* Modern gas objects to our runtime-conditional use of LDREX/STREX
++	 * in here. If we're building for pre-armv6 architectures, tell gas
++	 * that to allow armv6 instructions, but mark the resulting object
++	 * as armv4 compatible. */
++	.arch armv6
++	.object_arch armv4
++#endif
++
+ @ Disable context switches by incrementing the semaphore
+ @ May be called from USR or SVC mode
+ 	NAME	__pthread_disable_ints
+@@ -23,7 +32,7 @@
+ 	LDR	a1, .L0				@ =__ul_global
+  PICEQ "LDR	a1, [a2, a1]"
+ 	LDR	ip, [a1, #GBL_PTH_CALLEVERY_RMA]
+-#ifdef __ARM_EABI__
++#if defined(__ARM_EABI__) && defined(__ARM_ARCH) && (__ARM_ARCH >= 6)
+ 	ADD	a1, ip, #PTHREAD_CALLEVERY_RMA_WORKSEMAPHORE
+ #else
+ 	LDR	a4, [a1, #GBL_CPU_FLAGS]
+@@ -93,7 +102,7 @@
+ 	LDR	a4, .L2				@ =__ul_global
+  PICEQ "LDR	a4, [a1, a4]"
+ 	LDR	ip, [a4, #GBL_PTH_CALLEVERY_RMA]
+-#ifdef __ARM_EABI__
++#if defined(__ARM_EABI__) && defined(__ARM_ARCH) && (__ARM_ARCH >= 6)
+ 	ADD	a1, ip, #PTHREAD_CALLEVERY_RMA_WORKSEMAPHORE
+ #else
+ 	LDR	a2, [a4, #GBL_CPU_FLAGS]
+Index: libunixlib/sys/_syslib.s
+===================================================================
+--- libunixlib/sys/_syslib.s	(revision 7698)
++++ libunixlib/sys/_syslib.s	(working copy)
+@@ -49,6 +49,15 @@
+ 	.weak	__dynamic_da_max_size
+ 	.weak   __stack_size
+ 
++#if defined(__ARM_ARCH) && (__ARM_ARCH__ < 6)
++	/* Modern gas objects to our runtime-conditional use of LDREX/STREX
++	 * in here. If we're building for pre-armv6 architectures, tell gas
++	 * that to allow armv6 instructions, but mark the resulting object
++	 * as armv4 compatible. */
++	.arch armv6
++	.object_arch armv4
++#endif
++
+ 	@ RMEnsure the minimum version of the SharedUnixLibrary we need.
+ 	@ Now check System modules first as UnixLib package is deprecated.
+ #if !defined(__SOFTFP__) && defined(__VFP_FP__)
+@@ -1414,7 +1423,7 @@
+ 	@ we go for a straight OS_Exit scenario.  Anything better we
+ 	@ can do ?
+ 	ADD	a3, a4, #GBL_PANIC_MODE
+-#ifndef __ARM_EABI__
++#if !defined(__ARM_EABI__) || !defined(__ARM_ARCH) || (__ARM_ARCH < 6)
+ 	LDR	a2, [a4, #GBL_CPU_FLAGS]
+ 	TST	a2, #__CPUCAP_HAVE_SWP
+ 	BEQ	0f