[klibc] arm: use bx on thumb2 (v3)
Use klibc way to define a system dependent preprocessor
definition: disabled by default and enabled for newer arm.
Based on a patch by vorlon that got tested on his beagleboard,
should be functional equivalent. Tested on an arm Debian porter box
for the _KLIBC_ARM_USE_BX == 0 case.
Fixes: https://bugs.launchpad.net/ubuntu/+source/klibc/+bug/527720
Cc: Steve Langasek <steve.langasek@canonical.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: maximilian attems <max@stro.at>
diff --git a/usr/include/arch/arm/klibc/archconfig.h b/usr/include/arch/arm/klibc/archconfig.h
index e34bdb7..36e9ab5 100644
--- a/usr/include/arch/arm/klibc/archconfig.h
+++ b/usr/include/arch/arm/klibc/archconfig.h
@@ -9,6 +9,10 @@
#ifndef _KLIBC_ARCHCONFIG_H
#define _KLIBC_ARCHCONFIG_H
-/* All defaults */
+/* newer arm arch support bx instruction */
+#if (!defined(__ARM_ARCH_2__) && !defined(__ARM_ARCH_3__) \
+ && !defined(__ARM_ARCH_3M__) && !defined(__ARM_ARCH_4__))
+# define _KLIBC_ARM_USE_BX 1
+#endif
#endif /* _KLIBC_ARCHCONFIG_H */
diff --git a/usr/include/arch/arm/klibc/asmmacros.h b/usr/include/arch/arm/klibc/asmmacros.h
index 8a21c94..45bea0e 100644
--- a/usr/include/arch/arm/klibc/asmmacros.h
+++ b/usr/include/arch/arm/klibc/asmmacros.h
@@ -27,4 +27,10 @@
(((x) & ~0xf000000f) == 0) || \
(((x) & ~0xc000003f) == 0))
+#if _KLIBC_ARM_USE_BX
+# define BX(x) bx x
+#else
+# define BX(x) mov pc, x
+#endif
+
#endif /* _KLIBC_ASMMACROS_H */
diff --git a/usr/include/klibc/sysconfig.h b/usr/include/klibc/sysconfig.h
index bf1daf5..a1c37fd 100644
--- a/usr/include/klibc/sysconfig.h
+++ b/usr/include/klibc/sysconfig.h
@@ -196,4 +196,13 @@
# define _KLIBC_SYS_SOCKETCALL 0
#endif
+/*
+ * _KLIBC_ARM_USE_BX
+ *
+ * This arm architecture supports bx instruction.
+ */
+#ifndef _KLIBC_ARM_USE_BX
+# define _KLIBC_ARM_USE_BX 0
+#endif
+
#endif /* _KLIBC_SYSCONFIG_H */
diff --git a/usr/klibc/arch/arm/setjmp.S b/usr/klibc/arch/arm/setjmp.S
index 2232458..6018bda 100644
--- a/usr/klibc/arch/arm/setjmp.S
+++ b/usr/klibc/arch/arm/setjmp.S
@@ -4,6 +4,8 @@
# setjmp/longjmp for the ARM architecture
#
+#include <klibc/asmmacros.h>
+
#ifndef __thumb__
#
@@ -29,7 +31,7 @@
setjmp:
stmia r0, {r4, r5, r6, r7, r8, r9, r10, fp, sp, lr}
mov r0, #0
- mov pc, lr
+ BX(lr)
.size setjmp,.-setjmp
.text
@@ -39,7 +41,7 @@
longjmp:
ldmia r0, {r4, r5, r6, r7, r8, r9, r10, fp, sp, lr}
mov r0, r1
- mov pc, lr
+ BX(lr)
.size longjmp,.-longjmp
#else /* __thumb__ */
@@ -75,7 +77,7 @@
mov r7, sp
stmia r0!, {r3, r4, r5, r6, r7}
mov r0, #0
- mov pc, lr
+ BX(lr)
.size setjmp,.-setjmp
.text
@@ -96,7 +98,7 @@
mov r0, r1
bne 1f
mov r0, #1
-1: mov pc, r3
+1: BX(r3)
.size longjmp,.-longjmp
#endif /* __thumb__ */
diff --git a/usr/klibc/arch/arm/vfork.S b/usr/klibc/arch/arm/vfork.S
index 3b2d9f7..7130b65 100644
--- a/usr/klibc/arch/arm/vfork.S
+++ b/usr/klibc/arch/arm/vfork.S
@@ -4,6 +4,7 @@
* vfork - nasty system call which must not use the stack.
*/
+#include <klibc/asmmacros.h>
#include <asm/unistd.h>
.type vfork,#function
@@ -25,7 +26,7 @@
ldrcs r3, 1f
mvncs r0, #0
strcs r2, [r3]
- mov pc, lr
+ BX(lr)
.balign 4
1:
@@ -49,7 +50,7 @@
str r2, [r1]
neg r0, r0
1:
- mov pc, lr
+ BX(lr)
.balign 4
2: