ARM: Use a definition for the userspace cmpxchg emulation syscall
Use a definition for the cmpxchg SWI instead of hard-coding the number.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 7020217..4e506d0 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -403,6 +403,15 @@
#define __ARM_NR_set_tls (__ARM_NR_BASE+5)
/*
+ * *NOTE*: This is a ghost syscall private to the kernel. Only the
+ * __kuser_cmpxchg code in entry-armv.S should be aware of its
+ * existence. Don't ever use this from user code.
+ */
+#ifdef __KERNEL__
+#define __ARM_NR_cmpxchg (__ARM_NR_BASE+0x00fff0)
+#endif
+
+/*
* The following syscalls are obsolete and no longer available for EABI.
*/
#if defined(__ARM_EABI__) && !defined(__KERNEL__)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 0022b4d..d2903e3 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -21,6 +21,7 @@
#include <mach/entry-macro.S>
#include <asm/thread_notify.h>
#include <asm/unwind.h>
+#include <asm/unistd.h>
#include "entry-header.S"
@@ -908,10 +909,10 @@
* A special ghost syscall is used for that (see traps.c).
*/
stmfd sp!, {r7, lr}
- mov r7, #0xff00 @ 0xfff0 into r7 for EABI
- orr r7, r7, #0xf0
- swi #0x9ffff0
+ ldr r7, =1f @ it's 20 bits
+ swi __ARM_NR_cmpxchg
ldmfd sp!, {r7, pc}
+1: .word __ARM_NR_cmpxchg
#elif __LINUX_ARM_ARCH__ < 6
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 1bbda04..3f361a7 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -528,7 +528,7 @@
* __kuser_cmpxchg code in entry-armv.S should be aware of its
* existence. Don't ever use this from user code.
*/
- case 0xfff0:
+ case NR(cmpxchg):
for (;;) {
extern void do_DataAbort(unsigned long addr, unsigned int fsr,
struct pt_regs *regs);