ARM: 7471/1: Revert "7442/1: Revert "remove unused restart trampoline""

This reverts commit 3b0c062.

We no longer require the restart trampoline for syscall restarting.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/signal.c

@@ -27,7 +27,6 @@
  */
 #define SWI_SYS_SIGRETURN	(0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
 #define SWI_SYS_RT_SIGRETURN	(0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
-#define SWI_SYS_RESTART		(0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE)
 
 /*
  * With EABI, the syscall number has to be loaded into r7.
@@ -47,18 +46,6 @@ const unsigned long sigreturn_codes[7] = {
 	MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
 };
 
-/*
- * Either we support OABI only, or we have EABI with the OABI
- * compat layer enabled.  In the later case we don't know if
- * user space is EABI or not, and if not we must not clobber r7.
- * Always using the OABI syscall solves that issue and works for
- * all those cases.
- */
-const unsigned long syscall_restart_code[2] = {
-	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */
-	0xe49df004,		/* ldr	pc, [sp], #4 */
-};
-
 /*
  * atomically swap in the new signal mask, and wait for a signal.
  */

arch/arm/kernel/signal.h

@@ -8,7 +8,5 @@
  * published by the Free Software Foundation.
  */
 #define KERN_SIGRETURN_CODE	(CONFIG_VECTORS_BASE + 0x00000500)
-#define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
 
 extern const unsigned long sigreturn_codes[7];
-extern const unsigned long syscall_restart_code[2];

arch/arm/kernel/traps.c

@@ -820,8 +820,6 @@ void __init early_trap_init(void *vectors_base)
 	 */
 	memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
 	       sigreturn_codes, sizeof(sigreturn_codes));
-	memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
-	       syscall_restart_code, sizeof(syscall_restart_code));
 
 	flush_icache_range(vectors, vectors + PAGE_SIZE);
 	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);