parisc: Reduce sigreturn trampoline to 3 instructions

We can move the INSN_LDI_R20 instruction into the branch delay slot.

Signed-off-by: Helge Deller <deller@gmx.de>

Author: hdeller

arch/parisc/include/asm/rt_sigframe.h

@@ -2,7 +2,7 @@
 #ifndef _ASM_PARISC_RT_SIGFRAME_H
 #define _ASM_PARISC_RT_SIGFRAME_H
 
-#define SIGRETURN_TRAMP 4
+#define SIGRETURN_TRAMP 3
 #define SIGRESTARTBLOCK_TRAMP 5 
 #define TRAMP_SIZE (SIGRETURN_TRAMP + SIGRESTARTBLOCK_TRAMP)
 

arch/parisc/kernel/signal.c

@@ -288,22 +288,21 @@ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs,
 	   already in userspace. The first words of tramp are used to
 	   save the previous sigrestartblock trampoline that might be
 	   on the stack. We start the sigreturn trampoline at 
-	   SIGRESTARTBLOCK_TRAMP+X. */
+	   SIGRESTARTBLOCK_TRAMP. */
 	err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
-	err |= __put_user(INSN_LDI_R20, 
-			&frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
 	err |= __put_user(INSN_BLE_SR2_R0, 
+			&frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
+	err |= __put_user(INSN_LDI_R20,
 			&frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
-	err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);
 
-	start = (unsigned long) &frame->tramp[0];
-	end = (unsigned long) &frame->tramp[TRAMP_SIZE];
+	start = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP+0];
+	end = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP+3];
 	flush_user_dcache_range_asm(start, end);
 	flush_user_icache_range_asm(start, end);
 
 	/* TRAMP Words 0-4, Length 5 = SIGRESTARTBLOCK_TRAMP
-	 * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
+	 * TRAMP Words 5-7, Length 3 = SIGRETURN_TRAMP
 	 * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
 	 */
 	rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];

arch/parisc/kernel/signal32.h

@@ -36,7 +36,7 @@ struct compat_regfile {
         compat_int_t rf_sar;
 };
 
-#define COMPAT_SIGRETURN_TRAMP 4
+#define COMPAT_SIGRETURN_TRAMP 3
 #define COMPAT_SIGRESTARTBLOCK_TRAMP 5
 #define COMPAT_TRAMP_SIZE (COMPAT_SIGRETURN_TRAMP + \
 				COMPAT_SIGRESTARTBLOCK_TRAMP)