openrisc: sanitize use of orig_gpr11

The pt_regs struct had both a 'syscallno' field and an 'orig_gpr11' field
and it wasn't really clear how these were supposed to be used.  This patch
removes the syscallno field altogether and makes orig_gpr11 work more
like other architectures: keep track of syscall number in progress or
hold -1 for non-syscall exceptions.

Signed-off-by: Jonas Bonn <jonas@southpole.se>

arch/openrisc/include/asm/ptrace.h

@@ -73,9 +73,13 @@ struct pt_regs {
 		};
 	};
 	long  pc;
+	/* For restarting system calls:
+	 * Set to syscall number for syscall exceptions,
+	 * -1 for all other exceptions.
+	 */
 	long  orig_gpr11;	/* For restarting system calls */
-	long  syscallno;	/* Syscall number (used by strace) */
 	long dummy;		/* Cheap alignment fix */
+	long dummy2;		/* Cheap alignment fix */
 };
 
 /* TODO: Rename this to REDZONE because that's what it is */

arch/openrisc/include/asm/syscall.h

@@ -25,7 +25,7 @@
 static inline int
 syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 {
-	return regs->syscallno ? regs->syscallno : -1;
+	return regs->orig_gpr11;
 }
 
 static inline void
@@ -50,10 +50,7 @@ static inline void
 syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
 			 int error, long val)
 {
-	if (error)
-		regs->gpr[11] = -error;
-	else
-		regs->gpr[11] = val;
+	regs->gpr[11] = (long) error ?: val;
 }
 
 static inline void

arch/openrisc/kernel/entry.S

@@ -95,7 +95,6 @@ handler:							;\
 	/* r1, EPCR, ESR a already saved */			;\
 	l.sw	PT_GPR2(r1),r2					;\
 	l.sw    PT_GPR3(r1),r3					;\
-	l.sw    PT_ORIG_GPR11(r1),r11				;\
 	/* r4 already save */					;\
 	l.sw    PT_GPR5(r1),r5					;\
 	l.sw    PT_GPR6(r1),r6					;\
@@ -125,7 +124,9 @@ handler:							;\
 	/* r30 already save */					;\
 /*        l.sw    PT_GPR30(r1),r30*/					;\
 	l.sw    PT_GPR31(r1),r31					;\
-	l.sw    PT_SYSCALLNO(r1),r0
+	/* Store -1 in orig_gpr11 for non-syscall exceptions */	;\
+	l.addi	r30,r0,-1					;\
+	l.sw	PT_ORIG_GPR11(r1),r30
 
 #define UNHANDLED_EXCEPTION(handler,vector)			\
 	.global	handler						;\
@@ -133,7 +134,6 @@ handler:							;\
 	/* r1, EPCR, ESR already saved */			;\
 	l.sw    PT_GPR2(r1),r2					;\
 	l.sw    PT_GPR3(r1),r3					;\
-	l.sw    PT_ORIG_GPR11(r1),r11				;\
 	l.sw    PT_GPR5(r1),r5					;\
 	l.sw    PT_GPR6(r1),r6					;\
 	l.sw    PT_GPR7(r1),r7					;\
@@ -162,7 +162,9 @@ handler:							;\
 	/* r31 already saved */					;\
 	l.sw    PT_GPR30(r1),r30					;\
 /*        l.sw    PT_GPR31(r1),r31	*/				;\
-	l.sw    PT_SYSCALLNO(r1),r0				;\
+	/* Store -1 in orig_gpr11 for non-syscall exceptions */	;\
+	l.addi	r30,r0,-1					;\
+	l.sw	PT_ORIG_GPR11(r1),r30				;\
 	l.addi	r3,r1,0						;\
 	/* r4 is exception EA */				;\
 	l.addi	r5,r0,vector					;\
@@ -554,6 +556,7 @@ ENTRY(_sys_call_handler)
 	l.sw    PT_GPR9(r1),r9
 	/* r10 already saved */
 	l.sw    PT_GPR11(r1),r11
+	/* orig_gpr11 must be set for syscalls */
 	l.sw    PT_ORIG_GPR11(r1),r11
 	/* r12,r13 already saved */
 
@@ -567,9 +570,6 @@ ENTRY(_sys_call_handler)
 	/* r30 is the only register we clobber in the fast path */
 	/* r30 already saved */
 /*	l.sw    PT_GPR30(r1),r30 */
-	/* This is used by do_signal to determine whether to check for
-	 * syscall restart or not */
-	l.sw    PT_SYSCALLNO(r1),r11
 
 _syscall_check_trace_enter:
 	/* If TIF_SYSCALL_TRACE is set, then we want to do syscall tracing */
@@ -731,7 +731,7 @@ _syscall_trace_enter:
 	 * so that we can do the syscall for real and return to the syscall
 	 * hot path.
 	 */
-	l.lwz	r11,PT_SYSCALLNO(r1)
+	l.lwz	r11,PT_GPR11(r1)
 	l.lwz	r3,PT_GPR3(r1)
 	l.lwz	r4,PT_GPR4(r1)
 	l.lwz	r5,PT_GPR5(r1)

arch/openrisc/kernel/ptrace.c

@@ -188,11 +188,11 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 		 */
 		ret = -1L;
 
-	audit_syscall_entry(audit_arch(), regs->syscallno,
+	audit_syscall_entry(audit_arch(), regs->gpr[11],
 			    regs->gpr[3], regs->gpr[4],
 			    regs->gpr[5], regs->gpr[6]);
 
-	return ret ? : regs->syscallno;
+	return ret ? : regs->gpr[11];
 }
 
 asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)

arch/openrisc/kernel/signal.c

@@ -305,7 +305,7 @@ void do_signal(struct pt_regs *regs)
 	 * below mean that the syscall executed to completion and no
 	 * restart is necessary.
 	 */
-	if (regs->syscallno) {
+	if (regs->orig_gpr11) {
 		int restart = 0;
 
 		switch (regs->gpr[11]) {

arch/openrisc/kernel/traps.c

@@ -146,8 +146,8 @@ void show_registers(struct pt_regs *regs)
 	       regs->gpr[24], regs->gpr[25], regs->gpr[26], regs->gpr[27]);
 	printk("GPR28: %08lx GPR29: %08lx GPR30: %08lx GPR31: %08lx\n",
 	       regs->gpr[28], regs->gpr[29], regs->gpr[30], regs->gpr[31]);
-	printk("  RES: %08lx oGPR11: %08lx syscallno: %08lx\n",
-	       regs->gpr[11], regs->orig_gpr11, regs->syscallno);
+	printk("  RES: %08lx oGPR11: %08lx\n",
+	       regs->gpr[11], regs->orig_gpr11);
 
 	printk("Process %s (pid: %d, stackpage=%08lx)\n",
 	       current->comm, current->pid, (unsigned long)current);
@@ -208,8 +208,8 @@ void nommu_dump_state(struct pt_regs *regs,
 	       regs->gpr[24], regs->gpr[25], regs->gpr[26], regs->gpr[27]);
 	printk("GPR28: %08lx GPR29: %08lx GPR30: %08lx GPR31: %08lx\n",
 	       regs->gpr[28], regs->gpr[29], regs->gpr[30], regs->gpr[31]);
-	printk("  RES: %08lx oGPR11: %08lx syscallno: %08lx\n",
-	       regs->gpr[11], regs->orig_gpr11, regs->syscallno);
+	printk("  RES: %08lx oGPR11: %08lx\n",
+	       regs->gpr[11], regs->orig_gpr11);
 
 	printk("Process %s (pid: %d, stackpage=%08lx)\n",
 	       ((struct task_struct *)(__pa(current)))->comm,