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>

6 files changed, 22 insertions, 21 deletions

diff --git a/arch/openrisc/include/asm/ptrace.h b/arch/openrisc/include/asm/ptrace.h
index e612ce4512c7..4651a737591d 100644
--- a/arch/openrisc/include/asm/ptrace.h
+++ b/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 */
diff --git a/arch/openrisc/include/asm/syscall.h b/arch/openrisc/include/asm/syscall.h
index 9f0337055d26..b752bb67891d 100644
--- a/arch/openrisc/include/asm/syscall.h
+++ b/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
diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S
index d5f9c35a583f..6e61af8682b8 100644
--- a/arch/openrisc/kernel/entry.S
+++ b/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)
diff --git a/arch/openrisc/kernel/ptrace.c b/arch/openrisc/kernel/ptrace.c
index 7259047d5f9d..6deacb6b95a4 100644
--- a/arch/openrisc/kernel/ptrace.c
+++ b/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)
diff --git a/arch/openrisc/kernel/signal.c b/arch/openrisc/kernel/signal.c
index cf35ea032a70..e970743251ae 100644
--- a/arch/openrisc/kernel/signal.c
+++ b/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]) {
diff --git a/arch/openrisc/kernel/traps.c b/arch/openrisc/kernel/traps.c
index ab68ffc85750..a2ee12948f40 100644
--- a/arch/openrisc/kernel/traps.c
+++ b/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,