sh: don't pass saved userspace state to exception handlers

The compiler is permitted to generate code which overwrites the
parameters to a function.  If those parameters include the only saved
copy we have of userspace's registers, we're in trouble.

Signed-off-by: Bobby Bingham <koorogi@koorogi.info>
Cc: Paul Mundt <paul.mundt@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 11 insertions, 28 deletions

diff --git a/arch/sh/include/asm/traps_32.h b/arch/sh/include/asm/traps_32.h
index cfd55ff9dff2..17e129fe459c 100644
--- a/arch/sh/include/asm/traps_32.h
+++ b/arch/sh/include/asm/traps_32.h
@@ -42,18 +42,10 @@ static inline void trigger_address_error(void)
 asmlinkage void do_address_error(struct pt_regs *regs,
                                  unsigned long writeaccess,
                                  unsigned long address);
-asmlinkage void do_divide_error(unsigned long r4, unsigned long r5,
-                                unsigned long r6, unsigned long r7,
-                                struct pt_regs __regs);
-asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
-                                unsigned long r6, unsigned long r7,
-                                struct pt_regs __regs);
-asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
-                                unsigned long r6, unsigned long r7,
-                                struct pt_regs __regs);
-asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
-                                   unsigned long r6, unsigned long r7,
-                                   struct pt_regs __regs);
+asmlinkage void do_divide_error(unsigned long r4);
+asmlinkage void do_reserved_inst(void);
+asmlinkage void do_illegal_slot_inst(void);
+asmlinkage void do_exception_error(void);
 
 #define BUILD_TRAP_HANDLER(name)                                        \
 asmlinkage void name##_trap_handler(unsigned long r4, unsigned long r5, \
diff --git a/arch/sh/kernel/traps_32.c b/arch/sh/kernel/traps_32.c
index 68e99f09171d..ff639342a8be 100644
--- a/arch/sh/kernel/traps_32.c
+++ b/arch/sh/kernel/traps_32.c
@@ -594,9 +594,7 @@ int is_dsp_inst(struct pt_regs *regs)
 #endif /* CONFIG_SH_DSP */
 
 #ifdef CONFIG_CPU_SH2A
-asmlinkage void do_divide_error(unsigned long r4, unsigned long r5,
-                                unsigned long r6, unsigned long r7,
-                                struct pt_regs __regs)
+asmlinkage void do_divide_error(unsigned long r4)
 {
         siginfo_t info;
 
@@ -613,11 +611,9 @@ asmlinkage void do_divide_error(unsigned long r4, unsigned long r5,
 }
 #endif
 
-asmlinkage void do_reserved_inst(unsigned long r4, unsigned long r5,
-                                unsigned long r6, unsigned long r7,
-                                struct pt_regs __regs)
+asmlinkage void do_reserved_inst(void)
 {
-        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
+        struct pt_regs *regs = current_pt_regs();
         unsigned long error_code;
         struct task_struct *tsk = current;
 
@@ -701,11 +697,9 @@ static int emulate_branch(unsigned short inst, struct pt_regs *regs)
 }
 #endif
 
-asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
-                                unsigned long r6, unsigned long r7,
-                                struct pt_regs __regs)
+asmlinkage void do_illegal_slot_inst(void)
 {
-        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
+        struct pt_regs *regs = current_pt_regs();
         unsigned long inst;
         struct task_struct *tsk = current;
 
@@ -730,15 +724,12 @@ asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
         die_if_no_fixup("illegal slot instruction", regs, inst);
 }
 
-asmlinkage void do_exception_error(unsigned long r4, unsigned long r5,
-                                   unsigned long r6, unsigned long r7,
-                                   struct pt_regs __regs)
+asmlinkage void do_exception_error(void)
 {
-        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
         long ex;
 
         ex = lookup_exception_vector();
-        die_if_kernel("exception", regs, ex);
+        die_if_kernel("exception", current_pt_regs(), ex);
 }
 
 void per_cpu_trap_init(void)