x86-32 ptrace: use task_pt_regs

This cleans up the 32-bit ptrace code to use task_pt_regs instead of its
own redundant code that does the same thing a different way.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 16 insertions, 52 deletions

diff --git a/arch/x86/kernel/ptrace_32.c b/arch/x86/kernel/ptrace_32.c
index bd3668c2421a..a1425e9ad028 100644
--- a/arch/x86/kernel/ptrace_32.c
+++ b/arch/x86/kernel/ptrace_32.c
@@ -37,53 +37,20 @@
  */
 #define FLAG_MASK 0x00050dd5
 
-/*
- * Offset of eflags on child stack..
- */
-#define EFL_OFFSET offsetof(struct pt_regs, eflags)
-
-static inline struct pt_regs *get_child_regs(struct task_struct *task)
-{
-        void *stack_top = (void *)task->thread.esp0;
-        return stack_top - sizeof(struct pt_regs);
-}
-
-/*
- * This routine will get a word off of the processes privileged stack.
- * the offset is bytes into the pt_regs structure on the stack.
- * This routine assumes that all the privileged stacks are in our
- * data space.
- */   
-static inline int get_stack_long(struct task_struct *task, int offset)
+static long *pt_regs_access(struct pt_regs *regs, unsigned long regno)
 {
-        unsigned char *stack;
-
-        stack = (unsigned char *)task->thread.esp0 - sizeof(struct pt_regs);
-        stack += offset;
-        return (*((int *)stack));
-}
-
-/*
- * This routine will put a word on the processes privileged stack.
- * the offset is bytes into the pt_regs structure on the stack.
- * This routine assumes that all the privileged stacks are in our
- * data space.
- */
-static inline int put_stack_long(struct task_struct *task, int offset,
-        unsigned long data)
-{
-        unsigned char * stack;
-
-        stack = (unsigned char *)task->thread.esp0 - sizeof(struct pt_regs);
-        stack += offset;
-        *(unsigned long *) stack = data;
-        return 0;
+        BUILD_BUG_ON(offsetof(struct pt_regs, ebx) != 0);
+        if (regno > FS)
+                --regno;
+        return &regs->ebx + regno;
 }
 
 static int putreg(struct task_struct *child,
         unsigned long regno, unsigned long value)
 {
-        switch (regno >> 2) {
+        struct pt_regs *regs = task_pt_regs(child);
+        regno >>= 2;
+        switch (regno) {
                 case GS:
                         if (value && (value & 3) != 3)
                                 return -EIO;
@@ -113,26 +80,25 @@ static int putreg(struct task_struct *child,
                                 clear_tsk_thread_flag(child, TIF_FORCED_TF);
                         else if (test_tsk_thread_flag(child, TIF_FORCED_TF))
                                 value |= X86_EFLAGS_TF;
-                        value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
+                        value |= regs->eflags & ~FLAG_MASK;
                         break;
         }
-        if (regno > FS*4)
-                regno -= 1*4;
-        put_stack_long(child, regno, value);
+        *pt_regs_access(regs, regno) = value;
         return 0;
 }
 
-static unsigned long getreg(struct task_struct *child,
-        unsigned long regno)
+static unsigned long getreg(struct task_struct *child, unsigned long regno)
 {
+        struct pt_regs *regs = task_pt_regs(child);
         unsigned long retval = ~0UL;
 
-        switch (regno >> 2) {
+        regno >>= 2;
+        switch (regno) {
                 case EFL:
                         /*
                          * If the debugger set TF, hide it from the readout.
                          */
-                        retval = get_stack_long(child, EFL_OFFSET);
+                        retval = regs->eflags;
                         if (test_tsk_thread_flag(child, TIF_FORCED_TF))
                                 retval &= ~X86_EFLAGS_TF;
                         break;
@@ -147,9 +113,7 @@ static unsigned long getreg(struct task_struct *child,
                         retval = 0xffff;
                         /* fall through */
                 default:
-                        if (regno > FS*4)
-                                regno -= 1*4;
-                        retval &= get_stack_long(child, regno);
+                        retval &= *pt_regs_access(regs, regno);
         }
         return retval;
 }