x86: pass in pt_regs pointer for syscalls that need it

Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it.  This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to regparm(1) to receive the pt_regs pointer as the
first argument.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 28 deletions

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 8562387c75a7..d7a158367e38 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -549,39 +549,28 @@ sys_sigaction(int sig, const struct old_sigaction __user *act,
 #endif /* CONFIG_X86_32 */
 
 #ifdef CONFIG_X86_32
-asmlinkage int sys_sigaltstack(unsigned long bx)
-{
-        /*
-         * This is needed to make gcc realize it doesn't own the
-         * "struct pt_regs"
-         */
-        struct pt_regs *regs = (struct pt_regs *)&bx;
-        const stack_t __user *uss = (const stack_t __user *)bx;
-        stack_t __user *uoss = (stack_t __user *)regs->cx;
-
-        return do_sigaltstack(uss, uoss, regs->sp);
-}
+ptregscall int
+sys_sigaltstack(struct pt_regs *regs, const stack_t __user *uss,
+                stack_t __user *uoss)
 #else /* !CONFIG_X86_32 */
 asmlinkage long
 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
                 struct pt_regs *regs)
+#endif /* CONFIG_X86_32 */
 {
         return do_sigaltstack(uss, uoss, regs->sp);
 }
-#endif /* CONFIG_X86_32 */
 
 /*
  * Do a signal return; undo the signal stack.
  */
 #ifdef CONFIG_X86_32
-asmlinkage unsigned long sys_sigreturn(unsigned long __unused)
+ptregscall unsigned long sys_sigreturn(struct pt_regs *regs)
 {
         struct sigframe __user *frame;
-        struct pt_regs *regs;
         unsigned long ax;
         sigset_t set;
 
-        regs = (struct pt_regs *) &__unused;
         frame = (struct sigframe __user *)(regs->sp - 8);
 
         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
@@ -640,23 +629,13 @@ badframe:
 }
 
 #ifdef CONFIG_X86_32
-/*
- * Note: do not pass in pt_regs directly as with tail-call optimization
- * GCC will incorrectly stomp on the caller's frame and corrupt user-space
- * register state:
- */
-asmlinkage int sys_rt_sigreturn(unsigned long __unused)
-{
-        struct pt_regs *regs = (struct pt_regs *)&__unused;
-
-        return do_rt_sigreturn(regs);
-}
+ptregscall int sys_rt_sigreturn(struct pt_regs *regs)
 #else /* !CONFIG_X86_32 */
 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
+#endif /* CONFIG_X86_32 */
 {
         return do_rt_sigreturn(regs);
 }
-#endif /* CONFIG_X86_32 */
 
 /*
  * OK, we're invoking a handler: