powerpc: switch to generic sigaltstack

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/powerpc/Kconfig

@@ -144,6 +144,7 @@ config PPC
 	select HAVE_MOD_ARCH_SPECIFIC
 	select MODULES_USE_ELF_RELA
 	select CLONE_BACKWARDS
+	select GENERIC_SIGALTSTACK
 
 config EARLY_PRINTK
 	bool

arch/powerpc/include/asm/syscalls.h

@@ -22,9 +22,5 @@ asmlinkage long ppc64_personality(unsigned long personality);
 asmlinkage int ppc_rtas(struct rtas_args __user *uargs);
 asmlinkage time_t sys64_time(time_t __user * tloc);
 
-asmlinkage long sys_sigaltstack(const stack_t __user *uss,
-		stack_t __user *uoss, unsigned long r5, unsigned long r6,
-		unsigned long r7, unsigned long r8, struct pt_regs *regs);
-
 #endif /* __KERNEL__ */
 #endif /* __ASM_POWERPC_SYSCALLS_H */

arch/powerpc/kernel/ppc32.h

@@ -34,12 +34,6 @@ struct sigaction32 {
        compat_sigset_t sa_mask;		/* A 32 bit mask */
 };
 
-typedef struct sigaltstack_32 {
-	unsigned int ss_sp;
-	int ss_flags;
-	compat_size_t ss_size;
-} stack_32_t;
-
 struct pt_regs32 {
 	unsigned int gpr[32];
 	unsigned int nip;
@@ -75,7 +69,7 @@ struct mcontext32 {
 struct ucontext32 { 
 	unsigned int	  	uc_flags;
 	unsigned int 	  	uc_link;
-	stack_32_t	 	uc_stack;
+	compat_stack_t	 	uc_stack;
 	int		 	uc_pad[7];
 	compat_uptr_t		uc_regs;	/* points to uc_mcontext field */
 	compat_sigset_t	 	uc_sigmask;	/* mask last for extensibility */

arch/powerpc/kernel/signal.c

@@ -169,10 +169,3 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 		tracehook_notify_resume(regs);
 	}
 }
-
-long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
-		unsigned long r5, unsigned long r6, unsigned long r7,
-		unsigned long r8, struct pt_regs *regs)
-{
-	return do_sigaltstack(uss, uoss, regs->gpr[1]);
-}

arch/powerpc/kernel/signal_32.c

@@ -67,6 +67,8 @@
 #define mcontext	mcontext32
 #define ucontext	ucontext32
 
+#define __save_altstack __compat_save_altstack
+
 /*
  * Userspace code may pass a ucontext which doesn't include VSX added
  * at the end.  We need to check for this case.
@@ -763,55 +765,6 @@ long compat_sys_rt_sigqueueinfo(u32 pid, u32 sig, compat_siginfo_t __user *uinfo
 	set_fs (old_fs);
 	return ret;
 }
-/*
- *  Start Alternate signal stack support
- *
- *  System Calls
- *       sigaltatck               compat_sys_sigaltstack
- */
-
-int compat_sys_sigaltstack(u32 __new, u32 __old, int r5,
-		      int r6, int r7, int r8, struct pt_regs *regs)
-{
-	stack_32_t __user * newstack = compat_ptr(__new);
-	stack_32_t __user * oldstack = compat_ptr(__old);
-	stack_t uss, uoss;
-	int ret;
-	mm_segment_t old_fs;
-	unsigned long sp;
-	compat_uptr_t ss_sp;
-
-	/*
-	 * set sp to the user stack on entry to the system call
-	 * the system call router sets R9 to the saved registers
-	 */
-	sp = regs->gpr[1];
-
-	/* Put new stack info in local 64 bit stack struct */
-	if (newstack) {
-		if (get_user(ss_sp, &newstack->ss_sp) ||
-		    __get_user(uss.ss_flags, &newstack->ss_flags) ||
-		    __get_user(uss.ss_size, &newstack->ss_size))
-			return -EFAULT;
-		uss.ss_sp = compat_ptr(ss_sp);
-	}
-
-	old_fs = get_fs();
-	set_fs(KERNEL_DS);
-	/* The __user pointer casts are valid because of the set_fs() */
-	ret = do_sigaltstack(
-		newstack ? (stack_t __user *) &uss : NULL,
-		oldstack ? (stack_t __user *) &uoss : NULL,
-		sp);
-	set_fs(old_fs);
-	/* Copy the stack information to the user output buffer */
-	if (!ret && oldstack  &&
-		(put_user(ptr_to_compat(uoss.ss_sp), &oldstack->ss_sp) ||
-		 __put_user(uoss.ss_flags, &oldstack->ss_flags) ||
-		 __put_user(uoss.ss_size, &oldstack->ss_size)))
-		return -EFAULT;
-	return ret;
-}
 #endif /* CONFIG_PPC64 */
 
 /*
@@ -838,10 +791,7 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,
 	if (copy_siginfo_to_user(&rt_sf->info, info)
 	    || __put_user(0, &rt_sf->uc.uc_flags)
 	    || __put_user(0, &rt_sf->uc.uc_link)
-	    || __put_user(current->sas_ss_sp, &rt_sf->uc.uc_stack.ss_sp)
+	    || __save_altstack(&rt_sf->uc.uc_stack, regs->gpr[1])
-	    || __put_user(sas_ss_flags(regs->gpr[1]),
-			  &rt_sf->uc.uc_stack.ss_flags)
-	    || __put_user(current->sas_ss_size, &rt_sf->uc.uc_stack.ss_size)
 	    || __put_user(to_user_ptr(&rt_sf->uc.uc_mcontext),
 		    &rt_sf->uc.uc_regs)
 	    || put_sigset_t(&rt_sf->uc.uc_sigmask, oldset))
@@ -1038,14 +988,11 @@ long sys_rt_sigreturn(int r3, int r4, int r5, int r6, int r7, int r8,
 	 * change it.  -- paulus
 	 */
 #ifdef CONFIG_PPC64
-	/*
+	if (compat_restore_altstack(&rt_sf->uc.uc_stack))
-	 * We use the compat_sys_ version that does the 32/64 bits conversion
+		goto bad;
-	 * and takes userland pointer directly. What about error checking ?
-	 * nobody does any...
-	 */
-	compat_sys_sigaltstack((u32)(u64)&rt_sf->uc.uc_stack, 0, 0, 0, 0, 0, regs);
 #else
-	do_sigaltstack(&rt_sf->uc.uc_stack, NULL, regs->gpr[1]);
+	if (restore_altstack(&rt_sf->uc.uc_stack))
+		goto bad;
 #endif
 	set_thread_flag(TIF_RESTOREALL);
 	return 0;
@@ -1161,7 +1108,7 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
 	 * always done it up until now so it is probably better not to
 	 * change it.  -- paulus
 	 */
-	do_sigaltstack(&ctx->uc_stack, NULL, regs->gpr[1]);
+	restore_altstack(&ctx->uc_stack);
 
 	set_thread_flag(TIF_RESTOREALL);
  out:

arch/powerpc/kernel/signal_64.c

@@ -368,10 +368,8 @@ int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
 	if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
 		goto badframe;
 
-	/* do_sigaltstack expects a __user pointer and won't modify
+	if (restore_altstack(&uc->uc_stack))
-	 * what's in there anyway
+		goto badframe;
-	 */
-	do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]);
 
 	set_thread_flag(TIF_RESTOREALL);
 	return 0;
@@ -416,10 +414,7 @@ int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
 	/* Create the ucontext.  */
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(0, &frame->uc.uc_link);
-	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
+	err |= __save_altstack(&frame->uc.uc_stack, regs->gpr[1]);
-	err |= __put_user(sas_ss_flags(regs->gpr[1]),
-			  &frame->uc.uc_stack.ss_flags);
-	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
 				(unsigned long)ka->sa.sa_handler, 1);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));