s390: switch to generic sigaltstack

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

arch/s390/Kconfig

@@ -140,6 +140,7 @@ config S390
 	select HAVE_MOD_ARCH_SPECIFIC
 	select MODULES_USE_ELF_RELA
 	select CLONE_BACKWARDS2
+	select GENERIC_SIGALTSTACK
 
 config SCHED_OMIT_FRAME_POINTER
 	def_bool y

arch/s390/kernel/compat_linux.h

@@ -75,17 +75,11 @@ struct sigaction32 {
 	compat_sigset_t	sa_mask;        /* mask last for extensibility */
 };
 
-typedef struct {
-	__u32			ss_sp;		/* pointer */
-	int			ss_flags;
-	compat_size_t		ss_size;
-} stack_t32;
-
 /* asm/ucontext.h */
 struct ucontext32 {
 	__u32			uc_flags;
 	__u32			uc_link;	/* pointer */	
-	stack_t32		uc_stack;
+	compat_stack_t		uc_stack;
 	_sigregs32		uc_mcontext;
 	compat_sigset_t		uc_sigmask;	/* mask last for extensibility */
 };
@@ -153,5 +147,4 @@ long sys32_sigaction(int sig, const struct old_sigaction32 __user *act,
 		     struct old_sigaction32 __user *oact);
 long sys32_rt_sigaction(int sig, const struct sigaction32 __user *act,
 			struct sigaction32 __user *oact, size_t sigsetsize);
-long sys32_sigaltstack(const stack_t32 __user *uss, stack_t32 __user *uoss);
 #endif /* _ASM_S390X_S390_H */

arch/s390/kernel/compat_signal.c

@@ -234,45 +234,6 @@ sys32_rt_sigaction(int sig, const struct sigaction32 __user *act,
 	return ret;
 }
 
-asmlinkage long
-sys32_sigaltstack(const stack_t32 __user *uss, stack_t32 __user *uoss)
-{
-	struct pt_regs *regs = task_pt_regs(current);
-	stack_t kss, koss;
-	unsigned long ss_sp;
-	int ret, err = 0;
-	mm_segment_t old_fs = get_fs();
-
-	if (uss) {
-		if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
-			return -EFAULT;
-		err |= __get_user(ss_sp, &uss->ss_sp);
-		err |= __get_user(kss.ss_size, &uss->ss_size);
-		err |= __get_user(kss.ss_flags, &uss->ss_flags);
-		if (err)
-			return -EFAULT;
-		kss.ss_sp = (void __user *) ss_sp;
-	}
-
-	set_fs (KERNEL_DS);
-	ret = do_sigaltstack((stack_t __force __user *) (uss ? &kss : NULL),
-			     (stack_t __force __user *) (uoss ? &koss : NULL),
-			     regs->gprs[15]);
-	set_fs (old_fs);
-
-	if (!ret && uoss) {
-		if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
-			return -EFAULT;
-		ss_sp = (unsigned long) koss.ss_sp;
-		err |= __put_user(ss_sp, &uoss->ss_sp);
-		err |= __put_user(koss.ss_size, &uoss->ss_size);
-		err |= __put_user(koss.ss_flags, &uoss->ss_flags);
-		if (err)
-			return -EFAULT;
-	}
-	return ret;
-}
-
 static int save_sigregs32(struct pt_regs *regs, _sigregs32 __user *sregs)
 {
 	_s390_regs_common32 regs32;
@@ -380,10 +341,6 @@ asmlinkage long sys32_rt_sigreturn(void)
 	struct pt_regs *regs = task_pt_regs(current);
 	rt_sigframe32 __user *frame = (rt_sigframe32 __user *)regs->gprs[15];
 	sigset_t set;
-	stack_t st;
-	__u32 ss_sp;
-	int err;
-	mm_segment_t old_fs = get_fs();
 
 	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 		goto badframe;
@@ -394,15 +351,8 @@ asmlinkage long sys32_rt_sigreturn(void)
 		goto badframe;
 	if (restore_sigregs_gprs_high(regs, frame->gprs_high))
 		goto badframe;
-	err = __get_user(ss_sp, &frame->uc.uc_stack.ss_sp);
-	st.ss_sp = compat_ptr(ss_sp);
-	err |= __get_user(st.ss_size, &frame->uc.uc_stack.ss_size);
-	err |= __get_user(st.ss_flags, &frame->uc.uc_stack.ss_flags);
-	if (err)
+	if (compat_restore_altstack(&frame->uc.uc_stack))
 		goto badframe; 
-	set_fs (KERNEL_DS);
-	do_sigaltstack((stack_t __force __user *)&st, NULL, regs->gprs[15]);
-	set_fs (old_fs);
 	return regs->gprs[2];
 badframe:
 	force_sig(SIGSEGV, current);
@@ -530,10 +480,7 @@ static int setup_rt_frame32(int sig, struct k_sigaction *ka, siginfo_t *info,
 	/* Create the ucontext.  */
 	err |= __put_user(UC_EXTENDED, &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 |= __put_user(sas_ss_flags(regs->gprs[15]),
-	                  &frame->uc.uc_stack.ss_flags);
-	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+	err |= __compat_save_altstack(&frame->uc.uc_stack, regs->gprs[15]);
 	err |= save_sigregs32(regs, &frame->uc.uc_mcontext);
 	err |= save_sigregs_gprs_high(regs, frame->gprs_high);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

arch/s390/kernel/compat_wrapper.S

@@ -760,11 +760,6 @@ ENTRY(sys32_capset_wrapper)
 	llgtr	%r3,%r3			# const cap_user_data_t
 	jg	sys_capset		# branch to system call
 
-ENTRY(sys32_sigaltstack_wrapper)
-	llgtr	%r2,%r2			# const stack_emu31_t *
-	llgtr	%r3,%r3			# stack_emu31_t *
-	jg	sys32_sigaltstack
-
 ENTRY(sys32_sendfile_wrapper)
 	lgfr	%r2,%r2			# int
 	lgfr	%r3,%r3			# int

arch/s390/kernel/entry.h

@@ -76,7 +76,6 @@ long sys_s390_fallocate(int fd, int mode, loff_t offset, u32 len_high,
 long sys_sigsuspend(int history0, int history1, old_sigset_t mask);
 long sys_sigaction(int sig, const struct old_sigaction __user *act,
 		   struct old_sigaction __user *oact);
-long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss);
 long sys_sigreturn(void);
 long sys_rt_sigreturn(void);
 long sys32_sigreturn(void);

arch/s390/kernel/signal.c

@@ -89,13 +89,6 @@ SYSCALL_DEFINE3(sigaction, int, sig, const struct old_sigaction __user *, act,
 	return ret;
 }
 
-SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
-		stack_t __user *, uoss)
-{
-	struct pt_regs *regs = task_pt_regs(current);
-	return do_sigaltstack(uss, uoss, regs->gprs[15]);
-}
-
 /* Returns non-zero on fault. */
 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 {
@@ -190,8 +183,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	set_current_blocked(&set);
 	if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 		goto badframe;
-	if (do_sigaltstack(&frame->uc.uc_stack, NULL,
-			   regs->gprs[15]) == -EFAULT)
+	if (restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
 	return regs->gprs[2];
 badframe:
@@ -325,10 +317,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	/* Create the ucontext.  */
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(NULL, &frame->uc.uc_link);
-	err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-	err |= __put_user(sas_ss_flags(regs->gprs[15]),
-			  &frame->uc.uc_stack.ss_flags);
-	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+	err |= __save_altstack(&frame->uc.uc_stack, regs->gprs[15]);
 	err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 	if (err)

arch/s390/kernel/syscalls.S

@@ -194,7 +194,7 @@ SYSCALL(sys_chown16,sys_ni_syscall,sys32_chown16_wrapper)	/* old chown16 syscall
 SYSCALL(sys_getcwd,sys_getcwd,sys32_getcwd_wrapper)
 SYSCALL(sys_capget,sys_capget,sys32_capget_wrapper)
 SYSCALL(sys_capset,sys_capset,sys32_capset_wrapper)		/* 185 */
-SYSCALL(sys_sigaltstack,sys_sigaltstack,sys32_sigaltstack_wrapper)
+SYSCALL(sys_sigaltstack,sys_sigaltstack,compat_sys_sigaltstack)
 SYSCALL(sys_sendfile,sys_sendfile64,sys32_sendfile_wrapper)
 NI_SYSCALL							/* streams1 */
 NI_SYSCALL							/* streams2 */