[RFC 16/17] microblaze: clean up signal handling

From: arnd
Date: Mon Apr 27 2009 - 11:11:20 EST

When legacy signal handling is disabled, the
arch/microblaze/kernel/signal.c implementation can
be much simpler, as most of it is handled generically
from kernel/signal.c.

This is also a prerequisite for using the generic
asm/unistd.h, which does not provide __NR_sigreturn,
because this macro is referenced by the current signal.c
implementation.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
arch/microblaze/include/asm/signal.h | 166 1 + 165 - 0 !
arch/microblaze/include/asm/syscalls.h | 13 4 + 9 - 0 !
arch/microblaze/include/asm/thread_info.h | 11 11 + 0 - 0 !
arch/microblaze/include/asm/unistd.h | 2 1 + 1 - 0 !
arch/microblaze/kernel/signal.c | 250 38 + 212 - 0 !
5 files changed, 55 insertions(+), 387 deletions(-)

Index: linux-2.6/arch/microblaze/include/asm/signal.h
===================================================================
--- linux-2.6.orig/arch/microblaze/include/asm/signal.h
+++ linux-2.6/arch/microblaze/include/asm/signal.h
@@ -1,165 +1 @@
-/*
- * Copyright (C) 2006 Atmark Techno, Inc.
- * Yasushi SHOJI <yashi@xxxxxxxxxxxxxxxxx>
- * Tetsuya OHKAWA <tetsuya@xxxxxxxxxxxxxxxxx>
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file "COPYING" in the main directory of this archive
- * for more details.
- */
-
-#ifndef _ASM_MICROBLAZE_SIGNAL_H
-#define _ASM_MICROBLAZE_SIGNAL_H
-
-#define SIGHUP 1
-#define SIGINT 2
-#define SIGQUIT 3
-#define SIGILL 4
-#define SIGTRAP 5
-#define SIGABRT 6
-#define SIGIOT 6
-#define SIGBUS 7
-#define SIGFPE 8
-#define SIGKILL 9
-#define SIGUSR1 10
-#define SIGSEGV 11
-#define SIGUSR2 12
-#define SIGPIPE 13
-#define SIGALRM 14
-#define SIGTERM 15
-#define SIGSTKFLT 16
-#define SIGCHLD 17
-#define SIGCONT 18
-#define SIGSTOP 19
-#define SIGTSTP 20
-#define SIGTTIN 21
-#define SIGTTOU 22
-#define SIGURG 23
-#define SIGXCPU 24
-#define SIGXFSZ 25
-#define SIGVTALRM 26
-#define SIGPROF 27
-#define SIGWINCH 28
-#define SIGIO 29
-#define SIGPOLL SIGIO
-/*
-#define SIGLOST 29
-*/
-#define SIGPWR 30
-#define SIGSYS 31
-#define SIGUNUSED 31
-
-/* These should not be considered constants from userland. */
-#define SIGRTMIN 32
-#define SIGRTMAX _NSIG
-
-/*
- * SA_FLAGS values:
- *
- * SA_ONSTACK indicates that a registered stack_t will be used.
- * SA_RESTART flag to get restarting signals (which were the default long ago)
- * SA_NOCLDSTOP flag to turn off SIGCHLD when children stop.
- * SA_RESETHAND clears the handler when the signal is delivered.
- * SA_NOCLDWAIT flag on SIGCHLD to inhibit zombies.
- * SA_NODEFER prevents the current signal from being masked in the handler.
- *
- * SA_ONESHOT and SA_NOMASK are the historical Linux names for the Single
- * Unix names RESETHAND and NODEFER respectively.
- */
-#define SA_NOCLDSTOP 0x00000001
-#define SA_NOCLDWAIT 0x00000002
-#define SA_SIGINFO 0x00000004
-#define SA_ONSTACK 0x08000000
-#define SA_RESTART 0x10000000
-#define SA_NODEFER 0x40000000
-#define SA_RESETHAND 0x80000000
-
-#define SA_NOMASK SA_NODEFER
-#define SA_ONESHOT SA_RESETHAND
-
-#define SA_RESTORER 0x04000000
-
-/*
- * sigaltstack controls
- */
-#define SS_ONSTACK 1
-#define SS_DISABLE 2
-
-#define MINSIGSTKSZ 2048
-#define SIGSTKSZ 8192
-
-# ifndef __ASSEMBLY__
-# include <linux/types.h>
-# include <asm-generic/signal-defs.h>
-
-/* Avoid too many header ordering problems. */
-struct siginfo;
-
-# ifdef __KERNEL__
-/*
- * Most things should be clean enough to redefine this at will, if care
- * is taken to make libc match.
- */
-# define _NSIG 64
-# define _NSIG_BPW 32
-# define _NSIG_WORDS (_NSIG / _NSIG_BPW)
-
-typedef unsigned long old_sigset_t; /* at least 32 bits */
-
-typedef struct {
- unsigned long sig[_NSIG_WORDS];
-} sigset_t;
-
-struct old_sigaction {
- __sighandler_t sa_handler;
- old_sigset_t sa_mask;
- unsigned long sa_flags;
- void (*sa_restorer)(void);
-};
-
-struct sigaction {
- __sighandler_t sa_handler;
- unsigned long sa_flags;
- void (*sa_restorer)(void);
- sigset_t sa_mask; /* mask last for extensibility */
-};
-
-struct k_sigaction {
- struct sigaction sa;
-};
-
-# include <asm/sigcontext.h>
-# undef __HAVE_ARCH_SIG_BITOPS
-
-# define ptrace_signal_deliver(regs, cookie) do { } while (0)
-
-# else /* !__KERNEL__ */
-
-/* Here we must cater to libcs that poke about in kernel headers. */
-
-# define NSIG 32
-typedef unsigned long sigset_t;
-
-struct sigaction {
- union {
- __sighandler_t _sa_handler;
- void (*_sa_sigaction)(int, struct siginfo *, void *);
- } _u;
- sigset_t sa_mask;
- unsigned long sa_flags;
- void (*sa_restorer)(void);
-};
-
-# define sa_handler _u._sa_handler
-# define sa_sigaction _u._sa_sigaction
-
-# endif /* __KERNEL__ */
-
-typedef struct sigaltstack {
- void *ss_sp;
- int ss_flags;
- size_t ss_size;
-} stack_t;
-
-# endif /* __ASSEMBLY__ */
-#endif /* _ASM_MICROBLAZE_SIGNAL_H */
+#include <asm-generic/signal.h>
Index: linux-2.6/arch/microblaze/include/asm/syscalls.h
===================================================================
--- linux-2.6.orig/arch/microblaze/include/asm/syscalls.h
+++ linux-2.6/arch/microblaze/include/asm/syscalls.h
@@ -26,20 +26,15 @@ asmlinkage unsigned long sys_mmap(unsign
unsigned long fd, off_t offset);

/* from signal.c */
-asmlinkage int sys_sigsuspend(old_sigset_t mask, struct pt_regs *regs);
-
-asmlinkage int sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize,
+asmlinkage long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize,
struct pt_regs *regs);

-asmlinkage int sys_sigaction(int sig, const struct old_sigaction *act,
- struct old_sigaction *oact);
-
-asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
+asmlinkage long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
struct pt_regs *regs);

-asmlinkage int sys_sigreturn(struct pt_regs *regs);
+asmlinkage long sys_rt_sigaction(int sig, const struct sigaction __user * act, struct sigaction __user * oact, size_t sigsetsize);

-asmlinkage int sys_rt_sigreturn(struct pt_regs *regs);
+asmlinkage long sys_rt_sigreturn(struct pt_regs *regs);

#endif /* __KERNEL__ */
#endif /* __ASM_MICROBLAZE_SYSCALLS_H */
Index: linux-2.6/arch/microblaze/include/asm/thread_info.h
===================================================================
--- linux-2.6.orig/arch/microblaze/include/asm/thread_info.h
+++ linux-2.6/arch/microblaze/include/asm/thread_info.h
@@ -154,6 +154,17 @@ static inline struct thread_info *curren
*/
/* FPU was used by this task this quantum (SMP) */
#define TS_USEDFPU 0x0001
+#define TS_RESTORE_SIGMASK 0x0002
+
+#ifndef __ASSEMBLY__
+#define HAVE_SET_RESTORE_SIGMASK 1
+static inline void set_restore_sigmask(void)
+{
+ struct thread_info *ti = current_thread_info();
+ ti->status |= TS_RESTORE_SIGMASK;
+ set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
+}
+#endif

#endif /* __KERNEL__ */
#endif /* _ASM_MICROBLAZE_THREAD_INFO_H */
Index: linux-2.6/arch/microblaze/kernel/signal.c
===================================================================
--- linux-2.6.orig/arch/microblaze/kernel/signal.c
+++ linux-2.6/arch/microblaze/kernel/signal.c
@@ -45,91 +45,7 @@

asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset, int in_sycall);

-/*
- * Atomically swap in the new signal mask, and wait for a signal.
- */
-asmlinkage int
-sys_sigsuspend(old_sigset_t mask, struct pt_regs *regs)
-{
- sigset_t saveset;
-
- mask &= _BLOCKABLE;
- spin_lock_irq(&current->sighand->siglock);
- saveset = current->blocked;
- siginitset(&current->blocked, mask);
- recalc_sigpending();
- spin_unlock_irq(&current->sighand->siglock);
-
- regs->r3 = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(regs, &saveset, 1))
- return -EINTR;
- }
-}
-
-asmlinkage int
-sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize,
- struct pt_regs *regs)
-{
- sigset_t saveset, newset;
-
- /* XXX: Don't preclude handling different sized sigset_t's. */
- if (sigsetsize != sizeof(sigset_t))
- return -EINVAL;
-
- if (copy_from_user(&newset, unewset, sizeof(newset)))
- return -EFAULT;
- sigdelsetmask(&newset, ~_BLOCKABLE);
- spin_lock_irq(&current->sighand->siglock);
- saveset = current->blocked;
- current->blocked = newset;
- recalc_sigpending();
- spin_unlock_irq(&current->sighand->siglock);
-
- regs->r3 = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(regs, &saveset, 1))
- return -EINTR;
- }
-}
-
-asmlinkage int
-sys_sigaction(int sig, const struct old_sigaction *act,
- struct old_sigaction *oact)
-{
- struct k_sigaction new_ka, old_ka;
- int ret;
-
- if (act) {
- old_sigset_t mask;
- if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
- __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
- __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
- return -EFAULT;
- __get_user(new_ka.sa.sa_flags, &act->sa_flags);
- __get_user(mask, &act->sa_mask);
- siginitset(&new_ka.sa.sa_mask, mask);
- }
-
- ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
-
- if (!ret && oact) {
- if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
- __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
- __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
- return -EFAULT;
- __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
- __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
- }
-
- return ret;
-}
-
-asmlinkage int
+asmlinkage long
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
struct pt_regs *regs)
{
@@ -139,13 +55,13 @@ sys_sigaltstack(const stack_t __user *us
/*
* Do a signal return; undo the signal stack.
*/
-
struct sigframe {
struct sigcontext sc;
unsigned long extramask[_NSIG_WORDS-1];
unsigned long tramp[2]; /* signal trampoline */
};

+
struct rt_sigframe {
struct siginfo info;
struct ucontext uc;
@@ -176,40 +92,7 @@ restore_sigcontext(struct pt_regs *regs,
return err;
}

-asmlinkage int sys_sigreturn(struct pt_regs *regs)
-{
- struct sigframe *frame =
- (struct sigframe *)(regs->r1 + STATE_SAVE_ARG_SPACE);
-
- sigset_t set;
- int rval;
-
- if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
- goto badframe;
-
- if (__get_user(set.sig[0], &frame->sc.oldmask)
- || (_NSIG_WORDS > 1
- && __copy_from_user(&set.sig[1], &frame->extramask,
- sizeof(frame->extramask))))
- goto badframe;
-
- sigdelsetmask(&set, ~_BLOCKABLE);
-
- spin_lock_irq(&current->sighand->siglock);
- current->blocked = set;
- recalc_sigpending();
- spin_unlock_irq(&current->sighand->siglock);
-
- if (restore_sigcontext(regs, &frame->sc, &rval))
- goto badframe;
- return rval;
-
-badframe:
- force_sig(SIGSEGV, current);
- return 0;
-}
-
-asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
+asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe *frame =
(struct rt_sigframe *)(regs->r1 + STATE_SAVE_ARG_SPACE);
@@ -290,80 +173,6 @@ get_sigframe(struct k_sigaction *ka, str
return (void *)((sp - frame_size) & -8UL);
}

-static void setup_frame(int sig, struct k_sigaction *ka,
- sigset_t *set, struct pt_regs *regs)
-{
- struct sigframe *frame;
- int err = 0;
- int signal;
-
- frame = get_sigframe(ka, regs, sizeof(*frame));
-
- if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
- goto give_sigsegv;
-
- signal = current_thread_info()->exec_domain
- && current_thread_info()->exec_domain->signal_invmap
- && sig < 32
- ? current_thread_info()->exec_domain->signal_invmap[sig]
- : sig;
-
- err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
-
- if (_NSIG_WORDS > 1) {
- err |= __copy_to_user(frame->extramask, &set->sig[1],
- sizeof(frame->extramask));
- }
-
- /* Set up to return from userspace. If provided, use a stub
- already in userspace. */
- /* minus 8 is offset to cater for "rtsd r15,8" offset */
- if (ka->sa.sa_flags & SA_RESTORER) {
- regs->r15 = ((unsigned long)ka->sa.sa_restorer)-8;
- } else {
- /* Note, these encodings are _big endian_! */
-
- /* addi r12, r0, __NR_sigreturn */
- err |= __put_user(0x31800000 | __NR_sigreturn ,
- frame->tramp + 0);
- /* brki r14, 0x8 */
- err |= __put_user(0xb9cc0008, frame->tramp + 1);
-
- /* Return from sighandler will jump to the tramp.
- Negative 8 offset because return is rtsd r15, 8 */
- regs->r15 = ((unsigned long)frame->tramp)-8;
-
- __invalidate_cache_sigtramp((unsigned long)frame->tramp);
- }
-
- if (err)
- goto give_sigsegv;
-
- /* Set up registers for signal handler */
- regs->r1 = (unsigned long) frame - STATE_SAVE_ARG_SPACE;
-
- /* Signal handler args: */
- regs->r5 = signal; /* Arg 0: signum */
- regs->r6 = (unsigned long) &frame->sc; /* arg 1: sigcontext */
-
- /* Offset of 4 to handle microblaze rtid r14, 0 */
- regs->pc = (unsigned long)ka->sa.sa_handler;
-
- set_fs(USER_DS);
-
-#ifdef DEBUG_SIG
- printk(KERN_INFO "SIG deliver (%s:%d): sp=%p pc=%08lx\n",
- current->comm, current->pid, frame, regs->pc);
-#endif
-
- return;
-
-give_sigsegv:
- if (sig == SIGSEGV)
- ka->sa.sa_handler = SIG_DFL;
- force_sig(SIGSEGV, current);
-}
-
static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
@@ -399,21 +208,17 @@ static void setup_rt_frame(int sig, stru
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
/* minus 8 is offset to cater for "rtsd r15,8" */
- if (ka->sa.sa_flags & SA_RESTORER) {
- regs->r15 = ((unsigned long)ka->sa.sa_restorer)-8;
- } else {
- /* addi r12, r0, __NR_sigreturn */
- err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
- frame->tramp + 0);
- /* brki r14, 0x8 */
- err |= __put_user(0xb9cc0008, frame->tramp + 1);
-
- /* Return from sighandler will jump to the tramp.
- Negative 8 offset because return is rtsd r15, 8 */
- regs->r15 = ((unsigned long)frame->tramp)-8;
+ /* addi r12, r0, __NR_sigreturn */
+ err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
+ frame->tramp + 0);
+ /* brki r14, 0x8 */
+ err |= __put_user(0xb9cc0008, frame->tramp + 1);
+
+ /* Return from sighandler will jump to the tramp.
+ Negative 8 offset because return is rtsd r15, 8 */
+ regs->r15 = ((unsigned long)frame->tramp)-8;

- __invalidate_cache_sigtramp((unsigned long)frame->tramp);
- }
+ __invalidate_cache_sigtramp((unsigned long)frame->tramp);

if (err)
goto give_sigsegv;
@@ -472,7 +277,7 @@ do_restart:
* OK, we're invoking a handler
*/

-static void
+static int
handle_signal(unsigned long sig, struct k_sigaction *ka,
siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
@@ -480,7 +285,7 @@ handle_signal(unsigned long sig, struct
if (ka->sa.sa_flags & SA_SIGINFO)
setup_rt_frame(sig, ka, info, oldset, regs);
else
- setup_frame(sig, ka, oldset, regs);
+ setup_rt_frame(sig, ka, NULL, oldset, regs);

if (ka->sa.sa_flags & SA_ONESHOT)
ka->sa.sa_handler = SIG_DFL;
@@ -509,6 +314,7 @@ int do_signal(struct pt_regs *regs, sigs
siginfo_t info;
int signr;
struct k_sigaction ka;
+
#ifdef DEBUG_SIG
printk(KERN_INFO "do signal: %p %p %d\n", regs, oldset, in_syscall);
printk(KERN_INFO "do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
@@ -523,7 +329,9 @@ int do_signal(struct pt_regs *regs, sigs
if (kernel_mode(regs))
return 1;

- if (!oldset)
+ if (current_thread_info()->status & TS_RESTORE_SIGMASK)
+ oldset = &current->saved_sigmask;
+ else
oldset = &current->blocked;

signr = get_signal_to_deliver(&info, &ka, regs, NULL);
@@ -531,13 +339,31 @@ int do_signal(struct pt_regs *regs, sigs
/* Whee! Actually deliver the signal. */
if (in_syscall)
handle_restart(regs, &ka, 1);
- handle_signal(signr, &ka, &info, oldset, regs);
+ if (handle_signal(signr, &ka, &info, oldset, regs)) {
+ /*
+ * A signal was successfully delivered; the saved
+ * sigmask will have been stored in the signal frame,
+ * and will be restored by sigreturn, so we can simply
+ * clear the TS_RESTORE_SIGMASK flag.
+ */
+ current_thread_info()->status &=
+ ~TS_RESTORE_SIGMASK;
+ }
return 1;
}

if (in_syscall)
handle_restart(regs, NULL, 0);

+ /*
+ * If there's no signal to deliver, we just put the saved sigmask
+ * back.
+ */
+ if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
+ current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
+ sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
+ }
+
/* Did we come from a system call? */
return 0;
}
Index: linux-2.6/arch/microblaze/include/asm/unistd.h
===================================================================
--- linux-2.6.orig/arch/microblaze/include/asm/unistd.h
+++ linux-2.6/arch/microblaze/include/asm/unistd.h
@@ -408,7 +408,7 @@
#define __ARCH_WANT_SYS_SIGPENDING
#define __ARCH_WANT_SYS_SIGPROCMASK
#define __ARCH_WANT_SYS_RT_SIGACTION
-/* #define __ARCH_WANT_SYS_RT_SIGSUSPEND */
+#define __ARCH_WANT_SYS_RT_SIGSUSPEND

/*
* "Conditional" syscalls

--

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