[PATCH] CRIS v10: Correct do_signal to fix oops and clean up signal handling in general.

From: Jesper Nilsson
Date: Fri Jan 11 2008 - 13:59:49 EST

CRIS v10: Correct do_signal to fix oops and clean up signal handling in general.

This fixes a kernel panic on boot due to do_signal not being compatible
with it's callers.

- do_signal now returns void, and does not have the previous signal set
as a parameter.
- Remove sys_rt_sigsuspend, we can use the common one instead.
- Change sys_sigsuspend to be more like x86, don't call do_signal here.
- handle_signal, setup_frame and setup_rt_frame now return -EFAULT
if we've delivered a segfault, which is used by callers to perform
necessary cleanup.
- Break long lines, correct whitespace and formatting errors.

Signed-off-by: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
---
arch/cris/arch-v10/kernel/signal.c | 251 ++++++++++++++++--------------------
1 files changed, 112 insertions(+), 139 deletions(-)

diff --git a/arch/cris/arch-v10/kernel/signal.c b/arch/cris/arch-v10/kernel/signal.c
index 41d4a5f..b6be705 100644
--- a/arch/cris/arch-v10/kernel/signal.c
+++ b/arch/cris/arch-v10/kernel/signal.c
@@ -7,7 +7,7 @@
*
* Ideas also taken from arch/arm.
*
- * Copyright (C) 2000, 2001 Axis Communications AB
+ * Copyright (C) 2000-2007 Axis Communications AB
*
* Authors: Bjorn Wesen (bjornw@xxxxxxxx)
*
@@ -40,84 +40,30 @@
*/
#define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->irp -= 2;

-int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs);
+void do_signal(int canrestart, struct pt_regs *regs);

/*
- * Atomically swap in the new signal mask, and wait for a signal. Define
+ * Atomically swap in the new signal mask, and wait for a signal. Define
* dummy arguments to be able to reach the regs argument. (Note that this
* arrangement relies on old_sigset_t occupying one register.)
*/
-int
-sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
- long srp, struct pt_regs *regs)
+int sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof,
+ long srp, struct pt_regs *regs)
{
- sigset_t saveset;
-
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
- saveset = current->blocked;
+ current->saved_sigmask = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
-
- regs->r10 = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(0, &saveset, regs))
- /* We will get here twice: once to call the signal
- handler, then again to return from the
- sigsuspend system call. When calling the
- signal handler, R10 holds the signal number as
- set through do_signal. The sigsuspend call
- will return with the restored value set above;
- always -EINTR. */
- return regs->r10;
- }
+ current->state = TASK_INTERRUPTIBLE;
+ schedule();
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ return -ERESTARTNOHAND;
}

-/* Define dummy arguments to be able to reach the regs argument. (Note that
- * this arrangement relies on size_t occupying one register.)
- */
-int
-sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, long r12, long r13,
- long mof, long srp, 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->r10 = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(0, &saveset, regs))
- /* We will get here twice: once to call the signal
- handler, then again to return from the
- sigsuspend system call. When calling the
- signal handler, R10 holds the signal number as
- set through do_signal. The sigsuspend call
- will return with the restored value set above;
- always -EINTR. */
- return regs->r10;
- }
-}
-
-int
-sys_sigaction(int sig, const struct old_sigaction __user *act,
- struct old_sigaction *oact)
+int sys_sigaction(int sig, const struct old_sigaction __user *act,
+ struct old_sigaction *oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
@@ -147,8 +93,7 @@ sys_sigaction(int sig, const struct old_sigaction __user *act,
return ret;
}

-int
-sys_sigaltstack(const stack_t *uss, stack_t __user *uoss)
+int sys_sigaltstack(const stack_t *uss, stack_t __user *uoss)
{
return do_sigaltstack(uss, uoss, rdusp());
}
@@ -205,7 +150,7 @@ restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)

/* TODO: the other ports use regs->orig_XX to disable syscall checks
* after this completes, but we don't use that mechanism. maybe we can
- * use it now ?
+ * use it now ?
*/

return err;
@@ -216,7 +161,7 @@ badframe:

/* Define dummy arguments to be able to reach the regs argument. */

-asmlinkage int sys_sigreturn(long r10, long r11, long r12, long r13, long mof,
+asmlinkage int sys_sigreturn(long r10, long r11, long r12, long r13, long mof,
long srp, struct pt_regs *regs)
{
struct sigframe __user *frame = (struct sigframe *)rdusp();
@@ -243,7 +188,7 @@ asmlinkage int sys_sigreturn(long r10, long r11, long r12, long r13, long mof,
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
-
+
if (restore_sigcontext(regs, &frame->sc))
goto badframe;

@@ -254,11 +199,11 @@ asmlinkage int sys_sigreturn(long r10, long r11, long r12, long r13, long mof,
badframe:
force_sig(SIGSEGV, current);
return 0;
-}
+}

/* Define dummy arguments to be able to reach the regs argument. */

-asmlinkage int sys_rt_sigreturn(long r10, long r11, long r12, long r13,
+asmlinkage int sys_rt_sigreturn(long r10, long r11, long r12, long r13,
long mof, long srp, struct pt_regs *regs)
{
struct rt_sigframe __user *frame = (struct rt_sigframe *)rdusp();
@@ -282,7 +227,7 @@ asmlinkage int sys_rt_sigreturn(long r10, long r11, long r12, long r13,
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
-
+
if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;

@@ -294,14 +239,14 @@ asmlinkage int sys_rt_sigreturn(long r10, long r11, long r12, long r13,
badframe:
force_sig(SIGSEGV, current);
return 0;
-}
+}

/*
* Set up a signal frame.
*/

-static int
-setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask)
+static int setup_sigcontext(struct sigcontext __user *sc,
+ struct pt_regs *regs, unsigned long mask)
{
int err = 0;
unsigned long usp = rdusp();
@@ -324,10 +269,11 @@ setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned lo
return err;
}

-/* figure out where we want to put the new signal frame - usually on the stack */
+/* Figure out where we want to put the new signal frame
+ * - usually on the stack. */

static inline void __user *
-get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
+get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
unsigned long sp = rdusp();

@@ -345,15 +291,15 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
}

/* grab and setup a signal frame.
- *
+ *
* basically we stack a lot of state info, and arrange for the
* user-mode program to return to the kernel using either a
* trampoline which performs the syscall sigreturn, or a provided
* user-mode trampoline.
*/

-static void setup_frame(int sig, struct k_sigaction *ka,
- sigset_t *set, struct pt_regs * regs)
+static int setup_frame(int sig, struct k_sigaction *ka,
+ sigset_t *set, struct pt_regs *regs)
{
struct sigframe __user *frame;
unsigned long return_ip;
@@ -401,14 +347,15 @@ static void setup_frame(int sig, struct k_sigaction *ka,

wrusp((unsigned long)frame);

- return;
+ return 0;

give_sigsegv:
force_sigsegv(sig, current);
+ return -EFAULT;
}

-static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
- sigset_t *set, struct pt_regs * regs)
+static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+ sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
unsigned long return_ip;
@@ -443,9 +390,10 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
/* trampoline - the desired return ip is the retcode itself */
return_ip = (unsigned long)&frame->retcode;
/* This is movu.w __NR_rt_sigreturn, r9; break 13; */
- err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
- err |= __put_user(__NR_rt_sigreturn, (short __user*)(frame->retcode+2));
- err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
+ err |= __put_user(0x9c5f, (short __user *)(frame->retcode+0));
+ err |= __put_user(__NR_rt_sigreturn,
+ (short __user *)(frame->retcode+2));
+ err |= __put_user(0xe93d, (short __user *)(frame->retcode+4));
}

if (err)
@@ -455,73 +403,81 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,

/* Set up registers for signal handler */

- regs->irp = (unsigned long) ka->sa.sa_handler; /* what we enter NOW */
- regs->srp = return_ip; /* what we enter LATER */
- regs->r10 = sig; /* first argument is signo */
- regs->r11 = (unsigned long) &frame->info; /* second argument is (siginfo_t *) */
- regs->r12 = 0; /* third argument is unused */
-
- /* actually move the usp to reflect the stacked frame */
-
+ /* What we enter NOW */
+ regs->irp = (unsigned long) ka->sa.sa_handler;
+ /* What we enter LATER */
+ regs->srp = return_ip;
+ /* First argument is signo */
+ regs->r10 = sig;
+ /* Second argument is (siginfo_t *) */
+ regs->r11 = (unsigned long)&frame->info;
+ /* Third argument is unused */
+ regs->r12 = 0;
+
+ /* Actually move the usp to reflect the stacked frame */
wrusp((unsigned long)frame);

- return;
+ return 0;

give_sigsegv:
force_sigsegv(sig, current);
+ return -EFAULT;
}

/*
* OK, we're invoking a handler
- */
+ */

-static inline void
-handle_signal(int canrestart, unsigned long sig,
- siginfo_t *info, struct k_sigaction *ka,
- sigset_t *oldset, struct pt_regs * regs)
+static inline int handle_signal(int canrestart, unsigned long sig,
+ siginfo_t *info, struct k_sigaction *ka,
+ sigset_t *oldset, struct pt_regs *regs)
{
+ int ret;
+
/* Are we from a system call? */
if (canrestart) {
/* If so, check system call restarting.. */
switch (regs->r10) {
- case -ERESTART_RESTARTBLOCK:
- case -ERESTARTNOHAND:
- /* ERESTARTNOHAND means that the syscall should only be
- restarted if there was no handler for the signal, and since
- we only get here if there is a handler, we don't restart */
+ case -ERESTART_RESTARTBLOCK:
+ case -ERESTARTNOHAND:
+ /* ERESTARTNOHAND means that the syscall should
+ * only be restarted if there was no handler for
+ * the signal, and since we only get here if there
+ * is a handler, we don't restart */
+ regs->r10 = -EINTR;
+ break;
+ case -ERESTARTSYS:
+ /* ERESTARTSYS means to restart the syscall if
+ * there is no handler or the handler was
+ * registered with SA_RESTART */
+ if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->r10 = -EINTR;
break;
-
- case -ERESTARTSYS:
- /* ERESTARTSYS means to restart the syscall if there is no
- handler or the handler was registered with SA_RESTART */
- if (!(ka->sa.sa_flags & SA_RESTART)) {
- regs->r10 = -EINTR;
- break;
- }
- /* fallthrough */
- case -ERESTARTNOINTR:
- /* ERESTARTNOINTR means that the syscall should be called again
- after the signal handler returns. */
- RESTART_CRIS_SYS(regs);
+ }
+ /* fallthrough */
+ case -ERESTARTNOINTR:
+ /* ERESTARTNOINTR means that the syscall should
+ * be called again after the signal handler returns. */
+ RESTART_CRIS_SYS(regs);
}
}

/* Set up the stack frame */
if (ka->sa.sa_flags & SA_SIGINFO)
- setup_rt_frame(sig, ka, info, oldset, regs);
+ ret = setup_rt_frame(sig, ka, info, oldset, regs);
else
- setup_frame(sig, ka, oldset, regs);
-
- if (ka->sa.sa_flags & SA_ONESHOT)
- ka->sa.sa_handler = SIG_DFL;
-
- spin_lock_irq(&current->sighand->siglock);
- sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
- if (!(ka->sa.sa_flags & SA_NODEFER))
- sigaddset(&current->blocked,sig);
- recalc_sigpending();
- spin_unlock_irq(&current->sighand->siglock);
+ ret = setup_frame(sig, ka, oldset, regs);
+
+ if (ret == 0) {
+ spin_lock_irq(&current->sighand->siglock);
+ sigorsets(&current->blocked, &current->blocked,
+ &ka->sa.sa_mask);
+ if (!(ka->sa.sa_flags & SA_NODEFER))
+ sigaddset(&current->blocked, sig);
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ }
+ return ret;
}

/*
@@ -536,11 +492,12 @@ handle_signal(int canrestart, unsigned long sig,
* mode below.
*/

-int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs)
+void do_signal(int canrestart, struct pt_regs *regs)
{
siginfo_t info;
int signr;
struct k_sigaction ka;
+ sigset_t *oldset;

/*
* We want the common case to go fast, which
@@ -549,16 +506,26 @@ int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs)
* if so.
*/
if (!user_mode(regs))
- return 1;
+ return;

- if (!oldset)
+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ oldset = &current->saved_sigmask;
+ else
oldset = &current->blocked;

signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
/* Whee! Actually deliver the signal. */
- handle_signal(canrestart, signr, &info, &ka, oldset, regs);
- return 1;
+ if (handle_signal(canrestart, signr, &info, &ka,
+ 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 TIF_RESTORE_SIGMASK flag */
+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ clear_thread_flag(TIF_RESTORE_SIGMASK);
+ }
+ return;
}

/* Did we come from a system call? */
@@ -569,10 +536,16 @@ int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs)
regs->r10 == -ERESTARTNOINTR) {
RESTART_CRIS_SYS(regs);
}
- if (regs->r10 == -ERESTART_RESTARTBLOCK){
+ if (regs->r10 == -ERESTART_RESTARTBLOCK) {
regs->r10 = __NR_restart_syscall;
regs->irp -= 2;
}
}
- return 0;
+
+ /* if there's no signal to deliver, we just put the saved sigmask
+ * back */
+ if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
+ clear_thread_flag(TIF_RESTORE_SIGMASK);
+ sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
+ }
}
--
1.5.3.6.970.gd25430


/^JN - Jesper Nilsson
--
Jesper Nilsson -- jesper.nilsson@xxxxxxxx
--
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