diff options
author | Paul Mackerras <paulus@samba.org> | 2005-09-10 21:13:11 +1000 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-10 10:15:11 -0700 |
commit | bb0bb3b6596cdb08adb0b72453cc67d48e139c2c (patch) | |
tree | f9116ed650d499d405a3fe021c473f9558897d96 /arch | |
parent | 1e63bc7342c40f0f1dd83d80d368665bd06f4963 (diff) | |
download | op-kernel-dev-bb0bb3b6596cdb08adb0b72453cc67d48e139c2c.zip op-kernel-dev-bb0bb3b6596cdb08adb0b72453cc67d48e139c2c.tar.gz |
[PATCH] ppc32: Kill init on unhandled synchronous signals
This is a patch that I have had in my tree for ages. If init causes
an exception that raises a signal, such as a SIGSEGV, SIGILL or
SIGFPE, and it hasn't registered a handler for it, we don't deliver
the signal, since init doesn't get any signals that it doesn't have a
handler for. But that means that we just return to userland and
generate the same exception again immediately. With this patch we
print a message and kill init in this situation.
This is very useful when you have a bug in the kernel that means that
init doesn't get as far as executing its first instruction. :)
Without this patch the system hangs when it gets to starting the
userland init; with it you at least get a message giving you a clue
about what has gone wrong.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/ppc/kernel/traps.c | 22 | ||||
-rw-r--r-- | arch/ppc/mm/fault.c | 6 |
2 files changed, 23 insertions, 5 deletions
diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c index 8356d54..961ede8 100644 --- a/arch/ppc/kernel/traps.c +++ b/arch/ppc/kernel/traps.c @@ -118,6 +118,28 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr) info.si_code = code; info.si_addr = (void __user *) addr; force_sig_info(signr, &info, current); + + /* + * Init gets no signals that it doesn't have a handler for. + * That's all very well, but if it has caused a synchronous + * exception and we ignore the resulting signal, it will just + * generate the same exception over and over again and we get + * nowhere. Better to kill it and let the kernel panic. + */ + if (current->pid == 1) { + __sighandler_t handler; + + spin_lock_irq(¤t->sighand->siglock); + handler = current->sighand->action[signr-1].sa.sa_handler; + spin_unlock_irq(¤t->sighand->siglock); + if (handler == SIG_DFL) { + /* init has generated a synchronous exception + and it doesn't have a handler for the signal */ + printk(KERN_CRIT "init has generated signal %d " + "but has no handler for it\n", signr); + do_exit(signr); + } + } } /* diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c index 57d9930..ee5e9f2 100644 --- a/arch/ppc/mm/fault.c +++ b/arch/ppc/mm/fault.c @@ -278,11 +278,7 @@ bad_area: /* User mode accesses cause a SIGSEGV */ if (user_mode(regs)) { - info.si_signo = SIGSEGV; - info.si_errno = 0; - info.si_code = code; - info.si_addr = (void __user *) address; - force_sig_info(SIGSEGV, &info, current); + _exception(SIGSEGV, regs, code, address); return 0; } |