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authorPaul Mackerras <paulus@samba.org>2005-09-10 21:13:11 +1000
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-10 10:15:11 -0700
commitbb0bb3b6596cdb08adb0b72453cc67d48e139c2c (patch)
treef9116ed650d499d405a3fe021c473f9558897d96 /arch/ppc/kernel/traps.c
parent1e63bc7342c40f0f1dd83d80d368665bd06f4963 (diff)
downloadlinux-2.6.34-ux500-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/ppc/kernel/traps.c')
-rw-r--r--arch/ppc/kernel/traps.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
index 8356d544fa6..961ede87be7 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(&current->sighand->siglock);
+ handler = current->sighand->action[signr-1].sa.sa_handler;
+ spin_unlock_irq(&current->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);
+ }
+ }
}
/*