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authorMasoud Asgharifard Sharbiani <masouds@google.com>2007-07-22 11:12:28 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-22 11:03:37 -0700
commitabd4f7505bafdd6c5319fe3cb5caf9af6104e17a (patch)
treea543fce720331dbf6194a2c0471f36b7727b9736 /arch/i386/mm/fault.c
parent5fa63fccc579ac609fc7f86d29ccb3a2edf910d7 (diff)
x86: i386-show-unhandled-signals-v3
This patch makes the i386 behave the same way that x86_64 does when a segfault happens. A line gets printed to the kernel log so that tools that need to check for failures can behave more uniformly between debug.show_unhandled_signals sysctl variable to 0 (or by doing echo 0 > /proc/sys/debug/exception-trace) Also, all of the lines being printed are now using printk_ratelimit() to deny the ability of DoS from a local user with a program like the following: main() { while (1) if (!fork()) *(int *)0 = 0; } This new revision also includes the fix that Andrew did which got rid of new sysctl that was added to the system in earlier versions of this. Also, 'show-unhandled-signals' sysctl has been renamed back to the old 'exception-trace' to avoid breakage of people's scripts. AK: Enabling by default for i386 will be likely controversal, but let's see what happens AK: Really folks, before complaining just fix your segfaults AK: I bet this will find a lot of silent issues Signed-off-by: Masoud Sharbiani <masouds@google.com> Signed-off-by: Andi Kleen <ak@suse.de> [ Personally, I've found the complaints useful on x86-64, so I'm all for this. That said, I wonder if we could do it more prettily.. -Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/i386/mm/fault.c')
-rw-r--r--arch/i386/mm/fault.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index e92a1012493..01ffdd4964f 100644
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -283,6 +283,8 @@ static inline int vmalloc_fault(unsigned long address)
return 0;
}
+int show_unhandled_signals = 1;
+
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
@@ -469,6 +471,14 @@ bad_area_nosemaphore:
if (is_prefetch(regs, address, error_code))
return;
+ if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+ printk_ratelimit()) {
+ printk("%s%s[%d]: segfault at %08lx eip %08lx "
+ "esp %08lx error %lx\n",
+ tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
+ tsk->comm, tsk->pid, address, regs->eip,
+ regs->esp, error_code);
+ }
tsk->thread.cr2 = address;
/* Kernel addresses are always protection faults */
tsk->thread.error_code = error_code | (address >= TASK_SIZE);