From abd4f7505bafdd6c5319fe3cb5caf9af6104e17a Mon Sep 17 00:00:00 2001 From: Masoud Asgharifard Sharbiani Date: Sun, 22 Jul 2007 11:12:28 +0200 Subject: 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 Signed-off-by: Andi Kleen [ 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 --- arch/i386/mm/fault.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'arch/i386/mm') 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); -- cgit v1.2.3