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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/x86_64
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/x86_64')
-rw-r--r--arch/x86_64/kernel/signal.c2
-rw-r--r--arch/x86_64/kernel/traps.c6
-rw-r--r--arch/x86_64/mm/fault.c15
-rw-r--r--arch/x86_64/mm/init.c33
4 files changed, 8 insertions, 48 deletions
diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c
index 4886afcd628..739175b01e0 100644
--- a/arch/x86_64/kernel/signal.c
+++ b/arch/x86_64/kernel/signal.c
@@ -487,7 +487,7 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
{
struct task_struct *me = current;
- if (exception_trace)
+ if (show_unhandled_signals && printk_ratelimit())
printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n",
me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 8713ad4a4db..03888420775 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -584,7 +584,8 @@ static void __kprobes do_trap(int trapnr, int signr, char *str,
tsk->thread.error_code = error_code;
tsk->thread.trap_no = trapnr;
- if (exception_trace && unhandled_signal(tsk, signr))
+ if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
+ printk_ratelimit())
printk(KERN_INFO
"%s[%d] trap %s rip:%lx rsp:%lx error:%lx\n",
tsk->comm, tsk->pid, str,
@@ -688,7 +689,8 @@ asmlinkage void __kprobes do_general_protection(struct pt_regs * regs,
tsk->thread.error_code = error_code;
tsk->thread.trap_no = 13;
- if (exception_trace && unhandled_signal(tsk, SIGSEGV))
+ if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+ printk_ratelimit())
printk(KERN_INFO
"%s[%d] general protection rip:%lx rsp:%lx error:%lx\n",
tsk->comm, tsk->pid,
diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
index 2074bddd4f0..5e9ac70c135 100644
--- a/arch/x86_64/mm/fault.c
+++ b/arch/x86_64/mm/fault.c
@@ -221,16 +221,6 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
return 0;
}
-int unhandled_signal(struct task_struct *tsk, int sig)
-{
- if (is_init(tsk))
- return 1;
- if (tsk->ptrace & PT_PTRACED)
- return 0;
- return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) ||
- (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL);
-}
-
static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
unsigned long error_code)
{
@@ -302,7 +292,7 @@ static int vmalloc_fault(unsigned long address)
}
static int page_fault_trace;
-int exception_trace = 1;
+int show_unhandled_signals = 1;
/*
* This routine handles page faults. It determines the address,
@@ -494,7 +484,8 @@ bad_area_nosemaphore:
(address >> 32))
return;
- if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
+ if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+ printk_ratelimit()) {
printk(
"%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 381c2ecd407..88678e82e23 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -697,39 +697,6 @@ int kern_addr_valid(unsigned long addr)
return pfn_valid(pte_pfn(*pte));
}
-#ifdef CONFIG_SYSCTL
-#include <linux/sysctl.h>
-
-static ctl_table debug_table2[] = {
- {
- .ctl_name = 99,
- .procname = "exception-trace",
- .data = &exception_trace,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec
- },
- {}
-};
-
-static ctl_table debug_root_table2[] = {
- {
- .ctl_name = CTL_DEBUG,
- .procname = "debug",
- .mode = 0555,
- .child = debug_table2
- },
- {}
-};
-
-static __init int x8664_sysctl_init(void)
-{
- register_sysctl_table(debug_root_table2);
- return 0;
-}
-__initcall(x8664_sysctl_init);
-#endif
-
/* A pseudo VMA to allow ptrace access for the vsyscall page. This only
covers the 64bit vsyscall page now. 32bit has a real VMA now and does
not need special handling anymore. */