Hello,
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
different kernels. Like x86_64, it can be disabled by setting
debug.exception-trace sysctl variable to 0 (or by doing
echo 0 > /proc/sys/debug/exception-trace)
Same behaviour can be extended to other architectures, if needed.
cheers,
Masoud.
Signed-off-by: Masoud Sharbiani <[email protected]>
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index 29d7d61..6aa56db 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 exception_trace = 1;
+
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
@@ -464,7 +466,14 @@ bad_area_nosemaphore:
*/
if (is_prefetch(regs, address, error_code))
return;
-
+ if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
+ 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);
diff --git a/arch/i386/mm/init.c b/arch/i386/mm/init.c
index b22ce8d..a300ff8 100644
--- a/arch/i386/mm/init.c
+++ b/arch/i386/mm/init.c
@@ -854,3 +854,39 @@ void free_initrd_mem(unsigned long start, unsigned long end)
}
#endif
+#ifdef CONFIG_SYSCTL
+#include <linux/sysctl.h>
+
+extern int exception_trace;
+
+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 i386_sysctl_init(void)
+{
+ register_sysctl_table(debug_root_table2);
+ return 0;
+}
+__initcall(i386_sysctl_init);
+#endif
+
+
diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
index bfb62a1..863189a 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)
{
diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index 85255db..4fad501 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -75,8 +75,6 @@ extern void setup_node_bootmem(int nodeid, unsigned long start, unsigned long en
extern void early_quirks(void);
extern void check_efer(void);
-extern int unhandled_signal(struct task_struct *tsk, int sig);
-
extern void select_idle_routine(const struct cpuinfo_x86 *c);
extern unsigned long table_start, table_end;
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 9a5eac5..1ebe715 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -244,6 +244,8 @@ extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
extern struct kmem_cache *sighand_cachep;
+int unhandled_signal(struct task_struct *tsk, int sig);
+
/*
* In POSIX a signal is sent either to a specific thread (Linux task)
* or to the process as a whole (Linux thread group). How the signal
diff --git a/kernel/signal.c b/kernel/signal.c
index 364fc95..6ae6aac 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -174,6 +174,16 @@ static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
return(q);
}
+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 void __sigqueue_free(struct sigqueue *q)
{
if (q->flags & SIGQUEUE_PREALLOC)
On Tue, 5 Jun 2007 14:52:44 -0700
[email protected] (Masoud Asgharifard Sharbiani) wrote:
> Hello,
> 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
> different kernels. Like x86_64, it can be disabled by setting
> debug.exception-trace sysctl variable to 0 (or by doing
> echo 0 > /proc/sys/debug/exception-trace)
>
> Same behaviour can be extended to other architectures, if needed.
> cheers,
> Masoud.
>
>
> +#ifdef CONFIG_SYSCTL
> +#include <linux/sysctl.h>
> +
> +extern int exception_trace;
> +
> +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 i386_sysctl_init(void)
> +{
> + register_sysctl_table(debug_root_table2);
> + return 0;
> +}
> +__initcall(i386_sysctl_init);
> +#endif
There's still quite a bit of duplication here.
Perhaps we could move this sysctl stuff into kernel/sysctl.c (under a new
CONFIG_EXCEPTION_TRACE (which seems a poor name - maybe
CONFIG_REPORT_UNHANDLED_SIGNALS?))
akpm:/usr/src/25> grep -r exception_trace Documentation
akpm:/usr/src/25>
ho hum.
Masoud Asgharifard Sharbiani wrote:
> Hello,
> 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
> different kernels. Like x86_64, it can be disabled by setting
> debug.exception-trace sysctl variable to 0 (or by doing
> echo 0 > /proc/sys/debug/exception-trace)
>
> Same behaviour can be extended to other architectures, if needed.
> cheers,
> Masoud.
>
> Signed-off-by: Masoud Sharbiani <[email protected]>
>
> diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
> index 29d7d61..6aa56db 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 exception_trace = 1;
> +
> /*
> * This routine handles page faults. It determines the address,
> * and the problem, and then passes it off to one of the appropriate
> @@ -464,7 +466,14 @@ bad_area_nosemaphore:
> */
> if (is_prefetch(regs, address, error_code))
> return;
> -
> + if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
> + 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);
Shouldn't we use printk_ratelimit() here, to prevent some nasty person
from creating some rapidly-segfaulting process that floods the kernel
logs? (Same with the x86_64 version if it doesn't already..)
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from [email protected]
Home Page: http://www.roberthancock.com/
On Thu, 07 Jun 2007 20:04:41 -0600 Robert Hancock <[email protected]> wrote:
> Masoud Asgharifard Sharbiani wrote:
> > Hello,
> > 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
> > different kernels. Like x86_64, it can be disabled by setting
> > debug.exception-trace sysctl variable to 0 (or by doing
> > echo 0 > /proc/sys/debug/exception-trace)
> >
> > Same behaviour can be extended to other architectures, if needed.
> > cheers,
> > Masoud.
> >
> > Signed-off-by: Masoud Sharbiani <[email protected]>
> >
> > diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
> > index 29d7d61..6aa56db 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 exception_trace = 1;
> > +
> > /*
> > * This routine handles page faults. It determines the address,
> > * and the problem, and then passes it off to one of the appropriate
> > @@ -464,7 +466,14 @@ bad_area_nosemaphore:
> > */
> > if (is_prefetch(regs, address, error_code))
> > return;
> > -
> > + if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
> > + 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);
>
> Shouldn't we use printk_ratelimit() here, to prevent some nasty person
> from creating some rapidly-segfaulting process that floods the kernel
> logs? (Same with the x86_64 version if it doesn't already..)
Yes. In fact I thought that was in there, but I must have dreamed it.
On 6/7/07, Robert Hancock <[email protected]> wrote:
> Masoud Asgharifard Sharbiani wrote:
> > Hello,
> > 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
> > different kernels. Like x86_64, it can be disabled by setting
> > debug.exception-trace sysctl variable to 0 (or by doing
> > echo 0 > /proc/sys/debug/exception-trace)
> >
> > Same behaviour can be extended to other architectures, if needed.
> > cheers,
> > Masoud.
> >
> > Signed-off-by: Masoud Sharbiani <[email protected]>
> >
> > diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
> > index 29d7d61..6aa56db 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 exception_trace = 1;
> > +
> > /*
> > * This routine handles page faults. It determines the address,
> > * and the problem, and then passes it off to one of the appropriate
> > @@ -464,7 +466,14 @@ bad_area_nosemaphore:
> > */
> > if (is_prefetch(regs, address, error_code))
> > return;
> > -
> > + if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
> > + 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);
>
> Shouldn't we use printk_ratelimit() here, to prevent some nasty person
> from creating some rapidly-segfaulting process that floods the kernel
> logs? (Same with the x86_64 version if it doesn't already..)
Good call.
Masoud
> --
> Robert Hancock Saskatoon, SK, Canada
> To email, remove "nospam" from [email protected]
> Home Page: http://www.roberthancock.com/
>
>