[PATCH] Additional kgdb hooks

[PATCH] Additional kgdb hooks

[dhowells]

The attached patch adds a couple of extra hooks by which kgdb or an equivalent
gdbstub can catch bad_page() and panic() invocations.

Signed-Off-By: dhowells@redhat.com
---
diffstat kgdb-hooks-2610rc1mm3.diff
 include/asm-generic/bug.h |    8 ++++++++
 kernel/panic.c            |    1 +
 mm/page_alloc.c           |    1 +
 3 files changed, 10 insertions(+)

diff -uNrp /warthog/kernels/linux-2.6.10-rc1-mm3/include/asm-generic/bug.h linux-2.6.10-rc1-mm3-frv/include/asm-generic/bug.h
--- /warthog/kernels/linux-2.6.10-rc1-mm3/include/asm-generic/bug.h	2004-10-19 10:42:12.000000000 +0100
+++ linux-2.6.10-rc1-mm3-frv/include/asm-generic/bug.h	2004-11-05 14:13:04.327459964 +0000
@@ -18,6 +18,10 @@
 } while (0)
 #endif
 
+#ifndef HAVE_ARCH_KGDB_BAD_PAGE
+#define kgdb_bad_page(page) do {} while(0)
+#endif
+
 #ifndef HAVE_ARCH_BUG_ON
 #define BUG_ON(condition) do { if (unlikely((condition)!=0)) BUG(); } while(0)
 #endif
@@ -31,4 +35,8 @@
 } while (0)
 #endif
 
+#ifndef HAVE_ARCH_KGDB_RAISE
+#define kgdb_raise(signr) do {} while(0)
+#endif
+
 #endif
diff -uNrp /warthog/kernels/linux-2.6.10-rc1-mm3/kernel/panic.c linux-2.6.10-rc1-mm3-frv/kernel/panic.c
--- /warthog/kernels/linux-2.6.10-rc1-mm3/kernel/panic.c	2004-11-05 13:15:51.000000000 +0000
+++ linux-2.6.10-rc1-mm3-frv/kernel/panic.c	2004-11-05 14:13:04.528442988 +0000
@@ -73,6 +73,7 @@ NORET_TYPE void panic(const char * fmt, 
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
+	kgdb_raise(SIGABRT);
 	bust_spinlocks(0);
 
 	/* If we have crashed, perform a kexec reboot, for dump write-out */
diff -uNrp /warthog/kernels/linux-2.6.10-rc1-mm3/mm/page_alloc.c linux-2.6.10-rc1-mm3-frv/mm/page_alloc.c
--- /warthog/kernels/linux-2.6.10-rc1-mm3/mm/page_alloc.c	2004-11-05 13:15:52.000000000 +0000
+++ linux-2.6.10-rc1-mm3-frv/mm/page_alloc.c	2004-11-05 14:13:04.654432347 +0000
@@ -88,6 +89,7 @@ static void bad_page(const char *functio
 		page->mapping, page_mapcount(page), page_count(page));
 	printk(KERN_EMERG "Backtrace:\n");
 	dump_stack();
+	kgdb_bad_page(page);
 	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n");
 	page->flags &= ~(1 << PG_private	|
 			1 << PG_locked	|

Re: [PATCH] Additional kgdb hooks

[Tom Rini]

On Mon, Nov 08, 2004 at 02:32:41PM +0000, dhowells@redhat.com wrote:

> The attached patch adds a couple of extra hooks by which kgdb or an equivalent
> gdbstub can catch bad_page() and panic() invocations.

What stub are you using that doesn't catch these?

-- 
Tom Rini
http://gate.crashing.org/~trini/

Re: [PATCH] Additional kgdb hooks

[David Howells]

> > The attached patch adds a couple of extra hooks by which kgdb or an
> > equivalent gdbstub can catch bad_page() and panic() invocations.
> 
> What stub are you using that doesn't catch these?

FRV.

David

Re: [PATCH] Additional kgdb hooks

[Andrew Morton]

dhowells@redhat.com wrote:
>
> The attached patch adds a couple of extra hooks by which kgdb or an equivalent
> gdbstub can catch bad_page() and panic() invocations.

Tom is valiantly flogging his way through a generic KGDB implementation.  I
think it would be better to push ahead with that and to not put into
generic code hooks which are specific to one arch's kgdb implementation.

Re: [PATCH] Additional kgdb hooks

[George Anzinger]

Andrew Morton wrote:
> dhowells@redhat.com wrote:
> 
>>The attached patch adds a couple of extra hooks by which kgdb or an equivalent
>>gdbstub can catch bad_page() and panic() invocations.
> 
> 
> Tom is valiantly flogging his way through a generic KGDB implementation.  I
> think it would be better to push ahead with that and to not put into
> generic code hooks which are specific to one arch's kgdb implementation.
> 
IMNSHO the trap should be in dump_stack().  That way it catches a bunch of 
things all at once.

Also, panic has a notify option that kgdb should use just like everybody else.

-- 
George Anzinger   george@mvista.com
High-res-timers:  http://sourceforge.net/projects/high-res-timers/

Re: [PATCH] Additional kgdb hooks

[Tom Rini]

On Tue, Nov 09, 2004 at 03:29:28PM -0800, George Anzinger wrote:
> Andrew Morton wrote:
> >dhowells@redhat.com wrote:
> >
> >>The attached patch adds a couple of extra hooks by which kgdb or an 
> >>equivalent
> >>gdbstub can catch bad_page() and panic() invocations.
> >
> >
> >Tom is valiantly flogging his way through a generic KGDB implementation.  I
> >think it would be better to push ahead with that and to not put into
> >generic code hooks which are specific to one arch's kgdb implementation.
>
> IMNSHO the trap should be in dump_stack().  That way it catches a bunch of 
> things all at once.

The hard question is how to do this cleanly.  Perhaps changing things
slightly so that lib/dump_stack.c provides the 'true' dump_stack() (or
moving it to kernel/dump_stack.c) which calls a notify chain and then
arch_dump_stack() ?

> Also, panic has a notify option that kgdb should use just like everybody 
> else.

This is a good idea, I'm surprised we didn't already do, so I've just
done it.

-- 
Tom Rini
http://gate.crashing.org/~trini/