On Mon, Jan 05, 2009 at 10:26:19AM +0100, Johannes Weiner wrote:

BUG_ONs with early exceptions are always a big annoyance.

I did an EARLY_BUG_ON() infrastructure some time ago, but ended up not submitting it because the BUG_ONs I wanted it for originally disappeared before submission.

It would probably be a good idea to convert the bootmem bugs over to that.

-Andi

---

Add EARLY_BUG_ON infrastructure

EARLY_BUG_ON is larger than BUG_ON, but it works before traps_init and always outputs the line number without having to decode addresses from the early exception handler.

It always panics.

Shouldn't be used when multiple CPUs are active because it makes no attempt to stop the others.

Signed-off-by: Andi Kleen <ak...@linux.intel.com>

--- arch/x86/include/asm/bug.h | 11 +++++++++++ arch/x86/kernel/early_printk.c | 7 +++++++ include/linux/bug.h | 5 +++++ 3 files changed, 23 insertions(+)

Index: linux-2.6.28-test/arch/x86/include/asm/bug.h =================================================================== --- linux-2.6.28-test.orig/arch/x86/include/asm/bug.h 2008-10-24
13:34:40.000000000 +0200 +++ linux-2.6.28-test/arch/x86/include/asm/bug.h 2009-01-05 13:47:02.000000000
+0100 @@ -33,6 +33,17 @@ } while (0) #endif

+extern void early_bug(char *file, int line) __attribute__((noreturn)); + +/* All BUG_ONs before console_init should be EARLY_BUG_ONs. */ +#define EARLY_BUG() early_bug(__FILE__, __LINE__) +#define EARLY_BUG_ON(x) do { if (unlikely(!(x))) EARLY_BUG(); } while (0) + +#else + +#define EARLY_BUG() do {} while(0) +#define EARLY_BUG_ON(x) do {} while(0) + #endif /* !CONFIG_BUG */

#include <asm-generic/bug.h> Index: linux-2.6.28-test/arch/x86/kernel/early_printk.c =================================================================== --- linux-2.6.28-test.orig/arch/x86/kernel/early_printk.c 2008-10-24
13:34:40.000000000 +0200 +++ linux-2.6.28-test/arch/x86/kernel/early_printk.c 2009-01-05
13:48:46.000000000 +0100 @@ -934,6 +934,13 @@ va_end(ap); }

+void early_bug(char *file, int line) +{ + early_printk("PANIC: Early BUG at %s:%d\n", file, line); + printk("PANIC: Early BUG at %s:%d\n", file, line); + for (;;) + cpu_relax(); +}

static int __init setup_early_printk(char *buf) { Index: linux-2.6.28-test/include/linux/bug.h =================================================================== --- linux-2.6.28-test.orig/include/linux/bug.h 2008-07-05 14:11:02.000000000
+0200 +++ linux-2.6.28-test/include/linux/bug.h 2009-01-05 13:49:32.000000000 +0100 @@ -47,4 +47,9 @@ static inline void module_bug_cleanup(struct module *mod) {}

#endif /* CONFIG_GENERIC_BUG */ + +#ifndef EARLY_BUG_ON +#define EARLY_BUG_ON(x) BUG_ON(x) +#endif + #endif /* _LINUX_BUG_H */