[PATCH 11/15] misc: Allow dropping panic text strings from kernel image

Matt Mackall
2005-11-11T08:39:59Z

Configurable support for panic strings

This drops panic message strings from the kernel image while
maintaining normal panic functionality.

$ size vmlinux vmlinux-baseline
text data bss dec hex filename
3330172 529036 190556 4049764 3dcb64 vmlinux-baseline
3326488 529036 189532 4045056 3db900 vmlinux

Signed-off-by: Matt Mackall <mpm@selenic.com>

Index: 2.6.14-misc/include/linux/kernel.h
===================================================================
--- 2.6.14-misc.orig/include/linux/kernel.h 2005-11-09 11:27:15.000000000 -0800
+++ 2.6.14-misc/include/linux/kernel.h 2005-11-10 23:26:41.000000000 -0800
@@ -87,8 +87,13 @@ extern int cond_resched(void);

extern struct notifier_block *panic_notifier_list;
extern long (*panic_blink)(long time);
+#ifdef CONFIG_FULL_PANIC
NORET_TYPE void panic(const char * fmt, ...)
__attribute__ ((NORET_AND format (printf, 1, 2)));
+#else
+#define panic(fmt, ...) tiny_panic(0, ## __VA_ARGS__)
+NORET_TYPE void tiny_panic(int a, ...) ATTRIB_NORET;
+#endif
fastcall NORET_TYPE void do_exit(long error_code)
ATTRIB_NORET;
NORET_TYPE void complete_and_exit(struct completion *, long)
Index: 2.6.14-misc/init/Kconfig
===================================================================
--- 2.6.14-misc.orig/init/Kconfig 2005-11-09 11:27:15.000000000 -0800
+++ 2.6.14-misc/init/Kconfig 2005-11-10 23:26:41.000000000 -0800
@@ -324,6 +324,14 @@ config DOUBLEFAULT
would otherwise cause a system to silently reboot. Disabling this
option saves about 4k.

+config FULL_PANIC
+ default y
+ bool "Full panic reporting data" if EMBEDDED
+ help
+ This includes text descriptions of panics in addition to stack dumps.
+ Disabling compiles out the explanations for panics, saving
+ string space. Use with caution.
+
config BASE_FULL
default y
bool "Enable full-sized data structures for core" if EMBEDDED
Index: 2.6.14-misc/kernel/panic.c
===================================================================
--- 2.6.14-misc.orig/kernel/panic.c 2005-11-09 11:27:15.000000000 -0800
+++ 2.6.14-misc/kernel/panic.c 2005-11-10 23:26:41.000000000 -0800
@@ -54,12 +54,18 @@ EXPORT_SYMBOL(panic_blink);
*
* This function never returns.
*/
-
+
+#ifdef CONFIG_FULL_PANIC
NORET_TYPE void panic(const char * fmt, ...)
{
- long i;
static char buf[1024];
va_list args;
+#else
+NORET_TYPE void tiny_panic(int a, ...)
+{
+#endif
+ long i;
+
#if defined(CONFIG_ARCH_S390)
unsigned long caller = (unsigned long) __builtin_return_address(0);
#endif
@@ -72,10 +78,16 @@ NORET_TYPE void panic(const char * fmt,
preempt_disable();

bust_spinlocks(1);
+
+#ifdef CONFIG_FULL_PANIC
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
+#else
+ printk(KERN_EMERG "Kernel panic - not syncing\n");
+#endif
+
bust_spinlocks(0);

/*
@@ -94,7 +106,11 @@ NORET_TYPE void panic(const char * fmt,
smp_send_stop();
#endif

+#ifdef CONFIG_FULL_PANIC
notifier_call_chain(&panic_notifier_list, 0, buf);
+#else
+ notifier_call_chain(&panic_notifier_list, 0, "");
+#endif

if (!panic_blink)
panic_blink = no_blink;
@@ -136,7 +152,11 @@ NORET_TYPE void panic(const char * fmt,
}
}

+#ifdef CONFIG_FULL_PANIC
EXPORT_SYMBOL(panic);
+#else
+EXPORT_SYMBOL(tiny_panic);
+#endif

/**
* print_tainted - return a string to represent the kernel taint state.