[PATCH] kexec: add kexec syscalls

This patch introduces the architecture independent implementation the
sys_kexec_load, the compat_sys_kexec_load system calls.

Kexec on panic support has been integrated into the core patch and is
relatively clean.

In addition the hopefully architecture independent option
crashkernel=size@location has been docuemented.  It's purpose is to reserve
space for the panic kernel to live, and where no DMA transfer will ever be
setup to access.

Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Alexander Nyberg <alexn@telia.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 21 insertions, 2 deletions

diff --git a/kernel/panic.c b/kernel/panic.c
index 081f7465fc8d..66f43d33cd80 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -18,6 +18,7 @@
 #include <linux/sysrq.h>
 #include <linux/interrupt.h>
 #include <linux/nmi.h>
+#include <linux/kexec.h>
 
 int panic_timeout;
 int panic_on_oops;
@@ -63,6 +64,13 @@ NORET_TYPE void panic(const char * fmt, ...)
         unsigned long caller = (unsigned long) __builtin_return_address(0);
 #endif
 
+        /*
+         * It's possible to come here directly from a panic-assertion and not
+         * have preempt disabled. Some functions called from here want
+         * preempt to be disabled. No point enabling it later though...
+         */
+        preempt_disable();
+
         bust_spinlocks(1);
         va_start(args, fmt);
         vsnprintf(buf, sizeof(buf), fmt, args);
@@ -70,7 +78,19 @@ NORET_TYPE void panic(const char * fmt, ...)
         printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
         bust_spinlocks(0);
 
+        /*
+         * If we have crashed and we have a crash kernel loaded let it handle
+         * everything else.
+         * Do we want to call this before we try to display a message?
+         */
+        crash_kexec();
+
 #ifdef CONFIG_SMP
+        /*
+         * Note smp_send_stop is the usual smp shutdown function, which
+         * unfortunately means it may not be hardened to work in a panic
+         * situation.
+         */
         smp_send_stop();
 #endif
 
@@ -79,8 +99,7 @@ NORET_TYPE void panic(const char * fmt, ...)
         if (!panic_blink)
                 panic_blink = no_blink;
 
-        if (panic_timeout > 0)
-        {
+        if (panic_timeout > 0) {
                 /*
                  * Delay timeout seconds before rebooting the machine. 
                  * We can't use the "normal" timers since we just panicked..