On Sat, May 14, 2005 at 10:49:58PM +0200, Alexander Nyberg wrote:
> Makes kexec_crashdump() take a pt_regs * as an argument. This allows to
> get exact register state at the point of the crash. If we come from
> direct panic assertion NULL will be passed and the current registers
> saved before crashdump.
>
> This hooks into two places:
> die(): check the conditions under which we will panic when calling
> do_exit and go there directly with the pt_regs that caused the fatal
> fault.
>
> die_nmi(): If we receive an NMI lockup while in the kernel use the
> pt_regs and go directly to crash_kexec(). We're probably nested up badly
> at this point so this might be the only chance to escape with proper
> information.
>
>
> Signed-off-by: Alexander Nyberg <[email protected]>
>
Largely looks ok except few comments . Copying to LKML for more eyes.
I am tempted to think that if panic had been passed pt_regs, then
crash_kexec() call could have been placed at a single place that too in
architecture independent manner. But panic is called at too many a places
to change the function signature. Just a passing thought.
> Index: mm/include/linux/reboot.h
> ===================================================================
> --- mm.orig/include/linux/reboot.h 2005-05-14 22:29:16.000000000 +0200
> +++ mm/include/linux/reboot.h 2005-05-14 22:29:29.000000000 +0200
> @@ -50,9 +50,10 @@
> extern void machine_restart(char *cmd);
> extern void machine_halt(void);
> extern void machine_power_off(void);
> -
> extern void machine_shutdown(void);
> -extern void machine_crash_shutdown(void);
> +
> +struct pt_regs;
> +extern void machine_crash_shutdown(struct pt_regs *);
>
> #endif
>
> Index: mm/arch/i386/kernel/traps.c
> ===================================================================
> --- mm.orig/arch/i386/kernel/traps.c 2005-05-14 22:29:16.000000000 +0200
> +++ mm/arch/i386/kernel/traps.c 2005-05-14 22:48:14.000000000 +0200
> @@ -27,6 +27,7 @@
> #include <linux/ptrace.h>
> #include <linux/utsname.h>
> #include <linux/kprobes.h>
> +#include <linux/kexec.h>
>
> #ifdef CONFIG_EISA
> #include <linux/ioport.h>
> @@ -326,6 +327,9 @@
> printk("Kernel BUG\n");
> }
>
> +/* This is gone through when something in the kernel
> + * has done something bad and is about to be terminated.
> +*/
> void die(const char * str, struct pt_regs * regs, long err)
> {
> static struct {
> @@ -382,6 +386,10 @@
> bust_spinlocks(0);
> die.lock_owner = -1;
> spin_unlock_irq(&die.lock);
> +
> + if (in_interrupt() || !current->pid || current->pid == 1)
> + crash_kexec(regs);
> +
Would be nice if panic_on_oops case also can be covered. There also we want
to capture actual pt_regs register state.
> if (in_interrupt())
> panic("Fatal exception in interrupt");
>
> @@ -616,6 +624,15 @@
> console_silent();
> spin_unlock(&nmi_print_lock);
> bust_spinlocks(0);
> +
> + /* If we are in kernel we are probably nested up pretty bad
> + * and might aswell get out now while we still can.
> + */
> + if (!user_mode(regs)) {
> + current->thread.trap_no = 2;
> + crash_kexec(regs);
> + }
> +
> do_exit(SIGSEGV);
> }
>
> Index: mm/arch/i386/kernel/crash.c
> ===================================================================
> --- mm.orig/arch/i386/kernel/crash.c 2005-05-14 22:29:16.000000000 +0200
> +++ mm/arch/i386/kernel/crash.c 2005-05-14 22:48:53.000000000 +0200
> @@ -98,12 +98,19 @@
> regs->eip = (unsigned long)current_text_addr();
> }
>
> -static void crash_save_self(void)
> +/* We may have saved_regs from where the error came from
> + * or it is NULL if via a direct panic().
> + */
> +static void crash_save_self(struct pt_regs *saved_regs)
> {
> struct pt_regs regs;
> int cpu;
> cpu = smp_processor_id();
> - crash_get_current_regs(®s);
> +
> + if (saved_regs)
> + memcpy(®s, saved_regs, sizeof(regs));
saved_regs will not have proper value of ss and esp if exception occurred
which thread was running in kernel mode as cpu has not pushed these on stack
A fix something like following also might go here.
if (saved_regs) {
memcpy(®s, saved_regs, sizeof(regs));
if (!user_mode(saved_regs)) {
regs.esp = (unsigned long)&(saved_regs->esp);
__asm__ __volatile__("xorl %eax, %eax;");
__asm__ __volatile__ ("movw %%ss, %%ax;"
:"=a"(regs.xss));
}
}
> + else
> + crash_get_current_regs(®s);
> crash_save_this_cpu(®s, cpu);
> }
>
> @@ -175,7 +182,7 @@
> }
> #endif
>
> -void machine_crash_shutdown(void)
> +void machine_crash_shutdown(struct pt_regs *regs)
> {
> /* This function is only called after the system
> * has paniced or is otherwise in a critical state.
> @@ -192,5 +199,5 @@
> #if defined(CONFIG_X86_IO_APIC)
> disable_IO_APIC();
> #endif
> - crash_save_self();
> + crash_save_self(regs);
> }
> Index: mm/kernel/panic.c
> ===================================================================
> --- mm.orig/kernel/panic.c 2005-05-14 22:29:16.000000000 +0200
> +++ mm/kernel/panic.c 2005-05-14 22:29:29.000000000 +0200
> @@ -83,7 +83,7 @@
> * everything else.
> * Do we want to call this before we try to display a message?
> */
> - crash_kexec();
> + crash_kexec(NULL);
>
> #ifdef CONFIG_SMP
> /*
> Index: mm/kernel/kexec.c
> ===================================================================
> --- mm.orig/kernel/kexec.c 2005-05-14 22:29:16.000000000 +0200
> +++ mm/kernel/kexec.c 2005-05-14 22:29:29.000000000 +0200
> @@ -1010,7 +1010,7 @@
> }
> #endif
>
> -void crash_kexec(void)
> +void crash_kexec(struct pt_regs *regs)
> {
> struct kimage *image;
> int locked;
> @@ -1028,7 +1028,7 @@
> if (!locked) {
> image = xchg(&kexec_crash_image, NULL);
> if (image) {
> - machine_crash_shutdown();
> + machine_crash_shutdown(regs);
> machine_kexec(image);
> }
> xchg(&kexec_lock, 0);
> Index: mm/include/linux/kexec.h
> ===================================================================
> --- mm.orig/include/linux/kexec.h 2005-05-14 22:29:16.000000000 +0200
> +++ mm/include/linux/kexec.h 2005-05-14 22:29:29.000000000 +0200
> @@ -99,7 +99,7 @@
> unsigned long flags);
> #endif
> extern struct page *kimage_alloc_control_pages(struct kimage *image, unsigned int order);
> -extern void crash_kexec(void);
> +extern void crash_kexec(struct pt_regs *);
> extern struct kimage *kexec_image;
>
> #define KEXEC_ON_CRASH 0x00000001
> @@ -123,6 +123,6 @@
> extern struct resource crashk_res;
>
> #else /* !CONFIG_KEXEC */
> -static inline void crash_kexec(void) { }
> +static inline void crash_kexec(struct pt_regs *regs) { }
> #endif /* CONFIG_KEXEC */
> #endif /* LINUX_KEXEC_H */
> Index: mm/drivers/char/sysrq.c
> ===================================================================
> --- mm.orig/drivers/char/sysrq.c 2005-05-14 22:29:16.000000000 +0200
> +++ mm/drivers/char/sysrq.c 2005-05-14 22:29:29.000000000 +0200
> @@ -119,7 +119,7 @@
> static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
> struct tty_struct *tty)
> {
> - crash_kexec();
> + crash_kexec(pt_regs);
> }
> static struct sysrq_key_op sysrq_crashdump_op = {
> .handler = sysrq_handle_crashdump,
>
>
> _______________________________________________
> fastboot mailing list
> [email protected]
> http://lists.osdl.org/mailman/listinfo/fastboot
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