[PATCH] kdump: Save trap information for later analysis

If we are faulting in kernel it is quite possible this will lead to a
panic.  Save trap number, cr2 (in case of page fault) and error_code in the
current thread (these fields already exist for signal delivery but are not
used here).

This helps later kdump crash analyzing from user-space (a script has been
submitted to dig this info out in gdb).

Signed-off-by: Alexander Nyberg <alexn@telia.com>
Cc: <fastboot@lists.osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index e458463ebc0560257e328617ee77afa5e9badf88..c6077a5ef7ce2a598e7419303aa05ed2a904915a 100644 (file)
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -369,6 +369,10 @@ static inline void die_if_kernel(const char * str, struct pt_regs * regs, long e
 static void do_trap(int trapnr, int signr, char *str, int vm86,
                           struct pt_regs * regs, long error_code, siginfo_t *info)
 {
+       struct task_struct *tsk = current;
+       tsk->thread.error_code = error_code;
+       tsk->thread.trap_no = trapnr;
+
        if (regs->eflags & VM_MASK) {
                if (vm86)
                        goto vm86_trap;
@@ -379,9 +383,6 @@ static void do_trap(int trapnr, int signr, char *str, int vm86,
                goto kernel_trap;
 
        trap_signal: {
-               struct task_struct *tsk = current;
-               tsk->thread.error_code = error_code;
-               tsk->thread.trap_no = trapnr;
                if (info)
                        force_sig_info(signr, info, tsk);
                else
@@ -494,6 +495,9 @@ fastcall void do_general_protection(struct pt_regs * regs, long error_code)
        }
        put_cpu();
 
+       current->thread.error_code = error_code;
+       current->thread.trap_no = 13;
+
        if (regs->eflags & VM_MASK)
                goto gp_in_vm86;
 
@@ -897,9 +901,9 @@ fastcall void do_simd_coprocessor_error(struct pt_regs * regs,
                                          error_code);
                        return;
                }
-               die_if_kernel("cache flush denied", regs, error_code);
                current->thread.trap_no = 19;
                current->thread.error_code = error_code;
+               die_if_kernel("cache flush denied", regs, error_code);
                force_sig(SIGSEGV, current);
        }
 }

diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index a509237c4815ed6f8443e85b973dda2a0f2c0688..92ed6c0a55da12109db9e23a82395d7388e45439 100644 (file)
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -463,6 +463,9 @@ no_context:
                printk(KERN_ALERT "*pte = %08lx\n", page);
        }
 #endif
+       tsk->thread.cr2 = address;
+       tsk->thread.trap_no = 14;
+       tsk->thread.error_code = error_code;
        die("Oops", regs, error_code);
        bust_spinlocks(0);
        do_exit(SIGKILL);