[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>

2 files changed, 11 insertions, 4 deletions

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index e458463ebc05..c6077a5ef7ce 100644
--- 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 a509237c4815..92ed6c0a55da 100644
--- 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);