sparc64: Add global register dumping facility.

When a cpu really is stuck in the kernel, it can be often
impossible to figure out which cpu is stuck where.  The
worst case is when the stuck cpu has interrupts disabled.

Therefore, implement a global cpu state capture that uses
SMP message interrupts which are not disabled by the
normal IRQ enable/disable APIs of the kernel.

As long as we can get a sysrq 'y' to the kernel, we can
get a dump.  Even if the console interrupt cpu is wedged,
we can trigger it from userspace using /proc/sysrq-trigger

The output is made compact so that this facility is more
useful on high cpu count systems, which is where this
facility will likely find itself the most useful :)

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 25 insertions, 1 deletions

diff --git a/include/asm-sparc64/ptrace.h b/include/asm-sparc64/ptrace.h
index 90972a5ada59..d8a56cddf7f2 100644
--- a/include/asm-sparc64/ptrace.h
+++ b/include/asm-sparc64/ptrace.h
@@ -126,6 +126,17 @@ struct sparc_trapf {
 #define TRACEREG32_SZ   sizeof(struct pt_regs32)
 #define STACKFRAME32_SZ sizeof(struct sparc_stackf32)
 
+struct global_reg_snapshot {
+        unsigned long           tstate;
+        unsigned long           tpc;
+        unsigned long           tnpc;
+        unsigned long           o7;
+        unsigned long           i7;
+        struct thread_info      *thread;
+        unsigned long           pad1;
+        unsigned long           pad2;
+};
+
 #ifdef __KERNEL__
 
 #define __ARCH_WANT_COMPAT_SYS_PTRACE
@@ -295,6 +306,16 @@ extern void __show_regs(struct pt_regs *);
 #define SF_XARG5  0x58
 #define SF_XXARG  0x5c
 
+/* global_reg_snapshot offsets */
+#define GR_SNAP_TSTATE  0x00
+#define GR_SNAP_TPC     0x08
+#define GR_SNAP_TNPC    0x10
+#define GR_SNAP_O7      0x18
+#define GR_SNAP_I7      0x20
+#define GR_SNAP_THREAD  0x28
+#define GR_SNAP_PAD1    0x30
+#define GR_SNAP_PAD2    0x38
+
 /* Stuff for the ptrace system call */
 #define PTRACE_SPARC_DETACH       11
 #define PTRACE_GETREGS            12
diff --git a/include/asm-sparc64/smp.h b/include/asm-sparc64/smp.h
index 1c1c5ea5cea5..cd0311b2e19d 100644
--- a/include/asm-sparc64/smp.h
+++ b/include/asm-sparc64/smp.h
@@ -1,6 +1,6 @@
 /* smp.h: Sparc64 specific SMP stuff.
  *
- * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
+ * Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
  */
 
 #ifndef _SPARC64_SMP_H
@@ -44,6 +44,8 @@ extern int hard_smp_processor_id(void);
 extern void smp_fill_in_sib_core_maps(void);
 extern void cpu_play_dead(void);
 
+extern void smp_fetch_global_regs(void);
+
 #ifdef CONFIG_HOTPLUG_CPU
 extern int __cpu_disable(void);
 extern void __cpu_die(unsigned int cpu);
@@ -55,6 +57,7 @@ extern void __cpu_die(unsigned int cpu);
 
 #define hard_smp_processor_id()         0
 #define smp_fill_in_sib_core_maps() do { } while (0)
+#define smp_fetch_global_regs() do { } while (0)
 
 #endif /* !(CONFIG_SMP) */