Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  debug_core,kdb: fix crash when arch does not have single step
  kgdb,x86: use macro HBP_NUM to replace magic number 4
  kgdb,mips: remove unused kgdb_cpu_doing_single_step operations
  mm,kdb,kgdb: Add a debug reference for the kdb kmap usage
  KGDB: Remove set but unused newPC
  ftrace,kdb: Allow dumping a specific cpu's buffer with ftdump
  ftrace,kdb: Extend kdb to be able to dump the ftrace buffer
  kgdb,powerpc: Replace hardcoded offset by BREAK_INSTR_SIZE
  arm,kgdb: Add ability to trap into debugger on notify_die
  gdbstub: do not directly use dbg_reg_def[] in gdb_cmd_reg_set()
  gdbstub: Implement gdbserial 'p' and 'P' packets
  kgdb,arm: Individual register get/set for arm
  kgdb,mips: Individual register get/set for mips
  kgdb,x86: Individual register get/set for x86
  kgdb,kdb: individual register set and and get API
  gdbstub: Optimize kgdb's "thread:" response for the gdb serial protocol
  kgdb: remove custom hex_to_bin()implementation

7 files changed, 437 insertions, 87 deletions

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 51d14fe87648..3c2d4972d235 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -605,6 +605,8 @@ cpu_master_loop:
                 if (dbg_kdb_mode) {
                         kgdb_connected = 1;
                         error = kdb_stub(ks);
+                        if (error == -1)
+                                continue;
                         kgdb_connected = 0;
                 } else {
                         error = gdb_serial_stub(ks);
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index 6e81fd59566b..481a7bd2dfe7 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -52,17 +52,6 @@ static unsigned long		gdb_regs[(NUMREGBYTES +
  * GDB remote protocol parser:
  */
 
-static int hex(char ch)
-{
-        if ((ch >= 'a') && (ch <= 'f'))
-                return ch - 'a' + 10;
-        if ((ch >= '0') && (ch <= '9'))
-                return ch - '0';
-        if ((ch >= 'A') && (ch <= 'F'))
-                return ch - 'A' + 10;
-        return -1;
-}
-
 #ifdef CONFIG_KGDB_KDB
 static int gdbstub_read_wait(void)
 {
@@ -123,8 +112,8 @@ static void get_packet(char *buffer)
                 buffer[count] = 0;
 
                 if (ch == '#') {
-                        xmitcsum = hex(gdbstub_read_wait()) << 4;
-                        xmitcsum += hex(gdbstub_read_wait());
+                        xmitcsum = hex_to_bin(gdbstub_read_wait()) << 4;
+                        xmitcsum += hex_to_bin(gdbstub_read_wait());
 
                         if (checksum != xmitcsum)
                                 /* failed checksum */
@@ -236,7 +225,7 @@ void gdbstub_msg_write(const char *s, int len)
  * buf.  Return a pointer to the last char put in buf (null). May
  * return an error.
  */
-int kgdb_mem2hex(char *mem, char *buf, int count)
+char *kgdb_mem2hex(char *mem, char *buf, int count)
 {
         char *tmp;
         int err;
@@ -248,17 +237,16 @@ int kgdb_mem2hex(char *mem, char *buf, int count)
         tmp = buf + count;
 
         err = probe_kernel_read(tmp, mem, count);
-        if (!err) {
-                while (count > 0) {
-                        buf = pack_hex_byte(buf, *tmp);
-                        tmp++;
-                        count--;
-                }
-
-                *buf = 0;
+        if (err)
+                return NULL;
+        while (count > 0) {
+                buf = pack_hex_byte(buf, *tmp);
+                tmp++;
+                count--;
         }
+        *buf = 0;
 
-        return err;
+        return buf;
 }
 
 /*
@@ -280,8 +268,8 @@ int kgdb_hex2mem(char *buf, char *mem, int count)
         tmp_hex = tmp_raw - 1;
         while (tmp_hex >= buf) {
                 tmp_raw--;
-                *tmp_raw = hex(*tmp_hex--);
-                *tmp_raw |= hex(*tmp_hex--) << 4;
+                *tmp_raw = hex_to_bin(*tmp_hex--);
+                *tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
         }
 
         return probe_kernel_write(mem, tmp_raw, count);
@@ -304,7 +292,7 @@ int kgdb_hex2long(char **ptr, unsigned long *long_val)
                 (*ptr)++;
         }
         while (**ptr) {
-                hex_val = hex(**ptr);
+                hex_val = hex_to_bin(**ptr);
                 if (hex_val < 0)
                         break;
 
@@ -339,6 +327,32 @@ static int kgdb_ebin2mem(char *buf, char *mem, int count)
         return probe_kernel_write(mem, c, size);
 }
 
+#if DBG_MAX_REG_NUM > 0
+void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+        int i;
+        int idx = 0;
+        char *ptr = (char *)gdb_regs;
+
+        for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+                dbg_get_reg(i, ptr + idx, regs);
+                idx += dbg_reg_def[i].size;
+        }
+}
+
+void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
+{
+        int i;
+        int idx = 0;
+        char *ptr = (char *)gdb_regs;
+
+        for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+                dbg_set_reg(i, ptr + idx, regs);
+                idx += dbg_reg_def[i].size;
+        }
+}
+#endif /* DBG_MAX_REG_NUM > 0 */
+
 /* Write memory due to an 'M' or 'X' packet. */
 static int write_mem_msg(int binary)
 {
@@ -378,28 +392,31 @@ static void error_packet(char *pkt, int error)
  * remapped to negative TIDs.
  */
 
-#define BUF_THREAD_ID_SIZE      16
+#define BUF_THREAD_ID_SIZE      8
 
 static char *pack_threadid(char *pkt, unsigned char *id)
 {
-        char *limit;
+        unsigned char *limit;
+        int lzero = 1;
+
+        limit = id + (BUF_THREAD_ID_SIZE / 2);
+        while (id < limit) {
+                if (!lzero || *id != 0) {
+                        pkt = pack_hex_byte(pkt, *id);
+                        lzero = 0;
+                }
+                id++;
+        }
 
-        limit = pkt + BUF_THREAD_ID_SIZE;
-        while (pkt < limit)
-                pkt = pack_hex_byte(pkt, *id++);
+        if (lzero)
+                pkt = pack_hex_byte(pkt, 0);
 
         return pkt;
 }
 
 static void int_to_threadref(unsigned char *id, int value)
 {
-        unsigned char *scan;
-        int i = 4;
-
-        scan = (unsigned char *)id;
-        while (i--)
-                *scan++ = 0;
-        put_unaligned_be32(value, scan);
+        put_unaligned_be32(value, id);
 }
 
 static struct task_struct *getthread(struct pt_regs *regs, int tid)
@@ -463,8 +480,7 @@ static void gdb_cmd_status(struct kgdb_state *ks)
         pack_hex_byte(&remcom_out_buffer[1], ks->signo);
 }
 
-/* Handle the 'g' get registers request */
-static void gdb_cmd_getregs(struct kgdb_state *ks)
+static void gdb_get_regs_helper(struct kgdb_state *ks)
 {
         struct task_struct *thread;
         void *local_debuggerinfo;
@@ -505,6 +521,12 @@ static void gdb_cmd_getregs(struct kgdb_state *ks)
                  */
                 sleeping_thread_to_gdb_regs(gdb_regs, thread);
         }
+}
+
+/* Handle the 'g' get registers request */
+static void gdb_cmd_getregs(struct kgdb_state *ks)
+{
+        gdb_get_regs_helper(ks);
         kgdb_mem2hex((char *)gdb_regs, remcom_out_buffer, NUMREGBYTES);
 }
 
@@ -527,13 +549,13 @@ static void gdb_cmd_memread(struct kgdb_state *ks)
         char *ptr = &remcom_in_buffer[1];
         unsigned long length;
         unsigned long addr;
-        int err;
+        char *err;
 
         if (kgdb_hex2long(&ptr, &addr) > 0 && *ptr++ == ',' &&
                                         kgdb_hex2long(&ptr, &length) > 0) {
                 err = kgdb_mem2hex((char *)addr, remcom_out_buffer, length);
-                if (err)
-                        error_packet(remcom_out_buffer, err);
+                if (!err)
+                        error_packet(remcom_out_buffer, -EINVAL);
         } else {
                 error_packet(remcom_out_buffer, -EINVAL);
         }
@@ -550,6 +572,60 @@ static void gdb_cmd_memwrite(struct kgdb_state *ks)
                 strcpy(remcom_out_buffer, "OK");
 }
 
+#if DBG_MAX_REG_NUM > 0
+static char *gdb_hex_reg_helper(int regnum, char *out)
+{
+        int i;
+        int offset = 0;
+
+        for (i = 0; i < regnum; i++)
+                offset += dbg_reg_def[i].size;
+        return kgdb_mem2hex((char *)gdb_regs + offset, out,
+                            dbg_reg_def[i].size);
+}
+
+/* Handle the 'p' individual regster get */
+static void gdb_cmd_reg_get(struct kgdb_state *ks)
+{
+        unsigned long regnum;
+        char *ptr = &remcom_in_buffer[1];
+
+        kgdb_hex2long(&ptr, &regnum);
+        if (regnum >= DBG_MAX_REG_NUM) {
+                error_packet(remcom_out_buffer, -EINVAL);
+                return;
+        }
+        gdb_get_regs_helper(ks);
+        gdb_hex_reg_helper(regnum, remcom_out_buffer);
+}
+
+/* Handle the 'P' individual regster set */
+static void gdb_cmd_reg_set(struct kgdb_state *ks)
+{
+        unsigned long regnum;
+        char *ptr = &remcom_in_buffer[1];
+        int i = 0;
+
+        kgdb_hex2long(&ptr, &regnum);
+        if (*ptr++ != '=' ||
+            !(!kgdb_usethread || kgdb_usethread == current) ||
+            !dbg_get_reg(regnum, gdb_regs, ks->linux_regs)) {
+                error_packet(remcom_out_buffer, -EINVAL);
+                return;
+        }
+        memset(gdb_regs, 0, sizeof(gdb_regs));
+        while (i < sizeof(gdb_regs) * 2)
+                if (hex_to_bin(ptr[i]) >= 0)
+                        i++;
+                else
+                        break;
+        i = i / 2;
+        kgdb_hex2mem(ptr, (char *)gdb_regs, i);
+        dbg_set_reg(regnum, gdb_regs, ks->linux_regs);
+        strcpy(remcom_out_buffer, "OK");
+}
+#endif /* DBG_MAX_REG_NUM > 0 */
+
 /* Handle the 'X' memory binary write bytes */
 static void gdb_cmd_binwrite(struct kgdb_state *ks)
 {
@@ -612,7 +688,7 @@ static void gdb_cmd_query(struct kgdb_state *ks)
 {
         struct task_struct *g;
         struct task_struct *p;
-        unsigned char thref[8];
+        unsigned char thref[BUF_THREAD_ID_SIZE];
         char *ptr;
         int i;
         int cpu;
@@ -632,8 +708,7 @@ static void gdb_cmd_query(struct kgdb_state *ks)
                         for_each_online_cpu(cpu) {
                                 ks->thr_query = 0;
                                 int_to_threadref(thref, -cpu - 2);
-                                pack_threadid(ptr, thref);
-                                ptr += BUF_THREAD_ID_SIZE;
+                                ptr = pack_threadid(ptr, thref);
                                 *(ptr++) = ',';
                                 i++;
                         }
@@ -642,8 +717,7 @@ static void gdb_cmd_query(struct kgdb_state *ks)
                 do_each_thread(g, p) {
                         if (i >= ks->thr_query && !finished) {
                                 int_to_threadref(thref, p->pid);
-                                pack_threadid(ptr, thref);
-                                ptr += BUF_THREAD_ID_SIZE;
+                                ptr = pack_threadid(ptr, thref);
                                 *(ptr++) = ',';
                                 ks->thr_query++;
                                 if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
@@ -858,11 +932,14 @@ int gdb_serial_stub(struct kgdb_state *ks)
         int error = 0;
         int tmp;
 
-        /* Clear the out buffer. */
+        /* Initialize comm buffer and globals. */
         memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer));
+        kgdb_usethread = kgdb_info[ks->cpu].task;
+        ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
+        ks->pass_exception = 0;
 
         if (kgdb_connected) {
-                unsigned char thref[8];
+                unsigned char thref[BUF_THREAD_ID_SIZE];
                 char *ptr;
 
                 /* Reply to host that an exception has occurred */
@@ -876,10 +953,6 @@ int gdb_serial_stub(struct kgdb_state *ks)
                 put_packet(remcom_out_buffer);
         }
 
-        kgdb_usethread = kgdb_info[ks->cpu].task;
-        ks->kgdb_usethreadid = shadow_pid(kgdb_info[ks->cpu].task->pid);
-        ks->pass_exception = 0;
-
         while (1) {
                 error = 0;
 
@@ -904,6 +977,14 @@ int gdb_serial_stub(struct kgdb_state *ks)
                 case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA..AA */
                         gdb_cmd_memwrite(ks);
                         break;
+#if DBG_MAX_REG_NUM > 0
+                case 'p': /* pXX Return gdb register XX (in hex) */
+                        gdb_cmd_reg_get(ks);
+                        break;
+                case 'P': /* PXX=aaaa Set gdb register XX to aaaa (in hex) */
+                        gdb_cmd_reg_set(ks);
+                        break;
+#endif /* DBG_MAX_REG_NUM > 0 */
                 case 'X': /* XAA..AA,LLLL: Write LLLL bytes at address AA..AA */
                         gdb_cmd_binwrite(ks);
                         break;
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index ebe4a287419e..8577e45a9a58 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -312,7 +312,7 @@ int kdbgetularg(const char *arg, unsigned long *value)
 
         if (endp == arg) {
                 /*
-                 * Try base 16, for us folks too lazy to type the
+                 * Also try base 16, for us folks too lazy to type the
                  * leading 0x...
                  */
                 val = simple_strtoul(arg, &endp, 16);
@@ -325,6 +325,25 @@ int kdbgetularg(const char *arg, unsigned long *value)
         return 0;
 }
 
+int kdbgetu64arg(const char *arg, u64 *value)
+{
+        char *endp;
+        u64 val;
+
+        val = simple_strtoull(arg, &endp, 0);
+
+        if (endp == arg) {
+
+                val = simple_strtoull(arg, &endp, 16);
+                if (endp == arg)
+                        return KDB_BADINT;
+        }
+
+        *value = val;
+
+        return 0;
+}
+
 /*
  * kdb_set - This function implements the 'set' command.  Alter an
  *      existing environment variable or create a new one.
@@ -1770,11 +1789,65 @@ static int kdb_go(int argc, const char **argv)
  */
 static int kdb_rd(int argc, const char **argv)
 {
-        int diag = kdb_check_regs();
-        if (diag)
-                return diag;
+        int len = kdb_check_regs();
+#if DBG_MAX_REG_NUM > 0
+        int i;
+        char *rname;
+        int rsize;
+        u64 reg64;
+        u32 reg32;
+        u16 reg16;
+        u8 reg8;
+
+        if (len)
+                return len;
+
+        for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+                rsize = dbg_reg_def[i].size * 2;
+                if (rsize > 16)
+                        rsize = 2;
+                if (len + strlen(dbg_reg_def[i].name) + 4 + rsize > 80) {
+                        len = 0;
+                        kdb_printf("\n");
+                }
+                if (len)
+                        len += kdb_printf("  ");
+                switch(dbg_reg_def[i].size * 8) {
+                case 8:
+                        rname = dbg_get_reg(i, &reg8, kdb_current_regs);
+                        if (!rname)
+                                break;
+                        len += kdb_printf("%s: %02x", rname, reg8);
+                        break;
+                case 16:
+                        rname = dbg_get_reg(i, &reg16, kdb_current_regs);
+                        if (!rname)
+                                break;
+                        len += kdb_printf("%s: %04x", rname, reg16);
+                        break;
+                case 32:
+                        rname = dbg_get_reg(i, &reg32, kdb_current_regs);
+                        if (!rname)
+                                break;
+                        len += kdb_printf("%s: %08x", rname, reg32);
+                        break;
+                case 64:
+                        rname = dbg_get_reg(i, &reg64, kdb_current_regs);
+                        if (!rname)
+                                break;
+                        len += kdb_printf("%s: %016llx", rname, reg64);
+                        break;
+                default:
+                        len += kdb_printf("%s: ??", dbg_reg_def[i].name);
+                }
+        }
+        kdb_printf("\n");
+#else
+        if (len)
+                return len;
 
         kdb_dumpregs(kdb_current_regs);
+#endif
         return 0;
 }
 
@@ -1782,32 +1855,67 @@ static int kdb_rd(int argc, const char **argv)
  * kdb_rm - This function implements the 'rm' (register modify)  command.
  *      rm register-name new-contents
  * Remarks:
- *      Currently doesn't allow modification of control or
- *      debug registers.
+ *      Allows register modification with the same restrictions as gdb
  */
 static int kdb_rm(int argc, const char **argv)
 {
+#if DBG_MAX_REG_NUM > 0
         int diag;
-        int ind = 0;
-        unsigned long contents;
+        const char *rname;
+        int i;
+        u64 reg64;
+        u32 reg32;
+        u16 reg16;
+        u8 reg8;
 
         if (argc != 2)
                 return KDB_ARGCOUNT;
         /*
          * Allow presence or absence of leading '%' symbol.
          */
-        if (argv[1][0] == '%')
-                ind = 1;
+        rname = argv[1];
+        if (*rname == '%')
+                rname++;
 
-        diag = kdbgetularg(argv[2], &contents);
+        diag = kdbgetu64arg(argv[2], &reg64);
         if (diag)
                 return diag;
 
         diag = kdb_check_regs();
         if (diag)
                 return diag;
+
+        diag = KDB_BADREG;
+        for (i = 0; i < DBG_MAX_REG_NUM; i++) {
+                if (strcmp(rname, dbg_reg_def[i].name) == 0) {
+                        diag = 0;
+                        break;
+                }
+        }
+        if (!diag) {
+                switch(dbg_reg_def[i].size * 8) {
+                case 8:
+                        reg8 = reg64;
+                        dbg_set_reg(i, &reg8, kdb_current_regs);
+                        break;
+                case 16:
+                        reg16 = reg64;
+                        dbg_set_reg(i, &reg16, kdb_current_regs);
+                        break;
+                case 32:
+                        reg32 = reg64;
+                        dbg_set_reg(i, &reg32, kdb_current_regs);
+                        break;
+                case 64:
+                        dbg_set_reg(i, &reg64, kdb_current_regs);
+                        break;
+                }
+        }
+        return diag;
+#else
         kdb_printf("ERROR: Register set currently not implemented\n");
-        return 0;
+    return 0;
+#endif
 }
 
 #if defined(CONFIG_MAGIC_SYSRQ)
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index ffb1a5b0550e..4215530b490b 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -57,5 +57,8 @@ obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
 obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
 obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
 obj-$(CONFIG_EVENT_TRACING) += power-traces.o
+ifeq ($(CONFIG_TRACING),y)
+obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
+endif
 
 libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 086d36316805..d6736b93dc2a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -101,10 +101,7 @@ static inline void ftrace_enable_cpu(void)
         preempt_enable();
 }
 
-static cpumask_var_t __read_mostly      tracing_buffer_mask;
-
-#define for_each_tracing_cpu(cpu)       \
-        for_each_cpu(cpu, tracing_buffer_mask)
+cpumask_var_t __read_mostly     tracing_buffer_mask;
 
 /*
  * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
@@ -1539,11 +1536,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
 }
 EXPORT_SYMBOL_GPL(trace_vprintk);
 
-enum trace_file_type {
-        TRACE_FILE_LAT_FMT      = 1,
-        TRACE_FILE_ANNOTATE     = 2,
-};
-
 static void trace_iterator_increment(struct trace_iterator *iter)
 {
         /* Don't allow ftrace to trace into the ring buffers */
@@ -1641,7 +1633,7 @@ struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
 }
 
 /* Find the next real entry, and increment the iterator to the next entry */
-static void *find_next_entry_inc(struct trace_iterator *iter)
+void *trace_find_next_entry_inc(struct trace_iterator *iter)
 {
         iter->ent = __find_next_entry(iter, &iter->cpu,
                                       &iter->lost_events, &iter->ts);
@@ -1676,19 +1668,19 @@ static void *s_next(struct seq_file *m, void *v, loff_t *pos)
                 return NULL;
 
         if (iter->idx < 0)
-                ent = find_next_entry_inc(iter);
+                ent = trace_find_next_entry_inc(iter);
         else
                 ent = iter;
 
         while (ent && iter->idx < i)
-                ent = find_next_entry_inc(iter);
+                ent = trace_find_next_entry_inc(iter);
 
         iter->pos = *pos;
 
         return ent;
 }
 
-static void tracing_iter_reset(struct trace_iterator *iter, int cpu)
+void tracing_iter_reset(struct trace_iterator *iter, int cpu)
 {
         struct trace_array *tr = iter->tr;
         struct ring_buffer_event *event;
@@ -2049,7 +2041,7 @@ int trace_empty(struct trace_iterator *iter)
 }
 
 /*  Called with trace_event_read_lock() held. */
-static enum print_line_t print_trace_line(struct trace_iterator *iter)
+enum print_line_t print_trace_line(struct trace_iterator *iter)
 {
         enum print_line_t ret;
 
@@ -3211,7 +3203,7 @@ waitagain:
 
         trace_event_read_lock();
         trace_access_lock(iter->cpu_file);
-        while (find_next_entry_inc(iter) != NULL) {
+        while (trace_find_next_entry_inc(iter) != NULL) {
                 enum print_line_t ret;
                 int len = iter->seq.len;
 
@@ -3294,7 +3286,7 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
                 if (ret != TRACE_TYPE_NO_CONSUME)
                         trace_consume(iter);
                 rem -= count;
-                if (!find_next_entry_inc(iter)) {
+                if (!trace_find_next_entry_inc(iter))   {
                         rem = 0;
                         iter->ent = NULL;
                         break;
@@ -3350,7 +3342,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
         if (ret <= 0)
                 goto out_err;
 
-        if (!iter->ent && !find_next_entry_inc(iter)) {
+        if (!iter->ent && !trace_find_next_entry_inc(iter)) {
                 ret = -EFAULT;
                 goto out_err;
         }
@@ -4414,7 +4406,7 @@ static struct notifier_block trace_die_notifier = {
  */
 #define KERN_TRACE              KERN_EMERG
 
-static void
+void
 trace_printk_seq(struct trace_seq *s)
 {
         /* Probably should print a warning here. */
@@ -4429,6 +4421,13 @@ trace_printk_seq(struct trace_seq *s)
         trace_seq_init(s);
 }
 
+void trace_init_global_iter(struct trace_iterator *iter)
+{
+        iter->tr = &global_trace;
+        iter->trace = current_trace;
+        iter->cpu_file = TRACE_PIPE_ALL_CPU;
+}
+
 static void
 __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
 {
@@ -4454,8 +4453,10 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
         if (disable_tracing)
                 ftrace_kill();
 
+        trace_init_global_iter(&iter);
+
         for_each_tracing_cpu(cpu) {
-                atomic_inc(&global_trace.data[cpu]->disabled);
+                atomic_inc(&iter.tr->data[cpu]->disabled);
         }
 
         old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
@@ -4504,7 +4505,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
                 iter.iter_flags |= TRACE_FILE_LAT_FMT;
                 iter.pos = -1;
 
-                if (find_next_entry_inc(&iter) != NULL) {
+                if (trace_find_next_entry_inc(&iter) != NULL) {
                         int ret;
 
                         ret = print_trace_line(&iter);
@@ -4526,7 +4527,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
                 trace_flags |= old_userobj;
 
                 for_each_tracing_cpu(cpu) {
-                        atomic_dec(&global_trace.data[cpu]->disabled);
+                        atomic_dec(&iter.tr->data[cpu]->disabled);
                 }
                 tracing_on();
         }
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2cd96399463f..0605fc00c176 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -338,6 +338,14 @@ struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
                                           int *ent_cpu, u64 *ent_ts);
 
+int trace_empty(struct trace_iterator *iter);
+
+void *trace_find_next_entry_inc(struct trace_iterator *iter);
+
+void trace_init_global_iter(struct trace_iterator *iter);
+
+void tracing_iter_reset(struct trace_iterator *iter, int cpu);
+
 void default_wait_pipe(struct trace_iterator *iter);
 void poll_wait_pipe(struct trace_iterator *iter);
 
@@ -380,6 +388,15 @@ void tracing_start_sched_switch_record(void);
 int register_tracer(struct tracer *type);
 void unregister_tracer(struct tracer *type);
 int is_tracing_stopped(void);
+enum trace_file_type {
+        TRACE_FILE_LAT_FMT      = 1,
+        TRACE_FILE_ANNOTATE     = 2,
+};
+
+extern cpumask_var_t __read_mostly tracing_buffer_mask;
+
+#define for_each_tracing_cpu(cpu)       \
+        for_each_cpu(cpu, tracing_buffer_mask)
 
 extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
 
@@ -471,6 +488,8 @@ trace_array_vprintk(struct trace_array *tr,
                     unsigned long ip, const char *fmt, va_list args);
 int trace_array_printk(struct trace_array *tr,
                        unsigned long ip, const char *fmt, ...);
+void trace_printk_seq(struct trace_seq *s);
+enum print_line_t print_trace_line(struct trace_iterator *iter);
 
 extern unsigned long trace_flags;
 
diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
new file mode 100644
index 000000000000..7b8ecd751d93
--- /dev/null
+++ b/kernel/trace/trace_kdb.c
@@ -0,0 +1,136 @@
+/*
+ * kdb helper for dumping the ftrace buffer
+ *
+ * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
+ *
+ * ftrace_dump_buf based on ftrace_dump:
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ */
+#include <linux/init.h>
+#include <linux/kgdb.h>
+#include <linux/kdb.h>
+#include <linux/ftrace.h>
+
+#include "../debug/kdb/kdb_private.h"
+#include "trace.h"
+#include "trace_output.h"
+
+static void ftrace_dump_buf(int skip_lines, long cpu_file)
+{
+        /* use static because iter can be a bit big for the stack */
+        static struct trace_iterator iter;
+        unsigned int old_userobj;
+        int cnt = 0, cpu;
+
+        trace_init_global_iter(&iter);
+
+        for_each_tracing_cpu(cpu) {
+                atomic_inc(&iter.tr->data[cpu]->disabled);
+        }
+
+        old_userobj = trace_flags;
+
+        /* don't look at user memory in panic mode */
+        trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
+
+        kdb_printf("Dumping ftrace buffer:\n");
+
+        /* reset all but tr, trace, and overruns */
+        memset(&iter.seq, 0,
+                   sizeof(struct trace_iterator) -
+                   offsetof(struct trace_iterator, seq));
+        iter.iter_flags |= TRACE_FILE_LAT_FMT;
+        iter.pos = -1;
+
+        if (cpu_file == TRACE_PIPE_ALL_CPU) {
+                for_each_tracing_cpu(cpu) {
+                        iter.buffer_iter[cpu] =
+                        ring_buffer_read_prepare(iter.tr->buffer, cpu);
+                        ring_buffer_read_start(iter.buffer_iter[cpu]);
+                        tracing_iter_reset(&iter, cpu);
+                }
+        } else {
+                iter.cpu_file = cpu_file;
+                iter.buffer_iter[cpu_file] =
+                        ring_buffer_read_prepare(iter.tr->buffer, cpu_file);
+                ring_buffer_read_start(iter.buffer_iter[cpu_file]);
+                tracing_iter_reset(&iter, cpu_file);
+        }
+        if (!trace_empty(&iter))
+                trace_find_next_entry_inc(&iter);
+        while (!trace_empty(&iter)) {
+                if (!cnt)
+                        kdb_printf("---------------------------------\n");
+                cnt++;
+
+                if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines)
+                        print_trace_line(&iter);
+                if (!skip_lines)
+                        trace_printk_seq(&iter.seq);
+                else
+                        skip_lines--;
+                if (KDB_FLAG(CMD_INTERRUPT))
+                        goto out;
+        }
+
+        if (!cnt)
+                kdb_printf("   (ftrace buffer empty)\n");
+        else
+                kdb_printf("---------------------------------\n");
+
+out:
+        trace_flags = old_userobj;
+
+        for_each_tracing_cpu(cpu) {
+                atomic_dec(&iter.tr->data[cpu]->disabled);
+        }
+
+        for_each_tracing_cpu(cpu)
+                if (iter.buffer_iter[cpu])
+                        ring_buffer_read_finish(iter.buffer_iter[cpu]);
+}
+
+/*
+ * kdb_ftdump - Dump the ftrace log buffer
+ */
+static int kdb_ftdump(int argc, const char **argv)
+{
+        int skip_lines = 0;
+        long cpu_file;
+        char *cp;
+
+        if (argc > 2)
+                return KDB_ARGCOUNT;
+
+        if (argc) {
+                skip_lines = simple_strtol(argv[1], &cp, 0);
+                if (*cp)
+                        skip_lines = 0;
+        }
+
+        if (argc == 2) {
+                cpu_file = simple_strtol(argv[2], &cp, 0);
+                if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
+                    !cpu_online(cpu_file))
+                        return KDB_BADINT;
+        } else {
+                cpu_file = TRACE_PIPE_ALL_CPU;
+        }
+
+        kdb_trap_printk++;
+        ftrace_dump_buf(skip_lines, cpu_file);
+        kdb_trap_printk--;
+
+        return 0;
+}
+
+static __init int kdb_ftrace_register(void)
+{
+        kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
+                            "Dump ftrace log", 0, KDB_REPEAT_NONE);
+        return 0;
+}
+
+late_initcall(kdb_ftrace_register);