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:
kgdb: fix gdb serial thread queries
kgdb: fix kgdb_validate_break_address to perform a mem write
kgdb: remove the requirement for CONFIG_FRAME_POINTER
diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl
index e8acd1f..372dec2 100644
--- a/Documentation/DocBook/kgdb.tmpl
+++ b/Documentation/DocBook/kgdb.tmpl
@@ -98,6 +98,24 @@
"Kernel debugging" select "KGDB: kernel debugging with remote gdb".
</para>
<para>
+ It is advised, but not required that you turn on the
+ CONFIG_FRAME_POINTER kernel option. This option inserts code to
+ into the compiled executable which saves the frame information in
+ registers or on the stack at different points which will allow a
+ debugger such as gdb to more accurately construct stack back traces
+ while debugging the kernel.
+ </para>
+ <para>
+ If the architecture that you are using supports the kernel option
+ CONFIG_DEBUG_RODATA, you should consider turning it off. This
+ option will prevent the use of software breakpoints because it
+ marks certain regions of the kernel's memory space as read-only.
+ If kgdb supports it for the architecture you are using, you can
+ use hardware breakpoints if you desire to run with the
+ CONFIG_DEBUG_RODATA option turned on, else you need to turn off
+ this option.
+ </para>
+ <para>
Next you should choose one of more I/O drivers to interconnect debugging
host and debugged target. Early boot debugging requires a KGDB
I/O driver that supports early debugging and the driver must be
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 3ec23c3..eaa21fc 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -56,12 +56,14 @@
static int kgdb_break_asap;
+#define KGDB_MAX_THREAD_QUERY 17
struct kgdb_state {
int ex_vector;
int signo;
int err_code;
int cpu;
int pass_exception;
+ unsigned long thr_query;
unsigned long threadid;
long kgdb_usethreadid;
struct pt_regs *linux_regs;
@@ -166,13 +168,6 @@
* Weak aliases for breakpoint management,
* can be overriden by architectures when needed:
*/
-int __weak kgdb_validate_break_address(unsigned long addr)
-{
- char tmp_variable[BREAK_INSTR_SIZE];
-
- return probe_kernel_read(tmp_variable, (char *)addr, BREAK_INSTR_SIZE);
-}
-
int __weak kgdb_arch_set_breakpoint(unsigned long addr, char *saved_instr)
{
int err;
@@ -191,6 +186,25 @@
(char *)bundle, BREAK_INSTR_SIZE);
}
+int __weak kgdb_validate_break_address(unsigned long addr)
+{
+ char tmp_variable[BREAK_INSTR_SIZE];
+ int err;
+ /* Validate setting the breakpoint and then removing it. In the
+ * remove fails, the kernel needs to emit a bad message because we
+ * are deep trouble not being able to put things back the way we
+ * found them.
+ */
+ err = kgdb_arch_set_breakpoint(addr, tmp_variable);
+ if (err)
+ return err;
+ err = kgdb_arch_remove_breakpoint(addr, tmp_variable);
+ if (err)
+ printk(KERN_ERR "KGDB: Critical breakpoint error, kernel "
+ "memory destroyed at: %lx", addr);
+ return err;
+}
+
unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs)
{
return instruction_pointer(regs);
@@ -433,9 +447,14 @@
{
int hex_val;
int num = 0;
+ int negate = 0;
*long_val = 0;
+ if (**ptr == '-') {
+ negate = 1;
+ (*ptr)++;
+ }
while (**ptr) {
hex_val = hex(**ptr);
if (hex_val < 0)
@@ -446,6 +465,9 @@
(*ptr)++;
}
+ if (negate)
+ *long_val = -*long_val;
+
return num;
}
@@ -515,10 +537,16 @@
static struct task_struct *getthread(struct pt_regs *regs, int tid)
{
/*
- * Non-positive TIDs are remapped idle tasks:
+ * Non-positive TIDs are remapped to the cpu shadow information
*/
- if (tid <= 0)
- return idle_task(-tid);
+ if (tid == 0 || tid == -1)
+ tid = -atomic_read(&kgdb_active) - 2;
+ if (tid < 0) {
+ if (kgdb_info[-tid - 2].task)
+ return kgdb_info[-tid - 2].task;
+ else
+ return idle_task(-tid - 2);
+ }
/*
* find_task_by_pid_ns() does not take the tasklist lock anymore
@@ -725,14 +753,15 @@
}
/*
- * Remap normal tasks to their real PID, idle tasks to -1 ... -NR_CPUs:
+ * Remap normal tasks to their real PID,
+ * CPU shadow threads are mapped to -CPU - 2
*/
static inline int shadow_pid(int realpid)
{
if (realpid)
return realpid;
- return -1-raw_smp_processor_id();
+ return -raw_smp_processor_id() - 2;
}
static char gdbmsgbuf[BUFMAX + 1];
@@ -826,7 +855,7 @@
local_debuggerinfo = kgdb_info[ks->cpu].debuggerinfo;
} else {
local_debuggerinfo = NULL;
- for (i = 0; i < NR_CPUS; i++) {
+ for_each_online_cpu(i) {
/*
* Try to find the task on some other
* or possibly this node if we do not
@@ -960,10 +989,13 @@
/* Handle the 'q' query packets */
static void gdb_cmd_query(struct kgdb_state *ks)
{
- struct task_struct *thread;
+ struct task_struct *g;
+ struct task_struct *p;
unsigned char thref[8];
char *ptr;
int i;
+ int cpu;
+ int finished = 0;
switch (remcom_in_buffer[1]) {
case 's':
@@ -973,22 +1005,34 @@
break;
}
- if (remcom_in_buffer[1] == 'f')
- ks->threadid = 1;
-
+ i = 0;
remcom_out_buffer[0] = 'm';
ptr = remcom_out_buffer + 1;
-
- for (i = 0; i < 17; ks->threadid++) {
- thread = getthread(ks->linux_regs, ks->threadid);
- if (thread) {
- int_to_threadref(thref, ks->threadid);
+ if (remcom_in_buffer[1] == 'f') {
+ /* Each cpu is a shadow thread */
+ 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++) = ',';
i++;
}
}
+
+ 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++) = ',';
+ ks->thr_query++;
+ if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0)
+ finished = 1;
+ }
+ i++;
+ } while_each_thread(g, p);
+
*(--ptr) = '\0';
break;
@@ -1011,15 +1055,15 @@
error_packet(remcom_out_buffer, -EINVAL);
break;
}
- if (ks->threadid > 0) {
+ if ((int)ks->threadid > 0) {
kgdb_mem2hex(getthread(ks->linux_regs,
ks->threadid)->comm,
remcom_out_buffer, 16);
} else {
static char tmpstr[23 + BUF_THREAD_ID_SIZE];
- sprintf(tmpstr, "Shadow task %d for pid 0",
- (int)(-ks->threadid-1));
+ sprintf(tmpstr, "shadowCPU%d",
+ (int)(-ks->threadid - 2));
kgdb_mem2hex(tmpstr, remcom_out_buffer, strlen(tmpstr));
}
break;
diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
index 2cfd272..9b5d1d7 100644
--- a/lib/Kconfig.kgdb
+++ b/lib/Kconfig.kgdb
@@ -4,14 +4,17 @@
menuconfig KGDB
bool "KGDB: kernel debugging with remote gdb"
- select FRAME_POINTER
depends on HAVE_ARCH_KGDB
depends on DEBUG_KERNEL && EXPERIMENTAL
help
If you say Y here, it will be possible to remotely debug the
- kernel using gdb. Documentation of kernel debugger is available
- at http://kgdb.sourceforge.net as well as in DocBook form
- in Documentation/DocBook/. If unsure, say N.
+ kernel using gdb. It is recommended but not required, that
+ you also turn on the kernel config option
+ CONFIG_FRAME_POINTER to aid in producing more reliable stack
+ backtraces in the external debugger. Documentation of
+ kernel debugger is available at http://kgdb.sourceforge.net
+ as well as in DocBook form in Documentation/DocBook/. If
+ unsure, say N.
if KGDB