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Subject[PATCH 07/15] gdbstub,x86: Implement gdbserial 'p' and 'P' packets
Date
The gdbserial 'p' and 'P' packets allow gdb to individually get and
set registers instead of querying for all the available registers.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
include/linux/kgdb.h | 2 +-
kernel/debug/gdbstub.c | 97 ++++++++++++++++++++++++++++++++++++++----------
2 files changed, 78 insertions(+), 21 deletions(-)

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index d5eb882..cc96f0f 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -294,7 +294,7 @@ extern void kgdb_unregister_io_module(struct kgdb_io *local_kgdb_io_ops);
extern struct kgdb_io *dbg_io_ops;

extern int kgdb_hex2long(char **ptr, unsigned long *long_val);
-extern int kgdb_mem2hex(char *mem, char *buf, int count);
+extern char *kgdb_mem2hex(char *mem, char *buf, int count);
extern int kgdb_hex2mem(char *buf, char *mem, int count);

extern int kgdb_isremovedbreak(unsigned long addr);
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index 006bad8..4ef9ddd 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -225,7 +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;
@@ -237,17 +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;
}

/*
@@ -481,8 +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;
@@ -523,6 +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);
}

@@ -545,13 +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);
}
@@ -568,6 +572,52 @@ 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];
+
+ 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;
+ }
+ kgdb_hex2mem(ptr, (char *)gdb_regs, dbg_reg_def[regnum].size);
+ 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)
{
@@ -874,8 +924,11 @@ 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[BUF_THREAD_ID_SIZE];
@@ -892,10 +945,6 @@ 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;

@@ -920,6 +969,14 @@ 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;
--
1.6.4.rc1


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