gdbstub: Implement gdbserial 'p' and 'P' packets

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>

1 files changed, 77 insertions, 20 deletions

diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index 006bad8905d3..4ef9dddf4588 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;