frv: extend gdbstub to support more features of gdb

Extend gdbstub to support more features of gdb remote protocol to keep
gdb-7 and emacs gud mode happy:

 (*) The D command.  Detach debugger.

 (*) The H command.  Handle setting the target thread by ignoring it.

 (*) The qAttached command.  Indicate we 'attached' to an existing process.

 (*) The qC command.  Indicate that the current thread ID is 0.

 (*) The qOffsets command.  Indicate that no relocation has been done.

 (*) The qSymbol:: command.  Indicate that we're not interested in looking up
     any symbol addresses.

 (*) The qSupported command.  Indicate the maximum packet size and the fact
     that reverse step and continue aren't supported.

 (*) The vCont? command.  Indicate that we don't support any of its variants.

Also make it possible to trace the commands and replies without tracing
the individual character I/O.

[akpm@linux-foundation.org: make gdbstub_handle_query() static]
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 70 insertions, 2 deletions

diff --git a/arch/frv/include/asm/gdb-stub.h b/arch/frv/include/asm/gdb-stub.h
index 2da716407ff2..e6bedd0cd9a5 100644
--- a/arch/frv/include/asm/gdb-stub.h
+++ b/arch/frv/include/asm/gdb-stub.h
@@ -12,6 +12,7 @@
 #ifndef __ASM_GDB_STUB_H
 #define __ASM_GDB_STUB_H
 
+#undef GDBSTUB_DEBUG_IO
 #undef GDBSTUB_DEBUG_PROTOCOL
 
 #include <asm/ptrace.h>
@@ -108,6 +109,12 @@ extern void gdbstub_printk(const char *fmt, ...);
 extern void debug_to_serial(const char *p, int n);
 extern void console_set_baud(unsigned baud);
 
+#ifdef GDBSTUB_DEBUG_IO
+#define gdbstub_io(FMT,...) gdbstub_printk(FMT, ##__VA_ARGS__)
+#else
+#define gdbstub_io(FMT,...) ({ 0; })
+#endif
+
 #ifdef GDBSTUB_DEBUG_PROTOCOL
 #define gdbstub_proto(FMT,...) gdbstub_printk(FMT,##__VA_ARGS__)
 #else
diff --git a/arch/frv/kernel/gdb-io.c b/arch/frv/kernel/gdb-io.c
index c997bccb9221..2ca641d199f8 100644
--- a/arch/frv/kernel/gdb-io.c
+++ b/arch/frv/kernel/gdb-io.c
@@ -171,11 +171,11 @@ int gdbstub_rx_char(unsigned char *_ch, int nonblock)
                 return -EINTR;
         }
         else if (st & (UART_LSR_FE|UART_LSR_OE|UART_LSR_PE)) {
-                gdbstub_proto("### GDB Rx Error (st=%02x) ###\n",st);
+                gdbstub_io("### GDB Rx Error (st=%02x) ###\n",st);
                 return -EIO;
         }
         else {
-                gdbstub_proto("### GDB Rx %02x (st=%02x) ###\n",ch,st);
+                gdbstub_io("### GDB Rx %02x (st=%02x) ###\n",ch,st);
                 *_ch = ch & 0x7f;
                 return 0;
         }
diff --git a/arch/frv/kernel/gdb-stub.c b/arch/frv/kernel/gdb-stub.c
index 7ca8a6b19ac9..84d103c33c9c 100644
--- a/arch/frv/kernel/gdb-stub.c
+++ b/arch/frv/kernel/gdb-stub.c
@@ -1344,6 +1344,44 @@ void gdbstub_get_mmu_state(void)
 
 } /* end gdbstub_get_mmu_state() */
 
+/*
+ * handle general query commands of the form 'qXXXXX'
+ */
+static void gdbstub_handle_query(void)
+{
+        if (strcmp(input_buffer, "qAttached") == 0) {
+                /* return current thread ID */
+                sprintf(output_buffer, "1");
+                return;
+        }
+
+        if (strcmp(input_buffer, "qC") == 0) {
+                /* return current thread ID */
+                sprintf(output_buffer, "QC 0");
+                return;
+        }
+
+        if (strcmp(input_buffer, "qOffsets") == 0) {
+                /* return relocation offset of text and data segments */
+                sprintf(output_buffer, "Text=0;Data=0;Bss=0");
+                return;
+        }
+
+        if (strcmp(input_buffer, "qSymbol::") == 0) {
+                sprintf(output_buffer, "OK");
+                return;
+        }
+
+        if (strcmp(input_buffer, "qSupported") == 0) {
+                /* query of supported features */
+                sprintf(output_buffer, "PacketSize=%u;ReverseContinue-;ReverseStep-",
+                        sizeof(input_buffer));
+                return;
+        }
+
+        gdbstub_strcpy(output_buffer,"E01");
+}
+
 /*****************************************************************************/
 /*
  * handle event interception and GDB remote protocol processing
@@ -1840,6 +1878,10 @@ void gdbstub(int sigval)
                 case 'k' :
                         goto done;      /* just continue */
 
+                        /* detach */
+                case 'D':
+                        gdbstub_strcpy(output_buffer, "OK");
+                        break;
 
                         /* reset the whole machine (FIXME: system dependent) */
                 case 'r':
@@ -1852,6 +1894,14 @@ void gdbstub(int sigval)
                         __debug_status.dcr |= DCR_SE;
                         goto done;
 
+                        /* extended command */
+                case 'v':
+                        if (strcmp(input_buffer, "vCont?") == 0) {
+                                output_buffer[0] = 0;
+                                break;
+                        }
+                        goto unsupported_cmd;
+
                         /* set baud rate (bBB) */
                 case 'b':
                         ptr = &input_buffer[1];
@@ -1923,8 +1973,19 @@ void gdbstub(int sigval)
                         gdbstub_strcpy(output_buffer,"OK");
                         break;
 
+                        /* Thread-setting packet */
+                case 'H':
+                        gdbstub_strcpy(output_buffer, "OK");
+                        break;
+
+                case 'q':
+                        gdbstub_handle_query();
+                        break;
+
                 default:
+                unsupported_cmd:
                         gdbstub_proto("### GDB Unsupported Cmd '%s'\n",input_buffer);
+                        gdbstub_strcpy(output_buffer,"E01");
                         break;
                 }