[Qemu-devel] [PATCH 1/2] Add GDB qAttached support

[Qemu-devel] [PATCH 1/2] Add GDB qAttached support

[Jan Kiszka]

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From: Jan Kiszka <jan.kiszka@siemens.com>

With this patch QEMU handles qAttached request from gdb. When QEMU
replies 1, GDB sends a "detach" command at the end of a debugging
session otherwise GDB sends "kill".

The default value for qAttached is 1 on system emulation and 0 on user
emulation.

Based on original version by Fabien Chouteau.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

Long pending in my queue. Hope we can finally get these two in via
trivial (that's what they are).

 gdbstub.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/gdbstub.c b/gdbstub.c
index e4a1a79..da3e7cb 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -41,6 +41,12 @@
 #include "qemu/sockets.h"
 #include "sysemu/kvm.h"
 
+#ifdef CONFIG_USER_ONLY
+#define GDB_ATTACHED "0"
+#else
+#define GDB_ATTACHED "1"
+#endif
+
 static inline int target_memory_rw_debug(CPUState *cpu, target_ulong addr,
                                          uint8_t *buf, int len, bool is_write)
 {
@@ -1187,6 +1193,10 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             put_packet_binary(s, buf, len + 1);
             break;
         }
+        if (strncmp(p, "Attached", 8) == 0) {
+            put_packet(s, GDB_ATTACHED);
+            break;
+        }
         /* Unrecognised 'q' command.  */
         goto unknown_command;
 
-- 
2.1.4


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[Qemu-devel] [PATCH 2/2] Revert "gdbstub: Do not kill target in system emulation mode"

[Jan Kiszka]

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From: Fabien Chouteau <chouteau@adacore.com>

The requirements described in this patch are implemented by "Add GDB
qAttached support".

This reverts commit 00e94dbc7fd0110b0555d59592b004333adfb4b8.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 gdbstub.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/gdbstub.c b/gdbstub.c
index da3e7cb..14e1f0c 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -880,11 +880,9 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             goto unknown_command;
         }
     case 'k':
-#ifdef CONFIG_USER_ONLY
         /* Kill the target */
         fprintf(stderr, "\nQEMU: Terminated via GDBstub\n");
         exit(0);
-#endif
     case 'D':
         /* Detach packet */
         gdb_breakpoint_remove_all();
-- 
2.1.4


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Re: [Qemu-devel] [PATCH 1/2] Add GDB qAttached support

[Pedro Alves]

Hi, I was skimming the list, and noticed:

On 01/31/2015 10:28 AM, Jan Kiszka wrote:
> @@ -1187,6 +1193,10 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
>              put_packet_binary(s, buf, len + 1);
>              break;
>          }
> +        if (strncmp(p, "Attached", 8) == 0) {

This looks like it'd mishandle a future qAttached2 packet.

It should be doing something like:

       if (strncmp(p, "Attached", 8) == 0 &&
          (p[8] == '\0' || p[8] == ':')) {

or:

       if (strcmp(p, "Attached") == 0 || strncmp(p, "Attached:", 9) == 0) {


Likewise other packets, if they have the same issue.
(I'm not familiar with qemu's stub's internals.)

Thanks,
Pedro Alves

Re: [Qemu-devel] [PATCH 1/2] Add GDB qAttached support

[Jan Kiszka]

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On 2015-02-04 14:36, Pedro Alves wrote:
> Hi, I was skimming the list, and noticed:
> 
> On 01/31/2015 10:28 AM, Jan Kiszka wrote:
>> @@ -1187,6 +1193,10 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
>>              put_packet_binary(s, buf, len + 1);
>>              break;
>>          }
>> +        if (strncmp(p, "Attached", 8) == 0) {
> 
> This looks like it'd mishandle a future qAttached2 packet.
> 
> It should be doing something like:
> 
>        if (strncmp(p, "Attached", 8) == 0 &&
>           (p[8] == '\0' || p[8] == ':')) {
> 
> or:
> 
>        if (strcmp(p, "Attached") == 0 || strncmp(p, "Attached:", 9) == 0) {
> 
> 
> Likewise other packets, if they have the same issue.
> (I'm not familiar with qemu's stub's internals.)

Thanks for the remark! Will update the patch using the easier readable
second variant.

Jan



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Re: [Qemu-devel] [PATCH 1/2] Add GDB qAttached support

[Peter Maydell]

On 4 February 2015 at 13:36, Pedro Alves <palves@redhat.com> wrote:
>
> This looks like it'd mishandle a future qAttached2 packet.
>
> It should be doing something like:
>
>        if (strncmp(p, "Attached", 8) == 0 &&
>           (p[8] == '\0' || p[8] == ':')) {
>
> or:
>
>        if (strcmp(p, "Attached") == 0 || strncmp(p, "Attached:", 9) == 0) {
>
>
> Likewise other packets, if they have the same issue.
> (I'm not familiar with qemu's stub's internals.)

Looks like we get this wrong for a lot of our existing
query packet handling too... Maybe worth having a utility
function for "is this a foo query packet" rather than
raw strcmp/strncmp?

-- PMM

[Qemu-devel] [PATCH 0/2] Add GDB qAttached support

[Fabien Chouteau]

Fabien Chouteau (2):
  Add GDB qAttached support
  Revert "gdbstub: Do not kill target in system emulation mode"

 gdbstub.c              |   40 +++++++++++++++++++++++++++++++++++++---
 include/exec/gdbstub.h |    2 ++
 qemu-options.hx        |   17 +++++++++++++++++
 vl.c                   |    3 +++
 4 files changed, 59 insertions(+), 3 deletions(-)

-- 
1.7.9.5

[Qemu-devel] [PATCH 2/2] Revert "gdbstub: Do not kill target in system emulation mode"

[Fabien Chouteau]

The requirements described in this patch are implemented by "Add GDB
qAttached support".

This reverts commit 00e94dbc7fd0110b0555d59592b004333adfb4b8.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
---
 gdbstub.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/gdbstub.c b/gdbstub.c
index de95849..ee57124 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -2185,11 +2185,9 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             goto unknown_command;
         }
     case 'k':
-#ifdef CONFIG_USER_ONLY
         /* Kill the target */
         fprintf(stderr, "\nQEMU: Terminated via GDBstub\n");
         exit(0);
-#endif
     case 'D':
         /* Detach packet */
         gdb_breakpoint_remove_all();
-- 
1.7.9.5

[Qemu-devel] [PATCH 1/2] Add GDB qAttached support

[Fabien Chouteau]

With this patch GDB will issue a "detach" command at the end of a
debugging session instead of a "kill". This behavior can be inverted
with the new option -gdb-not-attached.

This patch implements the requirement described in Jan Kiszka's patch:
"gdbstub: Do not kill target in system emulation mode". The patch can
therefore be reverted.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
---
 gdbstub.c              |   13 ++++++++++++-
 include/exec/gdbstub.h |    2 ++
 qemu-options.hx        |    7 +++++++
 vl.c                   |    3 +++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/gdbstub.c b/gdbstub.c
index e414ad9..c0686a9 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -32,7 +32,6 @@
 #include "monitor/monitor.h"
 #include "char/char.h"
 #include "sysemu/sysemu.h"
-#include "exec/gdbstub.h"
 #endif
 
 #define MAX_PACKET_LENGTH 4096
@@ -41,6 +40,9 @@
 #include "qemu/sockets.h"
 #include "sysemu/kvm.h"
 #include "qemu/bitops.h"
+#include "exec/gdbstub.h"
+
+static bool gdb_attached = true;
 
 #ifndef TARGET_CPU_MEMORY_RW_DEBUG
 static inline int target_memory_rw_debug(CPUArchState *env, target_ulong addr,
@@ -2491,6 +2493,10 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             break;
         }
 #endif
+        if (strncmp(p, "Attached", 8) == 0) {
+            put_packet(s, gdb_attached ? "1" : "0");
+            break;
+        }
         /* Unrecognised 'q' command.  */
         goto unknown_command;
 
@@ -3055,3 +3061,8 @@ int gdbserver_start(const char *device)
     return 0;
 }
 #endif
+
+void gdb_set_attached(bool attached)
+{
+    gdb_attached = attached;
+}
diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index ba20afa..b2d3b13 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -50,4 +50,6 @@ int gdbserver_start(const char *port);
 /* in gdbstub-xml.c, generated by scripts/feature_to_c.sh */
 extern const char *const xml_builtin[][2];
 
+void gdb_set_attached(bool attached);
+
 #endif
diff --git a/qemu-options.hx b/qemu-options.hx
index 6f9334a..026d3eb 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2988,6 +2988,13 @@ property must be set.  These objects are placed in the
 '/objects' path.
 ETEXI
 
+DEF("gdb-not-attached", 0, QEMU_OPTION_gdb_not_attached,
+    "-gdb-not-attached\n"
+    "                Do not set Gdb remote server in attached mode.\n"
+    "                When exiting debugging session, Gdb will send a 'kill'\n"
+    "                command instead of a 'detach'.\n",
+    QEMU_ARCH_ALL)
+
 HXCOMM This is the last statement. Insert new options before this line!
 STEXI
 @end table
diff --git a/vl.c b/vl.c
index c03edf1..ccd7405 100644
--- a/vl.c
+++ b/vl.c
@@ -3815,6 +3815,9 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_gdb_not_attached:
+                gdb_set_attached(false);
+                break;
             default:
                 os_parse_cmd_args(popt->index, optarg);
             }
-- 
1.7.9.5

[Qemu-devel] [PATCH 2/2] Revert "gdbstub: Do not kill target in system emulation mode"

[Fabien Chouteau]

This reverts commit 00e94dbc7fd0110b0555d59592b004333adfb4b8.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
---
 gdbstub.c |    2 --
 1 file changed, 2 deletions(-)

diff --git a/gdbstub.c b/gdbstub.c
index c0686a9..22078df 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -2181,11 +2181,9 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
             goto unknown_command;
         }
     case 'k':
-#ifdef CONFIG_USER_ONLY
         /* Kill the target */
         fprintf(stderr, "\nQEMU: Terminated via GDBstub\n");
         exit(0);
-#endif
     case 'D':
         /* Detach packet */
         gdb_breakpoint_remove_all();
-- 
1.7.9.5

Re: [Qemu-devel] [PATCH 2/2] Revert "gdbstub: Do not kill target in system emulation mode"

[Jan Kiszka]

On 2013-03-05 17:03, Fabien Chouteau wrote:
> This reverts commit 00e94dbc7fd0110b0555d59592b004333adfb4b8.

Should also tell us why (by pointing to the other commit e.g.).

Will give this a try ASAP!

Thanks,
Jan

> 
> Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
> ---
>  gdbstub.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/gdbstub.c b/gdbstub.c
> index c0686a9..22078df 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -2181,11 +2181,9 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
>              goto unknown_command;
>          }
>      case 'k':
> -#ifdef CONFIG_USER_ONLY
>          /* Kill the target */
>          fprintf(stderr, "\nQEMU: Terminated via GDBstub\n");
>          exit(0);
> -#endif
>      case 'D':
>          /* Detach packet */
>          gdb_breakpoint_remove_all();
> 

-- 
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] [PATCH 2/2] Revert "gdbstub: Do not kill target in system emulation mode"

[Fabien Chouteau]

On 03/05/2013 05:07 PM, Jan Kiszka wrote:
> On 2013-03-05 17:03, Fabien Chouteau wrote:
>> This reverts commit 00e94dbc7fd0110b0555d59592b004333adfb4b8.
> 
> Should also tell us why (by pointing to the other commit e.g.).
> 

Yea, I should have put them together.

> Will give this a try ASAP!
> 

Thanks,


-- 
Fabien Chouteau