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Re: [PATCH 3/3] Fix "Remote 'g' packet reply is too long" problems with multiple inferiors
On 10/03/2017 01:21 PM, Pedro Alves wrote:
>
> On 10/03/2017 12:40 PM, Yao Qi wrote:
>> Pedro Alves <palves@redhat.com> writes:
>>
>>> struct gdbarch *
>>> default_thread_architecture (struct target_ops *ops, ptid_t ptid)
>>> {
>>> - return target_gdbarch ();
>>> + inferior *inf = find_inferior_ptid (ptid);
>>> + gdb_assert (inf != NULL);
>>> + return inf->gdbarch;
>>> }
>>
>> It is right, but forgot to mention that we need to update
>> spu_thread_architecture too,
>>
>> if (parse_spufs_run (ptid, &spufs_fd, &spufs_addr))
>> return spu_gdbarch (spufs_fd);
>>
>> return target_gdbarch ();
>>
>> it looks wrong to call target_gdbarch. We may need to replace
>> target_gdbarch with default_thread_architecture.
>
> I think you're right.
>
> The target_gdbarch reference in process_stop_reply looks incorrect
> as well (last hunk below). I'm current running test with the patch below
> on top. Kind of curious that I didn't run into this one before.
>
Here's the updated patch.
Instead of exporting default_thread_architecture,
I'm deferring to the target beneath. In practice ends up being the
same thing I think, but seems a bit more correct and future proof,
and is also simpler.
I've added the comment about target descriptions.
WDYT?
>From 8bcea3ea32a55a3cfac29dde1c97083843047e45 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Tue, 3 Oct 2017 13:26:42 +0100
Subject: [PATCH 3/3] Fix "Remote 'g' packet reply is too long" problems with
multiple inferiors
When debugging two inferiors (or more) against gdbserver, and the
inferiors have different architectures, such as e.g., on x86_64
GNU/Linux and one inferior is 64-bit while the other is 32-bit, then
GDB can get confused with the different architectures in a couple
spots.
In both cases I ran into, GDB incorrectly ended up using the
architecture of whatever happens to be the selected inferior instead
of the architecture of some other given inferior:
#1 - When parsing the expedited registers in stop replies.
#2 - In the default implementation of the target_thread_architecture
target method.
These resulted in instances of the infamous "Remote 'g' packet reply
is too long" error. For example, with the test added in this commit,
we get:
~~~
Continuing.
Remote 'g' packet reply is too long (expected 440 bytes, got 816 bytes): ad064000000000000[snip]
(gdb) FAIL: gdb.multi/multi-arch.exp: inf1 event with inf2 selected: continue to hello_loop
c
Continuing.
Truncated register 50 in remote 'g' packet
(gdb) PASS: gdb.multi/multi-arch.exp: inf2 event with inf1 selected: c
~~~
This commit fixes that.
gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>
* remote.c (get_remote_arch_state): New 'gdbarch' parameter. Use
it instead of target_gdbarch.
(get_remote_state, get_remote_packet_size): Adjust
get_remote_arch_state calls, passing down target_gdbarch
explicitly.
(packet_reg_from_regnum, packet_reg_from_pnum): New parameter
'gdbarch' and use it instead of target_gdbarch.
(get_memory_packet_size): Adjust get_remote_arch_state calls,
passing down target_gdbarch explicitly.
(struct stop_reply) <arch>: New field.
(remote_parse_stop_reply): Use the stopped thread's architecture,
not the current inferior's. Save the architecture in the
stop_reply.
(process_stop_reply): Use the stop reply's architecture.
(process_g_packet, remote_fetch_registers)
(remote_prepare_to_store, store_registers_using_G)
(remote_store_registers): Adjust get_remote_arch_state calls,
using the regcache's architecture.
(remote_get_trace_status): Adjust get_remote_arch_state calls,
passing down target_gdbarch explicitly.
* spu-multiarch.c (spu_thread_architecture): Defer to the target
beneath instead of calling target_gdbarch.
* target.c (default_thread_architecture): Use the specified
inferior's architecture, instead of the current inferior's
architecture (via target_gdbarch).
gdb/testsuite/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>
* gdb.multi/hangout.c: Include <unistd.h>.
(hangout_loop): New function.
(main): Call alarm. Call hangout_loop in a loop.
* gdb.multi/hello.c: Include <unistd.h>.
(hello_loop): New function.
(main): Call alarm. Call hangout_loop in a loop.
* gdb.multi/multi-arch.exp: Test running to a breakpoint one
inferior with the other selected.
---
gdb/remote.c | 100 ++++++++++++++++++++++++---------
gdb/spu-multiarch.c | 3 +-
gdb/target.c | 4 +-
gdb/testsuite/gdb.multi/hangout.c | 14 +++++
gdb/testsuite/gdb.multi/hello.c | 15 ++++-
gdb/testsuite/gdb.multi/multi-arch.exp | 24 ++++++++
6 files changed, 130 insertions(+), 30 deletions(-)
diff --git a/gdb/remote.c b/gdb/remote.c
index 54d810f..9bc69c2 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -654,11 +654,11 @@ remote_get_noisy_reply ()
static struct gdbarch_data *remote_gdbarch_data_handle;
static struct remote_arch_state *
-get_remote_arch_state (void)
+get_remote_arch_state (struct gdbarch *gdbarch)
{
- gdb_assert (target_gdbarch () != NULL);
+ gdb_assert (gdbarch != NULL);
return ((struct remote_arch_state *)
- gdbarch_data (target_gdbarch (), remote_gdbarch_data_handle));
+ gdbarch_data (gdbarch, remote_gdbarch_data_handle));
}
/* Fetch the global remote target state. */
@@ -671,7 +671,7 @@ get_remote_state (void)
function which calls getpkt also needs to be mindful of changes
to rs->buf, but this call limits the number of places which run
into trouble. */
- get_remote_arch_state ();
+ get_remote_arch_state (target_gdbarch ());
return get_remote_state_raw ();
}
@@ -878,7 +878,7 @@ static long
get_remote_packet_size (void)
{
struct remote_state *rs = get_remote_state ();
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ remote_arch_state *rsa = get_remote_arch_state (target_gdbarch ());
if (rs->explicit_packet_size)
return rs->explicit_packet_size;
@@ -887,9 +887,10 @@ get_remote_packet_size (void)
}
static struct packet_reg *
-packet_reg_from_regnum (struct remote_arch_state *rsa, long regnum)
+packet_reg_from_regnum (struct gdbarch *gdbarch, struct remote_arch_state *rsa,
+ long regnum)
{
- if (regnum < 0 && regnum >= gdbarch_num_regs (target_gdbarch ()))
+ if (regnum < 0 && regnum >= gdbarch_num_regs (gdbarch))
return NULL;
else
{
@@ -901,11 +902,12 @@ packet_reg_from_regnum (struct remote_arch_state *rsa, long regnum)
}
static struct packet_reg *
-packet_reg_from_pnum (struct remote_arch_state *rsa, LONGEST pnum)
+packet_reg_from_pnum (struct gdbarch *gdbarch, struct remote_arch_state *rsa,
+ LONGEST pnum)
{
int i;
- for (i = 0; i < gdbarch_num_regs (target_gdbarch ()); i++)
+ for (i = 0; i < gdbarch_num_regs (gdbarch); i++)
{
struct packet_reg *r = &rsa->regs[i];
@@ -1049,7 +1051,7 @@ static long
get_memory_packet_size (struct memory_packet_config *config)
{
struct remote_state *rs = get_remote_state ();
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ remote_arch_state *rsa = get_remote_arch_state (target_gdbarch ());
long what_they_get;
if (config->fixed_p)
@@ -6361,6 +6363,9 @@ typedef struct stop_reply
struct target_waitstatus ws;
+ /* The architecture associated with the expedited registers. */
+ gdbarch *arch;
+
/* Expedited registers. This makes remote debugging a bit more
efficient for those targets that provide critical registers as
part of their normal status mechanism (as another roundtrip to
@@ -6835,7 +6840,7 @@ strprefix (const char *p, const char *pend, const char *prefix)
static void
remote_parse_stop_reply (char *buf, struct stop_reply *event)
{
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ remote_arch_state *rsa = NULL;
ULONGEST addr;
const char *p;
int skipregs = 0;
@@ -7015,9 +7020,47 @@ Packet: '%s'\n"),
reason. */
if (p_temp == p1)
{
- struct packet_reg *reg = packet_reg_from_pnum (rsa, pnum);
+ /* If we haven't parsed the event's thread yet, find
+ it now, in order to find the architecture of the
+ reported expedited registers. */
+ if (event->ptid == null_ptid)
+ {
+ const char *thr = strstr (p1 + 1, ";thread:");
+ if (thr != NULL)
+ event->ptid = read_ptid (thr + strlen (";thread:"),
+ NULL);
+ else
+ event->ptid = magic_null_ptid;
+ }
+
+ if (rsa == NULL)
+ {
+ inferior *inf = (event->ptid == null_ptid
+ ? NULL
+ : find_inferior_ptid (event->ptid));
+ /* If this is the first time we learn anything
+ about this process, skip the registers
+ included in this packet, since we don't yet
+ know which architecture to use to parse them.
+ We'll determine the architecture later when
+ we process the stop reply and retrieve the
+ target description, via
+ remote_notice_new_inferior ->
+ post_create_inferior. */
+ if (inf == NULL)
+ {
+ p = strchrnul (p1 + 1, ';');
+ p++;
+ continue;
+ }
+
+ event->arch = inf->gdbarch;
+ rsa = get_remote_arch_state (event->arch);
+ }
+
+ packet_reg *reg
+ = packet_reg_from_pnum (event->arch, rsa, pnum);
cached_reg_t cached_reg;
- struct gdbarch *gdbarch = target_gdbarch ();
if (reg == NULL)
error (_("Remote sent bad register number %s: %s\n\
@@ -7026,13 +7069,13 @@ Packet: '%s'\n"),
cached_reg.num = reg->regnum;
cached_reg.data = (gdb_byte *)
- xmalloc (register_size (gdbarch, reg->regnum));
+ xmalloc (register_size (event->arch, reg->regnum));
p = p1 + 1;
fieldsize = hex2bin (p, cached_reg.data,
- register_size (gdbarch, reg->regnum));
+ register_size (event->arch, reg->regnum));
p += 2 * fieldsize;
- if (fieldsize < register_size (gdbarch, reg->regnum))
+ if (fieldsize < register_size (event->arch, reg->regnum))
warning (_("Remote reply is too short: %s"), buf);
VEC_safe_push (cached_reg_t, event->regcache, &cached_reg);
@@ -7248,7 +7291,7 @@ process_stop_reply (struct stop_reply *stop_reply,
if (stop_reply->regcache)
{
struct regcache *regcache
- = get_thread_arch_regcache (ptid, target_gdbarch ());
+ = get_thread_arch_regcache (ptid, stop_reply->arch);
cached_reg_t *reg;
int ix;
@@ -7605,7 +7648,7 @@ process_g_packet (struct regcache *regcache)
{
struct gdbarch *gdbarch = get_regcache_arch (regcache);
struct remote_state *rs = get_remote_state ();
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ remote_arch_state *rsa = get_remote_arch_state (gdbarch);
int i, buf_len;
char *p;
char *regs;
@@ -7739,7 +7782,8 @@ static void
remote_fetch_registers (struct target_ops *ops,
struct regcache *regcache, int regnum)
{
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ struct gdbarch *gdbarch = get_regcache_arch (regcache);
+ remote_arch_state *rsa = get_remote_arch_state (gdbarch);
int i;
set_remote_traceframe ();
@@ -7747,7 +7791,7 @@ remote_fetch_registers (struct target_ops *ops,
if (regnum >= 0)
{
- struct packet_reg *reg = packet_reg_from_regnum (rsa, regnum);
+ packet_reg *reg = packet_reg_from_regnum (gdbarch, rsa, regnum);
gdb_assert (reg != NULL);
@@ -7773,7 +7817,7 @@ remote_fetch_registers (struct target_ops *ops,
fetch_registers_using_g (regcache);
- for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
+ for (i = 0; i < gdbarch_num_regs (gdbarch); i++)
if (!rsa->regs[i].in_g_packet)
if (!fetch_register_using_p (regcache, &rsa->regs[i]))
{
@@ -7789,7 +7833,7 @@ remote_fetch_registers (struct target_ops *ops,
static void
remote_prepare_to_store (struct target_ops *self, struct regcache *regcache)
{
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ remote_arch_state *rsa = get_remote_arch_state (regcache->arch ());
int i;
/* Make sure the entire registers array is valid. */
@@ -7855,7 +7899,7 @@ static void
store_registers_using_G (const struct regcache *regcache)
{
struct remote_state *rs = get_remote_state ();
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ remote_arch_state *rsa = get_remote_arch_state (regcache->arch ());
gdb_byte *regs;
char *p;
@@ -7894,7 +7938,8 @@ static void
remote_store_registers (struct target_ops *ops,
struct regcache *regcache, int regnum)
{
- struct remote_arch_state *rsa = get_remote_arch_state ();
+ struct gdbarch *gdbarch = regcache->arch ();
+ remote_arch_state *rsa = get_remote_arch_state (gdbarch);
int i;
set_remote_traceframe ();
@@ -7902,7 +7947,7 @@ remote_store_registers (struct target_ops *ops,
if (regnum >= 0)
{
- struct packet_reg *reg = packet_reg_from_regnum (rsa, regnum);
+ packet_reg *reg = packet_reg_from_regnum (gdbarch, rsa, regnum);
gdb_assert (reg != NULL);
@@ -7926,7 +7971,7 @@ remote_store_registers (struct target_ops *ops,
store_registers_using_G (regcache);
- for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
+ for (i = 0; i < gdbarch_num_regs (gdbarch); i++)
if (!rsa->regs[i].in_g_packet)
if (!store_register_using_P (regcache, &rsa->regs[i]))
/* See above for why we do not issue an error here. */
@@ -12653,7 +12698,8 @@ remote_get_trace_status (struct target_ops *self, struct trace_status *ts)
if (packet_support (PACKET_qTStatus) == PACKET_DISABLE)
return -1;
- trace_regblock_size = get_remote_arch_state ()->sizeof_g_packet;
+ trace_regblock_size
+ = get_remote_arch_state (target_gdbarch ())->sizeof_g_packet;
putpkt ("qTStatus");
diff --git a/gdb/spu-multiarch.c b/gdb/spu-multiarch.c
index a935a72..e521c7e 100644
--- a/gdb/spu-multiarch.c
+++ b/gdb/spu-multiarch.c
@@ -121,7 +121,8 @@ spu_thread_architecture (struct target_ops *ops, ptid_t ptid)
if (parse_spufs_run (ptid, &spufs_fd, &spufs_addr))
return spu_gdbarch (spufs_fd);
- return target_gdbarch ();
+ target_ops *beneath = find_target_beneath (ops);
+ return beneath->to_thread_architecture (beneath, ptid);
}
/* Override the to_region_ok_for_hw_watchpoint routine. */
diff --git a/gdb/target.c b/gdb/target.c
index aded0ba..f2dccd2 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -3137,7 +3137,9 @@ default_watchpoint_addr_within_range (struct target_ops *target,
static struct gdbarch *
default_thread_architecture (struct target_ops *ops, ptid_t ptid)
{
- return target_gdbarch ();
+ inferior *inf = find_inferior_ptid (ptid);
+ gdb_assert (inf != NULL);
+ return inf->gdbarch;
}
static int
diff --git a/gdb/testsuite/gdb.multi/hangout.c b/gdb/testsuite/gdb.multi/hangout.c
index 44dfba6..7266a18 100644
--- a/gdb/testsuite/gdb.multi/hangout.c
+++ b/gdb/testsuite/gdb.multi/hangout.c
@@ -16,14 +16,28 @@
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <stdio.h>
+#include <unistd.h>
+
+static void
+hangout_loop (void)
+{
+}
int
main(int argc, char *argv[])
{
int i;
+ alarm (30);
+
for (i = 0; i < argc; ++i)
{
printf("Arg %d is %s\n", i, argv[i]);
}
+
+ while (1)
+ {
+ hangout_loop ();
+ usleep (20);
+ }
}
diff --git a/gdb/testsuite/gdb.multi/hello.c b/gdb/testsuite/gdb.multi/hello.c
index 2c5bee9..7cc5f3c 100644
--- a/gdb/testsuite/gdb.multi/hello.c
+++ b/gdb/testsuite/gdb.multi/hello.c
@@ -16,6 +16,7 @@
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <stdlib.h>
+#include <unistd.h>
short hglob = 1;
@@ -37,15 +38,27 @@ hello(int x)
return x + 45;
}
+static void
+hello_loop (void)
+{
+}
+
int
main()
{
int tmpx;
+ alarm (30);
+
bar();
tmpx = hello(glob);
commonfun();
glob = tmpx;
commonfun();
-}
+ while (1)
+ {
+ hello_loop ();
+ usleep (20);
+ }
+}
diff --git a/gdb/testsuite/gdb.multi/multi-arch.exp b/gdb/testsuite/gdb.multi/multi-arch.exp
index d73b4f7..733afa0 100644
--- a/gdb/testsuite/gdb.multi/multi-arch.exp
+++ b/gdb/testsuite/gdb.multi/multi-arch.exp
@@ -96,3 +96,27 @@ if ![runto_main] then {
gdb_test "info inferiors" \
"Executable.*${exec1}.*${exec2}.*"
+
+# Now select inferior 2, and trigger an event in inferior 1. This
+# tries to check that GDB doesn't incorrectly uses the architecture of
+# inferior 2 when parsing the expedited registers in a stop reply for
+# inferior 1 (when remote debugging).
+
+gdb_test_no_output "set schedule-multiple on"
+
+with_test_prefix "inf1 event with inf2 selected" {
+ gdb_test "inferior 2" "Switching to inferior 2.*thread 2\.1.*main.*${srcfile2}.*"
+ gdb_test "b hello_loop" "Breakpoint .* at .*${srcfile1}.*"
+ gdb_test "c" " hello_loop.*" "continue to hello_loop"
+}
+
+delete_breakpoints
+
+# Same, but the other way around: select inferior 1 and trigger an
+# event in inferior 2.
+
+with_test_prefix "inf2 event with inf1 selected" {
+ gdb_test "inferior 1" "Switching to inferior 1.*thread 1\.1.*hello_loop.*${srcfile1}.*"
+ gdb_test "b hangout_loop" "Breakpoint .* at .*${srcfile2}.*"
+ gdb_test "c" " hangout_loop.*" "continue to hangout_loop"
+}
--
2.5.5