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gdb_server: fake step if thread is not current rtos thread 

gdb assumes that a rtos can make any thread active at will in response
to a 'Hg' packet. It further assumes that it needs to step-over after
setting a breakpoint on frame #0 of any non-current thread. Both
assumptions are not valid for an actual rtos. We fake the step-over to
not trigger an internal error in gdb. See
https://sourceware.org/bugzilla/show_bug.cgi?id=22925 for details.

Change-Id: Ida60cd134033c1d58ada77b87fe664a58f61e2c0
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>
Reviewed-on: http://openocd.zylin.com/4448
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>
riscv-compliance-dev
Matthias Welwarsky 2018-03-05 14:50:51 +01:00 committed by Matthias Welwarsky
parent cbf7889873
commit 935f0c5cc2
1 changed files with 38 additions and 2 deletions
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40
src/server/gdb_server.c
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@ -2695,6 +2695,8 @@ static bool gdb_handle_vcont_packet(struct connection *connection, const char *p
/* single-step or step-over-breakpoint */ /* single-step or step-over-breakpoint */
if (parse[0] == 's') { if (parse[0] == 's') {
bool fake_step = false;
if (strncmp(parse, "s:", 2) == 0) { if (strncmp(parse, "s:", 2) == 0) {
struct target *ct = target; struct target *ct = target;
int current_pc = 1; int current_pc = 1;
@ -2710,9 +2712,20 @@ static bool gdb_handle_vcont_packet(struct connection *connection, const char *p
parse = endp; parse = endp;
} }
if (target->rtos != NULL) if (target->rtos != NULL) {
/* FIXME: why is this necessary? rtos state should be up-to-date here already! */
rtos_update_threads(target);
target->rtos->gdb_target_for_threadid(connection, thread_id, &ct); target->rtos->gdb_target_for_threadid(connection, thread_id, &ct);
/*
* check if the thread to be stepped is the current rtos thread
* if not, we must fake the step
*/
if (target->rtos->current_thread != thread_id)
fake_step = true;
}
if (parse[0] == ';') { if (parse[0] == ';') {
++parse; ++parse;
--packet_size; --packet_size;
@ -2746,10 +2759,33 @@ static bool gdb_handle_vcont_packet(struct connection *connection, const char *p
} }
} }
LOG_DEBUG("target %s single-step thread %"PRId64, target_name(ct), thread_id); LOG_DEBUG("target %s single-step thread %"PRIx64, target_name(ct), thread_id);
log_add_callback(gdb_log_callback, connection); log_add_callback(gdb_log_callback, connection);
target_call_event_callbacks(ct, TARGET_EVENT_GDB_START); target_call_event_callbacks(ct, TARGET_EVENT_GDB_START);
/*
* work around an annoying gdb behaviour: when the current thread
* is changed in gdb, it assumes that the target can follow and also
* make the thread current. This is an assumption that cannot hold
* for a real target running a multi-threading OS. We just fake
* the step to not trigger an internal error in gdb. See
* https://sourceware.org/bugzilla/show_bug.cgi?id=22925 for details
*/
if (fake_step) {
int sig_reply_len;
char sig_reply[128];
LOG_DEBUG("fake step thread %"PRIx64, thread_id);
sig_reply_len = snprintf(sig_reply, sizeof(sig_reply),
"T05thread:%016"PRIx64";", thread_id);
gdb_put_packet(connection, sig_reply, sig_reply_len);
log_remove_callback(gdb_log_callback, connection);
return true;
}
/* support for gdb_sync command */ /* support for gdb_sync command */
if (gdb_connection->sync) { if (gdb_connection->sync) {
gdb_connection->sync = false; gdb_connection->sync = false;