From 935f0c5cc28a3a2cc627ff25b30d65d8d82ad8c4 Mon Sep 17 00:00:00 2001 From: Matthias Welwarsky Date: Mon, 5 Mar 2018 14:50:51 +0100 Subject: [PATCH] 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 Reviewed-on: http://openocd.zylin.com/4448 Tested-by: jenkins Reviewed-by: Matthias Welwarsky --- src/server/gdb_server.c | 40 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 38 insertions(+), 2 deletions(-) diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c index 712c3934..74074a1f 100644 --- a/src/server/gdb_server.c +++ b/src/server/gdb_server.c @@ -2695,6 +2695,8 @@ static bool gdb_handle_vcont_packet(struct connection *connection, const char *p /* single-step or step-over-breakpoint */ if (parse[0] == 's') { + bool fake_step = false; + if (strncmp(parse, "s:", 2) == 0) { struct target *ct = target; int current_pc = 1; @@ -2710,9 +2712,20 @@ static bool gdb_handle_vcont_packet(struct connection *connection, const char *p 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); + /* + * 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] == ';') { ++parse; --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); 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 */ if (gdb_connection->sync) { gdb_connection->sync = false; -- 2.39.5