/* This testcase is part of GDB, the GNU debugger. Copyright 2015 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ #include #ifdef SYMBOL_PREFIX #define SYMBOL(str) SYMBOL_PREFIX #str #else #define SYMBOL(str) #str #endif /* Called if the testcase failed. */ static void fail (void) { } static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /* This function overrides gdb_collect in the in-process agent library. See gdbserver/tracepoint.c (gdb_collect). We want this function to be ran instead of the one from the library to easily check that only one thread is tracing at a time. This works as expected because GDBserver will ask GDB about symbols present in the inferior with the 'qSymbol' packet. And GDB will reply with the address of this function instead of the one from the in-process agent library. */ void gdb_agent_gdb_collect (void *tpoint, unsigned char *regs) { /* If we cannot acquire a lock, then this means another thread is tracing and the lock implemented by the jump pad is not working! */ if (pthread_mutex_trylock (&mutex) != 0) { fail (); return; } sleep (1); if (pthread_mutex_unlock (&mutex) != 0) { fail (); return; } } /* Called from asm. */ static void __attribute__((used)) func (void) { } static void * thread_function (void *arg) { /* `set_point' is the label at which to set a fast tracepoint. The insn at the label must be large enough to fit a fast tracepoint jump. */ asm (" .global " SYMBOL (set_point) "\n" SYMBOL (set_point) ":\n" #if (defined __x86_64__ || defined __i386__) " call " SYMBOL (func) "\n" #elif (defined __aarch64__) " nop\n" #endif ); } static void end (void) { } int main (int argc, char *argv[], char *envp[]) { pthread_t threads[NUM_THREADS]; int i; for (i = 0; i < NUM_THREADS; i++) pthread_create (&threads[i], NULL, thread_function, NULL); for (i = 0; i < NUM_THREADS; i++) pthread_join (threads[i], NULL); end (); return 0; }