06da0f77c2
When installing a fast tracepoint, we create a jump pad with a spin-lock. This way, only one thread can collect a given tracepoint at any time. This test case checks that this lock actually works as expected. This test works by creating a function which overrides the in-process agent library's gdb_collect function. On start up, GDBserver will ask GDB with the 'qSymbol' packet about symbols present in the inferior. GDB will reply with the gdb_agent_gdb_collect function from the test case instead of the one from the agent. gdb/testsuite/ChangeLog: * gdb.trace/ftrace-lock.c: New file. * gdb.trace/ftrace-lock.exp: New file.
106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
/* This testcase is part of GDB, the GNU debugger.
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Copyright 2015 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <pthread.h>
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#ifdef SYMBOL_PREFIX
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#define SYMBOL(str) SYMBOL_PREFIX #str
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#else
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#define SYMBOL(str) #str
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#endif
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/* Called if the testcase failed. */
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static void
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fail (void)
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{
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}
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static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
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/* This function overrides gdb_collect in the in-process agent library.
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See gdbserver/tracepoint.c (gdb_collect). We want this function to
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be ran instead of the one from the library to easily check that only
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one thread is tracing at a time.
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This works as expected because GDBserver will ask GDB about symbols
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present in the inferior with the 'qSymbol' packet. And GDB will
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reply with the address of this function instead of the one from the
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in-process agent library. */
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void
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gdb_agent_gdb_collect (void *tpoint, unsigned char *regs)
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{
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/* If we cannot acquire a lock, then this means another thread is
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tracing and the lock implemented by the jump pad is not working! */
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if (pthread_mutex_trylock (&mutex) != 0)
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{
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fail ();
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return;
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}
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sleep (1);
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if (pthread_mutex_unlock (&mutex) != 0)
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{
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fail ();
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return;
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}
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}
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/* Called from asm. */
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static void __attribute__((used))
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func (void)
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{
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}
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static void *
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thread_function (void *arg)
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{
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/* `set_point' is the label at which to set a fast tracepoint. The
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insn at the label must be large enough to fit a fast tracepoint
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jump. */
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asm (" .global " SYMBOL (set_point) "\n"
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SYMBOL (set_point) ":\n"
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#if (defined __x86_64__ || defined __i386__)
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" call " SYMBOL (func) "\n"
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#elif (defined __aarch64__)
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" nop\n"
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#endif
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);
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}
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static void
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end (void)
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{
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}
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int
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main (int argc, char *argv[], char *envp[])
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{
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pthread_t threads[NUM_THREADS];
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int i;
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for (i = 0; i < NUM_THREADS; i++)
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pthread_create (&threads[i], NULL, thread_function, NULL);
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for (i = 0; i < NUM_THREADS; i++)
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pthread_join (threads[i], NULL);
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end ();
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return 0;
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}
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