Either accept() fails or exits normally, we need to close the fd. Reported-by: Euler Robot <euler.robot@huawei.com> Signed-off-by: Alex Chen <alex.chen@huawei.com> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Message-Id: <20201109082829.87496-3-alex.chen@huawei.com> Message-Id: <20201110192316.26397-3-alex.bennee@linaro.org>
344 lines
9.3 KiB
C
344 lines
9.3 KiB
C
/*
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* Lockstep Execution Plugin
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*
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* Allows you to execute two QEMU instances in lockstep and report
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* when their execution diverges. This is mainly useful for developers
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* who want to see where a change to TCG code generation has
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* introduced a subtle and hard to find bug.
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*
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* Caveats:
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* - single-threaded linux-user apps only with non-deterministic syscalls
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* - no MTTCG enabled system emulation (icount may help)
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*
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* While icount makes things more deterministic it doesn't mean a
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* particular run may execute the exact same sequence of blocks. An
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* asynchronous event (for example X11 graphics update) may cause a
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* block to end early and a new partial block to start. This means
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* serial only test cases are a better bet. -d nochain may also help.
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*
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* This code is not thread safe!
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*
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* Copyright (c) 2020 Linaro Ltd
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include <glib.h>
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#include <inttypes.h>
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#include <unistd.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <stdio.h>
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#include <errno.h>
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#include <qemu-plugin.h>
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QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
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/* saved so we can uninstall later */
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static qemu_plugin_id_t our_id;
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static unsigned long bb_count;
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static unsigned long insn_count;
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/* Information about a translated block */
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typedef struct {
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uint64_t pc;
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uint64_t insns;
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} BlockInfo;
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/* Information about an execution state in the log */
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typedef struct {
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BlockInfo *block;
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unsigned long insn_count;
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unsigned long block_count;
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} ExecInfo;
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/* The execution state we compare */
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typedef struct {
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uint64_t pc;
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unsigned long insn_count;
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} ExecState;
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typedef struct {
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GSList *log_pos;
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int distance;
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} DivergeState;
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/* list of translated block info */
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static GSList *blocks;
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/* execution log and points of divergence */
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static GSList *log, *divergence_log;
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static int socket_fd;
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static char *path_to_unlink;
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static bool verbose;
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static void plugin_cleanup(qemu_plugin_id_t id)
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{
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/* Free our block data */
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g_slist_free_full(blocks, &g_free);
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g_slist_free_full(log, &g_free);
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g_slist_free(divergence_log);
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close(socket_fd);
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if (path_to_unlink) {
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unlink(path_to_unlink);
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}
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}
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static void plugin_exit(qemu_plugin_id_t id, void *p)
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{
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g_autoptr(GString) out = g_string_new("No divergence :-)\n");
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g_string_append_printf(out, "Executed %ld/%d blocks\n",
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bb_count, g_slist_length(log));
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g_string_append_printf(out, "Executed ~%ld instructions\n", insn_count);
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qemu_plugin_outs(out->str);
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plugin_cleanup(id);
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}
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static void report_divergance(ExecState *us, ExecState *them)
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{
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DivergeState divrec = { log, 0 };
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g_autoptr(GString) out = g_string_new("");
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bool diverged = false;
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/*
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* If we have diverged before did we get back on track or are we
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* totally loosing it?
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*/
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if (divergence_log) {
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DivergeState *last = (DivergeState *) divergence_log->data;
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GSList *entry;
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for (entry = log; g_slist_next(entry); entry = g_slist_next(entry)) {
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if (entry == last->log_pos) {
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break;
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}
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divrec.distance++;
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}
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/*
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* If the last two records are so close it is likely we will
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* not recover synchronisation with the other end.
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*/
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if (divrec.distance == 1 && last->distance == 1) {
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diverged = true;
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}
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}
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divergence_log = g_slist_prepend(divergence_log,
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g_memdup(&divrec, sizeof(divrec)));
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/* Output short log entry of going out of sync... */
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if (verbose || divrec.distance == 1 || diverged) {
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g_string_printf(out, "@ %#016lx vs %#016lx (%d/%d since last)\n",
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us->pc, them->pc, g_slist_length(divergence_log),
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divrec.distance);
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qemu_plugin_outs(out->str);
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}
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if (diverged) {
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int i;
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GSList *entry;
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g_string_printf(out, "Δ insn_count @ %#016lx (%ld) vs %#016lx (%ld)\n",
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us->pc, us->insn_count, them->pc, them->insn_count);
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for (entry = log, i = 0;
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g_slist_next(entry) && i < 5;
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entry = g_slist_next(entry), i++) {
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ExecInfo *prev = (ExecInfo *) entry->data;
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g_string_append_printf(out,
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" previously @ %#016lx/%ld (%ld insns)\n",
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prev->block->pc, prev->block->insns,
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prev->insn_count);
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}
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qemu_plugin_outs(out->str);
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qemu_plugin_outs("too much divergence... giving up.");
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qemu_plugin_uninstall(our_id, plugin_cleanup);
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}
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}
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static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
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{
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BlockInfo *bi = (BlockInfo *) udata;
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ExecState us, them;
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ssize_t bytes;
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ExecInfo *exec;
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us.pc = bi->pc;
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us.insn_count = insn_count;
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/*
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* Write our current position to the other end. If we fail the
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* other end has probably died and we should shut down gracefully.
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*/
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bytes = write(socket_fd, &us, sizeof(ExecState));
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if (bytes < sizeof(ExecState)) {
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qemu_plugin_outs(bytes < 0 ?
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"problem writing to socket" :
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"wrote less than expected to socket");
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qemu_plugin_uninstall(our_id, plugin_cleanup);
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return;
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}
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/*
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* Now read where our peer has reached. Again a failure probably
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* indicates the other end died and we should close down cleanly.
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*/
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bytes = read(socket_fd, &them, sizeof(ExecState));
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if (bytes < sizeof(ExecState)) {
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qemu_plugin_outs(bytes < 0 ?
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"problem reading from socket" :
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"read less than expected");
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qemu_plugin_uninstall(our_id, plugin_cleanup);
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return;
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}
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/*
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* Compare and report if we have diverged.
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*/
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if (us.pc != them.pc) {
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report_divergance(&us, &them);
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}
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/*
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* Assume this block will execute fully and record it
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* in the execution log.
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*/
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insn_count += bi->insns;
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bb_count++;
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exec = g_new0(ExecInfo, 1);
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exec->block = bi;
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exec->insn_count = insn_count;
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exec->block_count = bb_count;
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log = g_slist_prepend(log, exec);
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}
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static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
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{
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BlockInfo *bi = g_new0(BlockInfo, 1);
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bi->pc = qemu_plugin_tb_vaddr(tb);
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bi->insns = qemu_plugin_tb_n_insns(tb);
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/* save a reference so we can free later */
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blocks = g_slist_prepend(blocks, bi);
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qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
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QEMU_PLUGIN_CB_NO_REGS, (void *)bi);
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}
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/*
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* Instead of encoding master/slave status into what is essentially
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* two peers we shall just take the simple approach of checking for
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* the existence of the pipe and assuming if it's not there we are the
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* first process.
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*/
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static bool setup_socket(const char *path)
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{
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struct sockaddr_un sockaddr;
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int fd;
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fd = socket(AF_UNIX, SOCK_STREAM, 0);
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if (fd < 0) {
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perror("create socket");
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return false;
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}
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sockaddr.sun_family = AF_UNIX;
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g_strlcpy(sockaddr.sun_path, path, sizeof(sockaddr.sun_path) - 1);
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if (bind(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr)) < 0) {
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perror("bind socket");
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close(fd);
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return false;
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}
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/* remember to clean-up */
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path_to_unlink = g_strdup(path);
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if (listen(fd, 1) < 0) {
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perror("listen socket");
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close(fd);
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return false;
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}
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socket_fd = accept(fd, NULL, NULL);
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if (socket_fd < 0 && errno != EINTR) {
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perror("accept socket");
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close(fd);
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return false;
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}
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qemu_plugin_outs("setup_socket::ready\n");
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close(fd);
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return true;
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}
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static bool connect_socket(const char *path)
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{
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int fd;
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struct sockaddr_un sockaddr;
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fd = socket(AF_UNIX, SOCK_STREAM, 0);
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if (fd < 0) {
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perror("create socket");
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return false;
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}
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sockaddr.sun_family = AF_UNIX;
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g_strlcpy(sockaddr.sun_path, path, sizeof(sockaddr.sun_path) - 1);
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if (connect(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr)) < 0) {
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perror("failed to connect");
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close(fd);
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return false;
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}
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qemu_plugin_outs("connect_socket::ready\n");
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socket_fd = fd;
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return true;
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}
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static bool setup_unix_socket(const char *path)
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{
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if (g_file_test(path, G_FILE_TEST_EXISTS)) {
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return connect_socket(path);
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} else {
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return setup_socket(path);
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}
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}
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QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
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const qemu_info_t *info,
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int argc, char **argv)
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{
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int i;
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if (!argc || !argv[0]) {
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qemu_plugin_outs("Need a socket path to talk to other instance.");
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return -1;
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}
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for (i = 0; i < argc; i++) {
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char *p = argv[i];
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if (strcmp(p, "verbose") == 0) {
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verbose = true;
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} else if (!setup_unix_socket(argv[0])) {
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qemu_plugin_outs("Failed to setup socket for communications.");
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return -1;
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}
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}
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our_id = id;
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qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
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qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
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return 0;
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}
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