qemu/util/log.c
Josh Kunz 4b25a50674 linux-user: Use `qemu_log' for strace
This change switches linux-user strace logging to use the newer `qemu_log`
logging subsystem rather than the older `gemu_log` (notice the "g")
logger. `qemu_log` has several advantages, namely that it allows logging
to a file, and provides a more unified interface for configuration
of logging (via the QEMU_LOG environment variable or options).

This change introduces a new log mask: `LOG_STRACE` which is used for
logging of user-mode strace messages.

Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Josh Kunz <jkz@google.com>
Message-Id: <20200204025416.111409-3-jkz@google.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2020-02-19 11:17:40 +01:00

390 lines
11 KiB
C

/*
* Logging support
*
* Copyright (c) 2003 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/range.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "qemu/cutils.h"
#include "trace/control.h"
#include "qemu/thread.h"
static char *logfilename;
static QemuMutex qemu_logfile_mutex;
QemuLogFile *qemu_logfile;
int qemu_loglevel;
static int log_append = 0;
static GArray *debug_regions;
/* Return the number of characters emitted. */
int qemu_log(const char *fmt, ...)
{
int ret = 0;
QemuLogFile *logfile;
rcu_read_lock();
logfile = atomic_rcu_read(&qemu_logfile);
if (logfile) {
va_list ap;
va_start(ap, fmt);
ret = vfprintf(logfile->fd, fmt, ap);
va_end(ap);
/* Don't pass back error results. */
if (ret < 0) {
ret = 0;
}
}
rcu_read_unlock();
return ret;
}
static void __attribute__((__constructor__)) qemu_logfile_init(void)
{
qemu_mutex_init(&qemu_logfile_mutex);
}
static void qemu_logfile_free(QemuLogFile *logfile)
{
g_assert(logfile);
if (logfile->fd != stderr) {
fclose(logfile->fd);
}
g_free(logfile);
}
static bool log_uses_own_buffers;
/* enable or disable low levels log */
void qemu_set_log(int log_flags)
{
bool need_to_open_file = false;
QemuLogFile *logfile;
qemu_loglevel = log_flags;
#ifdef CONFIG_TRACE_LOG
qemu_loglevel |= LOG_TRACE;
#endif
/*
* In all cases we only log if qemu_loglevel is set.
* Also:
* If not daemonized we will always log either to stderr
* or to a file (if there is a logfilename).
* If we are daemonized,
* we will only log if there is a logfilename.
*/
if (qemu_loglevel && (!is_daemonized() || logfilename)) {
need_to_open_file = true;
}
qemu_mutex_lock(&qemu_logfile_mutex);
if (qemu_logfile && !need_to_open_file) {
logfile = qemu_logfile;
atomic_rcu_set(&qemu_logfile, NULL);
call_rcu(logfile, qemu_logfile_free, rcu);
} else if (!qemu_logfile && need_to_open_file) {
logfile = g_new0(QemuLogFile, 1);
if (logfilename) {
logfile->fd = fopen(logfilename, log_append ? "a" : "w");
if (!logfile->fd) {
g_free(logfile);
perror(logfilename);
_exit(1);
}
/* In case we are a daemon redirect stderr to logfile */
if (is_daemonized()) {
dup2(fileno(logfile->fd), STDERR_FILENO);
fclose(logfile->fd);
/* This will skip closing logfile in qemu_log_close() */
logfile->fd = stderr;
}
} else {
/* Default to stderr if no log file specified */
assert(!is_daemonized());
logfile->fd = stderr;
}
/* must avoid mmap() usage of glibc by setting a buffer "by hand" */
if (log_uses_own_buffers) {
static char logfile_buf[4096];
setvbuf(logfile->fd, logfile_buf, _IOLBF, sizeof(logfile_buf));
} else {
#if defined(_WIN32)
/* Win32 doesn't support line-buffering, so use unbuffered output. */
setvbuf(logfile->fd, NULL, _IONBF, 0);
#else
setvbuf(logfile->fd, NULL, _IOLBF, 0);
#endif
log_append = 1;
}
atomic_rcu_set(&qemu_logfile, logfile);
}
qemu_mutex_unlock(&qemu_logfile_mutex);
}
void qemu_log_needs_buffers(void)
{
log_uses_own_buffers = true;
}
/*
* Allow the user to include %d in their logfile which will be
* substituted with the current PID. This is useful for debugging many
* nested linux-user tasks but will result in lots of logs.
*
* filename may be NULL. In that case, log output is sent to stderr
*/
void qemu_set_log_filename(const char *filename, Error **errp)
{
g_free(logfilename);
logfilename = NULL;
if (filename) {
char *pidstr = strstr(filename, "%");
if (pidstr) {
/* We only accept one %d, no other format strings */
if (pidstr[1] != 'd' || strchr(pidstr + 2, '%')) {
error_setg(errp, "Bad logfile format: %s", filename);
return;
} else {
logfilename = g_strdup_printf(filename, getpid());
}
} else {
logfilename = g_strdup(filename);
}
}
qemu_log_close();
qemu_set_log(qemu_loglevel);
}
/* Returns true if addr is in our debug filter or no filter defined
*/
bool qemu_log_in_addr_range(uint64_t addr)
{
if (debug_regions) {
int i = 0;
for (i = 0; i < debug_regions->len; i++) {
Range *range = &g_array_index(debug_regions, Range, i);
if (range_contains(range, addr)) {
return true;
}
}
return false;
} else {
return true;
}
}
void qemu_set_dfilter_ranges(const char *filter_spec, Error **errp)
{
gchar **ranges = g_strsplit(filter_spec, ",", 0);
int i;
if (debug_regions) {
g_array_unref(debug_regions);
debug_regions = NULL;
}
debug_regions = g_array_sized_new(FALSE, FALSE,
sizeof(Range), g_strv_length(ranges));
for (i = 0; ranges[i]; i++) {
const char *r = ranges[i];
const char *range_op, *r2, *e;
uint64_t r1val, r2val, lob, upb;
struct Range range;
range_op = strstr(r, "-");
r2 = range_op ? range_op + 1 : NULL;
if (!range_op) {
range_op = strstr(r, "+");
r2 = range_op ? range_op + 1 : NULL;
}
if (!range_op) {
range_op = strstr(r, "..");
r2 = range_op ? range_op + 2 : NULL;
}
if (!range_op) {
error_setg(errp, "Bad range specifier");
goto out;
}
if (qemu_strtou64(r, &e, 0, &r1val)
|| e != range_op) {
error_setg(errp, "Invalid number to the left of %.*s",
(int)(r2 - range_op), range_op);
goto out;
}
if (qemu_strtou64(r2, NULL, 0, &r2val)) {
error_setg(errp, "Invalid number to the right of %.*s",
(int)(r2 - range_op), range_op);
goto out;
}
switch (*range_op) {
case '+':
lob = r1val;
upb = r1val + r2val - 1;
break;
case '-':
upb = r1val;
lob = r1val - (r2val - 1);
break;
case '.':
lob = r1val;
upb = r2val;
break;
default:
g_assert_not_reached();
}
if (lob > upb) {
error_setg(errp, "Invalid range");
goto out;
}
range_set_bounds(&range, lob, upb);
g_array_append_val(debug_regions, range);
}
out:
g_strfreev(ranges);
}
/* fflush() the log file */
void qemu_log_flush(void)
{
QemuLogFile *logfile;
rcu_read_lock();
logfile = atomic_rcu_read(&qemu_logfile);
if (logfile) {
fflush(logfile->fd);
}
rcu_read_unlock();
}
/* Close the log file */
void qemu_log_close(void)
{
QemuLogFile *logfile;
qemu_mutex_lock(&qemu_logfile_mutex);
logfile = qemu_logfile;
if (logfile) {
atomic_rcu_set(&qemu_logfile, NULL);
call_rcu(logfile, qemu_logfile_free, rcu);
}
qemu_mutex_unlock(&qemu_logfile_mutex);
}
const QEMULogItem qemu_log_items[] = {
{ CPU_LOG_TB_OUT_ASM, "out_asm",
"show generated host assembly code for each compiled TB" },
{ CPU_LOG_TB_IN_ASM, "in_asm",
"show target assembly code for each compiled TB" },
{ CPU_LOG_TB_OP, "op",
"show micro ops for each compiled TB" },
{ CPU_LOG_TB_OP_OPT, "op_opt",
"show micro ops after optimization" },
{ CPU_LOG_TB_OP_IND, "op_ind",
"show micro ops before indirect lowering" },
{ CPU_LOG_INT, "int",
"show interrupts/exceptions in short format" },
{ CPU_LOG_EXEC, "exec",
"show trace before each executed TB (lots of logs)" },
{ CPU_LOG_TB_CPU, "cpu",
"show CPU registers before entering a TB (lots of logs)" },
{ CPU_LOG_TB_FPU, "fpu",
"include FPU registers in the 'cpu' logging" },
{ CPU_LOG_MMU, "mmu",
"log MMU-related activities" },
{ CPU_LOG_PCALL, "pcall",
"x86 only: show protected mode far calls/returns/exceptions" },
{ CPU_LOG_RESET, "cpu_reset",
"show CPU state before CPU resets" },
{ LOG_UNIMP, "unimp",
"log unimplemented functionality" },
{ LOG_GUEST_ERROR, "guest_errors",
"log when the guest OS does something invalid (eg accessing a\n"
"non-existent register)" },
{ CPU_LOG_PAGE, "page",
"dump pages at beginning of user mode emulation" },
{ CPU_LOG_TB_NOCHAIN, "nochain",
"do not chain compiled TBs so that \"exec\" and \"cpu\" show\n"
"complete traces" },
#ifdef CONFIG_PLUGIN
{ CPU_LOG_PLUGIN, "plugin", "output from TCG plugins\n"},
#endif
{ LOG_STRACE, "strace",
"log every user-mode syscall, its input, and its result" },
{ 0, NULL, NULL },
};
/* takes a comma separated list of log masks. Return 0 if error. */
int qemu_str_to_log_mask(const char *str)
{
const QEMULogItem *item;
int mask = 0;
char **parts = g_strsplit(str, ",", 0);
char **tmp;
for (tmp = parts; tmp && *tmp; tmp++) {
if (g_str_equal(*tmp, "all")) {
for (item = qemu_log_items; item->mask != 0; item++) {
mask |= item->mask;
}
#ifdef CONFIG_TRACE_LOG
} else if (g_str_has_prefix(*tmp, "trace:") && (*tmp)[6] != '\0') {
trace_enable_events((*tmp) + 6);
mask |= LOG_TRACE;
#endif
} else {
for (item = qemu_log_items; item->mask != 0; item++) {
if (g_str_equal(*tmp, item->name)) {
goto found;
}
}
goto error;
found:
mask |= item->mask;
}
}
g_strfreev(parts);
return mask;
error:
g_strfreev(parts);
return 0;
}
void qemu_print_log_usage(FILE *f)
{
const QEMULogItem *item;
fprintf(f, "Log items (comma separated):\n");
for (item = qemu_log_items; item->mask != 0; item++) {
fprintf(f, "%-15s %s\n", item->name, item->help);
}
#ifdef CONFIG_TRACE_LOG
fprintf(f, "trace:PATTERN enable trace events\n");
fprintf(f, "\nUse \"-d trace:help\" to get a list of trace events.\n\n");
#endif
}