mirror of https://gitee.com/openkylin/linux.git
79 lines
1.7 KiB
C
79 lines
1.7 KiB
C
#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdbool.h>
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#include <sys/vfs.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/mount.h>
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#include <linux/kernel.h>
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#include "tracefs.h"
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#ifndef TRACEFS_DEFAULT_PATH
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#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
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#endif
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char tracefs_mountpoint[PATH_MAX + 1] = TRACEFS_DEFAULT_PATH;
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static const char * const tracefs_known_mountpoints[] = {
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TRACEFS_DEFAULT_PATH,
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"/sys/kernel/debug/tracing",
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"/tracing",
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"/trace",
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0,
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};
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static bool tracefs_found;
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bool tracefs_configured(void)
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{
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return tracefs_find_mountpoint() != NULL;
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}
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/* find the path to the mounted tracefs */
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const char *tracefs_find_mountpoint(void)
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{
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const char *ret;
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if (tracefs_found)
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return (const char *)tracefs_mountpoint;
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ret = find_mountpoint("tracefs", (long) TRACEFS_MAGIC,
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tracefs_mountpoint, PATH_MAX + 1,
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tracefs_known_mountpoints);
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if (ret)
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tracefs_found = true;
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return ret;
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}
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/* mount the tracefs somewhere if it's not mounted */
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char *tracefs_mount(const char *mountpoint)
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{
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/* see if it's already mounted */
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if (tracefs_find_mountpoint())
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goto out;
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/* if not mounted and no argument */
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if (mountpoint == NULL) {
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/* see if environment variable set */
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mountpoint = getenv(PERF_TRACEFS_ENVIRONMENT);
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/* if no environment variable, use default */
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if (mountpoint == NULL)
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mountpoint = TRACEFS_DEFAULT_PATH;
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}
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if (mount(NULL, mountpoint, "tracefs", 0, NULL) < 0)
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return NULL;
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/* save the mountpoint */
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tracefs_found = true;
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strncpy(tracefs_mountpoint, mountpoint, sizeof(tracefs_mountpoint));
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out:
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return tracefs_mountpoint;
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}
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