cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

ftrace.c (2533B)

      1/*
      2 * Ftrace trace backend
      3 *
      4 * Copyright (C) 2013 Hitachi, Ltd.
      5 * Created by Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
      6 *
      7 * This work is licensed under the terms of the GNU GPL, version 2.  See
      8 * the COPYING file in the top-level directory.
      9 *
     10 */
     11
     12#include "qemu/osdep.h"
     13#include "trace/control.h"
     14#include "trace/ftrace.h"
     15
     16int trace_marker_fd;
     17
     18static int find_mount(char *mount_point, const char *fstype)
     19{
     20    char type[100];
     21    FILE *fp;
     22    int ret = 0;
     23
     24    fp = fopen("/proc/mounts", "r");
     25    if (fp == NULL) {
     26        return 0;
     27    }
     28
     29    while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
     30                  mount_point, type) == 2) {
     31        if (strcmp(type, fstype) == 0) {
     32            ret = 1;
     33            break;
     34        }
     35    }
     36    fclose(fp);
     37
     38    return ret;
     39}
     40
     41bool ftrace_init(void)
     42{
     43    char mount_point[PATH_MAX];
     44    char path[PATH_MAX];
     45    int tracefs_found;
     46    int trace_fd = -1;
     47    const char *subdir = "";
     48
     49    tracefs_found = find_mount(mount_point, "tracefs");
     50    if (!tracefs_found) {
     51        tracefs_found = find_mount(mount_point, "debugfs");
     52        subdir = "/tracing";
     53    }
     54
     55    if (tracefs_found) {
     56        if (snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdir)
     57                >= sizeof(path)) {
     58            fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n");
     59            return false;
     60        }
     61        trace_fd = open(path, O_WRONLY);
     62        if (trace_fd < 0) {
     63            if (errno == EACCES) {
     64                trace_marker_fd = open("/dev/null", O_WRONLY);
     65                if (trace_marker_fd != -1) {
     66                    return true;
     67                }
     68            }
     69            perror("Could not open ftrace 'tracing_on' file");
     70            return false;
     71        } else {
     72            if (write(trace_fd, "1", 1) < 0) {
     73                perror("Could not write to 'tracing_on' file");
     74                close(trace_fd);
     75                return false;
     76            }
     77            close(trace_fd);
     78        }
     79        if (snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, subdir)
     80                >= sizeof(path)) {
     81            fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n");
     82            return false;
     83        }
     84        trace_marker_fd = open(path, O_WRONLY);
     85        if (trace_marker_fd < 0) {
     86            perror("Could not open ftrace 'trace_marker' file");
     87            return false;
     88        }
     89    } else {
     90        fprintf(stderr, "tracefs is not mounted\n");
     91        return false;
     92    }
     93
     94    return true;
     95}