mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 17:30:02 +00:00
2455f0e124
The canonical location for the tracefs filesystem is at /sys/kernel/tracing. But, from Documentation/trace/ftrace.rst: Before 4.1, all ftrace tracing control files were within the debugfs file system, which is typically located at /sys/kernel/debug/tracing. For backward compatibility, when mounting the debugfs file system, the tracefs file system will be automatically mounted at: /sys/kernel/debug/tracing Many comments and Kconfig help messages in the tracing code still refer to this older debugfs path, so let's update them to avoid confusion. Link: https://lore.kernel.org/linux-trace-kernel/20230215223350.2658616-2-zwisler@google.com Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com> Signed-off-by: Ross Zwisler <zwisler@google.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
102 lines
2 KiB
C
102 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Copyright (c) 2021, Microsoft Corporation.
|
|
*
|
|
* Authors:
|
|
* Beau Belgrave <beaub@linux.microsoft.com>
|
|
*/
|
|
|
|
#include <errno.h>
|
|
#include <sys/ioctl.h>
|
|
#include <sys/mman.h>
|
|
#include <fcntl.h>
|
|
#include <stdio.h>
|
|
#include <unistd.h>
|
|
#include <asm/bitsperlong.h>
|
|
#include <endian.h>
|
|
#include <linux/user_events.h>
|
|
|
|
#if __BITS_PER_LONG == 64
|
|
#define endian_swap(x) htole64(x)
|
|
#else
|
|
#define endian_swap(x) htole32(x)
|
|
#endif
|
|
|
|
/* Assumes debugfs is mounted */
|
|
const char *data_file = "/sys/kernel/tracing/user_events_data";
|
|
const char *status_file = "/sys/kernel/tracing/user_events_status";
|
|
|
|
static int event_status(long **status)
|
|
{
|
|
int fd = open(status_file, O_RDONLY);
|
|
|
|
*status = mmap(NULL, sysconf(_SC_PAGESIZE), PROT_READ,
|
|
MAP_SHARED, fd, 0);
|
|
|
|
close(fd);
|
|
|
|
if (*status == MAP_FAILED)
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int event_reg(int fd, const char *command, long *index, long *mask,
|
|
int *write)
|
|
{
|
|
struct user_reg reg = {0};
|
|
|
|
reg.size = sizeof(reg);
|
|
reg.name_args = (__u64)command;
|
|
|
|
if (ioctl(fd, DIAG_IOCSREG, ®) == -1)
|
|
return -1;
|
|
|
|
*index = reg.status_bit / __BITS_PER_LONG;
|
|
*mask = endian_swap(1L << (reg.status_bit % __BITS_PER_LONG));
|
|
*write = reg.write_index;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
int data_fd, write;
|
|
long index, mask;
|
|
long *status_page;
|
|
struct iovec io[2];
|
|
__u32 count = 0;
|
|
|
|
if (event_status(&status_page) == -1)
|
|
return errno;
|
|
|
|
data_fd = open(data_file, O_RDWR);
|
|
|
|
if (event_reg(data_fd, "test u32 count", &index, &mask, &write) == -1)
|
|
return errno;
|
|
|
|
/* Setup iovec */
|
|
io[0].iov_base = &write;
|
|
io[0].iov_len = sizeof(write);
|
|
io[1].iov_base = &count;
|
|
io[1].iov_len = sizeof(count);
|
|
|
|
ask:
|
|
printf("Press enter to check status...\n");
|
|
getchar();
|
|
|
|
/* Check if anyone is listening */
|
|
if (status_page[index] & mask) {
|
|
/* Yep, trace out our data */
|
|
writev(data_fd, (const struct iovec *)io, 2);
|
|
|
|
/* Increase the count */
|
|
count++;
|
|
|
|
printf("Something was attached, wrote data\n");
|
|
}
|
|
|
|
goto ask;
|
|
|
|
return 0;
|
|
}
|