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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /samples/user_events/example.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'samples/user_events/example.c')
-rw-r--r--samples/user_events/example.c102
1 files changed, 102 insertions, 0 deletions
diff --git a/samples/user_events/example.c b/samples/user_events/example.c
new file mode 100644
index 000000000..d06dc2415
--- /dev/null
+++ b/samples/user_events/example.c
@@ -0,0 +1,102 @@
+// 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/debug/tracing/user_events_data";
+const char *status_file = "/sys/kernel/debug/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, &reg) == -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;
+}