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tracing: Add new trace_marker_raw 

A new file is created:

 /sys/kernel/debug/tracing/trace_marker_raw

This allows for appications to create data structures and write the binary
data directly into it, and then read the trace data out from trace_pipe_raw
into the same type of data structure. This saves on converting numbers into
ASCII that would be required by trace_marker.

Suggested-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2016-07-06 15:25:08 -04:00
parent 9648dc1577
commit fa32e8557b
5 changed files with 187 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
Documentation/trace/ftrace.txt
View File

@ -396,6 +396,12 @@ of ftrace. Here is a list of some of the key files:
trace_fd = open("trace_marker", WR_ONLY);
trace_marker_raw:
This is similar to trace_marker above, but is meant for for binary data
to be written to it, where a tool can be used to parse the data
from trace_pipe_raw.
uprobe_events:
Add dynamic tracepoints in programs.

165
kernel/trace/trace.c
View File

@ -4054,6 +4054,7 @@ static const char readme_msg[] =
" x86-tsc: TSC cycle counter\n"
#endif
"\n trace_marker\t\t- Writes into this file writes into the kernel buffer\n"
"\n trace_marker_raw\t\t- Writes into this file writes binary data into the kernel buffer\n"
" tracing_cpumask\t- Limit which CPUs to trace\n"
" instances\t\t- Make sub-buffers with: mkdir instances/foo\n"
"\t\t\t Remove sub-buffer with rmdir\n"
@ -5514,35 +5515,15 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
return 0;
}
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
static inline int lock_user_pages(const char __user *ubuf, size_t cnt,
struct page **pages, void **map_page,
int *offset)
{
unsigned long addr = (unsigned long)ubuf;
struct trace_array *tr = filp->private_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
struct print_entry *entry;
unsigned long irq_flags;
struct page *pages[2];
void *map_page[2];
int nr_pages = 1;
ssize_t written;
int offset;
int size;
int len;
int ret;
int i;
if (tracing_disabled)
return -EINVAL;
if (!(tr->trace_flags & TRACE_ITER_MARKERS))
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;
/*
* Userspace is injecting traces into the kernel trace buffer.
* We want to be as non intrusive as possible.
@ -5557,26 +5538,70 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
* pages directly. We then write the data directly into the
* ring buffer.
*/
BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
/* check if we cross pages */
if ((addr & PAGE_MASK) != ((addr + cnt) & PAGE_MASK))
nr_pages = 2;
offset = addr & (PAGE_SIZE - 1);
*offset = addr & (PAGE_SIZE - 1);
addr &= PAGE_MASK;
ret = get_user_pages_fast(addr, nr_pages, 0, pages);
if (ret < nr_pages) {
while (--ret >= 0)
put_page(pages[ret]);
written = -EFAULT;
goto out;
return -EFAULT;
}
for (i = 0; i < nr_pages; i++)
map_page[i] = kmap_atomic(pages[i]);
return nr_pages;
}
static inline void unlock_user_pages(struct page **pages,
void **map_page, int nr_pages)
{
int i;
for (i = nr_pages - 1; i >= 0; i--) {
kunmap_atomic(map_page[i]);
put_page(pages[i]);
}
}
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
{
struct trace_array *tr = filp->private_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
struct print_entry *entry;
unsigned long irq_flags;
struct page *pages[2];
void *map_page[2];
int nr_pages = 1;
ssize_t written;
int offset;
int size;
int len;
if (tracing_disabled)
return -EINVAL;
if (!(tr->trace_flags & TRACE_ITER_MARKERS))
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;
BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
nr_pages = lock_user_pages(ubuf, cnt, pages, map_page, &offset);
if (nr_pages < 0)
return nr_pages;
local_save_flags(irq_flags);
size = sizeof(*entry) + cnt + 2; /* possible \n added */
buffer = tr->trace_buffer.buffer;
@ -5611,11 +5636,79 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
*fpos += written;
out_unlock:
for (i = nr_pages - 1; i >= 0; i--) {
kunmap_atomic(map_page[i]);
put_page(pages[i]);
unlock_user_pages(pages, map_page, nr_pages);
return written;
}
out:
/* Limit it for now to 3K (including tag) */
#define RAW_DATA_MAX_SIZE (1024*3)
static ssize_t
tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
{
struct trace_array *tr = filp->private_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
struct raw_data_entry *entry;
unsigned long irq_flags;
struct page *pages[2];
void *map_page[2];
int nr_pages = 1;
ssize_t written;
int offset;
int size;
int len;
if (tracing_disabled)
return -EINVAL;
if (!(tr->trace_flags & TRACE_ITER_MARKERS))
return -EINVAL;
/* The marker must at least have a tag id */
if (cnt < sizeof(unsigned int) || cnt > RAW_DATA_MAX_SIZE)
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;
BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE);
nr_pages = lock_user_pages(ubuf, cnt, pages, map_page, &offset);
if (nr_pages < 0)
return nr_pages;
local_save_flags(irq_flags);
size = sizeof(*entry) + cnt;
buffer = tr->trace_buffer.buffer;
event = trace_buffer_lock_reserve(buffer, TRACE_RAW_DATA, size,
irq_flags, preempt_count());
if (!event) {
/* Ring buffer disabled, return as if not open for write */
written = -EBADF;
goto out_unlock;
}
entry = ring_buffer_event_data(event);
if (nr_pages == 2) {
len = PAGE_SIZE - offset;
memcpy(&entry->id, map_page[0] + offset, len);
memcpy(((char *)&entry->id) + len, map_page[1], cnt - len);
} else
memcpy(&entry->id, map_page[0] + offset, cnt);
__buffer_unlock_commit(buffer, event);
written = cnt;
*fpos += written;
out_unlock:
unlock_user_pages(pages, map_page, nr_pages);
return written;
}
@ -5945,6 +6038,13 @@ static const struct file_operations tracing_mark_fops = {
.release = tracing_release_generic_tr,
};
static const struct file_operations tracing_mark_raw_fops = {
.open = tracing_open_generic_tr,
.write = tracing_mark_raw_write,
.llseek = generic_file_llseek,
.release = tracing_release_generic_tr,
};
static const struct file_operations trace_clock_fops = {
.open = tracing_clock_open,
.read = seq_read,
@ -7214,6 +7314,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
trace_create_file("trace_marker", 0220, d_tracer,
tr, &tracing_mark_fops);
trace_create_file("trace_marker_raw", 0220, d_tracer,
tr, &tracing_mark_raw_fops);
trace_create_file("trace_clock", 0644, d_tracer, tr,
&trace_clock_fops);

2
kernel/trace/trace.h
View File

@ -40,6 +40,7 @@ enum trace_type {
TRACE_BLK,
TRACE_BPUTS,
TRACE_HWLAT,
TRACE_RAW_DATA,
__TRACE_LAST_TYPE,
};
@ -331,6 +332,7 @@ extern void __ftrace_bad_type(void);
IF_ASSIGN(var, ent, struct bprint_entry, TRACE_BPRINT); \
IF_ASSIGN(var, ent, struct bputs_entry, TRACE_BPUTS); \
IF_ASSIGN(var, ent, struct hwlat_entry, TRACE_HWLAT); \
IF_ASSIGN(var, ent, struct raw_data_entry, TRACE_RAW_DATA);\
IF_ASSIGN(var, ent, struct trace_mmiotrace_rw, \
TRACE_MMIO_RW); \
IF_ASSIGN(var, ent, struct trace_mmiotrace_map, \

15
kernel/trace/trace_entries.h
View File

@ -244,6 +244,21 @@ FTRACE_ENTRY(print, print_entry,
FILTER_OTHER
);
FTRACE_ENTRY(raw_data, raw_data_entry,
TRACE_RAW_DATA,
F_STRUCT(
__field( unsigned int, id )
__dynamic_array( char, buf )
),
F_printk("id:%04x %08x",
__entry->id, (int)__entry->buf[0]),
FILTER_OTHER
);
FTRACE_ENTRY(bputs, bputs_entry,
TRACE_BPUTS,

30
kernel/trace/trace_output.c
View File

@ -1288,6 +1288,35 @@ static struct trace_event trace_print_event = {
.funcs = &trace_print_funcs,
};
static enum print_line_t trace_raw_data(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
struct raw_data_entry *field;
int i;
trace_assign_type(field, iter->ent);
trace_seq_printf(&iter->seq, "# %x buf:", field->id);
for (i = 0; i < iter->ent_size - offsetof(struct raw_data_entry, buf); i++)
trace_seq_printf(&iter->seq, " %02x",
(unsigned char)field->buf[i]);
trace_seq_putc(&iter->seq, '\n');
return trace_handle_return(&iter->seq);
}
static struct trace_event_functions trace_raw_data_funcs = {
.trace = trace_raw_data,
.raw = trace_raw_data,
};
static struct trace_event trace_raw_data_event = {
.type = TRACE_RAW_DATA,
.funcs = &trace_raw_data_funcs,
};
static struct trace_event *events[] __initdata = {
&trace_fn_event,
@ -1299,6 +1328,7 @@ static struct trace_event *events[] __initdata = {
&trace_bprint_event,
&trace_print_event,
&trace_hwlat_event,
&trace_raw_data_event,
NULL
};