tracing: Create seq_buf layer in trace_seq (3a161d99) · Commits · 戴 / test

include/linux/seq_buf.h

0 → 100644

+81 −0

Original line number	Diff line number	Diff line
		#ifndef _LINUX_SEQ_BUF_H
		#define _LINUX_SEQ_BUF_H

		#include <linux/fs.h>

		/*
		* Trace sequences are used to allow a function to call several other functions
		* to create a string of data to use.
		*/

		/**
		* seq_buf - seq buffer structure
		* @buffer: pointer to the buffer
		* @size: size of the buffer
		* @len: the amount of data inside the buffer
		* @readpos: The next position to read in the buffer.
		*/
		struct seq_buf {
		unsigned char *buffer;
		unsigned int size;
		unsigned int len;
		unsigned int readpos;
		};

		static inline void
		seq_buf_init(struct seq_buf s, unsigned char buf, unsigned int size)
		{
		s->buffer = buf;
		s->size = size;
		s->len = 0;
		s->readpos = 0;
		}

		/*
		* seq_buf have a buffer that might overflow. When this happens
		* the len and size are set to be equal.
		*/
		static inline bool
		seq_buf_has_overflowed(struct seq_buf *s)
		{
		return s->len == s->size;
		}

		static inline void
		seq_buf_set_overflow(struct seq_buf *s)
		{
		s->len = s->size;
		}

		/*
		* How much buffer is left on the seq_buf?
		*/
		static inline unsigned int
		seq_buf_buffer_left(struct seq_buf *s)
		{
		if (seq_buf_has_overflowed(s))
		return 0;

		return (s->size - 1) - s->len;
		}

		extern __printf(2, 3)
		int seq_buf_printf(struct seq_buf s, const char fmt, ...);
		extern __printf(2, 0)
		int seq_buf_vprintf(struct seq_buf s, const char fmt, va_list args);
		extern int
		seq_buf_bprintf(struct seq_buf s, const char fmt, const u32 *binary);
		extern int seq_buf_print_seq(struct seq_file m, struct seq_buf s);
		extern int seq_buf_to_user(struct seq_buf s, char __user ubuf,
		int cnt);
		extern int seq_buf_puts(struct seq_buf s, const char str);
		extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
		extern int seq_buf_putmem(struct seq_buf s, const void mem, unsigned int len);
		extern int seq_buf_putmem_hex(struct seq_buf s, const void mem,
		unsigned int len);
		extern int seq_buf_path(struct seq_buf s, const struct path path);

		extern int seq_buf_bitmask(struct seq_buf s, const unsigned long maskp,
		int nmaskbits);

		#endif /* _LINUX_SEQ_BUF_H */

include/linux/trace_seq.h

+5 −7

Original line number	Diff line number	Diff line
		#ifndef _LINUX_TRACE_SEQ_H
		#define _LINUX_TRACE_SEQ_H

		#include <linux/fs.h>
		#include <linux/seq_buf.h>

		#include <asm/page.h>

		@@ -12,16 +12,14 @@

		struct trace_seq {
		unsigned char buffer[PAGE_SIZE];
		unsigned int len;
		unsigned int readpos;
		struct seq_buf seq;
		int full;
		};

		static inline void
		trace_seq_init(struct trace_seq *s)
		{
		s->len = 0;
		s->readpos = 0;
		seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
		s->full = 0;
		}

		@@ -37,7 +35,7 @@ trace_seq_init(struct trace_seq *s)
		static inline unsigned char *
		trace_seq_buffer_ptr(struct trace_seq *s)
		{
		return s->buffer + s->len;
		return s->buffer + s->seq.len;
		}

		/**
		@@ -49,7 +47,7 @@ trace_seq_buffer_ptr(struct trace_seq *s)
		*/
		static inline bool trace_seq_has_overflowed(struct trace_seq *s)
		{
		return s->full \|\| s->len > PAGE_SIZE - 1;
		return s->full \|\| seq_buf_has_overflowed(&s->seq);
		}

		/*

kernel/trace/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -29,6 +29,7 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
		obj-$(CONFIG_TRACING) += trace.o
		obj-$(CONFIG_TRACING) += trace_output.o
		obj-$(CONFIG_TRACING) += trace_seq.o
		obj-$(CONFIG_TRACING) += seq_buf.o
		obj-$(CONFIG_TRACING) += trace_stat.o
		obj-$(CONFIG_TRACING) += trace_printk.o
		obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o

kernel/trace/seq_buf.c

0 → 100644

+341 −0

Original line number	Diff line number	Diff line
		/*
		* seq_buf.c
		*
		* Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
		*
		* The seq_buf is a handy tool that allows you to pass a descriptor around
		* to a buffer that other functions can write to. It is similar to the
		* seq_file functionality but has some differences.
		*
		* To use it, the seq_buf must be initialized with seq_buf_init().
		* This will set up the counters within the descriptor. You can call
		* seq_buf_init() more than once to reset the seq_buf to start
		* from scratch.
		*/
		#include <linux/uaccess.h>
		#include <linux/seq_file.h>
		#include <linux/seq_buf.h>

		/* How much buffer is written? */
		#define SEQ_BUF_USED(s) min((s)->len, (s)->size - 1)

		/**
		* seq_buf_print_seq - move the contents of seq_buf into a seq_file
		* @m: the seq_file descriptor that is the destination
		* @s: the seq_buf descriptor that is the source.
		*
		* Returns zero on success, non zero otherwise
		*/
		int seq_buf_print_seq(struct seq_file m, struct seq_buf s)
		{
		unsigned int len = SEQ_BUF_USED(s);

		return seq_write(m, s->buffer, len);
		}

		/**
		* seq_buf_vprintf - sequence printing of information.
		* @s: seq_buf descriptor
		* @fmt: printf format string
		* @args: va_list of arguments from a printf() type function
		*
		* Writes a vnprintf() format into the sequencce buffer.
		*
		* Returns zero on success, -1 on overflow.
		*/
		int seq_buf_vprintf(struct seq_buf s, const char fmt, va_list args)
		{
		int len;

		WARN_ON(s->size == 0);

		if (s->len < s->size) {
		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
		if (s->len + len < s->size) {
		s->len += len;
		return 0;
		}
		}
		seq_buf_set_overflow(s);
		return -1;
		}

		/**
		* seq_buf_printf - sequence printing of information
		* @s: seq_buf descriptor
		* @fmt: printf format string
		*
		* Writes a printf() format into the sequence buffer.
		*
		* Returns zero on success, -1 on overflow.
		*/
		int seq_buf_printf(struct seq_buf s, const char fmt, ...)
		{
		va_list ap;
		int ret;

		va_start(ap, fmt);
		ret = seq_buf_vprintf(s, fmt, ap);
		va_end(ap);

		return ret;
		}

		/**
		* seq_buf_bitmask - write a bitmask array in its ASCII representation
		* @s: seq_buf descriptor
		* @maskp: points to an array of unsigned longs that represent a bitmask
		* @nmaskbits: The number of bits that are valid in @maskp
		*
		* Writes a ASCII representation of a bitmask string into @s.
		*
		* Returns zero on success, -1 on overflow.
		*/
		int seq_buf_bitmask(struct seq_buf s, const unsigned long maskp,
		int nmaskbits)
		{
		unsigned int len = seq_buf_buffer_left(s);
		int ret;

		WARN_ON(s->size == 0);

		/*
		* The last byte of the buffer is used to determine if we
		* overflowed or not.
		*/
		if (len > 1) {
		ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
		if (ret < len) {
		s->len += ret;
		return 0;
		}
		}
		seq_buf_set_overflow(s);
		return -1;
		}

		/**
		* seq_buf_bprintf - Write the printf string from binary arguments
		* @s: seq_buf descriptor
		* @fmt: The format string for the @binary arguments
		* @binary: The binary arguments for @fmt.
		*
		* When recording in a fast path, a printf may be recorded with just
		* saving the format and the arguments as they were passed to the
		* function, instead of wasting cycles converting the arguments into
		* ASCII characters. Instead, the arguments are saved in a 32 bit
		* word array that is defined by the format string constraints.
		*
		* This function will take the format and the binary array and finish
		* the conversion into the ASCII string within the buffer.
		*
		* Returns zero on success, -1 on overflow.
		*/
		int seq_buf_bprintf(struct seq_buf s, const char fmt, const u32 *binary)
		{
		unsigned int len = seq_buf_buffer_left(s);
		int ret;

		WARN_ON(s->size == 0);

		if (s->len < s->size) {
		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
		if (s->len + ret < s->size) {
		s->len += ret;
		return 0;
		}
		}
		seq_buf_set_overflow(s);
		return -1;
		}

		/**
		* seq_buf_puts - sequence printing of simple string
		* @s: seq_buf descriptor
		* @str: simple string to record
		*
		* Copy a simple string into the sequence buffer.
		*
		* Returns zero on success, -1 on overflow
		*/
		int seq_buf_puts(struct seq_buf s, const char str)
		{
		unsigned int len = strlen(str);

		WARN_ON(s->size == 0);

		if (s->len + len < s->size) {
		memcpy(s->buffer + s->len, str, len);
		s->len += len;
		return 0;
		}
		seq_buf_set_overflow(s);
		return -1;
		}

		/**
		* seq_buf_putc - sequence printing of simple character
		* @s: seq_buf descriptor
		* @c: simple character to record
		*
		* Copy a single character into the sequence buffer.
		*
		* Returns zero on success, -1 on overflow
		*/
		int seq_buf_putc(struct seq_buf *s, unsigned char c)
		{
		WARN_ON(s->size == 0);

		if (s->len + 1 < s->size) {
		s->buffer[s->len++] = c;
		return 0;
		}
		seq_buf_set_overflow(s);
		return -1;
		}

		/**
		* seq_buf_putmem - write raw data into the sequenc buffer
		* @s: seq_buf descriptor
		* @mem: The raw memory to copy into the buffer
		* @len: The length of the raw memory to copy (in bytes)
		*
		* There may be cases where raw memory needs to be written into the
		* buffer and a strcpy() would not work. Using this function allows
		* for such cases.
		*
		* Returns zero on success, -1 on overflow
		*/
		int seq_buf_putmem(struct seq_buf s, const void mem, unsigned int len)
		{
		WARN_ON(s->size == 0);

		if (s->len + len < s->size) {
		memcpy(s->buffer + s->len, mem, len);
		s->len += len;
		return 0;
		}
		seq_buf_set_overflow(s);
		return -1;
		}

		#define MAX_MEMHEX_BYTES 8U
		#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)

		/**
		* seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
		* @s: seq_buf descriptor
		* @mem: The raw memory to write its hex ASCII representation of
		* @len: The length of the raw memory to copy (in bytes)
		*
		* This is similar to seq_buf_putmem() except instead of just copying the
		* raw memory into the buffer it writes its ASCII representation of it
		* in hex characters.
		*
		* Returns zero on success, -1 on overflow
		*/
		int seq_buf_putmem_hex(struct seq_buf s, const void mem,
		unsigned int len)
		{
		unsigned char hex[HEX_CHARS];
		const unsigned char *data = mem;
		unsigned int start_len;
		int i, j;

		WARN_ON(s->size == 0);

		while (len) {
		start_len = min(len, HEX_CHARS - 1);
		#ifdef __BIG_ENDIAN
		for (i = 0, j = 0; i < start_len; i++) {
		#else
		for (i = start_len-1, j = 0; i >= 0; i--) {
		#endif
		hex[j++] = hex_asc_hi(data[i]);
		hex[j++] = hex_asc_lo(data[i]);
		}
		if (WARN_ON_ONCE(j == 0 \|\| j/2 > len))
		break;

		/* j increments twice per loop */
		len -= j / 2;
		hex[j++] = ' ';

		seq_buf_putmem(s, hex, j);
		if (seq_buf_has_overflowed(s))
		return -1;
		}
		return 0;
		}

		/**
		* seq_buf_path - copy a path into the sequence buffer
		* @s: seq_buf descriptor
		* @path: path to write into the sequence buffer.
		*
		* Write a path name into the sequence buffer.
		*
		* Returns zero on success, -1 on overflow
		*/
		int seq_buf_path(struct seq_buf s, const struct path path)
		{
		unsigned int len = seq_buf_buffer_left(s);
		unsigned char *p;

		WARN_ON(s->size == 0);

		p = d_path(path, s->buffer + s->len, len);
		if (!IS_ERR(p)) {
		p = mangle_path(s->buffer + s->len, p, "\n");
		if (p) {
		s->len = p - s->buffer;
		return 0;
		}
		}
		seq_buf_set_overflow(s);
		return -1;
		}

		/**
		* seq_buf_to_user - copy the squence buffer to user space
		* @s: seq_buf descriptor
		* @ubuf: The userspace memory location to copy to
		* @cnt: The amount to copy
		*
		* Copies the sequence buffer into the userspace memory pointed to
		* by @ubuf. It starts from the last read position (@s->readpos)
		* and writes up to @cnt characters or till it reaches the end of
		* the content in the buffer (@s->len), which ever comes first.
		*
		* On success, it returns a positive number of the number of bytes
		* it copied.
		*
		* On failure it returns -EBUSY if all of the content in the
		* sequence has been already read, which includes nothing in the
		* sequence (@s->len == @s->readpos).
		*
		* Returns -EFAULT if the copy to userspace fails.
		*/
		int seq_buf_to_user(struct seq_buf s, char __user ubuf, int cnt)
		{
		int len;
		int ret;

		if (!cnt)
		return 0;

		if (s->len <= s->readpos)
		return -EBUSY;

		len = s->len - s->readpos;
		if (cnt > len)
		cnt = len;
		ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
		if (ret == cnt)
		return -EFAULT;

		cnt -= ret;

		s->readpos += cnt;
		return cnt;
		}

kernel/trace/trace.c

+21 −18

Original line number	Diff line number	Diff line
		@@ -939,19 +939,20 @@ out:
		return ret;
		}

		/* TODO add a seq_buf_to_buffer() */
		static ssize_t trace_seq_to_buffer(struct trace_seq s, void buf, size_t cnt)
		{
		int len;

		if (s->len <= s->readpos)
		if (s->seq.len <= s->seq.readpos)
		return -EBUSY;

		len = s->len - s->readpos;
		len = s->seq.len - s->seq.readpos;
		if (cnt > len)
		cnt = len;
		memcpy(buf, s->buffer + s->readpos, cnt);
		memcpy(buf, s->buffer + s->seq.readpos, cnt);

		s->readpos += cnt;
		s->seq.readpos += cnt;
		return cnt;
		}

		@@ -4315,6 +4316,8 @@ static int tracing_open_pipe(struct inode inode, struct file filp)
		goto out;
		}

		trace_seq_init(&iter->seq);

		/*
		* We make a copy of the current tracer to avoid concurrent
		* changes on it while we are reading.
		@@ -4511,18 +4514,18 @@ waitagain:
		trace_access_lock(iter->cpu_file);
		while (trace_find_next_entry_inc(iter) != NULL) {
		enum print_line_t ret;
		int len = iter->seq.len;
		int len = iter->seq.seq.len;

		ret = print_trace_line(iter);
		if (ret == TRACE_TYPE_PARTIAL_LINE) {
		/* don't print partial lines */
		iter->seq.len = len;
		iter->seq.seq.len = len;
		break;
		}
		if (ret != TRACE_TYPE_NO_CONSUME)
		trace_consume(iter);

		if (iter->seq.len >= cnt)
		if (iter->seq.seq.len >= cnt)
		break;

		/*
		@@ -4538,7 +4541,7 @@ waitagain:

		/* Now copy what we have to the user */
		sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
		if (iter->seq.readpos >= iter->seq.len)
		if (iter->seq.seq.readpos >= iter->seq.seq.len)
		trace_seq_init(&iter->seq);

		/*
		@@ -4576,16 +4579,16 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)

		/* Seq buffer is page-sized, exactly what we need. */
		for (;;) {
		count = iter->seq.len;
		count = iter->seq.seq.len;
		ret = print_trace_line(iter);
		count = iter->seq.len - count;
		count = iter->seq.seq.len - count;
		if (rem < count) {
		rem = 0;
		iter->seq.len -= count;
		iter->seq.seq.len -= count;
		break;
		}
		if (ret == TRACE_TYPE_PARTIAL_LINE) {
		iter->seq.len -= count;
		iter->seq.seq.len -= count;
		break;
		}

		@@ -4666,13 +4669,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
		/* Copy the data into the page, so we can start over. */
		ret = trace_seq_to_buffer(&iter->seq,
		page_address(spd.pages[i]),
		iter->seq.len);
		iter->seq.seq.len);
		if (ret < 0) {
		__free_page(spd.pages[i]);
		break;
		}
		spd.partial[i].offset = 0;
		spd.partial[i].len = iter->seq.len;
		spd.partial[i].len = iter->seq.seq.len;

		trace_seq_init(&iter->seq);
		}
		@@ -5673,7 +5676,7 @@ tracing_stats_read(struct file filp, char __user ubuf,
		cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
		trace_seq_printf(s, "read events: %ld\n", cnt);

		count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
		count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);

		kfree(s);

		@@ -6636,11 +6639,11 @@ void
		trace_printk_seq(struct trace_seq *s)
		{
		/* Probably should print a warning here. */
		if (s->len >= TRACE_MAX_PRINT)
		s->len = TRACE_MAX_PRINT;
		if (s->seq.len >= TRACE_MAX_PRINT)
		s->seq.len = TRACE_MAX_PRINT;

		/* should be zero ended, but we are paranoid. */
		s->buffer[s->len] = 0;
		s->buffer[s->seq.len] = 0;

		printk(KERN_TRACE "%s", s->buffer);

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