From: "Steven Rostedt (Red Hat)" <rost...@goodmis.org> commit 3a161d99c43ce74c76aecff309be4c3ba455e823 upstream.
Create a seq_buf layer that trace_seq sits on. The seq_buf will not be limited to page size. This will allow other usages of seq_buf instead of a hard set PAGE_SIZE one that trace_seq has. Link: http://lkml.kernel.org/r/20141104160221.864997...@goodmis.org Link: http://lkml.kernel.org/r/20141114011412.170377...@goodmis.org Tested-by: Jiri Kosina <jkos...@suse.cz> Acked-by: Jiri Kosina <jkos...@suse.cz> Reviewed-by: Petr Mladek <pmla...@suse.cz> [wanglong: backport to 3.10 stable - only backport seq_buf related - adjust context ] Signed-off-by: Wang Long <long.wangl...@huawei.com> Signed-off-by: Steven Rostedt <rost...@goodmis.org> --- include/linux/seq_buf.h | 81 ++++++++++++ kernel/trace/Makefile | 1 + kernel/trace/seq_buf.c | 341 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 423 insertions(+) create mode 100644 include/linux/seq_buf.h create mode 100644 kernel/trace/seq_buf.c diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h new file mode 100644 index 0000000..4f7a96a --- /dev/null +++ b/include/linux/seq_buf.h @@ -0,0 +1,81 @@ +#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 */ diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index d7e2068..cfb86f1 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -27,6 +27,7 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o obj-$(CONFIG_TRACING) += trace.o obj-$(CONFIG_TRACING) += trace_output.o +obj-$(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 diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c new file mode 100644 index 0000000..e9a7861 --- /dev/null +++ b/kernel/trace/seq_buf.c @@ -0,0 +1,341 @@ +/* + * seq_buf.c + * + * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srost...@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; +} -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
