diff options
| -rw-r--r-- | include/linux/trace_seq.h | 20 | ||||
| -rw-r--r-- | kernel/trace/trace_seq.c | 207 |
2 files changed, 185 insertions, 42 deletions
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h index 66ea365acf01..1f05317f51c4 100644 --- a/include/linux/trace_seq.h +++ b/include/linux/trace_seq.h @@ -38,14 +38,14 @@ int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args); extern int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary); extern int trace_print_seq(struct seq_file *m, struct trace_seq *s); -extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, - size_t cnt); +extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, + int cnt); extern int trace_seq_puts(struct trace_seq *s, const char *str); extern int trace_seq_putc(struct trace_seq *s, unsigned char c); -extern int trace_seq_putmem(struct trace_seq *s, const void *mem, size_t len); +extern int trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len); extern int trace_seq_putmem_hex(struct trace_seq *s, const void *mem, - size_t len); -extern void *trace_seq_reserve(struct trace_seq *s, size_t len); + unsigned int len); +extern void *trace_seq_reserve(struct trace_seq *s, unsigned int len); extern int trace_seq_path(struct trace_seq *s, const struct path *path); extern int trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp, @@ -73,8 +73,8 @@ static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s) { return 0; } -static inline ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, - size_t cnt) +static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, + int cnt) { return 0; } @@ -87,16 +87,16 @@ static inline int trace_seq_putc(struct trace_seq *s, unsigned char c) return 0; } static inline int -trace_seq_putmem(struct trace_seq *s, const void *mem, size_t len) +trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len) { return 0; } static inline int trace_seq_putmem_hex(struct trace_seq *s, const void *mem, - size_t len) + unsigned int len) { return 0; } -static inline void *trace_seq_reserve(struct trace_seq *s, size_t len) +static inline void *trace_seq_reserve(struct trace_seq *s, unsigned int len) { return NULL; } diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c index 5ba99c6cf834..0fabca773e51 100644 --- a/kernel/trace/trace_seq.c +++ b/kernel/trace/trace_seq.c @@ -3,21 +3,55 @@ * * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com> * + * The trace_seq 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 trace_seq must be initialized with trace_seq_init(). + * This will set up the counters within the descriptor. You can call + * trace_seq_init() more than once to reset the trace_seq to start + * from scratch. + * + * The buffer size is currently PAGE_SIZE, although it may become dynamic + * in the future. + * + * A write to the buffer will either succed or fail. That is, unlike + * sprintf() there will not be a partial write (well it may write into + * the buffer but it wont update the pointers). This allows users to + * try to write something into the trace_seq buffer and if it fails + * they can flush it and try again. + * */ #include <linux/uaccess.h> #include <linux/seq_file.h> #include <linux/trace_seq.h> +/* How much buffer is left on the trace_seq? */ +#define TRACE_SEQ_BUF_LEFT(s) ((PAGE_SIZE - 1) - (s)->len) + +/* How much buffer is written? */ +#define TRACE_SEQ_BUF_USED(s) min((s)->len, (unsigned int)(PAGE_SIZE - 1)) + +/** + * trace_print_seq - move the contents of trace_seq into a seq_file + * @m: the seq_file descriptor that is the destination + * @s: the trace_seq descriptor that is the source. + * + * Returns 0 on success and non zero on error. If it succeeds to + * write to the seq_file it will reset the trace_seq, otherwise + * it does not modify the trace_seq to let the caller try again. + */ int trace_print_seq(struct seq_file *m, struct trace_seq *s) { - int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len; + unsigned int len = TRACE_SEQ_BUF_USED(s); int ret; ret = seq_write(m, s->buffer, len); /* * Only reset this buffer if we successfully wrote to the - * seq_file buffer. + * seq_file buffer. This lets the caller try again or + * do something else with the contents. */ if (!ret) trace_seq_init(s); @@ -30,19 +64,20 @@ int trace_print_seq(struct seq_file *m, struct trace_seq *s) * @s: trace sequence descriptor * @fmt: printf format string * - * It returns 0 if the trace oversizes the buffer's free - * space, 1 otherwise. - * * The tracer may use either sequence operations or its own * copy to user routines. To simplify formating of a trace - * trace_seq_printf is used to store strings into a special + * trace_seq_printf() is used to store strings into a special * buffer (@s). Then the output may be either used by * the sequencer or pulled into another buffer. + * + * Returns 1 if we successfully written all the contents to + * the buffer. + * Returns 0 if we the length to write is bigger than the + * reserved buffer space. In this case, nothing gets written. */ -int -trace_seq_printf(struct trace_seq *s, const char *fmt, ...) +int trace_seq_printf(struct trace_seq *s, const char *fmt, ...) { - int len = (PAGE_SIZE - 1) - s->len; + unsigned int len = TRACE_SEQ_BUF_LEFT(s); va_list ap; int ret; @@ -66,21 +101,22 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...) EXPORT_SYMBOL_GPL(trace_seq_printf); /** - * trace_seq_bitmask - put a list of longs as a bitmask print output + * trace_seq_bitmask - write a bitmask array in its ASCII representation * @s: trace sequence descriptor * @maskp: points to an array of unsigned longs that represent a bitmask * @nmaskbits: The number of bits that are valid in @maskp * - * It returns 0 if the trace oversizes the buffer's free - * space, 1 otherwise. - * * Writes a ASCII representation of a bitmask string into @s. + * + * Returns 1 if we successfully written all the contents to + * the buffer. + * Returns 0 if we the length to write is bigger than the + * reserved buffer space. In this case, nothing gets written. */ -int -trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp, - int nmaskbits) +int trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp, + int nmaskbits) { - int len = (PAGE_SIZE - 1) - s->len; + unsigned int len = TRACE_SEQ_BUF_LEFT(s); int ret; if (s->full || !len) @@ -103,11 +139,12 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask); * trace_seq_printf is used to store strings into a special * buffer (@s). Then the output may be either used by * the sequencer or pulled into another buffer. + * + * Returns how much it wrote to the buffer. */ -int -trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args) +int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args) { - int len = (PAGE_SIZE - 1) - s->len; + unsigned int len = TRACE_SEQ_BUF_LEFT(s); int ret; if (s->full || !len) @@ -127,9 +164,26 @@ trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args) } EXPORT_SYMBOL_GPL(trace_seq_vprintf); +/** + * trace_seq_bprintf - Write the printf string from binary arguments + * @s: trace sequence 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 how much it wrote to the buffer. + */ int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary) { - int len = (PAGE_SIZE - 1) - s->len; + unsigned int len = TRACE_SEQ_BUF_LEFT(s); int ret; if (s->full || !len) @@ -147,6 +201,7 @@ int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary) return len; } +EXPORT_SYMBOL_GPL(trace_seq_bprintf); /** * trace_seq_puts - trace sequence printing of simple string @@ -157,15 +212,17 @@ int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary) * copy to user routines. This function records a simple string * into a special buffer (@s) for later retrieval by a sequencer * or other mechanism. + * + * Returns how much it wrote to the buffer. */ int trace_seq_puts(struct trace_seq *s, const char *str) { - int len = strlen(str); + unsigned int len = strlen(str); if (s->full) return 0; - if (len > ((PAGE_SIZE - 1) - s->len)) { + if (len > TRACE_SEQ_BUF_LEFT(s)) { s->full = 1; return 0; } @@ -175,13 +232,26 @@ int trace_seq_puts(struct trace_seq *s, const char *str) return len; } +EXPORT_SYMBOL_GPL(trace_seq_puts); +/** + * trace_seq_putc - trace sequence printing of simple character + * @s: trace sequence descriptor + * @c: simple character to record + * + * The tracer may use either the sequence operations or its own + * copy to user routines. This function records a simple charater + * into a special buffer (@s) for later retrieval by a sequencer + * or other mechanism. + * + * Returns how much it wrote to the buffer. + */ int trace_seq_putc(struct trace_seq *s, unsigned char c) { if (s->full) return 0; - if (s->len >= (PAGE_SIZE - 1)) { + if (TRACE_SEQ_BUF_LEFT(s) < 1) { s->full = 1; return 0; } @@ -190,14 +260,26 @@ int trace_seq_putc(struct trace_seq *s, unsigned char c) return 1; } -EXPORT_SYMBOL(trace_seq_putc); +EXPORT_SYMBOL_GPL(trace_seq_putc); -int trace_seq_putmem(struct trace_seq *s, const void *mem, size_t len) +/** + * trace_seq_putmem - write raw data into the trace_seq buffer + * @s: trace sequence 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 how much it wrote to the buffer. + */ +int trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len) { if (s->full) return 0; - if (len > ((PAGE_SIZE - 1) - s->len)) { + if (len > TRACE_SEQ_BUF_LEFT(s)) { s->full = 1; return 0; } @@ -207,10 +289,24 @@ int trace_seq_putmem(struct trace_seq *s, const void *mem, size_t len) return len; } +EXPORT_SYMBOL_GPL(trace_seq_putmem); #define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1) -int trace_seq_putmem_hex(struct trace_seq *s, const void *mem, size_t len) +/** + * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex + * @s: trace sequence 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 trace_seq_putmem() except instead of just copying the + * raw memory into the buffer it writes its ASCII representation of it + * in hex characters. + * + * Returns how much it wrote to the buffer. + */ +int trace_seq_putmem_hex(struct trace_seq *s, const void *mem, + unsigned int len) { unsigned char hex[HEX_CHARS]; const unsigned char *data = mem; @@ -231,15 +327,27 @@ int trace_seq_putmem_hex(struct trace_seq *s, const void *mem, size_t len) return trace_seq_putmem(s, hex, j); } +EXPORT_SYMBOL_GPL(trace_seq_putmem_hex); -void *trace_seq_reserve(struct trace_seq *s, size_t len) +/** + * trace_seq_reserve - reserve space on the sequence buffer + * @s: trace sequence descriptor + * @len: The amount to reserver. + * + * If for some reason there is a need to save some space on the + * buffer to fill in later, this function is used for that purpose. + * The given length will be reserved and the pointer to that + * location on the buffer is returned, unless there is not enough + * buffer left to hold the given length then NULL is returned. + */ +void *trace_seq_reserve(struct trace_seq *s, unsigned int len) { void *ret; if (s->full) return NULL; - if (len > ((PAGE_SIZE - 1) - s->len)) { + if (len > TRACE_SEQ_BUF_LEFT(s)) { s->full = 1; return NULL; } @@ -249,7 +357,20 @@ void *trace_seq_reserve(struct trace_seq *s, size_t len) return ret; } +EXPORT_SYMBOL_GPL(trace_seq_reserve); +/** + * trace_seq_path - copy a path into the sequence buffer + * @s: trace sequence descriptor + * @path: path to write into the sequence buffer. + * + * Write a path name into the sequence buffer. + * + * Returns 1 if we successfully written all the contents to + * the buffer. + * Returns 0 if we the length to write is bigger than the + * reserved buffer space. In this case, nothing gets written. + */ int trace_seq_path(struct trace_seq *s, const struct path *path) { unsigned char *p; @@ -257,7 +378,7 @@ int trace_seq_path(struct trace_seq *s, const struct path *path) if (s->full) return 0; - if (s->len >= (PAGE_SIZE - 1)) { + if (TRACE_SEQ_BUF_LEFT(s) < 1) { s->full = 1; return 0; } @@ -277,8 +398,29 @@ int trace_seq_path(struct trace_seq *s, const struct path *path) s->full = 1; return 0; } +EXPORT_SYMBOL_GPL(trace_seq_path); -ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt) +/** + * trace_seq_to_user - copy the squence buffer to user space + * @s: trace sequence 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 + * sequenc (@s->len == @s->readpos). + * + * Returns -EFAULT if the copy to userspace fails. + */ +int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt) { int len; int ret; @@ -301,3 +443,4 @@ ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt) s->readpos += cnt; return cnt; } +EXPORT_SYMBOL_GPL(trace_seq_to_user); |