diff options
| -rw-r--r-- | include/linux/ftrace.h | 31 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 253 |
2 files changed, 246 insertions, 38 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 26eafcef75be..4f0b6fec379d 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -133,6 +133,8 @@ struct ftrace_func_command { int ftrace_arch_code_modify_prepare(void); int ftrace_arch_code_modify_post_process(void); +void ftrace_bug(int err, unsigned long ip); + struct seq_file; struct ftrace_probe_ops { @@ -190,6 +192,35 @@ void ftrace_set_global_notrace(unsigned char *buf, int len, int reset); int register_ftrace_command(struct ftrace_func_command *cmd); int unregister_ftrace_command(struct ftrace_func_command *cmd); +enum { + FTRACE_UPDATE_CALLS = (1 << 0), + FTRACE_DISABLE_CALLS = (1 << 1), + FTRACE_UPDATE_TRACE_FUNC = (1 << 2), + FTRACE_START_FUNC_RET = (1 << 3), + FTRACE_STOP_FUNC_RET = (1 << 4), +}; + +enum { + FTRACE_UPDATE_IGNORE, + FTRACE_UPDATE_MAKE_CALL, + FTRACE_UPDATE_MAKE_NOP, +}; + +void arch_ftrace_update_code(int command); + +struct ftrace_rec_iter; + +struct ftrace_rec_iter *ftrace_rec_iter_start(void); +struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter); +struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter); + +int ftrace_update_record(struct dyn_ftrace *rec, int enable); +int ftrace_test_record(struct dyn_ftrace *rec, int enable); +void ftrace_run_stop_machine(int command); +int ftrace_location(unsigned long ip); + +extern ftrace_func_t ftrace_trace_function; + /* defined in arch */ extern int ftrace_ip_converted(unsigned long ip); extern int ftrace_dyn_arch_init(void *data); diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 25b4f4da0fe8..655b432fb890 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -947,13 +947,6 @@ struct ftrace_func_probe { struct rcu_head rcu; }; -enum { - FTRACE_UPDATE_CALLS = (1 << 0), - FTRACE_DISABLE_CALLS = (1 << 1), - FTRACE_UPDATE_TRACE_FUNC = (1 << 2), - FTRACE_START_FUNC_RET = (1 << 3), - FTRACE_STOP_FUNC_RET = (1 << 4), -}; struct ftrace_func_entry { struct hlist_node hlist; unsigned long ip; @@ -1307,6 +1300,28 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip) } \ } +/** + * ftrace_location - return true if the ip giving is a traced location + * @ip: the instruction pointer to check + * + * Returns 1 if @ip given is a pointer to a ftrace location. + * That is, the instruction that is either a NOP or call to + * the function tracer. It checks the ftrace internal tables to + * determine if the address belongs or not. + */ +int ftrace_location(unsigned long ip) +{ + struct ftrace_page *pg; + struct dyn_ftrace *rec; + + do_for_each_ftrace_rec(pg, rec) { + if (rec->ip == ip) + return 1; + } while_for_each_ftrace_rec(); + + return 0; +} + static void __ftrace_hash_rec_update(struct ftrace_ops *ops, int filter_hash, bool inc) @@ -1475,7 +1490,19 @@ static void print_ip_ins(const char *fmt, unsigned char *p) printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]); } -static void ftrace_bug(int failed, unsigned long ip) +/** + * ftrace_bug - report and shutdown function tracer + * @failed: The failed type (EFAULT, EINVAL, EPERM) + * @ip: The address that failed + * + * The arch code that enables or disables the function tracing + * can call ftrace_bug() when it has detected a problem in + * modifying the code. @failed should be one of either: + * EFAULT - if the problem happens on reading the @ip address + * EINVAL - if what is read at @ip is not what was expected + * EPERM - if the problem happens on writting to the @ip address + */ +void ftrace_bug(int failed, unsigned long ip) { switch (failed) { case -EFAULT: @@ -1517,15 +1544,10 @@ int ftrace_text_reserved(void *start, void *end) return 0; } - -static int -__ftrace_replace_code(struct dyn_ftrace *rec, int update) +static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update) { - unsigned long ftrace_addr; unsigned long flag = 0UL; - ftrace_addr = (unsigned long)FTRACE_ADDR; - /* * If we are updating calls: * @@ -1537,20 +1559,74 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int update) * If we are disabling calls, then disable all records that * are enabled. */ - if (update && (rec->flags & ~FTRACE_FL_MASK)) + if (enable && (rec->flags & ~FTRACE_FL_MASK)) flag = FTRACE_FL_ENABLED; /* If the state of this record hasn't changed, then do nothing */ if ((rec->flags & FTRACE_FL_ENABLED) == flag) - return 0; + return FTRACE_UPDATE_IGNORE; if (flag) { - rec->flags |= FTRACE_FL_ENABLED; + if (update) + rec->flags |= FTRACE_FL_ENABLED; + return FTRACE_UPDATE_MAKE_CALL; + } + + if (update) + rec->flags &= ~FTRACE_FL_ENABLED; + + return FTRACE_UPDATE_MAKE_NOP; +} + +/** + * ftrace_update_record, set a record that now is tracing or not + * @rec: the record to update + * @enable: set to 1 if the record is tracing, zero to force disable + * + * The records that represent all functions that can be traced need + * to be updated when tracing has been enabled. + */ +int ftrace_update_record(struct dyn_ftrace *rec, int enable) +{ + return ftrace_check_record(rec, enable, 1); +} + +/** + * ftrace_test_record, check if the record has been enabled or not + * @rec: the record to test + * @enable: set to 1 to check if enabled, 0 if it is disabled + * + * The arch code may need to test if a record is already set to + * tracing to determine how to modify the function code that it + * represents. + */ +int ftrace_test_record(struct dyn_ftrace *rec, int enable) +{ + return ftrace_check_record(rec, enable, 0); +} + +static int +__ftrace_replace_code(struct dyn_ftrace *rec, int enable) +{ + unsigned long ftrace_addr; + int ret; + + ftrace_addr = (unsigned long)FTRACE_ADDR; + + ret = ftrace_update_record(rec, enable); + + switch (ret) { + case FTRACE_UPDATE_IGNORE: + return 0; + + case FTRACE_UPDATE_MAKE_CALL: return ftrace_make_call(rec, ftrace_addr); + + case FTRACE_UPDATE_MAKE_NOP: + return ftrace_make_nop(NULL, rec, ftrace_addr); } - rec->flags &= ~FTRACE_FL_ENABLED; - return ftrace_make_nop(NULL, rec, ftrace_addr); + return -1; /* unknow ftrace bug */ } static void ftrace_replace_code(int update) @@ -1576,6 +1652,78 @@ static void ftrace_replace_code(int update) } while_for_each_ftrace_rec(); } +struct ftrace_rec_iter { + struct ftrace_page *pg; + int index; +}; + +/** + * ftrace_rec_iter_start, start up iterating over traced functions + * + * Returns an iterator handle that is used to iterate over all + * the records that represent address locations where functions + * are traced. + * + * May return NULL if no records are available. + */ +struct ftrace_rec_iter *ftrace_rec_iter_start(void) +{ + /* + * We only use a single iterator. + * Protected by the ftrace_lock mutex. + */ + static struct ftrace_rec_iter ftrace_rec_iter; + struct ftrace_rec_iter *iter = &ftrace_rec_iter; + + iter->pg = ftrace_pages_start; + iter->index = 0; + + /* Could have empty pages */ + while (iter->pg && !iter->pg->index) + iter->pg = iter->pg->next; + + if (!iter->pg) + return NULL; + + return iter; +} + +/** + * ftrace_rec_iter_next, get the next record to process. + * @iter: The handle to the iterator. + * + * Returns the next iterator after the given iterator @iter. + */ +struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter) +{ + iter->index++; + + if (iter->index >= iter->pg->index) { + iter->pg = iter->pg->next; + iter->index = 0; + + /* Could have empty pages */ + while (iter->pg && !iter->pg->index) + iter->pg = iter->pg->next; + } + + if (!iter->pg) + return NULL; + + return iter; +} + +/** + * ftrace_rec_iter_record, get the record at the iterator location + * @iter: The current iterator location + * + * Returns the record that the current @iter is at. + */ +struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter) +{ + return &iter->pg->records[iter->index]; +} + static int ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec) { @@ -1617,12 +1765,6 @@ static int __ftrace_modify_code(void *data) { int *command = data; - /* - * Do not call function tracer while we update the code. - * We are in stop machine, no worrying about races. - */ - function_trace_stop++; - if (*command & FTRACE_UPDATE_CALLS) ftrace_replace_code(1); else if (*command & FTRACE_DISABLE_CALLS) @@ -1636,21 +1778,33 @@ static int __ftrace_modify_code(void *data) else if (*command & FTRACE_STOP_FUNC_RET) ftrace_disable_ftrace_graph_caller(); -#ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST - /* - * For archs that call ftrace_test_stop_func(), we must - * wait till after we update all the function callers - * before we update the callback. This keeps different - * ops that record different functions from corrupting - * each other. - */ - __ftrace_trace_function = __ftrace_trace_function_delay; -#endif - function_trace_stop--; - return 0; } +/** + * ftrace_run_stop_machine, go back to the stop machine method + * @command: The command to tell ftrace what to do + * + * If an arch needs to fall back to the stop machine method, the + * it can call this function. + */ +void ftrace_run_stop_machine(int command) +{ + stop_machine(__ftrace_modify_code, &command, NULL); +} + +/** + * arch_ftrace_update_code, modify the code to trace or not trace + * @command: The command that needs to be done + * + * Archs can override this function if it does not need to + * run stop_machine() to modify code. + */ +void __weak arch_ftrace_update_code(int command) +{ + ftrace_run_stop_machine(command); +} + static void ftrace_run_update_code(int command) { int ret; @@ -1659,8 +1813,31 @@ static void ftrace_run_update_code(int command) FTRACE_WARN_ON(ret); if (ret) return; + /* + * Do not call function tracer while we update the code. + * We are in stop machine. + */ + function_trace_stop++; - stop_machine(__ftrace_modify_code, &command, NULL); + /* + * By default we use stop_machine() to modify the code. + * But archs can do what ever they want as long as it + * is safe. The stop_machine() is the safest, but also + * produces the most overhead. + */ + arch_ftrace_update_code(command); + +#ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST + /* + * For archs that call ftrace_test_stop_func(), we must + * wait till after we update all the function callers + * before we update the callback. This keeps different + * ops that record different functions from corrupting + * each other. + */ + __ftrace_trace_function = __ftrace_trace_function_delay; +#endif + function_trace_stop--; ret = ftrace_arch_code_modify_post_process(); FTRACE_WARN_ON(ret); |