From 45959ee7aa645815a5ce303a0ea1e48a21e67c6a Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 12 Dec 2011 15:22:41 -0500 Subject: ftrace: Do not function trace inlined functions When gcc inlines a function, it does not mark it with the mcount prologue, which in turn means that inlined functions are not traced by the function tracer. But if CONFIG_OPTIMIZE_INLINING is set, then gcc is allowed not to inline a function that is marked inline. Depending on the options and the compiler, a function may or may not be traced by the function tracer, depending on whether gcc decides to inline a function or not. This has caused several problems in the pass becaues gcc is not always consistent with what it decides to inline between different gcc versions. Some places should not be traced (like paravirt native_* functions) and these are mostly marked as inline. When gcc decides not to inline the function, and if that function should not be traced, then the ftrace function tracer will suddenly break when it use to work fine. This becomes even harder to debug when different versions of gcc will not inline that function, making the same kernel and config work for some gcc versions and not work for others. By making all functions marked inline to not be traced will remove the ambiguity that gcc adds when it comes to tracing functions marked inline. All gcc versions will be consistent with what functions are traced and having volatile working code will be removed. Note, only the inline macro when CONFIG_OPTIMIZE_INLINING is set needs to have notrace added, as the attribute __always_inline will force the function to be inlined and then not traced. Signed-off-by: Steven Rostedt --- include/linux/compiler-gcc.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include') diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 59e4028e833d..3fd17c249221 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -50,6 +50,11 @@ # define inline inline __attribute__((always_inline)) # define __inline__ __inline__ __attribute__((always_inline)) # define __inline __inline __attribute__((always_inline)) +#else +/* A lot of inline functions can cause havoc with function tracing */ +# define inline inline notrace +# define __inline__ __inline__ notrace +# define __inline __inline notrace #endif #define __deprecated __attribute__((deprecated)) -- cgit v1.2.2 From c88fd8634ea68e74c7d19fd2621b4078fd22864c Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 16 Aug 2011 09:53:39 -0400 Subject: ftrace: Allow archs to modify code without stop machine The stop machine method to modify all functions in the kernel (some 20,000 of them) is the safest way to do so across all archs. But some archs may not need this big hammer approach to modify code on SMP machines, and can simply just update the code it needs. Adding a weak function arch_ftrace_update_code() that now does the stop machine, will also let any arch override this method. If the arch needs to check the system and then decide if it can avoid stop machine, it can still call ftrace_run_stop_machine() to use the old method. Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'include') 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); -- cgit v1.2.2 From 3208230983a0ee3d95be22d463257e530c684956 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 16 Dec 2011 14:42:37 -0500 Subject: ftrace: Remove usage of "freed" records Records that are added to the function trace table are permanently there, except for modules. By separating out the modules to their own pages that can be freed in one shot we can remove the "freed" flag and simplify some of the record management. Another benefit of doing this is that we can also move the records around; sort them. Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 4f0b6fec379d..3f79bc458bff 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -163,7 +163,6 @@ extern int ftrace_text_reserved(void *start, void *end); enum { FTRACE_FL_ENABLED = (1 << 30), - FTRACE_FL_FREE = (1 << 31), }; #define FTRACE_FL_MASK (0x3UL << 30) -- cgit v1.2.2 From 85ae32ae019bc1c2cc22e5f51fe0c9f2812ef68c Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 16 Dec 2011 16:30:31 -0500 Subject: ftrace: Replace record newlist with record page list As new functions come in to be initalized from mcount to nop, they are done by groups of pages. Whether it is the core kernel or a module. There's no need to keep track of these on a per record basis. At startup, and as any module is loaded, the functions to be traced are stored in a group of pages and added to the function list at the end. We just need to keep a pointer to the first page of the list that was added, and use that to know where to start on the list for initializing functions. Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'include') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 3f79bc458bff..31b9fd7aedcd 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -173,10 +173,7 @@ struct dyn_ftrace { unsigned long ip; /* address of mcount call-site */ struct dyn_ftrace *freelist; }; - union { - unsigned long flags; - struct dyn_ftrace *newlist; - }; + unsigned long flags; struct dyn_arch_ftrace arch; }; -- cgit v1.2.2 From fc13cb0ce45296f331263a6034aa1814203e1ac3 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 19 Dec 2011 14:41:25 -0500 Subject: ftrace: Allow other users of function tracing to use the output listing The function tracer is set up to allow any other subsystem (like perf) to use it. Ftrace already has a way to list what functions are enabled by the global_ops. It would be very helpful to let other users of the function tracer to be able to use the same code. Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'include') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 31b9fd7aedcd..aa7559f0a224 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -202,6 +202,14 @@ enum { FTRACE_UPDATE_MAKE_NOP, }; +enum { + FTRACE_ITER_FILTER = (1 << 0), + FTRACE_ITER_NOTRACE = (1 << 1), + FTRACE_ITER_PRINTALL = (1 << 2), + FTRACE_ITER_HASH = (1 << 3), + FTRACE_ITER_ENABLED = (1 << 4), +}; + void arch_ftrace_update_code(int command); struct ftrace_rec_iter; @@ -217,6 +225,15 @@ int ftrace_location(unsigned long ip); extern ftrace_func_t ftrace_trace_function; +int ftrace_regex_open(struct ftrace_ops *ops, int flag, + struct inode *inode, struct file *file); +ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf, + size_t cnt, loff_t *ppos); +ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf, + size_t cnt, loff_t *ppos); +loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int origin); +int ftrace_regex_release(struct inode *inode, struct file *file); + /* defined in arch */ extern int ftrace_ip_converted(unsigned long ip); extern int ftrace_dyn_arch_init(void *data); @@ -311,6 +328,24 @@ static inline int ftrace_text_reserved(void *start, void *end) { return 0; } + +/* + * Again users of functions that have ftrace_ops may not + * have them defined when ftrace is not enabled, but these + * functions may still be called. Use a macro instead of inline. + */ +#define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; }) + +static inline ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf, + size_t cnt, loff_t *ppos) { return -ENODEV; } +static inline ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf, + size_t cnt, loff_t *ppos) { return -ENODEV; } +static inline loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int origin) +{ + return -ENODEV; +} +static inline int +ftrace_regex_release(struct inode *inode, struct file *file) { return -ENODEV; } #endif /* CONFIG_DYNAMIC_FTRACE */ /* totally disable ftrace - can not re-enable after this */ -- cgit v1.2.2 From 69a3083c4a7df0322d97bb2b43a33cb12af8131a Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 19 Dec 2011 15:21:16 -0500 Subject: ftrace: Decouple hash items from showing filtered functions The set_ftrace_filter shows "hashed" functions, which are functions that are added with operations to them (like traceon and traceoff). As other subsystems may be able to show what functions they are using for function tracing, the hash items should no longer be shown just because the FILTER flag is set. As they have nothing to do with other subsystems filters. Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index aa7559f0a224..d1ff0de18970 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -206,8 +206,9 @@ enum { FTRACE_ITER_FILTER = (1 << 0), FTRACE_ITER_NOTRACE = (1 << 1), FTRACE_ITER_PRINTALL = (1 << 2), - FTRACE_ITER_HASH = (1 << 3), - FTRACE_ITER_ENABLED = (1 << 4), + FTRACE_ITER_DO_HASH = (1 << 3), + FTRACE_ITER_HASH = (1 << 4), + FTRACE_ITER_ENABLED = (1 << 5), }; void arch_ftrace_update_code(int command); -- cgit v1.2.2 From 2a85a37f168d2b4d74d493b578af4dc9032be92e Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 19 Dec 2011 21:57:44 -0500 Subject: ftrace: Allow access to the boot time function enabling Change set_ftrace_early_filter() to ftrace_set_early_filter() and make it a global function. This will allow other subsystems in the kernel to be able to enable function tracing at start up and reuse the ftrace function parsing code. Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index d1ff0de18970..41df6f501656 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -235,6 +235,9 @@ ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf, loff_t ftrace_regex_lseek(struct file *file, loff_t offset, int origin); int ftrace_regex_release(struct inode *inode, struct file *file); +void __init +ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable); + /* defined in arch */ extern int ftrace_ip_converted(unsigned long ip); extern int ftrace_dyn_arch_init(void *data); -- cgit v1.2.2 From 96de37b62ca525cd77d2e85aea1472846ee31c4d Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Sat, 7 Jan 2012 17:26:49 -0500 Subject: tracing: Fix compile error when static ftrace is enabled The stack tracer uses the call ftrace_set_early_filter() function to allow the stack tracer to pick its own functions on boot. But this function is not defined if dynamic ftrace is not set. This causes a compiler error when stack tracer is enabled and dynamic ftrace is not. Reported-by: Ingo Molnar Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 41df6f501656..028e26f0bf08 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -339,6 +339,7 @@ static inline int ftrace_text_reserved(void *start, void *end) * functions may still be called. Use a macro instead of inline. */ #define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; }) +#define ftrace_set_early_filter(ops, buf, enable) do { } while (0) static inline ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf, size_t cnt, loff_t *ppos) { return -ENODEV; } -- cgit v1.2.2