diff options
| -rw-r--r-- | Documentation/trace/ftrace-design.txt | 26 | ||||
| -rw-r--r-- | Documentation/trace/ftrace.txt | 2 | ||||
| -rw-r--r-- | kernel/trace/Kconfig | 4 | ||||
| -rw-r--r-- | kernel/trace/ring_buffer.c | 24 | ||||
| -rw-r--r-- | kernel/trace/trace.c | 5 |
5 files changed, 51 insertions, 10 deletions
diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt index 239f14b..6a5a579 100644 --- a/Documentation/trace/ftrace-design.txt +++ b/Documentation/trace/ftrace-design.txt @@ -1,5 +1,6 @@ function tracer guts ==================== + By Mike Frysinger Introduction ------------ @@ -173,14 +174,16 @@ void ftrace_graph_caller(void) unsigned long *frompc = &...; unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE; - prepare_ftrace_return(frompc, selfpc); + /* passing frame pointer up is optional -- see below */ + prepare_ftrace_return(frompc, selfpc, frame_pointer); /* restore all state needed by the ABI */ } #endif -For information on how to implement prepare_ftrace_return(), simply look at -the x86 version. The only architecture-specific piece in it is the setup of +For information on how to implement prepare_ftrace_return(), simply look at the +x86 version (the frame pointer passing is optional; see the next section for +more information). The only architecture-specific piece in it is the setup of the fault recovery table (the asm(...) code). The rest should be the same across architectures. @@ -205,6 +208,23 @@ void return_to_handler(void) #endif +HAVE_FUNCTION_GRAPH_FP_TEST +--------------------------- + +An arch may pass in a unique value (frame pointer) to both the entering and +exiting of a function. On exit, the value is compared and if it does not +match, then it will panic the kernel. This is largely a sanity check for bad +code generation with gcc. If gcc for your port sanely updates the frame +pointer under different opitmization levels, then ignore this option. + +However, adding support for it isn't terribly difficult. In your assembly code +that calls prepare_ftrace_return(), pass the frame pointer as the 3rd argument. +Then in the C version of that function, do what the x86 port does and pass it +along to ftrace_push_return_trace() instead of a stub value of 0. + +Similarly, when you call ftrace_return_to_handler(), pass it the frame pointer. + + HAVE_FTRACE_NMI_ENTER --------------------- diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 8179692..bab3040 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -1625,7 +1625,7 @@ If I am only interested in sys_nanosleep and hrtimer_interrupt: # echo sys_nanosleep hrtimer_interrupt \ > set_ftrace_filter - # echo ftrace > current_tracer + # echo function > current_tracer # echo 1 > tracing_enabled # usleep 1 # echo 0 > tracing_enabled diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 6c22d8a..60e2ce0 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -27,9 +27,7 @@ config HAVE_FUNCTION_GRAPH_TRACER config HAVE_FUNCTION_GRAPH_FP_TEST bool help - An arch may pass in a unique value (frame pointer) to both the - entering and exiting of a function. On exit, the value is compared - and if it does not match, then it will panic the kernel. + See Documentation/trace/ftrace-design.txt config HAVE_FUNCTION_TRACE_MCOUNT_TEST bool diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index edefe3b..8c1b2d2 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -464,6 +464,8 @@ struct ring_buffer_iter { struct ring_buffer_per_cpu *cpu_buffer; unsigned long head; struct buffer_page *head_page; + struct buffer_page *cache_reader_page; + unsigned long cache_read; u64 read_stamp; }; @@ -2716,6 +2718,8 @@ static void rb_iter_reset(struct ring_buffer_iter *iter) iter->read_stamp = cpu_buffer->read_stamp; else iter->read_stamp = iter->head_page->page->time_stamp; + iter->cache_reader_page = cpu_buffer->reader_page; + iter->cache_read = cpu_buffer->read; } /** @@ -3060,13 +3064,22 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) struct ring_buffer_event *event; int nr_loops = 0; - if (ring_buffer_iter_empty(iter)) - return NULL; - cpu_buffer = iter->cpu_buffer; buffer = cpu_buffer->buffer; + /* + * Check if someone performed a consuming read to + * the buffer. A consuming read invalidates the iterator + * and we need to reset the iterator in this case. + */ + if (unlikely(iter->cache_read != cpu_buffer->read || + iter->cache_reader_page != cpu_buffer->reader_page)) + rb_iter_reset(iter); + again: + if (ring_buffer_iter_empty(iter)) + return NULL; + /* * We repeat when a timestamp is encountered. * We can get multiple timestamps by nested interrupts or also @@ -3081,6 +3094,11 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) if (rb_per_cpu_empty(cpu_buffer)) return NULL; + if (iter->head >= local_read(&iter->head_page->page->commit)) { + rb_inc_iter(iter); + goto again; + } + event = rb_iter_head_event(iter); switch (event->type_len) { diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0df1b0f..eac6875 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -951,6 +951,11 @@ void trace_find_cmdline(int pid, char comm[]) return; } + if (WARN_ON_ONCE(pid < 0)) { + strcpy(comm, "<XXX>"); + return; + } + if (pid > PID_MAX_DEFAULT) { strcpy(comm, "<...>"); return; |
