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ftrace: Add sample with custom ops When reworking core ftrace code or architectural ftrace code, it's often necessary to test/analyse/benchmark a number of ftrace_ops configurations. This patch adds a module which can be used to explore some of those configurations. I'm using this to benchmark various options for changing the way trampolines and handling of ftrace_ops work on arm64, and ensuring other architectures aren't adversely affected. For example, in a QEMU+KVM VM running on a 2GHz Xeon E5-2660 workstation, loading the module in various configurations produces: | # insmod ftrace-ops.ko | ftrace_ops: registering: | relevant ops: 1 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 0 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: NO | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1681558ns (16ns / call) | # insmod ftrace-ops.ko nr_ops_irrelevant=5 | ftrace_ops: registering: | relevant ops: 1 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 5 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: NO | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1693042ns (16ns / call) | # insmod ftrace-ops.ko nr_ops_relevant=2 | ftrace_ops: registering: | relevant ops: 2 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 0 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: NO | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 11965582ns (119ns / call) | # insmod ftrace-ops.ko save_regs=true | ftrace_ops: registering: | relevant ops: 1 | tracee: tracee_relevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | irrelevant ops: 0 | tracee: tracee_irrelevant [ftrace_ops] | tracer: ops_func_nop [ftrace_ops] | saving registers: YES | assist recursion: NO | assist RCU: NO | ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 4459624ns (44ns / call) Link: https://lkml.kernel.org/r/20230103124912.2948963-4-mark.rutland@arm.com Cc: Florent Revest <revest@chromium.org> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> | 3 年前 | |
samples/ftrace: Adjust LoongArch register restore order in direct calls stable inclusion from stable-v6.6.120 commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8839 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a94bd2d93f7efb856d75dfd43fbe6e333723f58a -------------------------------- commit bb85d206be208bbf834883e948125a35ac59993a upstream. Ensure that in the ftrace direct call logic, the CPU register state (with ra = parent return address) is restored to the correct state after the execution of the custom trampoline function and before returning to the traced function. Additionally, guarantee the correctness of the jump logic for jr t0 (traced function address). Cc: stable@vger.kernel.org Fixes: 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support") Reported-by: Youling Tang <tangyouling@kylinos.cn> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a) Signed-off-by: Wentao Guan <guanwentao@uniontech.com> | 2 个月前 | |
samples/ftrace: Adjust LoongArch register restore order in direct calls stable inclusion from stable-v6.6.120 commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8839 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a94bd2d93f7efb856d75dfd43fbe6e333723f58a -------------------------------- commit bb85d206be208bbf834883e948125a35ac59993a upstream. Ensure that in the ftrace direct call logic, the CPU register state (with ra = parent return address) is restored to the correct state after the execution of the custom trampoline function and before returning to the traced function. Additionally, guarantee the correctness of the jump logic for jr t0 (traced function address). Cc: stable@vger.kernel.org Fixes: 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support") Reported-by: Youling Tang <tangyouling@kylinos.cn> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a) Signed-off-by: Wentao Guan <guanwentao@uniontech.com> | 2 个月前 | |
samples/ftrace: Adjust LoongArch register restore order in direct calls stable inclusion from stable-v6.6.120 commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8839 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a94bd2d93f7efb856d75dfd43fbe6e333723f58a -------------------------------- commit bb85d206be208bbf834883e948125a35ac59993a upstream. Ensure that in the ftrace direct call logic, the CPU register state (with ra = parent return address) is restored to the correct state after the execution of the custom trampoline function and before returning to the traced function. Additionally, guarantee the correctness of the jump logic for jr t0 (traced function address). Cc: stable@vger.kernel.org Fixes: 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support") Reported-by: Youling Tang <tangyouling@kylinos.cn> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a) Signed-off-by: Wentao Guan <guanwentao@uniontech.com> | 2 个月前 | |
samples/ftrace: Adjust LoongArch register restore order in direct calls stable inclusion from stable-v6.6.120 commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8839 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a94bd2d93f7efb856d75dfd43fbe6e333723f58a -------------------------------- commit bb85d206be208bbf834883e948125a35ac59993a upstream. Ensure that in the ftrace direct call logic, the CPU register state (with ra = parent return address) is restored to the correct state after the execution of the custom trampoline function and before returning to the traced function. Additionally, guarantee the correctness of the jump logic for jr t0 (traced function address). Cc: stable@vger.kernel.org Fixes: 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support") Reported-by: Youling Tang <tangyouling@kylinos.cn> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a) Signed-off-by: Wentao Guan <guanwentao@uniontech.com> | 2 个月前 | |
samples/ftrace: Adjust LoongArch register restore order in direct calls stable inclusion from stable-v6.6.120 commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8839 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a94bd2d93f7efb856d75dfd43fbe6e333723f58a -------------------------------- commit bb85d206be208bbf834883e948125a35ac59993a upstream. Ensure that in the ftrace direct call logic, the CPU register state (with ra = parent return address) is restored to the correct state after the execution of the custom trampoline function and before returning to the traced function. Additionally, guarantee the correctness of the jump logic for jr t0 (traced function address). Cc: stable@vger.kernel.org Fixes: 9cdc3b6a299c ("LoongArch: ftrace: Add direct call support") Reported-by: Youling Tang <tangyouling@kylinos.cn> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit a94bd2d93f7efb856d75dfd43fbe6e333723f58a) Signed-off-by: Wentao Guan <guanwentao@uniontech.com> | 2 个月前 | |
samples: ftrace: Make some global variables static smatch reports this representative issue samples/ftrace/ftrace-ops.c:15:14: warning: symbol 'nr_function_calls' was not declared. Should it be static? The nr_functions_calls and several other global variables are only used in ftrace-ops.c, so they should be static. Remove the instances of initializing static int to 0. Link: https://lore.kernel.org/linux-trace-kernel/20230130193708.1378108-1-trix@redhat.com Signed-off-by: Tom Rix <trix@redhat.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> | 3 年前 | |
tracing: samples: Initialize trace_array_printk() with the correct function stable inclusion from stable-v6.6.92 commit b1627af84e1eaf3a427e1546bf1c1673cd85b240 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/8365 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b1627af84e1eaf3a427e1546bf1c1673cd85b240 -------------------------------- commit 1b0c192c92ea1fe2dcb178f84adf15fe37c3e7c8 upstream. When using trace_array_printk() on a created instance, the correct function to use to initialize it is: trace_array_init_printk() Not trace_printk_init_buffer() The former is a proper function to use, the latter is for initializing trace_printk() and causes the NOTICE banner to be displayed. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Divya Indi <divya.indi@oracle.com> Link: https://lore.kernel.org/20250509152657.0f6744d9@gandalf.local.home Fixes: 89ed42495ef4a ("tracing: Sample module to demonstrate kernel access to Ftrace instances.") Fixes: 38ce2a9e33db6 ("tracing: Add trace_array_init_printk() to initialize instance trace_printk() buffers") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit b1627af84e1eaf3a427e1546bf1c1673cd85b240) Signed-off-by: Wentao Guan <guanwentao@uniontech.com> | 5 个月前 | |
tracing: Sample module to demonstrate kernel access to Ftrace instances. This is a sample module to demonstrate the use of the newly introduced and exported APIs to access Ftrace instances from within the kernel. Newly introduced APIs used here - 1. Create/Lookup a trace array with the given name. struct trace_array *trace_array_get_by_name(const char *name) 2. Destroy/Remove a trace array. int trace_array_destroy(struct trace_array *tr) 4. Enable/Disable trace events: int trace_array_set_clr_event(struct trace_array *tr, const char *system, const char *event, bool enable); Exported APIs - 1. trace_printk equivalent for instances. int trace_array_printk(struct trace_array *tr, unsigned long ip, const char *fmt, ...); 2. Helper function. void trace_printk_init_buffers(void); 3. To decrement the reference counter. void trace_array_put(struct trace_array *tr) Sample output(contents of /sys/kernel/tracing/instances/sample-instance) NOTE: Tracing disabled after ~5 sec) _-----=> irqs-off / _----=> need-resched | / _---=> hardirq/softirq || / _--=> preempt-depth ||| / delay TASK-PID CPU# |||| TIMESTAMP FUNCTION | | | |||| | | sample-instance-1452 [002] .... 49.430948: simple_thread: trace_array_printk: count=0 sample-instance-1452 [002] .... 49.430951: sample_event: count value=0 at jiffies=4294716608 sample-instance-1452 [002] .... 50.454847: simple_thread: trace_array_printk: count=1 sample-instance-1452 [002] .... 50.454849: sample_event: count value=1 at jiffies=4294717632 sample-instance-1452 [002] .... 51.478748: simple_thread: trace_array_printk: count=2 sample-instance-1452 [002] .... 51.478750: sample_event: count value=2 at jiffies=4294718656 sample-instance-1452 [002] .... 52.502652: simple_thread: trace_array_printk: count=3 sample-instance-1452 [002] .... 52.502655: sample_event: count value=3 at jiffies=4294719680 sample-instance-1452 [002] .... 53.526533: simple_thread: trace_array_printk: count=4 sample-instance-1452 [002] .... 53.526535: sample_event: count value=4 at jiffies=4294720704 sample-instance-1452 [002] .... 54.550438: simple_thread: trace_array_printk: count=5 sample-instance-1452 [002] .... 55.574336: simple_thread: trace_array_printk: count=6 Link: http://lkml.kernel.org/r/1574276919-11119-3-git-send-email-divya.indi@oracle.com Reviewed-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Signed-off-by: Divya Indi <divya.indi@oracle.com> [ Moved to samples/ftrace ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> | 6 年前 |
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