Currently ftrace only dumps the global trace buffer on an OOPs. For debugging a production usecase, instance trace will be helpful to check specific problems since global trace buffer may be used for other purposes.
This patch extend the ftrace_dump_on_oops parameter to dump a specific trace instance: - ftrace_dump_on_oops=0: as before -- don't dump - ftrace_dump_on_oops[=1]: as before -- dump the global trace buffer on all CPUs - ftrace_dump_on_oops=2 or =orig_cpu: as before -- dump the global trace buffer on CPU that triggered the oops - ftrace_dump_on_oops=<instance_name>: new behavior -- dump the tracing instance matching <instance_name> Also, the sysctl node can handle the input accordingly. Cc: Ross Zwisler <zwis...@google.com> Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org> Signed-off-by: Huang Yiwei <quic_hyi...@quicinc.com> --- Link: https://lore.kernel.org/linux-trace-kernel/20221209125310.450ae...@gandalf.local.home/ .../admin-guide/kernel-parameters.txt | 9 +-- Documentation/admin-guide/sysctl/kernel.rst | 11 ++-- include/linux/ftrace.h | 4 +- include/linux/kernel.h | 1 + kernel/sysctl.c | 4 +- kernel/trace/trace.c | 64 ++++++++++++++----- kernel/trace/trace_selftest.c | 2 +- 7 files changed, 65 insertions(+), 30 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a36cf8cc582c..b3aa533253f1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1559,12 +1559,13 @@ The above will cause the "foo" tracing instance to trigger a snapshot at the end of boot up. - ftrace_dump_on_oops[=orig_cpu] + ftrace_dump_on_oops[=orig_cpu | =<instance>] [FTRACE] will dump the trace buffers on oops. - If no parameter is passed, ftrace will dump - buffers of all CPUs, but if you pass orig_cpu, it will + If no parameter is passed, ftrace will dump global + buffers of all CPUs, if you pass orig_cpu, it will dump only the buffer of the CPU that triggered the - oops. + oops, or specific instance will be dumped if instance + name is passed. ftrace_filter=[function-list] [FTRACE] Limit the functions traced by the function diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 6584a1f9bfe3..ecf036b63c48 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -296,11 +296,12 @@ kernel panic). This will output the contents of the ftrace buffers to the console. This is very useful for capturing traces that lead to crashes and outputting them to a serial console. -= =================================================== -0 Disabled (default). -1 Dump buffers of all CPUs. -2 Dump the buffer of the CPU that triggered the oops. -= =================================================== +=========== =================================================== +0 Disabled (default). +1 Dump buffers of all CPUs. +2(orig_cpu) Dump the buffer of the CPU that triggered the oops. +<instance> Dump the specific instance buffer. +=========== =================================================== ftrace_enabled, stack_tracer_enabled diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index e8921871ef9a..f20de4621ec1 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -1151,7 +1151,9 @@ static inline void unpause_graph_tracing(void) { } #ifdef CONFIG_TRACING enum ftrace_dump_mode; -extern enum ftrace_dump_mode ftrace_dump_on_oops; +#define MAX_TRACER_SIZE 100 +extern char ftrace_dump_on_oops[]; +extern enum ftrace_dump_mode get_ftrace_dump_mode(void); extern int tracepoint_printk; extern void disable_trace_on_warning(void); diff --git a/include/linux/kernel.h b/include/linux/kernel.h index d9ad21058eed..de4a76036372 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -255,6 +255,7 @@ enum ftrace_dump_mode { DUMP_NONE, DUMP_ALL, DUMP_ORIG, + DUMP_INSTANCE, }; #ifdef CONFIG_TRACING diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 157f7ce2942d..81cc974913bb 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1710,9 +1710,9 @@ static struct ctl_table kern_table[] = { { .procname = "ftrace_dump_on_oops", .data = &ftrace_dump_on_oops, - .maxlen = sizeof(int), + .maxlen = MAX_TRACER_SIZE, .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = proc_dostring, }, { .procname = "traceoff_on_warning", diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a0defe156b57..9a76a278e5c3 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -130,9 +130,10 @@ cpumask_var_t __read_mostly tracing_buffer_mask; * /proc/sys/kernel/ftrace_dump_on_oops * Set 1 if you want to dump buffers of all CPUs * Set 2 if you want to dump the buffer of the CPU that triggered oops + * Set instance name if you want to dump the specific trace instance */ - -enum ftrace_dump_mode ftrace_dump_on_oops; +/* Set to string format zero to disable by default */ +char ftrace_dump_on_oops[MAX_TRACER_SIZE] = "0"; /* When set, tracing will stop when a WARN*() is hit */ int __disable_trace_on_warning; @@ -178,7 +179,6 @@ static void ftrace_trace_userstack(struct trace_array *tr, struct trace_buffer *buffer, unsigned int trace_ctx); -#define MAX_TRACER_SIZE 100 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata; static char *default_bootup_tracer; @@ -201,19 +201,32 @@ static int __init set_cmdline_ftrace(char *str) } __setup("ftrace=", set_cmdline_ftrace); +enum ftrace_dump_mode get_ftrace_dump_mode(void) +{ + if (!strcmp("0", ftrace_dump_on_oops)) + return DUMP_NONE; + else if (!strcmp("1", ftrace_dump_on_oops)) + return DUMP_ALL; + else if (!strcmp("orig_cpu", ftrace_dump_on_oops) || + !strcmp("2", ftrace_dump_on_oops)) + return DUMP_ORIG; + else + return DUMP_INSTANCE; +} + static int __init set_ftrace_dump_on_oops(char *str) { - if (*str++ != '=' || !*str || !strcmp("1", str)) { - ftrace_dump_on_oops = DUMP_ALL; + if (!*str) { + strscpy(ftrace_dump_on_oops, "1", MAX_TRACER_SIZE); return 1; } - if (!strcmp("orig_cpu", str) || !strcmp("2", str)) { - ftrace_dump_on_oops = DUMP_ORIG; - return 1; - } + if (*str++ == '=') { + strscpy(ftrace_dump_on_oops, str, MAX_TRACER_SIZE); + return 1; + } - return 0; + return 0; } __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops); @@ -10085,14 +10098,16 @@ static struct notifier_block trace_die_notifier = { static int trace_die_panic_handler(struct notifier_block *self, unsigned long ev, void *unused) { - if (!ftrace_dump_on_oops) + enum ftrace_dump_mode dump_mode = get_ftrace_dump_mode(); + + if (!dump_mode) return NOTIFY_DONE; /* The die notifier requires DIE_OOPS to trigger */ if (self == &trace_die_notifier && ev != DIE_OOPS) return NOTIFY_DONE; - ftrace_dump(ftrace_dump_on_oops); + ftrace_dump(dump_mode); return NOTIFY_DONE; } @@ -10133,12 +10148,12 @@ trace_printk_seq(struct trace_seq *s) trace_seq_init(s); } -void trace_init_global_iter(struct trace_iterator *iter) +static void trace_init_iter(struct trace_iterator *iter, struct trace_array *tr) { - iter->tr = &global_trace; + iter->tr = tr; iter->trace = iter->tr->current_trace; iter->cpu_file = RING_BUFFER_ALL_CPUS; - iter->array_buffer = &global_trace.array_buffer; + iter->array_buffer = &tr->array_buffer; if (iter->trace && iter->trace->open) iter->trace->open(iter); @@ -10158,6 +10173,11 @@ void trace_init_global_iter(struct trace_iterator *iter) iter->fmt_size = STATIC_FMT_BUF_SIZE; } +void trace_init_global_iter(struct trace_iterator *iter) +{ + trace_init_iter(iter, &global_trace); +} + void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { /* use static because iter can be a bit big for the stack */ @@ -10168,6 +10188,15 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) unsigned long flags; int cnt = 0, cpu; + if (oops_dump_mode == DUMP_INSTANCE) { + tr = trace_array_find(ftrace_dump_on_oops); + if (!tr) { + printk(KERN_TRACE "Instance %s not found\n", + ftrace_dump_on_oops); + return; + } + } + /* Only allow one dump user at a time. */ if (atomic_inc_return(&dump_running) != 1) { atomic_dec(&dump_running); @@ -10182,12 +10211,12 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) * If the user does a sysrq-z, then they can re-enable * tracing with echo 1 > tracing_on. */ - tracing_off(); + tracer_tracing_off(tr); local_irq_save(flags); /* Simulate the iterator */ - trace_init_global_iter(&iter); + trace_init_iter(&iter, tr); for_each_tracing_cpu(cpu) { atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); @@ -10200,6 +10229,7 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) switch (oops_dump_mode) { case DUMP_ALL: + case DUMP_INSTANCE: iter.cpu_file = RING_BUFFER_ALL_CPUS; break; case DUMP_ORIG: diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index 529590499b1f..a9750a680324 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -768,7 +768,7 @@ static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace) if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) { ftrace_graph_stop(); printk(KERN_WARNING "BUG: Function graph tracer hang!\n"); - if (ftrace_dump_on_oops) { + if (get_ftrace_dump_mode()) { ftrace_dump(DUMP_ALL); /* ftrace_dump() disables tracing */ tracing_on(); -- 2.25.1
