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 or multiple trace instances: - 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> - ftrace_dump_on_oops[=2/orig_cpu],<instance1_name>[=2/orig_cpu], <instrance2_name>[=2/orig_cpu]: new behavior -- dump the global trace buffer and multiple instance buffer on all CPUs, or only dump on CPU that triggered the oops if =2 or =orig_cpu is given 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/20240119080824.907101-1-quic_hyi...@quicinc.com/ .../admin-guide/kernel-parameters.txt | 26 ++- Documentation/admin-guide/sysctl/kernel.rst | 30 +++- include/linux/ftrace.h | 4 +- include/linux/kernel.h | 1 + kernel/sysctl.c | 4 +- kernel/trace/trace.c | 156 +++++++++++++----- kernel/trace/trace_selftest.c | 2 +- 7 files changed, 168 insertions(+), 55 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 31b3a25680d0..f4c05a43b561 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1561,12 +1561,28 @@ 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_opps[=2(orig_cpu) | =<instance>][,<instance> | + ,<instance>=2(orig_cpu)] [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 - dump only the buffer of the CPU that triggered the - oops. + If no parameter is passed, ftrace will dump global + buffers of all CPUs, if you pass 2 or orig_cpu, it + will dump only the buffer of the CPU that triggered + the oops, or the specific instance will be dumped if + its name is passed. Multiple instance dump is also + supported, and instances are separated by commas. Each + instance supports only dump on CPU that triggered the + oops by passing 2 or orig_cpu to it. + + ftrace_dump_on_opps=foo=orig_cpu + + The above will dump only the buffer of "foo" instance + on CPU that triggered the oops. + + ftrace_dump_on_opps,foo,bar=orig_cpu + + The above will dump global buffer on all CPUs, the + buffer of "foo" instance on all CPUs and the buffer + of "bar" instance on CPU that triggered the oops. 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..ea8e5f152edc 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -296,12 +296,30 @@ 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 on all CPUs. +<instance>=2(orig_cpu) Dump the specific instance buffer on the CPU + that triggered the oops. +======================= =========================================== + +Multiple instance dump is also supported, and instances are separated +by commas. If global buffer also needs to be dumped, please specify +the dump mode (1/2/orig_cpu) first for global buffer. + +So for example to dump "foo" and "bar" instance buffer on all CPUs, +user can:: + + echo "foo,bar" > /proc/sys/kernel/ftrace_dump_on_oops + +To dump global buffer and "foo" instance buffer on all +CPUs along with the "bar" instance buffer on CPU that triggered the +oops, user can:: + + echo "1,foo,bar=2" > /proc/sys/kernel/ftrace_dump_on_oops ftrace_enabled, stack_tracer_enabled ==================================== diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index e8921871ef9a..54d53f345d14 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 int ftrace_dump_on_oops_enabled(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..b142a4f41d34 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_PARAM, }; #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 2a7c6fd934e9..5622614d3035 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -130,9 +130,12 @@ 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 + * Multiple instance dump is also supported, and instances are seperated + * by commas. */ - -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 +181,6 @@ 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 +203,33 @@ static int __init set_cmdline_ftrace(char *str) } __setup("ftrace=", set_cmdline_ftrace); +int ftrace_dump_on_oops_enabled(void) +{ + if (!strcmp("0", ftrace_dump_on_oops)) + return 0; + else + return 1; +} + 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, "1", MAX_TRACER_SIZE); + strscpy(ftrace_dump_on_oops + 1, str, MAX_TRACER_SIZE - 1); + 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); @@ -10243,14 +10259,14 @@ 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) + if (!ftrace_dump_on_oops_enabled()) 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_PARAM); return NOTIFY_DONE; } @@ -10291,12 +10307,12 @@ 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); @@ -10316,22 +10332,19 @@ void trace_init_global_iter(struct trace_iterator *iter) iter->fmt_size = STATIC_FMT_BUF_SIZE; } -void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) +void trace_init_global_iter(struct trace_iterator *iter) +{ + trace_init_iter(iter, &global_trace); +} + +void ftrace_dump_one(struct trace_array *tr, enum ftrace_dump_mode dump_mode) { /* use static because iter can be a bit big for the stack */ static struct trace_iterator iter; - static atomic_t dump_running; - struct trace_array *tr = &global_trace; unsigned int old_userobj; unsigned long flags; int cnt = 0, cpu; - /* Only allow one dump user at a time. */ - if (atomic_inc_return(&dump_running) != 1) { - atomic_dec(&dump_running); - return; - } - /* * Always turn off tracing when we dump. * We don't need to show trace output of what happens @@ -10340,12 +10353,12 @@ 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); @@ -10356,21 +10369,15 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) /* don't look at user memory in panic mode */ tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ; - switch (oops_dump_mode) { - case DUMP_ALL: - iter.cpu_file = RING_BUFFER_ALL_CPUS; - break; - case DUMP_ORIG: + if (dump_mode == DUMP_ORIG) iter.cpu_file = raw_smp_processor_id(); - break; - case DUMP_NONE: - goto out_enable; - default: - printk(KERN_TRACE "Bad dumping mode, switching to all CPUs dump\n"); + else iter.cpu_file = RING_BUFFER_ALL_CPUS; - } - printk(KERN_TRACE "Dumping ftrace buffer:\n"); + if (tr == &global_trace) + printk(KERN_TRACE "Dumping ftrace buffer:\n"); + else + printk(KERN_TRACE "Dumping ftrace instance %s buffer:\n", tr->name); /* Did function tracer already get disabled? */ if (ftrace_is_dead()) { @@ -10412,15 +10419,84 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) else printk(KERN_TRACE "---------------------------------\n"); - out_enable: tr->trace_flags |= old_userobj; for_each_tracing_cpu(cpu) { atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); } - atomic_dec(&dump_running); local_irq_restore(flags); } + +static void ftrace_dump_by_param(void) +{ + bool first_param = true; + char dump_param[MAX_TRACER_SIZE]; + char *buf, *token, *inst_name; + struct trace_array *tr; + + strscpy(dump_param, ftrace_dump_on_oops, MAX_TRACER_SIZE); + buf = dump_param; + + while ((token = strsep(&buf, ",")) != NULL) { + if (first_param) { + first_param = false; + if (!strcmp("0", token)) + continue; + else if (!strcmp("1", token)) { + ftrace_dump_one(&global_trace, DUMP_ALL); + continue; + } + else if (!strcmp("2", token) || + !strcmp("orig_cpu", token)) { + ftrace_dump_one(&global_trace, DUMP_ORIG); + continue; + } + } + + inst_name = strsep(&token, "="); + tr = trace_array_find(inst_name); + if (!tr) { + printk(KERN_TRACE "Instance %s not found\n", inst_name); + continue; + } + + if (token && (!strcmp("2", token) || + !strcmp("orig_cpu", token))) + ftrace_dump_one(tr, DUMP_ORIG); + else + ftrace_dump_one(tr, DUMP_ALL); + } +} + +void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) +{ + static atomic_t dump_running; + + /* Only allow one dump user at a time. */ + if (atomic_inc_return(&dump_running) != 1) { + atomic_dec(&dump_running); + return; + } + + switch (oops_dump_mode) { + case DUMP_ALL: + ftrace_dump_one(&global_trace, DUMP_ALL); + break; + case DUMP_ORIG: + ftrace_dump_one(&global_trace, DUMP_ORIG); + break; + case DUMP_PARAM: + ftrace_dump_by_param(); + break; + case DUMP_NONE: + break; + default: + printk(KERN_TRACE "Bad dumping mode, switching to all CPUs dump\n"); + ftrace_dump_one(&global_trace, DUMP_ALL); + } + + atomic_dec(&dump_running); +} EXPORT_SYMBOL_GPL(ftrace_dump); #define WRITE_BUFSIZE 4096 diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index 529590499b1f..e9c5058a8efd 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 (ftrace_dump_on_oops_enabled()) { ftrace_dump(DUMP_ALL); /* ftrace_dump() disables tracing */ tracing_on(); -- 2.25.1
