From: Masami Hiramatsu mhiramat@kernel.org

Disable ftrace selftests when any tracer (kernel command line options like ftrace=, trace_events=, kprobe_events=, and boot-time tracing) starts running because selftest can disturb it.

Currently ftrace= and trace_events= are checked, but kprobe_events has a different flag, and boot-time tracing didn't checked. This unifies the disabled flag and all of those boot-time tracing features sets the flag.

This also fixes warnings on kprobe-event selftest (CONFIG_FTRACE_STARTUP_TEST=y and CONFIG_KPROBE_EVENTS=y) with boot-time tracing (ftrace.event.kprobes.EVENT.probes) like below;

[ 59.803496] trace_kprobe: Testing kprobe tracing: [ 59.804258] ------------[ cut here ]------------ [ 59.805682] WARNING: CPU: 3 PID: 1 at kernel/trace/trace_kprobe.c:1987 kprobe_trace_self_tests_ib [ 59.806944] Modules linked in: [ 59.807335] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.10.0-rc7+ #172 [ 59.808029] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/204 [ 59.808999] RIP: 0010:kprobe_trace_self_tests_init+0x5f/0x42b [ 59.809696] Code: e8 03 00 00 48 c7 c7 30 8e 07 82 e8 6d 3c 46 ff 48 c7 c6 00 b2 1a 81 48 c7 c7 7 [ 59.812439] RSP: 0018:ffffc90000013e78 EFLAGS: 00010282 [ 59.813038] RAX: 00000000ffffffef RBX: 0000000000000000 RCX: 0000000000049443 [ 59.813780] RDX: 0000000000049403 RSI: 0000000000049403 RDI: 000000000002deb0 [ 59.814589] RBP: ffffc90000013e90 R08: 0000000000000001 R09: 0000000000000001 [ 59.815349] R10: 0000000000000001 R11: 0000000000000000 R12: 00000000ffffffef [ 59.816138] R13: ffff888004613d80 R14: ffffffff82696940 R15: ffff888004429138 [ 59.816877] FS: 0000000000000000(0000) GS:ffff88807dcc0000(0000) knlGS:0000000000000000 [ 59.817772] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 59.818395] CR2: 0000000001a8dd38 CR3: 0000000002222000 CR4: 00000000000006a0 [ 59.819144] Call Trace: [ 59.819469] ? init_kprobe_trace+0x6b/0x6b [ 59.819948] do_one_initcall+0x5f/0x300 [ 59.820392] ? rcu_read_lock_sched_held+0x4f/0x80 [ 59.820916] kernel_init_freeable+0x22a/0x271 [ 59.821416] ? rest_init+0x241/0x241 [ 59.821841] kernel_init+0xe/0x10f [ 59.822251] ret_from_fork+0x22/0x30 [ 59.822683] irq event stamp: 16403349 [ 59.823121] hardirqs last enabled at (16403359): [<ffffffff810db81e>] console_unlock+0x48e/0x580 [ 59.824074] hardirqs last disabled at (16403368): [<ffffffff810db786>] console_unlock+0x3f6/0x580 [ 59.825036] softirqs last enabled at (16403200): [<ffffffff81c0033a>] __do_softirq+0x33a/0x484 [ 59.825982] softirqs last disabled at (16403087): [<ffffffff81a00f02>] asm_call_irq_on_stack+0x10 [ 59.827034] ---[ end trace 200c544775cdfeb3 ]--- [ 59.827635] trace_kprobe: error on probing function entry.

Link: https://lkml.kernel.org/r/160741764955.3448999.3347769358299456915.stgit@dev...

Fixes: 4d655281eb1b ("tracing/boot Add kprobe event support") Cc: Ingo Molnar mingo@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org --- kernel/trace/trace.c | 19 +++++++++++++------ kernel/trace/trace.h | 5 +++++ kernel/trace/trace_boot.c | 2 ++ kernel/trace/trace_events.c | 2 +- kernel/trace/trace_kprobe.c | 9 +++------ kernel/trace/trace_selftest.c | 2 +- 6 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6a282bbc7e7f..eee484afcc51 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -68,10 +68,21 @@ bool ring_buffer_expanded; static bool __read_mostly tracing_selftest_running;

/* - * If a tracer is running, we do not want to run SELFTEST. + * If boot-time tracing including tracers/events via kernel cmdline + * is running, we do not want to run SELFTEST. */ bool __read_mostly tracing_selftest_disabled;

+#ifdef CONFIG_FTRACE_STARTUP_TEST +void __init disable_tracing_selftest(const char *reason) +{ + if (!tracing_selftest_disabled) { + tracing_selftest_disabled = true; + pr_info("Ftrace startup test is disabled due to %s\n", reason); + } +} +#endif + /* Pipe tracepoints to printk */ struct trace_iterator *tracepoint_print_iter; int tracepoint_printk; @@ -2112,11 +2123,7 @@ int __init register_tracer(struct tracer *type) apply_trace_boot_options();

/* disable other selftests, since this will break it. */ - tracing_selftest_disabled = true; -#ifdef CONFIG_FTRACE_STARTUP_TEST - printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n", - type->name); -#endif + disable_tracing_selftest("running a tracer");

out_unlock: return ret; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 9462251cab92..e448d2da0b99 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -719,6 +719,8 @@ extern bool ring_buffer_expanded; extern bool tracing_selftest_disabled;

#ifdef CONFIG_FTRACE_STARTUP_TEST +extern void __init disable_tracing_selftest(const char *reason); + extern int trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr); extern int trace_selftest_startup_function_graph(struct tracer *trace, @@ -742,6 +744,9 @@ extern int trace_selftest_startup_branch(struct tracer *trace, */ #define __tracer_data __refdata #else +static inline void __init disable_tracing_selftest(const char *reason) +{ +} /* Tracers are seldom changed. Optimize when selftests are disabled. */ #define __tracer_data __read_mostly #endif /* CONFIG_FTRACE_STARTUP_TEST */ diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c index c22a152ef0b4..a82f03f385f8 100644 --- a/kernel/trace/trace_boot.c +++ b/kernel/trace/trace_boot.c @@ -344,6 +344,8 @@ static int __init trace_boot_init(void) trace_boot_init_one_instance(tr, trace_node); trace_boot_init_instances(trace_node);

+ disable_tracing_selftest("running boot-time tracing"); + return 0; } /* diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 98d194d8460e..7d207c5e9802 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -3201,7 +3201,7 @@ static __init int setup_trace_event(char *str) { strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE); ring_buffer_expanded = true; - tracing_selftest_disabled = true; + disable_tracing_selftest("running event tracing");

return 1; } diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index b911e9f6d9f5..b29f92c51b1a 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -25,11 +25,12 @@

/* Kprobe early definition from command line */ static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata; -static bool kprobe_boot_events_enabled __initdata;

static int __init set_kprobe_boot_events(char *str) { strlcpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE); + disable_tracing_selftest("running kprobe events"); + return 0; } __setup("kprobe_event=", set_kprobe_boot_events); @@ -1887,8 +1888,6 @@ static __init void setup_boot_kprobe_events(void) ret = trace_run_command(cmd, create_or_delete_trace_kprobe); if (ret) pr_warn("Failed to add event(%d): %s\n", ret, cmd); - else - kprobe_boot_events_enabled = true;

cmd = p; } @@ -1973,10 +1972,8 @@ static __init int kprobe_trace_self_tests_init(void) if (tracing_is_disabled()) return -ENODEV;

- if (kprobe_boot_events_enabled) { - pr_info("Skipping kprobe tests due to kprobe_event on cmdline\n"); + if (tracing_selftest_disabled) return 0; - }

target = kprobe_trace_selftest_target;

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index 5ed081c6471c..73ef12092250 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -786,7 +786,7 @@ trace_selftest_startup_function_graph(struct tracer *trace,

/* Have we just recovered from a hang? */ if (graph_hang_thresh > GRAPH_MAX_FUNC_TEST) { - tracing_selftest_disabled = true; + disable_tracing_selftest("recovering from a hang"); ret = -1; goto out; }