ftrace: mcount call site on boot nops core
This is the infrastructure to the converting the mcount call sites recorded by the __mcount_loc section into nops on boot. It also allows for using these sites to enable tracing as normal. When the __mcount_loc section is used, the "ftraced" kernel thread is disabled. This uses the current infrastructure to record the mcount call sites as well as convert them to nops. The mcount function is kept as a stub on boot up and not converted to the ftrace_record_ip function. We use the ftrace_record_ip to only record from the table. This patch does not handle modules. That comes with a later patch. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt
committed by
Ingo Molnar
Ingo Molnar
parent
8da3821ba5
commit
68bf21aa15
@@ -792,47 +792,7 @@ static int ftrace_update_code(void)
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return 1;
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}
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static int ftraced(void *ignore)
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{
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unsigned long usecs;
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while (!kthread_should_stop()) {
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set_current_state(TASK_INTERRUPTIBLE);
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/* check once a second */
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schedule_timeout(HZ);
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if (unlikely(ftrace_disabled))
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continue;
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mutex_lock(&ftrace_sysctl_lock);
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mutex_lock(&ftraced_lock);
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if (!ftraced_suspend && !ftraced_stop &&
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ftrace_update_code()) {
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usecs = nsecs_to_usecs(ftrace_update_time);
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if (ftrace_update_tot_cnt > 100000) {
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ftrace_update_tot_cnt = 0;
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pr_info("hm, dftrace overflow: %lu change%s"
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" (%lu total) in %lu usec%s\n",
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ftrace_update_cnt,
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ftrace_update_cnt != 1 ? "s" : "",
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ftrace_update_tot_cnt,
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usecs, usecs != 1 ? "s" : "");
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ftrace_disabled = 1;
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WARN_ON_ONCE(1);
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}
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}
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mutex_unlock(&ftraced_lock);
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mutex_unlock(&ftrace_sysctl_lock);
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ftrace_shutdown_replenish();
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}
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__set_current_state(TASK_RUNNING);
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return 0;
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}
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static int __init ftrace_dyn_table_alloc(void)
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static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
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{
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struct ftrace_page *pg;
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int cnt;
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@@ -859,7 +819,9 @@ static int __init ftrace_dyn_table_alloc(void)
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pg = ftrace_pages = ftrace_pages_start;
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cnt = NR_TO_INIT / ENTRIES_PER_PAGE;
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cnt = num_to_init / ENTRIES_PER_PAGE;
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pr_info("ftrace: allocating %ld hash entries in %d pages\n",
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num_to_init, cnt);
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for (i = 0; i < cnt; i++) {
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pg->next = (void *)get_zeroed_page(GFP_KERNEL);
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@@ -1556,6 +1518,104 @@ static __init int ftrace_init_debugfs(void)
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fs_initcall(ftrace_init_debugfs);
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#ifdef CONFIG_FTRACE_MCOUNT_RECORD
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static int ftrace_convert_nops(unsigned long *start,
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unsigned long *end)
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{
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unsigned long *p;
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unsigned long addr;
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unsigned long flags;
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p = start;
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while (p < end) {
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addr = ftrace_call_adjust(*p++);
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ftrace_record_ip(addr);
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ftrace_shutdown_replenish();
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}
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/* p is ignored */
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local_irq_save(flags);
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__ftrace_update_code(p);
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local_irq_restore(flags);
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return 0;
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}
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extern unsigned long __start_mcount_loc[];
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extern unsigned long __stop_mcount_loc[];
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void __init ftrace_init(void)
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{
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unsigned long count, addr, flags;
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int ret;
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/* Keep the ftrace pointer to the stub */
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addr = (unsigned long)ftrace_stub;
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local_irq_save(flags);
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ftrace_dyn_arch_init(&addr);
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local_irq_restore(flags);
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/* ftrace_dyn_arch_init places the return code in addr */
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if (addr)
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goto failed;
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count = __stop_mcount_loc - __start_mcount_loc;
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ret = ftrace_dyn_table_alloc(count);
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if (ret)
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goto failed;
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last_ftrace_enabled = ftrace_enabled = 1;
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ret = ftrace_convert_nops(__start_mcount_loc,
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__stop_mcount_loc);
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return;
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failed:
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ftrace_disabled = 1;
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}
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#else /* CONFIG_FTRACE_MCOUNT_RECORD */
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static int ftraced(void *ignore)
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{
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unsigned long usecs;
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while (!kthread_should_stop()) {
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set_current_state(TASK_INTERRUPTIBLE);
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/* check once a second */
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schedule_timeout(HZ);
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if (unlikely(ftrace_disabled))
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continue;
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mutex_lock(&ftrace_sysctl_lock);
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mutex_lock(&ftraced_lock);
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if (!ftraced_suspend && !ftraced_stop &&
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ftrace_update_code()) {
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usecs = nsecs_to_usecs(ftrace_update_time);
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if (ftrace_update_tot_cnt > 100000) {
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ftrace_update_tot_cnt = 0;
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pr_info("hm, dftrace overflow: %lu change%s"
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" (%lu total) in %lu usec%s\n",
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ftrace_update_cnt,
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ftrace_update_cnt != 1 ? "s" : "",
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ftrace_update_tot_cnt,
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usecs, usecs != 1 ? "s" : "");
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ftrace_disabled = 1;
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WARN_ON_ONCE(1);
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}
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}
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mutex_unlock(&ftraced_lock);
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mutex_unlock(&ftrace_sysctl_lock);
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ftrace_shutdown_replenish();
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}
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__set_current_state(TASK_RUNNING);
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return 0;
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}
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static int __init ftrace_dynamic_init(void)
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{
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struct task_struct *p;
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@@ -1572,7 +1632,7 @@ static int __init ftrace_dynamic_init(void)
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goto failed;
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}
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ret = ftrace_dyn_table_alloc();
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ret = ftrace_dyn_table_alloc(NR_TO_INIT);
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if (ret)
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goto failed;
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@@ -1593,6 +1653,8 @@ static int __init ftrace_dynamic_init(void)
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}
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core_initcall(ftrace_dynamic_init);
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#endif /* CONFIG_FTRACE_MCOUNT_RECORD */
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#else
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# define ftrace_startup() do { } while (0)
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# define ftrace_shutdown() do { } while (0)
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