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author | 2012-07-17 14:26:15 -0700 | |
---|---|---|
committer | 2012-09-06 22:16:58 -0700 | |
commit | 65f8c95e46a1827ae8bbc52a817ea308dd7d65ae (patch) | |
tree | adc856e8b50441b055350d8f1d83e3f641c77456 /fs/pstore | |
parent | pstore/ram: Add missing platform_device_unregister (diff) | |
download | linux-65f8c95e46a1827ae8bbc52a817ea308dd7d65ae.tar.gz linux-65f8c95e46a1827ae8bbc52a817ea308dd7d65ae.tar.bz2 linux-65f8c95e46a1827ae8bbc52a817ea308dd7d65ae.zip |
pstore/ftrace: Convert to its own enable/disable debugfs knob
With this patch we no longer reuse function tracer infrastructure, now
we register our own tracer back-end via a debugfs knob.
It's a bit more code, but that is the only downside. On the bright side we
have:
- Ability to make persistent_ram module removable (when needed, we can
move ftrace_ops struct into a module). Note that persistent_ram is still
not removable for other reasons, but with this patch it's just one
thing less to worry about;
- Pstore part is more isolated from the generic function tracer. We tried
it already by registering our own tracer in available_tracers, but that
way we're loosing ability to see the traces while we record them to
pstore. This solution is somewhere in the middle: we only register
"internal ftracer" back-end, but not the "front-end";
- When there is only pstore tracing enabled, the kernel will only write
to the pstore buffer, omitting function tracer buffer (which, of course,
still can be enabled via 'echo function > current_tracer').
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Diffstat (limited to 'fs/pstore')
-rw-r--r-- | fs/pstore/Kconfig | 1 | ||||
-rw-r--r-- | fs/pstore/ftrace.c | 96 | ||||
-rw-r--r-- | fs/pstore/internal.h | 6 | ||||
-rw-r--r-- | fs/pstore/platform.c | 1 |
4 files changed, 103 insertions, 1 deletions
diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig index d39bb5cce883..ca71db69da07 100644 --- a/fs/pstore/Kconfig +++ b/fs/pstore/Kconfig @@ -23,6 +23,7 @@ config PSTORE_FTRACE bool "Persistent function tracer" depends on PSTORE depends on FUNCTION_TRACER + depends on DEBUG_FS help With this option kernel traces function calls into a persistent ram buffer that can be decoded and dumped after reboot through diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c index a130d484b7d3..2d57e1ac0115 100644 --- a/fs/pstore/ftrace.c +++ b/fs/pstore/ftrace.c @@ -17,19 +17,113 @@ #include <linux/percpu.h> #include <linux/smp.h> #include <linux/atomic.h> +#include <linux/types.h> +#include <linux/mutex.h> +#include <linux/ftrace.h> +#include <linux/fs.h> +#include <linux/debugfs.h> +#include <linux/err.h> +#include <linux/cache.h> #include <asm/barrier.h> #include "internal.h" -void notrace pstore_ftrace_call(unsigned long ip, unsigned long parent_ip) +static void notrace pstore_ftrace_call(unsigned long ip, + unsigned long parent_ip) { + unsigned long flags; struct pstore_ftrace_record rec = {}; if (unlikely(oops_in_progress)) return; + local_irq_save(flags); + rec.ip = ip; rec.parent_ip = parent_ip; pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id()); psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec, sizeof(rec), psinfo); + + local_irq_restore(flags); +} + +static struct ftrace_ops pstore_ftrace_ops __read_mostly = { + .func = pstore_ftrace_call, +}; + +static DEFINE_MUTEX(pstore_ftrace_lock); +static bool pstore_ftrace_enabled; + +static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf, + size_t count, loff_t *ppos) +{ + u8 on; + ssize_t ret; + + ret = kstrtou8_from_user(buf, count, 2, &on); + if (ret) + return ret; + + mutex_lock(&pstore_ftrace_lock); + + if (!on ^ pstore_ftrace_enabled) + goto out; + + if (on) + ret = register_ftrace_function(&pstore_ftrace_ops); + else + ret = unregister_ftrace_function(&pstore_ftrace_ops); + if (ret) { + pr_err("%s: unable to %sregister ftrace ops: %zd\n", + __func__, on ? "" : "un", ret); + goto err; + } + + pstore_ftrace_enabled = on; +out: + ret = count; +err: + mutex_unlock(&pstore_ftrace_lock); + + return ret; +} + +static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf, + size_t count, loff_t *ppos) +{ + char val[] = { '0' + pstore_ftrace_enabled, '\n' }; + + return simple_read_from_buffer(buf, count, ppos, val, sizeof(val)); +} + +static const struct file_operations pstore_knob_fops = { + .open = simple_open, + .read = pstore_ftrace_knob_read, + .write = pstore_ftrace_knob_write, +}; + +void pstore_register_ftrace(void) +{ + struct dentry *dir; + struct dentry *file; + + if (!psinfo->write_buf) + return; + + dir = debugfs_create_dir("pstore", NULL); + if (!dir) { + pr_err("%s: unable to create pstore directory\n", __func__); + return; + } + + file = debugfs_create_file("record_ftrace", 0600, dir, NULL, + &pstore_knob_fops); + if (!file) { + pr_err("%s: unable to create record_ftrace file\n", __func__); + goto err_file; + } + + return; +err_file: + debugfs_remove(dir); } diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h index 0d0d3b7d5f12..4847f588b7d5 100644 --- a/fs/pstore/internal.h +++ b/fs/pstore/internal.h @@ -39,6 +39,12 @@ pstore_ftrace_decode_cpu(struct pstore_ftrace_record *rec) #endif } +#ifdef CONFIG_PSTORE_FTRACE +extern void pstore_register_ftrace(void); +#else +static inline void pstore_register_ftrace(void) {} +#endif + extern struct pstore_info *psinfo; extern void pstore_set_kmsg_bytes(int); diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index 29996e8793a7..6c23eab7f76c 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -236,6 +236,7 @@ int pstore_register(struct pstore_info *psi) kmsg_dump_register(&pstore_dumper); pstore_register_console(); + pstore_register_ftrace(); if (pstore_update_ms >= 0) { pstore_timer.expires = jiffies + |