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-rw-r--r--kernel/power/hibernate.c6
-rw-r--r--kernel/power/suspend.c2
-rw-r--r--kernel/trace/Kconfig5
-rw-r--r--kernel/trace/Makefile1
-rw-r--r--kernel/trace/ftrace.c445
-rw-r--r--kernel/trace/ring_buffer.c26
-rw-r--r--kernel/trace/trace.c96
-rw-r--r--kernel/trace/trace.h2
-rw-r--r--kernel/trace/trace_events.c56
-rw-r--r--kernel/trace/trace_functions_graph.c43
-rw-r--r--kernel/trace/trace_output.c282
-rw-r--r--kernel/trace/trace_output.h4
-rw-r--r--kernel/trace/trace_seq.c428
13 files changed, 932 insertions, 464 deletions
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index fcc2611d3f14..a9dfa79b6bab 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -371,7 +371,6 @@ int hibernation_snapshot(int platform_mode)
}
suspend_console();
- ftrace_stop();
pm_restrict_gfp_mask();
error = dpm_suspend(PMSG_FREEZE);
@@ -397,7 +396,6 @@ int hibernation_snapshot(int platform_mode)
if (error || !in_suspend)
pm_restore_gfp_mask();
- ftrace_start();
resume_console();
dpm_complete(msg);
@@ -500,7 +498,6 @@ int hibernation_restore(int platform_mode)
pm_prepare_console();
suspend_console();
- ftrace_stop();
pm_restrict_gfp_mask();
error = dpm_suspend_start(PMSG_QUIESCE);
if (!error) {
@@ -508,7 +505,6 @@ int hibernation_restore(int platform_mode)
dpm_resume_end(PMSG_RECOVER);
}
pm_restore_gfp_mask();
- ftrace_start();
resume_console();
pm_restore_console();
return error;
@@ -535,7 +531,6 @@ int hibernation_platform_enter(void)
entering_platform_hibernation = true;
suspend_console();
- ftrace_stop();
error = dpm_suspend_start(PMSG_HIBERNATE);
if (error) {
if (hibernation_ops->recover)
@@ -579,7 +574,6 @@ int hibernation_platform_enter(void)
Resume_devices:
entering_platform_hibernation = false;
dpm_resume_end(PMSG_RESTORE);
- ftrace_start();
resume_console();
Close:
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index ed35a4790afe..4b736b4dfa96 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -248,7 +248,6 @@ static int suspend_enter(suspend_state_t state, bool *wakeup)
goto Platform_wake;
}
- ftrace_stop();
error = disable_nonboot_cpus();
if (error || suspend_test(TEST_CPUS))
goto Enable_cpus;
@@ -275,7 +274,6 @@ static int suspend_enter(suspend_state_t state, bool *wakeup)
Enable_cpus:
enable_nonboot_cpus();
- ftrace_start();
Platform_wake:
if (need_suspend_ops(state) && suspend_ops->wake)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index d4409356f40d..a5da09c899dd 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -29,11 +29,6 @@ config HAVE_FUNCTION_GRAPH_FP_TEST
help
See Documentation/trace/ftrace-design.txt
-config HAVE_FUNCTION_TRACE_MCOUNT_TEST
- bool
- help
- See Documentation/trace/ftrace-design.txt
-
config HAVE_DYNAMIC_FTRACE
bool
help
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 2611613f14f1..67d6369ddf83 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
obj-$(CONFIG_TRACING) += trace.o
obj-$(CONFIG_TRACING) += trace_output.o
+obj-$(CONFIG_TRACING) += trace_seq.o
obj-$(CONFIG_TRACING) += trace_stat.o
obj-$(CONFIG_TRACING) += trace_printk.o
obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index ac9d1dad630b..1654b12c891a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -80,9 +80,6 @@ static struct ftrace_ops ftrace_list_end __read_mostly = {
int ftrace_enabled __read_mostly;
static int last_ftrace_enabled;
-/* Quick disabling of function tracer. */
-int function_trace_stop __read_mostly;
-
/* Current function tracing op */
struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end;
/* What to set function_trace_op to */
@@ -1042,6 +1039,8 @@ static struct pid * const ftrace_swapper_pid = &init_struct_pid;
#ifdef CONFIG_DYNAMIC_FTRACE
+static struct ftrace_ops *removed_ops;
+
#ifndef CONFIG_FTRACE_MCOUNT_RECORD
# error Dynamic ftrace depends on MCOUNT_RECORD
#endif
@@ -1304,25 +1303,15 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
struct ftrace_hash *new_hash;
int size = src->count;
int bits = 0;
- int ret;
int i;
/*
- * Remove the current set, update the hash and add
- * them back.
- */
- ftrace_hash_rec_disable(ops, enable);
-
- /*
* If the new source is empty, just free dst and assign it
* the empty_hash.
*/
if (!src->count) {
- free_ftrace_hash_rcu(*dst);
- rcu_assign_pointer(*dst, EMPTY_HASH);
- /* still need to update the function records */
- ret = 0;
- goto out;
+ new_hash = EMPTY_HASH;
+ goto update;
}
/*
@@ -1335,10 +1324,9 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
if (bits > FTRACE_HASH_MAX_BITS)
bits = FTRACE_HASH_MAX_BITS;
- ret = -ENOMEM;
new_hash = alloc_ftrace_hash(bits);
if (!new_hash)
- goto out;
+ return -ENOMEM;
size = 1 << src->size_bits;
for (i = 0; i < size; i++) {
@@ -1349,20 +1337,20 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
}
}
+update:
+ /*
+ * Remove the current set, update the hash and add
+ * them back.
+ */
+ ftrace_hash_rec_disable(ops, enable);
+
old_hash = *dst;
rcu_assign_pointer(*dst, new_hash);
free_ftrace_hash_rcu(old_hash);
- ret = 0;
- out:
- /*
- * Enable regardless of ret:
- * On success, we enable the new hash.
- * On failure, we re-enable the original hash.
- */
ftrace_hash_rec_enable(ops, enable);
- return ret;
+ return 0;
}
/*
@@ -1492,6 +1480,53 @@ int ftrace_text_reserved(const void *start, const void *end)
return (int)!!ret;
}
+/* Test if ops registered to this rec needs regs */
+static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
+{
+ struct ftrace_ops *ops;
+ bool keep_regs = false;
+
+ for (ops = ftrace_ops_list;
+ ops != &ftrace_list_end; ops = ops->next) {
+ /* pass rec in as regs to have non-NULL val */
+ if (ftrace_ops_test(ops, rec->ip, rec)) {
+ if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
+ keep_regs = true;
+ break;
+ }
+ }
+ }
+
+ return keep_regs;
+}
+
+static void ftrace_remove_tramp(struct ftrace_ops *ops,
+ struct dyn_ftrace *rec)
+{
+ struct ftrace_func_entry *entry;
+
+ entry = ftrace_lookup_ip(ops->tramp_hash, rec->ip);
+ if (!entry)
+ return;
+
+ /*
+ * The tramp_hash entry will be removed at time
+ * of update.
+ */
+ ops->nr_trampolines--;
+ rec->flags &= ~FTRACE_FL_TRAMP;
+}
+
+static void ftrace_clear_tramps(struct dyn_ftrace *rec)
+{
+ struct ftrace_ops *op;
+
+ do_for_each_ftrace_op(op, ftrace_ops_list) {
+ if (op->nr_trampolines)
+ ftrace_remove_tramp(op, rec);
+ } while_for_each_ftrace_op(op);
+}
+
static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
int filter_hash,
bool inc)
@@ -1572,8 +1607,30 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
if (inc) {
rec->flags++;
- if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == FTRACE_REF_MAX))
+ if (FTRACE_WARN_ON(ftrace_rec_count(rec) == FTRACE_REF_MAX))
return;
+
+ /*
+ * If there's only a single callback registered to a
+ * function, and the ops has a trampoline registered
+ * for it, then we can call it directly.
+ */
+ if (ftrace_rec_count(rec) == 1 && ops->trampoline) {
+ rec->flags |= FTRACE_FL_TRAMP;
+ ops->nr_trampolines++;
+ } else {
+ /*
+ * If we are adding another function callback
+ * to this function, and the previous had a
+ * trampoline used, then we need to go back to
+ * the default trampoline.
+ */
+ rec->flags &= ~FTRACE_FL_TRAMP;
+
+ /* remove trampolines from any ops for this rec */
+ ftrace_clear_tramps(rec);
+ }
+
/*
* If any ops wants regs saved for this function
* then all ops will get saved regs.
@@ -1581,9 +1638,30 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
rec->flags |= FTRACE_FL_REGS;
} else {
- if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
+ if (FTRACE_WARN_ON(ftrace_rec_count(rec) == 0))
return;
rec->flags--;
+
+ if (ops->trampoline && !ftrace_rec_count(rec))
+ ftrace_remove_tramp(ops, rec);
+
+ /*
+ * If the rec had REGS enabled and the ops that is
+ * being removed had REGS set, then see if there is
+ * still any ops for this record that wants regs.
+ * If not, we can stop recording them.
+ */
+ if (ftrace_rec_count(rec) > 0 &&
+ rec->flags & FTRACE_FL_REGS &&
+ ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
+ if (!test_rec_ops_needs_regs(rec))
+ rec->flags &= ~FTRACE_FL_REGS;
+ }
+
+ /*
+ * flags will be cleared in ftrace_check_record()
+ * if rec count is zero.
+ */
}
count++;
/* Shortcut, if we handled all records, we are done. */
@@ -1668,17 +1746,23 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
* If we are disabling calls, then disable all records that
* are enabled.
*/
- if (enable && (rec->flags & ~FTRACE_FL_MASK))
+ if (enable && ftrace_rec_count(rec))
flag = FTRACE_FL_ENABLED;
/*
- * If enabling and the REGS flag does not match the REGS_EN, then
- * do not ignore this record. Set flags to fail the compare against
- * ENABLED.
+ * If enabling and the REGS flag does not match the REGS_EN, or
+ * the TRAMP flag doesn't match the TRAMP_EN, then do not ignore
+ * this record. Set flags to fail the compare against ENABLED.
*/
- if (flag &&
- (!(rec->flags & FTRACE_FL_REGS) != !(rec->flags & FTRACE_FL_REGS_EN)))
- flag |= FTRACE_FL_REGS;
+ if (flag) {
+ if (!(rec->flags & FTRACE_FL_REGS) !=
+ !(rec->flags & FTRACE_FL_REGS_EN))
+ flag |= FTRACE_FL_REGS;
+
+ if (!(rec->flags & FTRACE_FL_TRAMP) !=
+ !(rec->flags & FTRACE_FL_TRAMP_EN))
+ flag |= FTRACE_FL_TRAMP;
+ }
/* If the state of this record hasn't changed, then do nothing */
if ((rec->flags & FTRACE_FL_ENABLED) == flag)
@@ -1696,6 +1780,12 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
else
rec->flags &= ~FTRACE_FL_REGS_EN;
}
+ if (flag & FTRACE_FL_TRAMP) {
+ if (rec->flags & FTRACE_FL_TRAMP)
+ rec->flags |= FTRACE_FL_TRAMP_EN;
+ else
+ rec->flags &= ~FTRACE_FL_TRAMP_EN;
+ }
}
/*
@@ -1704,7 +1794,7 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
* Otherwise,
* return UPDATE_MODIFY_CALL to tell the caller to convert
* from the save regs, to a non-save regs function or
- * vice versa.
+ * vice versa, or from a trampoline call.
*/
if (flag & FTRACE_FL_ENABLED)
return FTRACE_UPDATE_MAKE_CALL;
@@ -1714,7 +1804,7 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
if (update) {
/* If there's no more users, clear all flags */
- if (!(rec->flags & ~FTRACE_FL_MASK))
+ if (!ftrace_rec_count(rec))
rec->flags = 0;
else
/* Just disable the record (keep REGS state) */
@@ -1751,6 +1841,43 @@ int ftrace_test_record(struct dyn_ftrace *rec, int enable)
return ftrace_check_record(rec, enable, 0);
}
+static struct ftrace_ops *
+ftrace_find_tramp_ops_curr(struct dyn_ftrace *rec)
+{
+ struct ftrace_ops *op;
+
+ /* Removed ops need to be tested first */
+ if (removed_ops && removed_ops->tramp_hash) {
+ if (ftrace_lookup_ip(removed_ops->tramp_hash, rec->ip))
+ return removed_ops;
+ }
+
+ do_for_each_ftrace_op(op, ftrace_ops_list) {
+ if (!op->tramp_hash)
+ continue;
+
+ if (ftrace_lookup_ip(op->tramp_hash, rec->ip))
+ return op;
+
+ } while_for_each_ftrace_op(op);
+
+ return NULL;
+}
+
+static struct ftrace_ops *
+ftrace_find_tramp_ops_new(struct dyn_ftrace *rec)
+{
+ struct ftrace_ops *op;
+
+ do_for_each_ftrace_op(op, ftrace_ops_list) {
+ /* pass rec in as regs to have non-NULL val */
+ if (ftrace_ops_test(op, rec->ip, rec))
+ return op;
+ } while_for_each_ftrace_op(op);
+
+ return NULL;
+}
+
/**
* ftrace_get_addr_new - Get the call address to set to
* @rec: The ftrace record descriptor
@@ -1763,6 +1890,20 @@ int ftrace_test_record(struct dyn_ftrace *rec, int enable)
*/
unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec)
{
+ struct ftrace_ops *ops;
+
+ /* Trampolines take precedence over regs */
+ if (rec->flags & FTRACE_FL_TRAMP) {
+ ops = ftrace_find_tramp_ops_new(rec);
+ if (FTRACE_WARN_ON(!ops || !ops->trampoline)) {
+ pr_warning("Bad trampoline accounting at: %p (%pS)\n",
+ (void *)rec->ip, (void *)rec->ip);
+ /* Ftrace is shutting down, return anything */
+ return (unsigned long)FTRACE_ADDR;
+ }
+ return ops->trampoline;
+ }
+
if (rec->flags & FTRACE_FL_REGS)
return (unsigned long)FTRACE_REGS_ADDR;
else
@@ -1781,6 +1922,20 @@ unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec)
*/
unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec)
{
+ struct ftrace_ops *ops;
+
+ /* Trampolines take precedence over regs */
+ if (rec->flags & FTRACE_FL_TRAMP_EN) {
+ ops = ftrace_find_tramp_ops_curr(rec);
+ if (FTRACE_WARN_ON(!ops)) {
+ pr_warning("Bad trampoline accounting at: %p (%pS)\n",
+ (void *)rec->ip, (void *)rec->ip);
+ /* Ftrace is shutting down, return anything */
+ return (unsigned long)FTRACE_ADDR;
+ }
+ return ops->trampoline;
+ }
+
if (rec->flags & FTRACE_FL_REGS_EN)
return (unsigned long)FTRACE_REGS_ADDR;
else
@@ -2023,6 +2178,89 @@ void __weak arch_ftrace_update_code(int command)
ftrace_run_stop_machine(command);
}
+static int ftrace_save_ops_tramp_hash(struct ftrace_ops *ops)
+{
+ struct ftrace_page *pg;
+ struct dyn_ftrace *rec;
+ int size, bits;
+ int ret;
+
+ size = ops->nr_trampolines;
+ bits = 0;
+ /*
+ * Make the hash size about 1/2 the # found
+ */
+ for (size /= 2; size; size >>= 1)
+ bits++;
+
+ ops->tramp_hash = alloc_ftrace_hash(bits);
+ /*
+ * TODO: a failed allocation is going to screw up
+ * the accounting of what needs to be modified
+ * and not. For now, we kill ftrace if we fail
+ * to allocate here. But there are ways around this,
+ * but that will take a little more work.
+ */
+ if (!ops->tramp_hash)
+ return -ENOMEM;
+
+ do_for_each_ftrace_rec(pg, rec) {
+ if (ftrace_rec_count(rec) == 1 &&
+ ftrace_ops_test(ops, rec->ip, rec)) {
+
+ /*
+ * If another ops adds to a rec, the rec will
+ * lose its trampoline and never get it back
+ * until all ops are off of it.
+ */
+ if (!(rec->flags & FTRACE_FL_TRAMP))
+ continue;
+
+ /* This record had better have a trampoline */
+ if (FTRACE_WARN_ON(!(rec->flags & FTRACE_FL_TRAMP_EN)))
+ return -1;
+
+ ret = add_hash_entry(ops->tramp_hash, rec->ip);
+ if (ret < 0)
+ return ret;
+ }
+ } while_for_each_ftrace_rec();
+
+ /* The number of recs in the hash must match nr_trampolines */
+ FTRACE_WARN_ON(ops->tramp_hash->count != ops->nr_trampolines);
+
+ return 0;
+}
+
+static int ftrace_save_tramp_hashes(void)
+{
+ struct ftrace_ops *op;
+ int ret;
+
+ /*
+ * Now that any trampoline is being used, we need to save the
+ * hashes for the ops that have them. This allows the mapping
+ * back from the record to the ops that has the trampoline to
+ * know what code is being replaced. Modifying code must always
+ * verify what it is changing.
+ */
+ do_for_each_ftrace_op(op, ftrace_ops_list) {
+
+ /* The tramp_hash is recreated each time. */
+ free_ftrace_hash(op->tramp_hash);
+ op->tramp_hash = NULL;
+
+ if (op->nr_trampolines) {
+ ret = ftrace_save_ops_tramp_hash(op);
+ if (ret)
+ return ret;
+ }
+
+ } while_for_each_ftrace_op(op);
+
+ return 0;
+}
+
static void ftrace_run_update_code(int command)
{
int ret;
@@ -2031,11 +2269,6 @@ static void ftrace_run_update_code(int command)
FTRACE_WARN_ON(ret);
if (ret)
return;
- /*
- * Do not call function tracer while we update the code.
- * We are in stop machine.
- */
- function_trace_stop++;
/*
* By default we use stop_machine() to modify the code.
@@ -2045,15 +2278,15 @@ static void ftrace_run_update_code(int command)
*/
arch_ftrace_update_code(command);
- function_trace_stop--;
-
ret = ftrace_arch_code_modify_post_process();
FTRACE_WARN_ON(ret);
+
+ ret = ftrace_save_tramp_hashes();
+ FTRACE_WARN_ON(ret);
}
static ftrace_func_t saved_ftrace_func;
static int ftrace_start_up;
-static int global_start_up;
static void control_ops_free(struct ftrace_ops *ops)
{
@@ -2117,8 +2350,7 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
ftrace_hash_rec_disable(ops, 1);
- if (!global_start_up)
- ops->flags &= ~FTRACE_OPS_FL_ENABLED;
+ ops->flags &= ~FTRACE_OPS_FL_ENABLED;
command |= FTRACE_UPDATE_CALLS;
@@ -2139,8 +2371,16 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
return 0;
}
+ /*
+ * If the ops uses a trampoline, then it needs to be
+ * tested first on update.
+ */
+ removed_ops = ops;
+
ftrace_run_update_code(command);
+ removed_ops = NULL;
+
/*
* Dynamic ops may be freed, we must make sure that all
* callers are done before leaving this function.
@@ -2398,7 +2638,8 @@ ftrace_allocate_pages(unsigned long num_to_init)
return start_pg;
free_pages:
- while (start_pg) {
+ pg = start_pg;
+ while (pg) {
order = get_count_order(pg->size / ENTRIES_PER_PAGE);
free_pages((unsigned long)pg->records, order);
start_pg = pg->next;
@@ -2595,8 +2836,10 @@ static void *t_start(struct seq_file *m, loff_t *pos)
* off, we can short cut and just print out that all
* functions are enabled.
*/
- if (iter->flags & FTRACE_ITER_FILTER &&
- ftrace_hash_empty(ops->filter_hash)) {
+ if ((iter->flags & FTRACE_ITER_FILTER &&
+ ftrace_hash_empty(ops->filter_hash)) ||
+ (iter->flags & FTRACE_ITER_NOTRACE &&
+ ftrace_hash_empty(ops->notrace_hash))) {
if (*pos > 0)
return t_hash_start(m, pos);
iter->flags |= FTRACE_ITER_PRINTALL;
@@ -2641,7 +2884,10 @@ static int t_show(struct seq_file *m, void *v)
return t_hash_show(m, iter);
if (iter->flags & FTRACE_ITER_PRINTALL) {
- seq_printf(m, "#### all functions enabled ####\n");
+ if (iter->flags & FTRACE_ITER_NOTRACE)
+ seq_printf(m, "#### no functions disabled ####\n");
+ else
+ seq_printf(m, "#### all functions enabled ####\n");
return 0;
}
@@ -2651,10 +2897,22 @@ static int t_show(struct seq_file *m, void *v)
return 0;
seq_printf(m, "%ps", (void *)rec->ip);
- if (iter->flags & FTRACE_ITER_ENABLED)
+ if (iter->flags & FTRACE_ITER_ENABLED) {
seq_printf(m, " (%ld)%s",
- rec->flags & ~FTRACE_FL_MASK,
- rec->flags & FTRACE_FL_REGS ? " R" : "");
+ ftrace_rec_count(rec),
+ rec->flags & FTRACE_FL_REGS ? " R" : " ");
+ if (rec->flags & FTRACE_FL_TRAMP_EN) {
+ struct ftrace_ops *ops;
+
+ ops = ftrace_find_tramp_ops_curr(rec);
+ if (ops && ops->trampoline)
+ seq_printf(m, "\ttramp: %pS",
+ (void *)ops->trampoline);
+ else
+ seq_printf(m, "\ttramp: ERROR!");
+ }
+ }
+
seq_printf(m, "\n");
return 0;
@@ -2702,13 +2960,6 @@ ftrace_enabled_open(struct inode *inode, struct file *file)
return iter ? 0 : -ENOMEM;
}
-static void ftrace_filter_reset(struct ftrace_hash *hash)
-{
- mutex_lock(&ftrace_lock);
- ftrace_hash_clear(hash);
- mutex_unlock(&ftrace_lock);
-}
-
/**
* ftrace_regex_open - initialize function tracer filter files
* @ops: The ftrace_ops that hold the hash filters
@@ -2758,7 +3009,13 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
hash = ops->filter_hash;
if (file->f_mode & FMODE_WRITE) {
- iter->hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, hash);
+ const int size_bits = FTRACE_HASH_DEFAULT_BITS;
+
+ if (file->f_flags & O_TRUNC)
+ iter->hash = alloc_ftrace_hash(size_bits);
+ else
+ iter->hash = alloc_and_copy_ftrace_hash(size_bits, hash);
+
if (!iter->hash) {
trace_parser_put(&iter->parser);
kfree(iter);
@@ -2767,10 +3024,6 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
}
}
- if ((file->f_mode & FMODE_WRITE) &&
- (file->f_flags & O_TRUNC))
- ftrace_filter_reset(iter->hash);
-
if (file->f_mode & FMODE_READ) {
iter->pg = ftrace_pages_start;
@@ -3471,14 +3724,16 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
else
orig_hash = &ops->notrace_hash;
- hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+ if (reset)
+ hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
+ else
+ hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
+
if (!hash) {
ret = -ENOMEM;
goto out_regex_unlock;
}
- if (reset)
- ftrace_filter_reset(hash);
if (buf && !ftrace_match_records(hash, buf, len)) {
ret = -EINVAL;
goto out_regex_unlock;
@@ -3630,6 +3885,7 @@ __setup("ftrace_filter=", set_ftrace_filter);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
+static char ftrace_graph_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
static int ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer);
static int __init set_graph_function(char *str)
@@ -3639,16 +3895,29 @@ static int __init set_graph_function(char *str)
}
__setup("ftrace_graph_filter=", set_graph_function);
-static void __init set_ftrace_early_graph(char *buf)
+static int __init set_graph_notrace_function(char *str)
+{
+ strlcpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE);
+ return 1;
+}
+__setup("ftrace_graph_notrace=", set_graph_notrace_function);
+
+static void __init set_ftrace_early_graph(char *buf, int enable)
{
int ret;
char *func;
+ unsigned long *table = ftrace_graph_funcs;
+ int *count = &ftrace_graph_count;
+
+ if (!enable) {
+ table = ftrace_graph_notrace_funcs;
+ count = &ftrace_graph_notrace_count;
+ }
while (buf) {
func = strsep(&buf, ",");
/* we allow only one expression at a time */
- ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,
- FTRACE_GRAPH_MAX_FUNCS, func);
+ ret = ftrace_set_func(table, count, FTRACE_GRAPH_MAX_FUNCS, func);
if (ret)
printk(KERN_DEBUG "ftrace: function %s not "
"traceable\n", func);
@@ -3677,7 +3946,9 @@ static void __init set_ftrace_early_filters(void)
ftrace_set_early_filter(&global_ops, ftrace_notrace_buf, 0);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
if (ftrace_graph_buf[0])
- set_ftrace_early_graph(ftrace_graph_buf);
+ set_ftrace_early_graph(ftrace_graph_buf, 1);
+ if (ftrace_graph_notrace_buf[0])
+ set_ftrace_early_graph(ftrace_graph_notrace_buf, 0);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
}
@@ -3819,7 +4090,12 @@ static int g_show(struct seq_file *m, void *v)
return 0;
if (ptr == (unsigned long *)1) {
- seq_printf(m, "#### all functions enabled ####\n");
+ struct ftrace_graph_data *fgd = m->private;
+
+ if (fgd->table == ftrace_graph_funcs)
+ seq_printf(m, "#### all functions enabled ####\n");
+ else
+ seq_printf(m, "#### no functions disabled ####\n");
return 0;
}
@@ -4447,9 +4723,6 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op;
int bit;
- if (function_trace_stop)
- return;
-
bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX);
if (bit < 0)
return;
@@ -4461,9 +4734,8 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
preempt_disable_notrace();
do_for_each_ftrace_op(op, ftrace_ops_list) {
if (ftrace_ops_test(op, ip, regs)) {
- if (WARN_ON(!op->func)) {
- function_trace_stop = 1;
- printk("op=%p %pS\n", op, op);
+ if (FTRACE_WARN_ON(!op->func)) {
+ pr_warn("op=%p %pS\n", op, op);
goto out;
}
op->func(ip, parent_ip, op, regs);
@@ -5084,6 +5356,12 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
/* Function graph doesn't use the .func field of global_ops */
global_ops.flags |= FTRACE_OPS_FL_STUB;
+#ifdef CONFIG_DYNAMIC_FTRACE
+ /* Optimize function graph calling (if implemented by arch) */
+ if (FTRACE_GRAPH_TRAMP_ADDR != 0)
+ global_ops.trampoline = FTRACE_GRAPH_TRAMP_ADDR;
+#endif
+
ret = ftrace_startup(&global_ops, FTRACE_START_FUNC_RET);
out:
@@ -5104,6 +5382,10 @@ void unregister_ftrace_graph(void)
__ftrace_graph_entry = ftrace_graph_entry_stub;
ftrace_shutdown(&global_ops, FTRACE_STOP_FUNC_RET);
global_ops.flags &= ~FTRACE_OPS_FL_STUB;
+#ifdef CONFIG_DYNAMIC_FTRACE
+ if (FTRACE_GRAPH_TRAMP_ADDR != 0)
+ global_ops.trampoline = 0;
+#endif
unregister_pm_notifier(&ftrace_suspend_notifier);
unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
@@ -5183,9 +5465,4 @@ void ftrace_graph_exit_task(struct task_struct *t)
kfree(ret_stack);
}
-
-void ftrace_graph_stop(void)
-{
- ftrace_stop();
-}
#endif
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index ff7027199a9a..925f629658d6 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1689,22 +1689,14 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
if (!cpu_buffer->nr_pages_to_update)
continue;
- /* The update must run on the CPU that is being updated. */
- preempt_disable();
- if (cpu == smp_processor_id() || !cpu_online(cpu)) {
+ /* Can't run something on an offline CPU. */
+ if (!cpu_online(cpu)) {
rb_update_pages(cpu_buffer);
cpu_buffer->nr_pages_to_update = 0;
} else {
- /*
- * Can not disable preemption for schedule_work_on()
- * on PREEMPT_RT.
- */
- preempt_enable();
schedule_work_on(cpu,
&cpu_buffer->update_pages_work);
- preempt_disable();
}
- preempt_enable();
}
/* wait for all the updates to complete */
@@ -1742,22 +1734,14 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
get_online_cpus();
- preempt_disable();
- /* The update must run on the CPU that is being updated. */
- if (cpu_id == smp_processor_id() || !cpu_online(cpu_id))
+ /* Can't run something on an offline CPU. */
+ if (!cpu_online(cpu_id))
rb_update_pages(cpu_buffer);
else {
- /*
- * Can not disable preemption for schedule_work_on()
- * on PREEMPT_RT.
- */
- preempt_enable();
schedule_work_on(cpu_id,
&cpu_buffer->update_pages_work);
wait_for_completion(&cpu_buffer->update_done);
- preempt_disable();
}
- preempt_enable();
cpu_buffer->nr_pages_to_update = 0;
put_online_cpus();
@@ -3775,7 +3759,7 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts)
if (rb_per_cpu_empty(cpu_buffer))
return NULL;
- if (iter->head >= local_read(&iter->head_page->page->commit)) {
+ if (iter->head >= rb_page_size(iter->head_page)) {
rb_inc_iter(iter);
goto again;
}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 291397e66669..8bb80fe08767 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -937,30 +937,6 @@ out:
return ret;
}
-ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
-{
- int len;
- int ret;
-
- if (!cnt)
- return 0;
-
- if (s->len <= s->readpos)
- return -EBUSY;
-
- len = s->len - s->readpos;
- if (cnt > len)
- cnt = len;
- ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
- if (ret == cnt)
- return -EFAULT;
-
- cnt -= ret;
-
- s->readpos += cnt;
- return cnt;
-}
-
static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
@@ -3699,6 +3675,7 @@ static const char readme_msg[] =
#endif
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
" set_graph_function\t- Trace the nested calls of a function (function_graph)\n"
+ " set_graph_notrace\t- Do not trace the nested calls of a function (function_graph)\n"
" max_graph_depth\t- Trace a limited depth of nested calls (0 is unlimited)\n"
#endif
#ifdef CONFIG_TRACER_SNAPSHOT
@@ -4238,10 +4215,9 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf,
}
static ssize_t
-tracing_max_lat_read(struct file *filp, char __user *ubuf,
- size_t cnt, loff_t *ppos)
+tracing_nsecs_read(unsigned long *ptr, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
{
- unsigned long *ptr = filp->private_data;
char buf[64];
int r;
@@ -4253,10 +4229,9 @@ tracing_max_lat_read(struct file *filp, char __user *ubuf,
}
static ssize_t
-tracing_max_lat_write(struct file *filp, const char __user *ubuf,
- size_t cnt, loff_t *ppos)
+tracing_nsecs_write(unsigned long *ptr, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
{
- unsigned long *ptr = filp->private_data;
unsigned long val;
int ret;
@@ -4269,6 +4244,52 @@ tracing_max_lat_write(struct file *filp, const char __user *ubuf,
return cnt;
}
+static ssize_t
+tracing_thresh_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ return tracing_nsecs_read(&tracing_thresh, ubuf, cnt, ppos);
+}
+
+static ssize_t
+tracing_thresh_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct trace_array *tr = filp->private_data;
+ int ret;
+
+ mutex_lock(&trace_types_lock);
+ ret = tracing_nsecs_write(&tracing_thresh, ubuf, cnt, ppos);
+ if (ret < 0)
+ goto out;
+
+ if (tr->current_trace->update_thresh) {
+ ret = tr->current_trace->update_thresh(tr);
+ if (ret < 0)
+ goto out;
+ }
+
+ ret = cnt;
+out:
+ mutex_unlock(&trace_types_lock);
+
+ return ret;
+}
+
+static ssize_t
+tracing_max_lat_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ return tracing_nsecs_read(filp->private_data, ubuf, cnt, ppos);
+}
+
+static ssize_t
+tracing_max_lat_write(struct file *filp, const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ return tracing_nsecs_write(filp->private_data, ubuf, cnt, ppos);
+}
+
static int tracing_open_pipe(struct inode *inode, struct file *filp)
{
struct trace_array *tr = inode->i_private;
@@ -5170,6 +5191,13 @@ static int snapshot_raw_open(struct inode *inode, struct file *filp)
#endif /* CONFIG_TRACER_SNAPSHOT */
+static const struct file_operations tracing_thresh_fops = {
+ .open = tracing_open_generic,
+ .read = tracing_thresh_read,
+ .write = tracing_thresh_write,
+ .llseek = generic_file_llseek,
+};
+
static const struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
@@ -6107,10 +6135,8 @@ destroy_trace_option_files(struct trace_option_dentry *topts)
if (!topts)
return;
- for (cnt = 0; topts[cnt].opt; cnt++) {
- if (topts[cnt].entry)
- debugfs_remove(topts[cnt].entry);
- }
+ for (cnt = 0; topts[cnt].opt; cnt++)
+ debugfs_remove(topts[cnt].entry);
kfree(topts);
}
@@ -6533,7 +6559,7 @@ static __init int tracer_init_debugfs(void)
init_tracer_debugfs(&global_trace, d_tracer);
trace_create_file("tracing_thresh", 0644, d_tracer,
- &tracing_thresh, &tracing_max_lat_fops);
+ &global_trace, &tracing_thresh_fops);
trace_create_file("README", 0444, d_tracer,
NULL, &tracing_readme_fops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9258f5a815db..385391fb1d3b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -339,6 +339,7 @@ struct tracer_flags {
* @reset: called when one switches to another tracer
* @start: called when tracing is unpaused (echo 1 > tracing_enabled)
* @stop: called when tracing is paused (echo 0 > tracing_enabled)
+ * @update_thresh: called when tracing_thresh is updated
* @open: called when the trace file is opened
* @pipe_open: called when the trace_pipe file is opened
* @close: called when the trace file is released
@@ -357,6 +358,7 @@ struct tracer {
void (*reset)(struct trace_array *tr);
void (*start)(struct trace_array *tr);
void (*stop)(struct trace_array *tr);
+ int (*update_thresh)(struct trace_array *tr);
void (*open)(struct trace_iterator *iter);
void (*pipe_open)(struct trace_iterator *iter);
void (*close)(struct trace_iterator *iter);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 2de53628689f..3154eb39241d 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -8,6 +8,8 @@
*
*/
+#define pr_fmt(fmt) fmt
+
#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
@@ -1491,7 +1493,7 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
dir->entry = debugfs_create_dir(name, parent);
if (!dir->entry) {
- pr_warning("Failed to create system directory %s\n", name);
+ pr_warn("Failed to create system directory %s\n", name);
__put_system(system);
goto out_free;
}
@@ -1507,7 +1509,7 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
if (!entry) {
kfree(system->filter);
system->filter = NULL;
- pr_warning("Could not create debugfs '%s/filter' entry\n", name);
+ pr_warn("Could not create debugfs '%s/filter' entry\n", name);
}
trace_create_file("enable", 0644, dir->entry, dir,
@@ -1522,8 +1524,7 @@ event_subsystem_dir(struct trace_array *tr, const char *name,
out_fail:
/* Only print this message if failed on memory allocation */
if (!dir || !system)
- pr_warning("No memory to create event subsystem %s\n",
- name);
+ pr_warn("No memory to create event subsystem %s\n", name);
return NULL;
}
@@ -1551,8 +1552,7 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
name = ftrace_event_name(call);
file->dir = debugfs_create_dir(name, d_events);
if (!file->dir) {
- pr_warning("Could not create debugfs '%s' directory\n",
- name);
+ pr_warn("Could not create debugfs '%s' directory\n", name);
return -1;
}
@@ -1575,8 +1575,8 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
if (list_empty(head)) {
ret = call->class->define_fields(call);
if (ret < 0) {
- pr_warning("Could not initialize trace point"
- " events/%s\n", name);
+ pr_warn("Could not initialize trace point events/%s\n",
+ name);
return -1;
}
}
@@ -1649,8 +1649,7 @@ static int event_init(struct ftrace_event_call *call)
if (call->class->raw_init) {
ret = call->class->raw_init(call);
if (ret < 0 && ret != -ENOSYS)
- pr_warn("Could not initialize trace events/%s\n",
- name);
+ pr_warn("Could not initialize trace events/%s\n", name);
}
return ret;
@@ -1895,8 +1894,8 @@ __trace_add_event_dirs(struct trace_array *tr)
list_for_each_entry(call, &ftrace_events, list) {
ret = __trace_add_new_event(call, tr);
if (ret < 0)
- pr_warning("Could not create directory for event %s\n",
- ftrace_event_name(call));
+ pr_warn("Could not create directory for event %s\n",
+ ftrace_event_name(call));
}
}
@@ -2208,8 +2207,8 @@ __trace_early_add_event_dirs(struct trace_array *tr)
list_for_each_entry(file, &tr->events, list) {
ret = event_create_dir(tr->event_dir, file);
if (ret < 0)
- pr_warning("Could not create directory for event %s\n",
- ftrace_event_name(file->event_call));
+ pr_warn("Could not create directory for event %s\n",
+ ftrace_event_name(file->event_call));
}
}
@@ -2232,8 +2231,8 @@ __trace_early_add_events(struct trace_array *tr)
ret = __trace_early_add_new_event(call, tr);
if (ret < 0)
- pr_warning("Could not create early event %s\n",
- ftrace_event_name(call));
+ pr_warn("Could not create early event %s\n",
+ ftrace_event_name(call));
}
}
@@ -2280,13 +2279,13 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
entry = debugfs_create_file("set_event", 0644, parent,
tr, &ftrace_set_event_fops);
if (!entry) {
- pr_warning("Could not create debugfs 'set_event' entry\n");
+ pr_warn("Could not create debugfs 'set_event' entry\n");
return -ENOMEM;
}
d_events = debugfs_create_dir("events", parent);
if (!d_events) {
- pr_warning("Could not create debugfs 'events' directory\n");
+ pr_warn("Could not create debugfs 'events' directory\n");
return -ENOMEM;
}
@@ -2462,11 +2461,10 @@ static __init int event_trace_init(void)
entry = debugfs_create_file("available_events", 0444, d_tracer,
tr, &ftrace_avail_fops);
if (!entry)
- pr_warning("Could not create debugfs "
- "'available_events' entry\n");
+ pr_warn("Could not create debugfs 'available_events' entry\n");
if (trace_define_common_fields())
- pr_warning("tracing: Failed to allocate common fields");
+ pr_warn("tracing: Failed to allocate common fields");
ret = early_event_add_tracer(d_tracer, tr);
if (ret)
@@ -2475,7 +2473,7 @@ static __init int event_trace_init(void)
#ifdef CONFIG_MODULES
ret = register_module_notifier(&trace_module_nb);
if (ret)
- pr_warning("Failed to register trace events module notifier\n");
+ pr_warn("Failed to register trace events module notifier\n");
#endif
return 0;
}
@@ -2579,7 +2577,7 @@ static __init void event_trace_self_tests(void)
* it and the self test should not be on.
*/
if (file->flags & FTRACE_EVENT_FL_ENABLED) {
- pr_warning("Enabled event during self test!\n");
+ pr_warn("Enabled event during self test!\n");
WARN_ON_ONCE(1);
continue;
}
@@ -2607,8 +2605,8 @@ static __init void event_trace_self_tests(void)
ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error enabling system %s\n",
- system->name);
+ pr_warn("error enabling system %s\n",
+ system->name);
continue;
}
@@ -2616,8 +2614,8 @@ static __init void event_trace_self_tests(void)
ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error disabling system %s\n",
- system->name);
+ pr_warn("error disabling system %s\n",
+ system->name);
continue;
}
@@ -2631,7 +2629,7 @@ static __init void event_trace_self_tests(void)
ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error enabling all events\n");
+ pr_warn("error enabling all events\n");
return;
}
@@ -2640,7 +2638,7 @@ static __init void event_trace_self_tests(void)
/* reset sysname */
ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
if (WARN_ON_ONCE(ret)) {
- pr_warning("error disabling all events\n");
+ pr_warn("error disabling all events\n");
return;
}
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 4de3e57f723c..f0a0c982cde3 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -15,6 +15,33 @@
#include "trace.h"
#include "trace_output.h"
+static bool kill_ftrace_graph;
+
+/**
+ * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called
+ *
+ * ftrace_graph_stop() is called when a severe error is detected in
+ * the function graph tracing. This function is called by the critical
+ * paths of function graph to keep those paths from doing any more harm.
+ */
+bool ftrace_graph_is_dead(void)
+{
+ return kill_ftrace_graph;
+}
+
+/**
+ * ftrace_graph_stop - set to permanently disable function graph tracincg
+ *
+ * In case of an error int function graph tracing, this is called
+ * to try to keep function graph tracing from causing any more harm.
+ * Usually this is pretty severe and this is called to try to at least
+ * get a warning out to the user.
+ */
+void ftrace_graph_stop(void)
+{
+ kill_ftrace_graph = true;
+}
+
/* When set, irq functions will be ignored */
static int ftrace_graph_skip_irqs;
@@ -92,6 +119,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
unsigned long long calltime;
int index;
+ if (unlikely(ftrace_graph_is_dead()))
+ return -EBUSY;
+
if (!current->ret_stack)
return -EBUSY;
@@ -323,7 +353,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
return ret;
}
-int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
+static int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
{
if (tracing_thresh)
return 1;
@@ -412,7 +442,7 @@ void set_graph_array(struct trace_array *tr)
smp_mb();
}
-void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
+static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
{
if (tracing_thresh &&
(trace->rettime - trace->calltime < tracing_thresh))
@@ -445,6 +475,12 @@ static void graph_trace_reset(struct trace_array *tr)
unregister_ftrace_graph();
}
+static int graph_trace_update_thresh(struct trace_array *tr)
+{
+ graph_trace_reset(tr);
+ return graph_trace_init(tr);
+}
+
static int max_bytes_for_cpu;
static enum print_line_t
@@ -1399,7 +1435,7 @@ static void __print_graph_headers_flags(struct seq_file *s, u32 flags)
seq_printf(s, " | | | |\n");
}
-void print_graph_headers(struct seq_file *s)
+static void print_graph_headers(struct seq_file *s)
{
print_graph_headers_flags(s, tracer_flags.val);
}
@@ -1495,6 +1531,7 @@ static struct trace_event graph_trace_ret_event = {
static struct tracer graph_trace __tracer_data = {
.name = "function_graph",
+ .update_thresh = graph_trace_update_thresh,
.open = graph_trace_open,
.pipe_open = graph_trace_open,
.close = graph_trace_close,
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index f3dad80c20b2..c6977d5a9b12 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -20,23 +20,6 @@ static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
static int next_event_type = __TRACE_LAST_TYPE + 1;
-int trace_print_seq(struct seq_file *m, struct trace_seq *s)
-{
- int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
- int ret;
-
- ret = seq_write(m, s->buffer, len);
-
- /*
- * Only reset this buffer if we successfully wrote to the
- * seq_file buffer.
- */
- if (!ret)
- trace_seq_init(s);
-
- return ret;
-}
-
enum print_line_t trace_print_bputs_msg_only(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
@@ -85,257 +68,6 @@ enum print_line_t trace_print_printk_msg_only(struct trace_iterator *iter)
return TRACE_TYPE_HANDLED;
}
-/**
- * trace_seq_printf - sequence printing of trace information
- * @s: trace sequence descriptor
- * @fmt: printf format string
- *
- * It returns 0 if the trace oversizes the buffer's free
- * space, 1 otherwise.
- *
- * The tracer may use either sequence operations or its own
- * copy to user routines. To simplify formating of a trace
- * trace_seq_printf is used to store strings into a special
- * buffer (@s). Then the output may be either used by
- * the sequencer or pulled into another buffer.
- */
-int
-trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
-{
- int len = (PAGE_SIZE - 1) - s->len;
- va_list ap;
- int ret;
-
- if (s->full || !len)
- return 0;
-
- va_start(ap, fmt);
- ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
- va_end(ap);
-
- /* If we can't write it all, don't bother writing anything */
- if (ret >= len) {
- s->full = 1;
- return 0;
- }
-
- s->len += ret;
-
- return 1;
-}
-EXPORT_SYMBOL_GPL(trace_seq_printf);
-
-/**
- * trace_seq_bitmask - put a list of longs as a bitmask print output
- * @s: trace sequence descriptor
- * @maskp: points to an array of unsigned longs that represent a bitmask
- * @nmaskbits: The number of bits that are valid in @maskp
- *
- * It returns 0 if the trace oversizes the buffer's free
- * space, 1 otherwise.
- *
- * Writes a ASCII representation of a bitmask string into @s.
- */
-int
-trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
- int nmaskbits)
-{
- int len = (PAGE_SIZE - 1) - s->len;
- int ret;
-
- if (s->full || !len)
- return 0;
-
- ret = bitmap_scnprintf(s->buffer, len, maskp, nmaskbits);
- s->len += ret;
-
- return 1;
-}
-EXPORT_SYMBOL_GPL(trace_seq_bitmask);
-
-/**
- * trace_seq_vprintf - sequence printing of trace information
- * @s: trace sequence descriptor
- * @fmt: printf format string
- *
- * The tracer may use either sequence operations or its own
- * copy to user routines. To simplify formating of a trace
- * trace_seq_printf is used to store strings into a special
- * buffer (@s). Then the output may be either used by
- * the sequencer or pulled into another buffer.
- */
-int
-trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
-{
- int len = (PAGE_SIZE - 1) - s->len;
- int ret;
-
- if (s->full || !len)
- return 0;
-
- ret = vsnprintf(s->buffer + s->len, len, fmt, args);
-
- /* If we can't write it all, don't bother writing anything */
- if (ret >= len) {
- s->full = 1;
- return 0;
- }
-
- s->len += ret;
-
- return len;
-}
-EXPORT_SYMBOL_GPL(trace_seq_vprintf);
-
-int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
-{
- int len = (PAGE_SIZE - 1) - s->len;
- int ret;
-
- if (s->full || !len)
- return 0;
-
- ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
-
- /* If we can't write it all, don't bother writing anything */
- if (ret >= len) {
- s->full = 1;
- return 0;
- }
-
- s->len += ret;
-
- return len;
-}
-
-/**
- * trace_seq_puts - trace sequence printing of simple string
- * @s: trace sequence descriptor
- * @str: simple string to record
- *
- * The tracer may use either the sequence operations or its own
- * copy to user routines. This function records a simple string
- * into a special buffer (@s) for later retrieval by a sequencer
- * or other mechanism.
- */
-int trace_seq_puts(struct trace_seq *s, const char *str)
-{
- int len = strlen(str);
-
- if (s->full)
- return 0;
-
- if (len > ((PAGE_SIZE - 1) - s->len)) {
- s->full = 1;
- return 0;
- }
-
- memcpy(s->buffer + s->len, str, len);
- s->len += len;
-
- return len;
-}
-
-int trace_seq_putc(struct trace_seq *s, unsigned char c)
-{
- if (s->full)
- return 0;
-
- if (s->len >= (PAGE_SIZE - 1)) {
- s->full = 1;
- return 0;
- }
-
- s->buffer[s->len++] = c;
-
- return 1;
-}
-EXPORT_SYMBOL(trace_seq_putc);
-
-int trace_seq_putmem(struct trace_seq *s, const void *mem, size_t len)
-{
- if (s->full)
- return 0;
-
- if (len > ((PAGE_SIZE - 1) - s->len)) {
- s->full = 1;
- return 0;
- }
-
- memcpy(s->buffer + s->len, mem, len);
- s->len += len;
-
- return len;
-}
-
-int trace_seq_putmem_hex(struct trace_seq *s, const void *mem, size_t len)
-{
- unsigned char hex[HEX_CHARS];
- const unsigned char *data = mem;
- int i, j;
-
- if (s->full)
- return 0;
-
-#ifdef __BIG_ENDIAN
- for (i = 0, j = 0; i < len; i++) {
-#else
- for (i = len-1, j = 0; i >= 0; i--) {
-#endif
- hex[j++] = hex_asc_hi(data[i]);
- hex[j++] = hex_asc_lo(data[i]);
- }
- hex[j++] = ' ';
-
- return trace_seq_putmem(s, hex, j);
-}
-
-void *trace_seq_reserve(struct trace_seq *s, size_t len)
-{
- void *ret;
-
- if (s->full)
- return NULL;
-
- if (len > ((PAGE_SIZE - 1) - s->len)) {
- s->full = 1;
- return NULL;
- }
-
- ret = s->buffer + s->len;
- s->len += len;
-
- return ret;
-}
-
-int trace_seq_path(struct trace_seq *s, const struct path *path)
-{
- unsigned char *p;
-
- if (s->full)
- return 0;
-
- if (s->len >= (PAGE_SIZE - 1)) {
- s->full = 1;
- return 0;
- }
-
- p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
- if (!IS_ERR(p)) {
- p = mangle_path(s->buffer + s->len, p, "\n");
- if (p) {
- s->len = p - s->buffer;
- return 1;
- }
- } else {
- s->buffer[s->len++] = '?';
- return 1;
- }
-
- s->full = 1;
- return 0;
-}
-
const char *
ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
unsigned long flags,
@@ -343,7 +75,7 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
{
unsigned long mask;
const char *str;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
int i, first = 1;
for (i = 0; flag_array[i].name && flags; i++) {
@@ -379,7 +111,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
const struct trace_print_flags *symbol_array)
{
int i;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
for (i = 0; symbol_array[i].name; i++) {
@@ -390,7 +122,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
break;
}
- if (ret == (const char *)(p->buffer + p->len))
+ if (ret == (const char *)(trace_seq_buffer_ptr(p)))
trace_seq_printf(p, "0x%lx", val);
trace_seq_putc(p, 0);
@@ -405,7 +137,7 @@ ftrace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
const struct trace_print_flags_u64 *symbol_array)
{
int i;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
for (i = 0; symbol_array[i].name; i++) {
@@ -416,7 +148,7 @@ ftrace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
break;
}
- if (ret == (const char *)(p->buffer + p->len))
+ if (ret == (const char *)(trace_seq_buffer_ptr(p)))
trace_seq_printf(p, "0x%llx", val);
trace_seq_putc(p, 0);
@@ -430,7 +162,7 @@ const char *
ftrace_print_bitmask_seq(struct trace_seq *p, void *bitmask_ptr,
unsigned int bitmask_size)
{
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
trace_seq_bitmask(p, bitmask_ptr, bitmask_size * 8);
trace_seq_putc(p, 0);
@@ -443,7 +175,7 @@ const char *
ftrace_print_hex_seq(struct trace_seq *p, const unsigned char *buf, int buf_len)
{
int i;
- const char *ret = p->buffer + p->len;
+ const char *ret = trace_seq_buffer_ptr(p);
for (i = 0; i < buf_len; i++)
trace_seq_printf(p, "%s%2.2x", i == 0 ? "" : " ", buf[i]);
diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h
index 127a9d8c8357..80b25b585a70 100644
--- a/kernel/trace/trace_output.h
+++ b/kernel/trace/trace_output.h
@@ -35,9 +35,6 @@ trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry);
extern int __unregister_ftrace_event(struct trace_event *event);
extern struct rw_semaphore trace_event_sem;
-#define MAX_MEMHEX_BYTES 8
-#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
-
#define SEQ_PUT_FIELD_RET(s, x) \
do { \
if (!trace_seq_putmem(s, &(x), sizeof(x))) \
@@ -46,7 +43,6 @@ do { \
#define SEQ_PUT_HEX_FIELD_RET(s, x) \
do { \
- BUILD_BUG_ON(sizeof(x) > MAX_MEMHEX_BYTES); \
if (!trace_seq_putmem_hex(s, &(x), sizeof(x))) \
return TRACE_TYPE_PARTIAL_LINE; \
} while (0)
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
new file mode 100644
index 000000000000..1f24ed99dca2
--- /dev/null
+++ b/kernel/trace/trace_seq.c
@@ -0,0 +1,428 @@
+/*
+ * trace_seq.c
+ *
+ * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * The trace_seq is a handy tool that allows you to pass a descriptor around
+ * to a buffer that other functions can write to. It is similar to the
+ * seq_file functionality but has some differences.
+ *
+ * To use it, the trace_seq must be initialized with trace_seq_init().
+ * This will set up the counters within the descriptor. You can call
+ * trace_seq_init() more than once to reset the trace_seq to start
+ * from scratch.
+ *
+ * The buffer size is currently PAGE_SIZE, although it may become dynamic
+ * in the future.
+ *
+ * A write to the buffer will either succed or fail. That is, unlike
+ * sprintf() there will not be a partial write (well it may write into
+ * the buffer but it wont update the pointers). This allows users to
+ * try to write something into the trace_seq buffer and if it fails
+ * they can flush it and try again.
+ *
+ */
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/trace_seq.h>
+
+/* How much buffer is left on the trace_seq? */
+#define TRACE_SEQ_BUF_LEFT(s) ((PAGE_SIZE - 1) - (s)->len)
+
+/* How much buffer is written? */
+#define TRACE_SEQ_BUF_USED(s) min((s)->len, (unsigned int)(PAGE_SIZE - 1))
+
+/**
+ * trace_print_seq - move the contents of trace_seq into a seq_file
+ * @m: the seq_file descriptor that is the destination
+ * @s: the trace_seq descriptor that is the source.
+ *
+ * Returns 0 on success and non zero on error. If it succeeds to
+ * write to the seq_file it will reset the trace_seq, otherwise
+ * it does not modify the trace_seq to let the caller try again.
+ */
+int trace_print_seq(struct seq_file *m, struct trace_seq *s)
+{
+ unsigned int len = TRACE_SEQ_BUF_USED(s);
+ int ret;
+
+ ret = seq_write(m, s->buffer, len);
+
+ /*
+ * Only reset this buffer if we successfully wrote to the
+ * seq_file buffer. This lets the caller try again or
+ * do something else with the contents.
+ */
+ if (!ret)
+ trace_seq_init(s);
+
+ return ret;
+}
+
+/**
+ * trace_seq_printf - sequence printing of trace information
+ * @s: trace sequence descriptor
+ * @fmt: printf format string
+ *
+ * The tracer may use either sequence operations or its own
+ * copy to user routines. To simplify formating of a trace
+ * trace_seq_printf() is used to store strings into a special
+ * buffer (@s). Then the output may be either used by
+ * the sequencer or pulled into another buffer.
+ *
+ * Returns 1 if we successfully written all the contents to
+ * the buffer.
+ * Returns 0 if we the length to write is bigger than the
+ * reserved buffer space. In this case, nothing gets written.
+ */
+int trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
+{
+ unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+ va_list ap;
+ int ret;
+
+ if (s->full || !len)
+ return 0;
+
+ va_start(ap, fmt);
+ ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+ va_end(ap);
+
+ /* If we can't write it all, don't bother writing anything */
+ if (ret >= len) {
+ s->full = 1;
+ return 0;
+ }
+
+ s->len += ret;
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(trace_seq_printf);
+
+/**
+ * trace_seq_bitmask - write a bitmask array in its ASCII representation
+ * @s: trace sequence descriptor
+ * @maskp: points to an array of unsigned longs that represent a bitmask
+ * @nmaskbits: The number of bits that are valid in @maskp
+ *
+ * Writes a ASCII representation of a bitmask string into @s.
+ *
+ * Returns 1 if we successfully written all the contents to
+ * the buffer.
+ * Returns 0 if we the length to write is bigger than the
+ * reserved buffer space. In this case, nothing gets written.
+ */
+int trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
+ int nmaskbits)
+{
+ unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+ int ret;
+
+ if (s->full || !len)
+ return 0;
+
+ ret = bitmap_scnprintf(s->buffer, len, maskp, nmaskbits);
+ s->len += ret;
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(trace_seq_bitmask);
+
+/**
+ * trace_seq_vprintf - sequence printing of trace information
+ * @s: trace sequence descriptor
+ * @fmt: printf format string
+ *
+ * The tracer may use either sequence operations or its own
+ * copy to user routines. To simplify formating of a trace
+ * trace_seq_printf is used to store strings into a special
+ * buffer (@s). Then the output may be either used by
+ * the sequencer or pulled into another buffer.
+ *
+ * Returns how much it wrote to the buffer.
+ */
+int trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
+{
+ unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+ int ret;
+
+ if (s->full || !len)
+ return 0;
+
+ ret = vsnprintf(s->buffer + s->len, len, fmt, args);
+
+ /* If we can't write it all, don't bother writing anything */
+ if (ret >= len) {
+ s->full = 1;
+ return 0;
+ }
+
+ s->len += ret;
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(trace_seq_vprintf);
+
+/**
+ * trace_seq_bprintf - Write the printf string from binary arguments
+ * @s: trace sequence descriptor
+ * @fmt: The format string for the @binary arguments
+ * @binary: The binary arguments for @fmt.
+ *
+ * When recording in a fast path, a printf may be recorded with just
+ * saving the format and the arguments as they were passed to the
+ * function, instead of wasting cycles converting the arguments into
+ * ASCII characters. Instead, the arguments are saved in a 32 bit
+ * word array that is defined by the format string constraints.
+ *
+ * This function will take the format and the binary array and finish
+ * the conversion into the ASCII string within the buffer.
+ *
+ * Returns how much it wrote to the buffer.
+ */
+int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
+{
+ unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+ int ret;
+
+ if (s->full || !len)
+ return 0;
+
+ ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+
+ /* If we can't write it all, don't bother writing anything */
+ if (ret >= len) {
+ s->full = 1;
+ return 0;
+ }
+
+ s->len += ret;
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(trace_seq_bprintf);
+
+/**
+ * trace_seq_puts - trace sequence printing of simple string
+ * @s: trace sequence descriptor
+ * @str: simple string to record
+ *
+ * The tracer may use either the sequence operations or its own
+ * copy to user routines. This function records a simple string
+ * into a special buffer (@s) for later retrieval by a sequencer
+ * or other mechanism.
+ *
+ * Returns how much it wrote to the buffer.
+ */
+int trace_seq_puts(struct trace_seq *s, const char *str)
+{
+ unsigned int len = strlen(str);
+
+ if (s->full)
+ return 0;
+
+ if (len > TRACE_SEQ_BUF_LEFT(s)) {
+ s->full = 1;
+ return 0;
+ }
+
+ memcpy(s->buffer + s->len, str, len);
+ s->len += len;
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(trace_seq_puts);
+
+/**
+ * trace_seq_putc - trace sequence printing of simple character
+ * @s: trace sequence descriptor
+ * @c: simple character to record
+ *
+ * The tracer may use either the sequence operations or its own
+ * copy to user routines. This function records a simple charater
+ * into a special buffer (@s) for later retrieval by a sequencer
+ * or other mechanism.
+ *
+ * Returns how much it wrote to the buffer.
+ */
+int trace_seq_putc(struct trace_seq *s, unsigned char c)
+{
+ if (s->full)
+ return 0;
+
+ if (TRACE_SEQ_BUF_LEFT(s) < 1) {
+ s->full = 1;
+ return 0;
+ }
+
+ s->buffer[s->len++] = c;
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(trace_seq_putc);
+
+/**
+ * trace_seq_putmem - write raw data into the trace_seq buffer
+ * @s: trace sequence descriptor
+ * @mem: The raw memory to copy into the buffer
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * There may be cases where raw memory needs to be written into the
+ * buffer and a strcpy() would not work. Using this function allows
+ * for such cases.
+ *
+ * Returns how much it wrote to the buffer.
+ */
+int trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
+{
+ if (s->full)
+ return 0;
+
+ if (len > TRACE_SEQ_BUF_LEFT(s)) {
+ s->full = 1;
+ return 0;
+ }
+
+ memcpy(s->buffer + s->len, mem, len);
+ s->len += len;
+
+ return len;
+}
+EXPORT_SYMBOL_GPL(trace_seq_putmem);
+
+#define MAX_MEMHEX_BYTES 8U
+#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
+
+/**
+ * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
+ * @s: trace sequence descriptor
+ * @mem: The raw memory to write its hex ASCII representation of
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * This is similar to trace_seq_putmem() except instead of just copying the
+ * raw memory into the buffer it writes its ASCII representation of it
+ * in hex characters.
+ *
+ * Returns how much it wrote to the buffer.
+ */
+int trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
+ unsigned int len)
+{
+ unsigned char hex[HEX_CHARS];
+ const unsigned char *data = mem;
+ unsigned int start_len;
+ int i, j;
+ int cnt = 0;
+
+ if (s->full)
+ return 0;
+
+ while (len) {
+ start_len = min(len, HEX_CHARS - 1);
+#ifdef __BIG_ENDIAN
+ for (i = 0, j = 0; i < start_len; i++) {
+#else
+ for (i = start_len-1, j = 0; i >= 0; i--) {
+#endif
+ hex[j++] = hex_asc_hi(data[i]);
+ hex[j++] = hex_asc_lo(data[i]);
+ }
+ if (WARN_ON_ONCE(j == 0 || j/2 > len))
+ break;
+
+ /* j increments twice per loop */
+ len -= j / 2;
+ hex[j++] = ' ';
+
+ cnt += trace_seq_putmem(s, hex, j);
+ }
+ return cnt;
+}
+EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
+
+/**
+ * trace_seq_path - copy a path into the sequence buffer
+ * @s: trace sequence descriptor
+ * @path: path to write into the sequence buffer.
+ *
+ * Write a path name into the sequence buffer.
+ *
+ * Returns 1 if we successfully written all the contents to
+ * the buffer.
+ * Returns 0 if we the length to write is bigger than the
+ * reserved buffer space. In this case, nothing gets written.
+ */
+int trace_seq_path(struct trace_seq *s, const struct path *path)
+{
+ unsigned char *p;
+
+ if (s->full)
+ return 0;
+
+ if (TRACE_SEQ_BUF_LEFT(s) < 1) {
+ s->full = 1;
+ return 0;
+ }
+
+ p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
+ if (!IS_ERR(p)) {
+ p = mangle_path(s->buffer + s->len, p, "\n");
+ if (p) {
+ s->len = p - s->buffer;
+ return 1;
+ }
+ } else {
+ s->buffer[s->len++] = '?';
+ return 1;
+ }
+
+ s->full = 1;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(trace_seq_path);
+
+/**
+ * trace_seq_to_user - copy the squence buffer to user space
+ * @s: trace sequence descriptor
+ * @ubuf: The userspace memory location to copy to
+ * @cnt: The amount to copy
+ *
+ * Copies the sequence buffer into the userspace memory pointed to
+ * by @ubuf. It starts from the last read position (@s->readpos)
+ * and writes up to @cnt characters or till it reaches the end of
+ * the content in the buffer (@s->len), which ever comes first.
+ *
+ * On success, it returns a positive number of the number of bytes
+ * it copied.
+ *
+ * On failure it returns -EBUSY if all of the content in the
+ * sequence has been already read, which includes nothing in the
+ * sequenc (@s->len == @s->readpos).
+ *
+ * Returns -EFAULT if the copy to userspace fails.
+ */
+int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
+{
+ int len;
+ int ret;
+
+ if (!cnt)
+ return 0;
+
+ if (s->len <= s->readpos)
+ return -EBUSY;
+
+ len = s->len - s->readpos;
+ if (cnt > len)
+ cnt = len;
+ ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+ if (ret == cnt)
+ return -EFAULT;
+
+ cnt -= ret;
+
+ s->readpos += cnt;
+ return cnt;
+}
+EXPORT_SYMBOL_GPL(trace_seq_to_user);