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ftrace: Allow for function tracing to record init functions on boot up

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Adding a hook into free_reserve_area() that informs ftrace that boot up init
text is being free, lets ftrace safely remove those init functions from its
records, which keeps ftrace from trying to modify text that no longer
exists.

Note, this still does not allow for tracing .init text of modules, as
modules require different work for freeing its init code.

Link: http://lkml.kernel.org/r/1488502497.7212.24.camel@linux.intel.com

Cc: linux-mm@kvack.org
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Requested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware)
2017-03-03 16:15:39 -05:00
parent dbeafd0d61
commit 42c269c88d
6 changed files with 58 additions and 1 deletions
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44
kernel/trace/ftrace.c
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@@ -5262,6 +5262,50 @@ void ftrace_module_init(struct module *mod)
}
#endif /* CONFIG_MODULES */
void ftrace_free_mem(void *start_ptr, void *end_ptr)
{
unsigned long start = (unsigned long)start_ptr;
unsigned long end = (unsigned long)end_ptr;
struct ftrace_page **last_pg = &ftrace_pages_start;
struct ftrace_page *pg;
struct dyn_ftrace *rec;
struct dyn_ftrace key;
int order;
key.ip = start;
key.flags = end; /* overload flags, as it is unsigned long */
mutex_lock(&ftrace_lock);
for (pg = ftrace_pages_start; pg; last_pg = &pg->next, pg = *last_pg) {
if (end < pg->records[0].ip ||
start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
continue;
again:
rec = bsearch(&key, pg->records, pg->index,
sizeof(struct dyn_ftrace),
ftrace_cmp_recs);
if (!rec)
continue;
pg->index--;
if (!pg->index) {
*last_pg = pg->next;
order = get_count_order(pg->size / ENTRIES_PER_PAGE);
free_pages((unsigned long)pg->records, order);
kfree(pg);
pg = container_of(last_pg, struct ftrace_page, next);
if (!(*last_pg))
ftrace_pages = pg;
continue;
}
memmove(rec, rec + 1,
(pg->index - (rec - pg->records)) * sizeof(*rec));
/* More than one function may be in this block */
goto again;
}
mutex_unlock(&ftrace_lock);
}
void __init ftrace_init(void)
{
extern unsigned long __start_mcount_loc[];