ftrace: enable mcount recording for modules
This patch enables the loading of the __mcount_section of modules and
changing all the callers of mcount into nops.
The modification is done before the init_module function is called, so
again, we do not need to use kstop_machine to make these changes.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/module.c b/kernel/module.c
index 661d73d..d753fd9 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -47,6 +47,7 @@
#include <linux/license.h>
#include <asm/sections.h>
#include <linux/tracepoint.h>
+#include <linux/ftrace.h>
#if 0
#define DEBUGP printk
@@ -1834,6 +1835,7 @@
unsigned int markersstringsindex;
unsigned int tracepointsindex;
unsigned int tracepointsstringsindex;
+ unsigned int mcountindex;
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -2124,6 +2126,9 @@
tracepointsstringsindex = find_sec(hdr, sechdrs, secstrings,
"__tracepoints_strings");
+ mcountindex = find_sec(hdr, sechdrs, secstrings,
+ "__mcount_loc");
+
/* Now do relocations. */
for (i = 1; i < hdr->e_shnum; i++) {
const char *strtab = (char *)sechdrs[strindex].sh_addr;
@@ -2184,6 +2189,12 @@
mod->tracepoints + mod->num_tracepoints);
#endif
}
+
+ if (mcountindex) {
+ void *mseg = (void *)sechdrs[mcountindex].sh_addr;
+ ftrace_init_module(mseg, mseg + sechdrs[mcountindex].sh_size);
+ }
+
err = module_finalize(hdr, sechdrs, mod);
if (err < 0)
goto cleanup;