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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>
This commit is contained in:
Steven Rostedt 2008-08-14 15:45:09 -04:00 committed by Ingo Molnar
parent 68bf21aa15
commit 90d595fe5c
3 changed files with 19 additions and 0 deletions
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3
include/linux/ftrace.h
View File

@ -164,8 +164,11 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
extern void ftrace_init(void);
extern void ftrace_init_module(unsigned long *start, unsigned long *end);
#else
static inline void ftrace_init(void) { }
static inline void
ftrace_init_module(unsigned long *start, unsigned long *end) { }
#endif
#endif /* _LINUX_FTRACE_H */

11
kernel/module.c
View File

@ -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 @@ static noinline struct module *load_module(void __user *umod,
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 @@ static noinline struct module *load_module(void __user *umod,
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 @@ static noinline struct module *load_module(void __user *umod,
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;

5
kernel/trace/ftrace.c
View File

@ -1541,6 +1541,11 @@ static int ftrace_convert_nops(unsigned long *start,
return 0;
}
void ftrace_init_module(unsigned long *start, unsigned long *end)
{
ftrace_convert_nops(start, end);
}
extern unsigned long __start_mcount_loc[];
extern unsigned long __stop_mcount_loc[];