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Commit 90d595fe authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

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: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 68bf21aa

include/linux/ftrace.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */

kernel/module.c

+11 −0
Original line number Diff line number Diff line
@@ -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;

kernel/trace/ftrace.c

+5 −0
Original line number Diff line number Diff line
@@ -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[];