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Commit 7deb18dc authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

x86: Introduce text_poke_smp_batch() for batch-code modifying 



Introduce text_poke_smp_batch(). This function modifies several
text areas with one stop_machine() on SMP. Because calling
stop_machine() is heavy task, it is better to aggregate
text_poke requests.

( Note: I've talked with Rusty about this interface, and
  he would not like to expand stop_machine() interface, since
  it is not for generic use. )

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <20101203095422.2961.51217.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 0490cd1f

arch/x86/include/asm/alternative.h

+7 −0
Original line number Diff line number Diff line
@@ -180,8 +180,15 @@ extern void *text_poke_early(void *addr, const void *opcode, size_t len); 
 * On the local CPU you need to be protected again NMI or MCE handlers seeing an

 * inconsistent instruction while you patch.

 */

struct text_poke_param {

	void *addr;

	const void *opcode;

	size_t len;

};



extern void *text_poke(void *addr, const void *opcode, size_t len);

extern void *text_poke_smp(void *addr, const void *opcode, size_t len);

extern void text_poke_smp_batch(struct text_poke_param *params, int n);



#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)

#define IDEAL_NOP_SIZE_5 5

arch/x86/kernel/alternative.c

+40 −9
Original line number Diff line number Diff line
@@ -591,17 +591,21 @@ static atomic_t stop_machine_first; 
static int wrote_text;



struct text_poke_params {

	void *addr;

	const void *opcode;

	size_t len;

	struct text_poke_param *params;

	int nparams;

};



static int __kprobes stop_machine_text_poke(void *data)

{

	struct text_poke_params *tpp = data;

	struct text_poke_param *p;

	int i;



	if (atomic_dec_and_test(&stop_machine_first)) {

		text_poke(tpp->addr, tpp->opcode, tpp->len);

		for (i = 0; i < tpp->nparams; i++) {

			p = &tpp->params[i];

			text_poke(p->addr, p->opcode, p->len);

		}

		smp_wmb();	/* Make sure other cpus see that this has run */

		wrote_text = 1;

	} else {
@@ -610,8 +614,12 @@ static int __kprobes stop_machine_text_poke(void *data) 
		smp_mb();	/* Load wrote_text before following execution */

	}



	flush_icache_range((unsigned long)tpp->addr,

			   (unsigned long)tpp->addr + tpp->len);

	for (i = 0; i < tpp->nparams; i++) {

		p = &tpp->params[i];

		flush_icache_range((unsigned long)p->addr,

				   (unsigned long)p->addr + p->len);

	}



	return 0;

}
@@ -631,10 +639,13 @@ static int __kprobes stop_machine_text_poke(void *data) 
void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len)

{

	struct text_poke_params tpp;

	struct text_poke_param p;



	tpp.addr = addr;

	tpp.opcode = opcode;

	tpp.len = len;

	p.addr = addr;

	p.opcode = opcode;

	p.len = len;

	tpp.params = &p;

	tpp.nparams = 1;

	atomic_set(&stop_machine_first, 1);

	wrote_text = 0;

	/* Use __stop_machine() because the caller already got online_cpus. */
@@ -642,6 +653,26 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len) 
	return addr;

}



/**

 * text_poke_smp_batch - Update instructions on a live kernel on SMP

 * @params: an array of text_poke parameters

 * @n: the number of elements in params.

 *

 * Modify multi-byte instruction by using stop_machine() on SMP. Since the

 * stop_machine() is heavy task, it is better to aggregate text_poke requests

 * and do it once if possible.

 *

 * Note: Must be called under get_online_cpus() and text_mutex.

 */

void __kprobes text_poke_smp_batch(struct text_poke_param *params, int n)

{

	struct text_poke_params tpp = {.params = params, .nparams = n};



	atomic_set(&stop_machine_first, 1);

	wrote_text = 0;

	stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);

}



#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)



#ifdef CONFIG_X86_64