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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: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Steven 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: Ingo Molnar <mingo@elte.hu>
master
Masami Hiramatsu 11 years ago
committed by Ingo Molnar
parent
commit
7deb18dcf0
  1. 7
      arch/x86/include/asm/alternative.h
  2. 49
      arch/x86/kernel/alternative.c

7
arch/x86/include/asm/alternative.h

@ -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

49
arch/x86/kernel/alternative.c

@ -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

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