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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2010-12-03 18:54:22 +0900
committerIngo Molnar <mingo@elte.hu>2010-12-06 17:59:31 +0100
commit7deb18dcf0478940ac979de002db1ed8ba6531dc (patch)
tree6fb52200daf5d02cb5aa59c46b856d25c44ea037 /arch
parent0490cd1f9d99569d3bd64e17adc88db06a5007be (diff)
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/alternative.h7
-rw-r--r--arch/x86/kernel/alternative.c49
2 files changed, 47 insertions, 9 deletions
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 76561d20ea2..4a2adaa9aef 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/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
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 5079f24c955..553d0b0d639 100644
--- a/arch/x86/kernel/alternative.c
+++ b/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