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Commit 3945dab4 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
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tracing, Text Edit Lock - SMP alternatives support 



Use the mutual exclusion provided by the text edit lock in alternatives code.
Since alternative_smp_* will be called from module init code, etc,
we'd better protect it from other subsystems.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <49B14332.9030109@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 4460fdad

arch/x86/kernel/alternative.c

+5 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include <linux/kprobes.h>

#include <linux/mm.h>

#include <linux/vmalloc.h>

#include <linux/memory.h>

#include <asm/alternative.h>

#include <asm/sections.h>

#include <asm/pgtable.h>
@@ -226,6 +227,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end) 
{

	u8 **ptr;



	mutex_lock(&text_mutex);

	for (ptr = start; ptr < end; ptr++) {

		if (*ptr < text)

			continue;
@@ -234,6 +236,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end) 
		/* turn DS segment override prefix into lock prefix */

		text_poke(*ptr, ((unsigned char []){0xf0}), 1);

	};

	mutex_unlock(&text_mutex);

}



static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end)
@@ -243,6 +246,7 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end 
	if (noreplace_smp)

		return;



	mutex_lock(&text_mutex);

	for (ptr = start; ptr < end; ptr++) {

		if (*ptr < text)

			continue;
@@ -251,6 +255,7 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end 
		/* turn lock prefix into DS segment override prefix */

		text_poke(*ptr, ((unsigned char []){0x3E}), 1);

	};

	mutex_unlock(&text_mutex);

}



struct smp_alt_module {