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jump label: Base patch for jump label

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base patch to implement 'jump labeling'. Based on a new 'asm goto' inline
assembly gcc mechanism, we can now branch to labels from an 'asm goto'
statment. This allows us to create a 'no-op' fastpath, which can subsequently
be patched with a jump to the slowpath code. This is useful for code which
might be rarely used, but which we'd like to be able to call, if needed.
Tracepoints are the current usecase that these are being implemented for.

Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <ee8b3595967989fdaf84e698dc7447d315ce972a.1284733808.git.jbaron@redhat.com>

[ cleaned up some formating ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jason Baron
2010-09-17 11:09:00 -04:00
committed by Steven Rostedt
parent fa6f2cc770
commit bf5438fca2
12 changed files with 442 additions and 4 deletions
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3
arch/x86/include/asm/alternative.h
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@@ -4,6 +4,7 @@
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/stringify.h>
#include <linux/jump_label.h>
#include <asm/asm.h>
/*
@@ -182,7 +183,7 @@ extern void *text_poke_early(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);
#if defined(CONFIG_DYNAMIC_FTRACE)
#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
#define IDEAL_NOP_SIZE_5 5
extern unsigned char ideal_nop5[IDEAL_NOP_SIZE_5];
extern void arch_init_ideal_nop5(void);