[PATCH -tip v5 10/10] [RFC] kprobes/x86: Use text_poke_fixup() for jump optimization

Masami Hiramatsu
2009-11-23T23:20:28Z

Use text_poke_fixup() for jump optimization instead of text_poke() with
stop_machine().

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Anders Kaseorg <andersk@ksplice.com>
Cc: Tim Abbott <tabbott@ksplice.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

arch/x86/kernel/kprobes.c | 54 +++------------------------------------------
1 files changed, 3 insertions(+), 51 deletions(-)

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 6d81c11..3c5e30f 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -49,7 +49,6 @@
#include <linux/module.h>
#include <linux/kdebug.h>
#include <linux/kallsyms.h>
-#include <linux/stop_machine.h>

#include <asm/cacheflush.h>
#include <asm/desc.h>
@@ -1355,54 +1354,6 @@ int __kprobes arch_prepare_optimized_kprobe(struct optimized_kprobe *op)
return 0;
}

-/*
- * Cross-modifying kernel text with stop_machine().
- * This code originally comes from immediate value.
- * This does _not_ protect against NMI and MCE. However,
- * since kprobes can't probe NMI/MCE handler, it is OK for kprobes.
- */
-static atomic_t stop_machine_first;
-static int wrote_text;
-
-struct text_poke_param {
- void *addr;
- const void *opcode;
- size_t len;
-};
-
-static int __kprobes stop_machine_multibyte_poke(void *data)
-{
- struct text_poke_param *tpp = data;
-
- if (atomic_dec_and_test(&stop_machine_first)) {
- text_poke(tpp->addr, tpp->opcode, tpp->len);
- smp_wmb(); /* Make sure other cpus see that this has run */
- wrote_text = 1;
- } else {
- while (!wrote_text)
- smp_rmb();
- sync_core();
- }
-
- flush_icache_range((unsigned long)tpp->addr,
- (unsigned long)tpp->addr + tpp->len);
- return 0;
-}
-
-static void *__kprobes __multibyte_poke(void *addr, const void *opcode,
- size_t len)
-{
- struct text_poke_param tpp;
-
- tpp.addr = addr;
- tpp.opcode = opcode;
- tpp.len = len;
- atomic_set(&stop_machine_first, 1);
- wrote_text = 0;
- stop_machine(stop_machine_multibyte_poke, (void *)&tpp, NULL);
- return addr;
-}
-
/* Replace a breakpoint (int3) with a relative jump. */
int __kprobes arch_optimize_kprobe(struct optimized_kprobe *op)
{
@@ -1418,7 +1369,8 @@ int __kprobes arch_optimize_kprobe(struct optimized_kprobe *op)
jmp_code[0] = RELATIVEJUMP_OPCODE;
*(s32 *)(&jmp_code[1]) = rel;

- __multibyte_poke(op->kp.addr, jmp_code, RELATIVEJUMP_SIZE);
+ text_poke_fixup(op->kp.addr, jmp_code, RELATIVEJUMP_SIZE,
+ op->optinsn.insn);
return 0;
}

@@ -1430,7 +1382,7 @@ void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op)
/* Set int3 to first byte for kprobes */
buf[0] = BREAKPOINT_INSTRUCTION;
memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
- __multibyte_poke(op->kp.addr, buf, RELATIVEJUMP_SIZE);
+ text_poke_fixup(op->kp.addr, buf, RELATIVEJUMP_SIZE, op->optinsn.insn);
}

static int __kprobes setup_detour_execution(struct kprobe *p,