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kprobes: Use text_poke_smp_batch for unoptimizing

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Use text_poke_smp_batch() on unoptimization path for reducing
the number of stop_machine() issues. If the number of
unoptimizing probes is more than MAX_OPTIMIZE_PROBES(=256),
kprobes unoptimizes first MAX_OPTIMIZE_PROBES probes and kicks
optimizer for remaining probes.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
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: 2nddept-manager@sdl.hitachi.co.jp
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20101203095434.2961.22657.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Masami Hiramatsu 2010-12-03 18:54:34 +09:00 • committed by Ingo Molnar
parent cd7ebe2298
commit f984ba4eb5
3 changed files with 46 additions and 6 deletions
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40
arch/x86/kernel/kprobes.c
View file

@ -1457,6 +1457,46 @@ void __kprobes arch_optimize_kprobes(struct list_head *oplist)
text_poke_smp_batch(jump_poke_params, c); text_poke_smp_batch(jump_poke_params, c);
} }
static void __kprobes setup_unoptimize_kprobe(struct text_poke_param *tprm,
u8 *insn_buf,
struct optimized_kprobe *op)
{
/* Set int3 to first byte for kprobes */
insn_buf[0] = BREAKPOINT_INSTRUCTION;
memcpy(insn_buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
tprm->addr = op->kp.addr;
tprm->opcode = insn_buf;
tprm->len = RELATIVEJUMP_SIZE;
}
/*
* Recover original instructions and breakpoints from relative jumps.
* Caller must call with locking kprobe_mutex.
*/
extern void arch_unoptimize_kprobes(struct list_head *oplist,
struct list_head *done_list)
{
struct optimized_kprobe *op, *tmp;
int c = 0;
list_for_each_entry_safe(op, tmp, oplist, list) {
/* Setup param */
setup_unoptimize_kprobe(&jump_poke_params[c],
jump_poke_bufs[c].buf, op);
list_move(&op->list, done_list);
if (++c >= MAX_OPTIMIZE_PROBES)
break;
}
/*
* text_poke_smp doesn't support NMI/MCE code modifying.
* However, since kprobes itself also doesn't support NMI/MCE
* code probing, it's not a problem.
*/
text_poke_smp_batch(jump_poke_params, c);
}
/* Replace a relative jump with a breakpoint (int3). */ /* Replace a relative jump with a breakpoint (int3). */
void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op) void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op)
{ {

2
include/linux/kprobes.h
View file

@ -276,6 +276,8 @@ extern int arch_check_optimized_kprobe(struct optimized_kprobe *op);
extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op); extern int arch_prepare_optimized_kprobe(struct optimized_kprobe *op);
extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op); extern void arch_remove_optimized_kprobe(struct optimized_kprobe *op);
extern void arch_optimize_kprobes(struct list_head *oplist); extern void arch_optimize_kprobes(struct list_head *oplist);
extern void arch_unoptimize_kprobes(struct list_head *oplist,
struct list_head *done_list);
extern void arch_unoptimize_kprobe(struct optimized_kprobe *op); extern void arch_unoptimize_kprobe(struct optimized_kprobe *op);
extern kprobe_opcode_t *get_optinsn_slot(void); extern kprobe_opcode_t *get_optinsn_slot(void);
extern void free_optinsn_slot(kprobe_opcode_t *slot, int dirty); extern void free_optinsn_slot(kprobe_opcode_t *slot, int dirty);

10
kernel/kprobes.c
View file

@ -517,9 +517,9 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
/* Ditto to do_optimize_kprobes */ /* Ditto to do_optimize_kprobes */
get_online_cpus(); get_online_cpus();
mutex_lock(&text_mutex); mutex_lock(&text_mutex);
list_for_each_entry_safe(op, tmp, &unoptimizing_list, list) { arch_unoptimize_kprobes(&unoptimizing_list, free_list);
/* Unoptimize kprobes */ /* Loop free_list for disarming */
arch_unoptimize_kprobe(op); list_for_each_entry_safe(op, tmp, free_list, list) {
/* Disarm probes if marked disabled */ /* Disarm probes if marked disabled */
if (kprobe_disabled(&op->kp)) if (kprobe_disabled(&op->kp))
arch_disarm_kprobe(&op->kp); arch_disarm_kprobe(&op->kp);
@ -530,8 +530,6 @@ static __kprobes void do_unoptimize_kprobes(struct list_head *free_list)
* (reclaiming is done by do_free_cleaned_kprobes.) * (reclaiming is done by do_free_cleaned_kprobes.)
*/ */
hlist_del_rcu(&op->kp.hlist); hlist_del_rcu(&op->kp.hlist);
/* Move only unused probes on free_list */
list_move(&op->list, free_list);
} else } else
list_del_init(&op->list); list_del_init(&op->list);
} }
@ -592,7 +590,7 @@ static __kprobes void kprobe_optimizer(struct work_struct *work)
mutex_unlock(&module_mutex); mutex_unlock(&module_mutex);
/* Step 5: Kick optimizer again if needed */ /* Step 5: Kick optimizer again if needed */
if (!list_empty(&optimizing_list)) if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
kick_kprobe_optimizer(); kick_kprobe_optimizer();
else else
/* Wake up all waiters */ /* Wake up all waiters */