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[PATCH] kprobes: enable booster on the preemptible kernel

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When we are unregistering a kprobe-booster, we can't release its
instruction buffer immediately on the preemptive kernel, because some
processes might be preempted on the buffer.  The freeze_processes() and
thaw_processes() functions can clean most of processes up from the buffer.
There are still some non-frozen threads who have the PF_NOFREEZE flag.  If
those threads are sleeping (not preempted) at the known place outside the
buffer, we can ensure safety of freeing.

However, the processing of this check routine takes a long time.  So, this
patch introduces the garbage collection mechanism of insn_slot.  It also
introduces the "dirty" flag to free_insn_slot because of efficiency.

The "clean" instruction slots (dirty flag is cleared) are released
immediately.  But the "dirty" slots which are used by boosted kprobes, are
marked as garbages.  collect_garbage_slots() will be invoked to release
"dirty" slots if there are more than INSNS_PER_PAGE garbage slots or if
there are no unused slots.

Cc: "Keshavamurthy, Anil S" <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: "bibo,mao" <[email protected]>
Cc: Prasanna S Panchamukhi <[email protected]>
Cc: Yumiko Sugita <[email protected]>
Cc: Satoshi Oshima <[email protected]>
Cc: Hideo Aoki <[email protected]>
Signed-off-by: Masami Hiramatsu <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Masami Hiramatsu 2006-12-06 20:38:11 -08:00 • committed by Linus Torvalds
commit b4c6c34a53
7 changed files with 103 additions and 28 deletions
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2
include/linux/kprobes.h
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@ -165,7 +165,7 @@ extern void arch_disarm_kprobe(struct kprobe *p);
extern int arch_init_kprobes(void);
extern void show_registers(struct pt_regs *regs);
extern kprobe_opcode_t *get_insn_slot(void);
extern void free_insn_slot(kprobe_opcode_t *slot);
extern void free_insn_slot(kprobe_opcode_t *slot, int dirty);
extern void kprobes_inc_nmissed_count(struct kprobe *p);
/* Get the kprobe at this addr (if any) - called with preemption disabled */