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kprobes: Introduce generic insn_slot framework

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Make insn_slot framework support various size slots.
Current insn_slot just supports one-size instruction buffer
slot. However, kprobes jump optimization needs larger size
buffers.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
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: 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 <compudj@krystal.dyndns.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
LKML-Reference: <20100225133358.6725.82430.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
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 <compudj@krystal.dyndns.org>
This commit is contained in:
Masami Hiramatsu 2010-02-25 08:33:59 -05:00 committed by Ingo Molnar
parent d498f76395
commit 4610ee1d36
1 changed files with 71 additions and 45 deletions
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116
kernel/kprobes.c
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@ -105,57 +105,74 @@ static struct kprobe_blackpoint kprobe_blacklist[] = {
* stepping on the instruction on a vmalloced/kmalloced/data page * stepping on the instruction on a vmalloced/kmalloced/data page
* is a recipe for disaster * is a recipe for disaster
*/ */
#define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
struct kprobe_insn_page { struct kprobe_insn_page {
struct list_head list; struct list_head list;
kprobe_opcode_t *insns; /* Page of instruction slots */ kprobe_opcode_t *insns; /* Page of instruction slots */
char slot_used[INSNS_PER_PAGE];
int nused; int nused;
int ngarbage; int ngarbage;
char slot_used[];
}; };
#define KPROBE_INSN_PAGE_SIZE(slots) \
(offsetof(struct kprobe_insn_page, slot_used) + \
(sizeof(char) * (slots)))
struct kprobe_insn_cache {
struct list_head pages; /* list of kprobe_insn_page */
size_t insn_size; /* size of instruction slot */
int nr_garbage;
};
static int slots_per_page(struct kprobe_insn_cache *c)
{
return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
}
enum kprobe_slot_state { enum kprobe_slot_state {
SLOT_CLEAN = 0, SLOT_CLEAN = 0,
SLOT_DIRTY = 1, SLOT_DIRTY = 1,
SLOT_USED = 2, SLOT_USED = 2,
}; };
static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_pages */ static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
static LIST_HEAD(kprobe_insn_pages); static struct kprobe_insn_cache kprobe_insn_slots = {
static int kprobe_garbage_slots; .pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
static int collect_garbage_slots(void); .insn_size = MAX_INSN_SIZE,
.nr_garbage = 0,
};
static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
/** /**
* __get_insn_slot() - Find a slot on an executable page for an instruction. * __get_insn_slot() - Find a slot on an executable page for an instruction.
* We allocate an executable page if there's no room on existing ones. * We allocate an executable page if there's no room on existing ones.
*/ */
static kprobe_opcode_t __kprobes *__get_insn_slot(void) static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
{ {
struct kprobe_insn_page *kip; struct kprobe_insn_page *kip;
retry: retry:
list_for_each_entry(kip, &kprobe_insn_pages, list) { list_for_each_entry(kip, &c->pages, list) {
if (kip->nused < INSNS_PER_PAGE) { if (kip->nused < slots_per_page(c)) {
int i; int i;
for (i = 0; i < INSNS_PER_PAGE; i++) { for (i = 0; i < slots_per_page(c); i++) {
if (kip->slot_used[i] == SLOT_CLEAN) { if (kip->slot_used[i] == SLOT_CLEAN) {
kip->slot_used[i] = SLOT_USED; kip->slot_used[i] = SLOT_USED;
kip->nused++; kip->nused++;
return kip->insns + (i * MAX_INSN_SIZE); return kip->insns + (i * c->insn_size);
} }
} }
/* Surprise! No unused slots. Fix kip->nused. */ /* kip->nused is broken. Fix it. */
kip->nused = INSNS_PER_PAGE; kip->nused = slots_per_page(c);
WARN_ON(1);
} }
} }
/* If there are any garbage slots, collect it and try again. */ /* If there are any garbage slots, collect it and try again. */
if (kprobe_garbage_slots && collect_garbage_slots() == 0) { if (c->nr_garbage && collect_garbage_slots(c) == 0)
goto retry; goto retry;
}
/* All out of space. Need to allocate a new page. Use slot 0. */ /* All out of space. Need to allocate a new page. */
kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL); kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
if (!kip) if (!kip)
return NULL; return NULL;
@ -170,20 +187,23 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(void)
return NULL; return NULL;
} }
INIT_LIST_HEAD(&kip->list); INIT_LIST_HEAD(&kip->list);
list_add(&kip->list, &kprobe_insn_pages); memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
kip->slot_used[0] = SLOT_USED; kip->slot_used[0] = SLOT_USED;
kip->nused = 1; kip->nused = 1;
kip->ngarbage = 0; kip->ngarbage = 0;
list_add(&kip->list, &c->pages);
return kip->insns; return kip->insns;
} }
kprobe_opcode_t __kprobes *get_insn_slot(void) kprobe_opcode_t __kprobes *get_insn_slot(void)
{ {
kprobe_opcode_t *ret; kprobe_opcode_t *ret = NULL;
mutex_lock(&kprobe_insn_mutex); mutex_lock(&kprobe_insn_mutex);
ret = __get_insn_slot(); ret = __get_insn_slot(&kprobe_insn_slots);
mutex_unlock(&kprobe_insn_mutex); mutex_unlock(&kprobe_insn_mutex);
return ret; return ret;
} }
@ -199,7 +219,7 @@ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
* so as not to have to set it up again the * so as not to have to set it up again the
* next time somebody inserts a probe. * next time somebody inserts a probe.
*/ */
if (!list_is_singular(&kprobe_insn_pages)) { if (!list_is_singular(&kip->list)) {
list_del(&kip->list); list_del(&kip->list);
module_free(NULL, kip->insns); module_free(NULL, kip->insns);
kfree(kip); kfree(kip);
@ -209,49 +229,55 @@ static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
return 0; return 0;
} }
static int __kprobes collect_garbage_slots(void) static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
{ {
struct kprobe_insn_page *kip, *next; struct kprobe_insn_page *kip, *next;
/* Ensure no-one is interrupted on the garbages */ /* Ensure no-one is interrupted on the garbages */
synchronize_sched(); synchronize_sched();
list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) { list_for_each_entry_safe(kip, next, &c->pages, list) {
int i; int i;
if (kip->ngarbage == 0) if (kip->ngarbage == 0)
continue; continue;
kip->ngarbage = 0; /* we will collect all garbages */ kip->ngarbage = 0; /* we will collect all garbages */
for (i = 0; i < INSNS_PER_PAGE; i++) { for (i = 0; i < slots_per_page(c); i++) {
if (kip->slot_used[i] == SLOT_DIRTY && if (kip->slot_used[i] == SLOT_DIRTY &&
collect_one_slot(kip, i)) collect_one_slot(kip, i))
break; break;
} }
} }
kprobe_garbage_slots = 0; c->nr_garbage = 0;
return 0; return 0;
} }
static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
kprobe_opcode_t *slot, int dirty)
{
struct kprobe_insn_page *kip;
list_for_each_entry(kip, &c->pages, list) {
long idx = ((long)slot - (long)kip->insns) / c->insn_size;
if (idx >= 0 && idx < slots_per_page(c)) {
WARN_ON(kip->slot_used[idx] != SLOT_USED);
if (dirty) {
kip->slot_used[idx] = SLOT_DIRTY;
kip->ngarbage++;
if (++c->nr_garbage > slots_per_page(c))
collect_garbage_slots(c);
} else
collect_one_slot(kip, idx);
return;
}
}
/* Could not free this slot. */
WARN_ON(1);
}
void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty) void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
{ {
struct kprobe_insn_page *kip;
mutex_lock(&kprobe_insn_mutex); mutex_lock(&kprobe_insn_mutex);
list_for_each_entry(kip, &kprobe_insn_pages, list) { __free_insn_slot(&kprobe_insn_slots, slot, dirty);
if (kip->insns <= slot &&
slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
int i = (slot - kip->insns) / MAX_INSN_SIZE;
if (dirty) {
kip->slot_used[i] = SLOT_DIRTY;
kip->ngarbage++;
} else
collect_one_slot(kip, i);
break;
}
}
if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
collect_garbage_slots();
mutex_unlock(&kprobe_insn_mutex); mutex_unlock(&kprobe_insn_mutex);
} }
#endif #endif