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authorHeiko Carstens <heiko.carstens@de.ibm.com>2013-09-11 14:24:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:58:52 -0700
commitc802d64a356b5cf349121ac4c5e005f037ce548d (patch)
tree654c5af4d00a40eeaa576acc1aee238e7c8a8a87 /kernel
parentae79744975cb0b3b9c469fe1a05db37d2943c863 (diff)
downloadlinaro-lsk-c802d64a356b5cf349121ac4c5e005f037ce548d.tar.gz
kprobes: unify insn caches
The current kpropes insn caches allocate memory areas for insn slots with module_alloc(). The assumption is that the kernel image and module area are both within the same +/- 2GB memory area. This however is not true for s390 where the kernel image resides within the first 2GB (DMA memory area), but the module area is far away in the vmalloc area, usually somewhere close below the 4TB area. For new pc relative instructions s390 needs insn slots that are within +/- 2GB of each area. That way we can patch displacements of pc-relative instructions within the insn slots just like x86 and powerpc. The module area works already with the normal insn slot allocator, however there is currently no way to get insn slots that are within the first 2GB on s390 (aka DMA area). Therefore this patch set modifies the kprobes insn slot cache code in order to allow to specify a custom allocator for the insn slot cache pages. In addition architecure can now have private insn slot caches withhout the need to modify common code. Patch 1 unifies and simplifies the current insn and optinsn caches implementation. This is a preparation which allows to add more insn caches in a simple way. Patch 2 adds the possibility to specify a custom allocator. Patch 3 makes s390 use the new insn slot mechanisms and adds support for pc-relative instructions with long displacements. This patch (of 3): The two insn caches (insn, and optinsn) each have an own mutex and alloc/free functions (get_[opt]insn_slot() / free_[opt]insn_slot()). Since there is the need for yet another insn cache which satifies dma allocations on s390, unify and simplify the current implementation: - Move the per insn cache mutex into struct kprobe_insn_cache. - Move the alloc/free functions to kprobe.h so they are simply wrappers for the generic __get_insn_slot/__free_insn_slot functions. The implementation is done with a DEFINE_INSN_CACHE_OPS() macro which provides the alloc/free functions for each cache if needed. - move the struct kprobe_insn_cache to kprobe.h which allows to generate architecture specific insn slot caches outside of the core kprobes code. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kprobes.c75
1 files changed, 21 insertions, 54 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 6e33498d665..9e4912dc555 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -121,12 +121,6 @@ struct kprobe_insn_page {
(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));
@@ -138,8 +132,8 @@ enum kprobe_slot_state {
SLOT_USED = 2,
};
-static DEFINE_MUTEX(kprobe_insn_mutex); /* Protects kprobe_insn_slots */
-static struct kprobe_insn_cache kprobe_insn_slots = {
+struct kprobe_insn_cache kprobe_insn_slots = {
+ .mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
.pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
.insn_size = MAX_INSN_SIZE,
.nr_garbage = 0,
@@ -150,10 +144,12 @@ static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c);
* __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.
*/
-static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
+kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
{
struct kprobe_insn_page *kip;
+ kprobe_opcode_t *slot = NULL;
+ mutex_lock(&c->mutex);
retry:
list_for_each_entry(kip, &c->pages, list) {
if (kip->nused < slots_per_page(c)) {
@@ -162,7 +158,8 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
if (kip->slot_used[i] == SLOT_CLEAN) {
kip->slot_used[i] = SLOT_USED;
kip->nused++;
- return kip->insns + (i * c->insn_size);
+ slot = kip->insns + (i * c->insn_size);
+ goto out;
}
}
/* kip->nused is broken. Fix it. */
@@ -178,7 +175,7 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
/* All out of space. Need to allocate a new page. */
kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
if (!kip)
- return NULL;
+ goto out;
/*
* Use module_alloc so this page is within +/- 2GB of where the
@@ -188,7 +185,7 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
kip->insns = module_alloc(PAGE_SIZE);
if (!kip->insns) {
kfree(kip);
- return NULL;
+ goto out;
}
INIT_LIST_HEAD(&kip->list);
memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
@@ -196,19 +193,10 @@ static kprobe_opcode_t __kprobes *__get_insn_slot(struct kprobe_insn_cache *c)
kip->nused = 1;
kip->ngarbage = 0;
list_add(&kip->list, &c->pages);
- return kip->insns;
-}
-
-
-kprobe_opcode_t __kprobes *get_insn_slot(void)
-{
- kprobe_opcode_t *ret = NULL;
-
- mutex_lock(&kprobe_insn_mutex);
- ret = __get_insn_slot(&kprobe_insn_slots);
- mutex_unlock(&kprobe_insn_mutex);
-
- return ret;
+ slot = kip->insns;
+out:
+ mutex_unlock(&c->mutex);
+ return slot;
}
/* Return 1 if all garbages are collected, otherwise 0. */
@@ -255,11 +243,12 @@ static int __kprobes collect_garbage_slots(struct kprobe_insn_cache *c)
return 0;
}
-static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
- kprobe_opcode_t *slot, int dirty)
+void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
+ kprobe_opcode_t *slot, int dirty)
{
struct kprobe_insn_page *kip;
+ mutex_lock(&c->mutex);
list_for_each_entry(kip, &c->pages, list) {
long idx = ((long)slot - (long)kip->insns) /
(c->insn_size * sizeof(kprobe_opcode_t));
@@ -272,45 +261,23 @@ static void __kprobes __free_insn_slot(struct kprobe_insn_cache *c,
collect_garbage_slots(c);
} else
collect_one_slot(kip, idx);
- return;
+ goto out;
}
}
/* Could not free this slot. */
WARN_ON(1);
+out:
+ mutex_unlock(&c->mutex);
}
-void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
-{
- mutex_lock(&kprobe_insn_mutex);
- __free_insn_slot(&kprobe_insn_slots, slot, dirty);
- mutex_unlock(&kprobe_insn_mutex);
-}
#ifdef CONFIG_OPTPROBES
/* For optimized_kprobe buffer */
-static DEFINE_MUTEX(kprobe_optinsn_mutex); /* Protects kprobe_optinsn_slots */
-static struct kprobe_insn_cache kprobe_optinsn_slots = {
+struct kprobe_insn_cache kprobe_optinsn_slots = {
+ .mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
/* .insn_size is initialized later */
.nr_garbage = 0,
};
-/* Get a slot for optimized_kprobe buffer */
-kprobe_opcode_t __kprobes *get_optinsn_slot(void)
-{
- kprobe_opcode_t *ret = NULL;
-
- mutex_lock(&kprobe_optinsn_mutex);
- ret = __get_insn_slot(&kprobe_optinsn_slots);
- mutex_unlock(&kprobe_optinsn_mutex);
-
- return ret;
-}
-
-void __kprobes free_optinsn_slot(kprobe_opcode_t * slot, int dirty)
-{
- mutex_lock(&kprobe_optinsn_mutex);
- __free_insn_slot(&kprobe_optinsn_slots, slot, dirty);
- mutex_unlock(&kprobe_optinsn_mutex);
-}
#endif
#endif