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Subject[RFC PATCH 08/11] kprobes: allows __alloc_insn_slot() from early kprobes slots.
Date
Introduces early_slots_start/end and bitmap for struct kprobe_insn_cache
then uses previous introduced macro to generate allocator. This patch
makes get/free_insn_slot() and get/free_optinsn_slot() transparent to
early kprobes.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
include/linux/kprobes.h | 33 +++++++++++++++++++++++++++++++++
kernel/kprobes.c | 14 ++++++++++++++
2 files changed, 47 insertions(+)

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 9a18188..27a27ed 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -316,6 +316,10 @@ static inline int ek_free_##__name(__t *__s) \
(__ek_##__name##_bitmap)); \
}

+extern kprobe_opcode_t __early_kprobes_code_area_start[];
+extern kprobe_opcode_t __early_kprobes_code_area_end[];
+extern kprobe_opcode_t __early_kprobes_insn_slot_start[];
+extern kprobe_opcode_t __early_kprobes_insn_slot_end[];

#else
#define __DEFINE_EKPROBE_ALLOC_OPS(__t, __name) \
@@ -339,6 +343,8 @@ static inline void ek_free_##__name(__t *__s) \

#endif

+__DEFINE_EKPROBE_ALLOC_OPS(kprobe_opcode_t, opcode)
+
struct kprobe_insn_cache {
struct mutex mutex;
void *(*alloc)(void); /* allocate insn page */
@@ -346,8 +352,35 @@ struct kprobe_insn_cache {
struct list_head pages; /* list of kprobe_insn_page */
size_t insn_size; /* size of instruction slot */
int nr_garbage;
+#ifdef CONFIG_EARLY_KPROBES
+# define slots_start(c) ((c)->early_slots_start)
+# define slots_end(c) ((c)->early_slots_end)
+# define slots_bitmap(c) ((c)->early_slots_bitmap)
+ kprobe_opcode_t *early_slots_start;
+ kprobe_opcode_t *early_slots_end;
+ unsigned long early_slots_bitmap[EARLY_KPROBES_BITMAP_SZ];
+#else
+# define slots_start(c) NULL
+# define slots_end(c) NULL
+# define slots_bitmap(c) NULL
+#endif
};

+static inline kprobe_opcode_t *
+__get_insn_slot_early(struct kprobe_insn_cache *c)
+{
+ return __ek_alloc_opcode(slots_start(c),
+ slots_end(c), slots_bitmap(c));
+}
+
+static inline int
+__free_insn_slot_early(struct kprobe_insn_cache *c,
+ kprobe_opcode_t *slot)
+{
+ return __ek_free_opcode(slot, slots_start(c),
+ slots_end(c), slots_bitmap(c));
+}
+
extern kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c);
extern void __free_insn_slot(struct kprobe_insn_cache *c,
kprobe_opcode_t *slot, int dirty);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 4591cae..1882bfa 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -137,6 +137,10 @@ struct kprobe_insn_cache kprobe_insn_slots = {
.pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
.insn_size = MAX_INSN_SIZE,
.nr_garbage = 0,
+#ifdef CONFIG_EARLY_KPROBES
+ .early_slots_start = __early_kprobes_insn_slot_start,
+ .early_slots_end = __early_kprobes_insn_slot_end,
+#endif
};
static int collect_garbage_slots(struct kprobe_insn_cache *c);

@@ -149,6 +153,9 @@ kprobe_opcode_t *__get_insn_slot(struct kprobe_insn_cache *c)
struct kprobe_insn_page *kip;
kprobe_opcode_t *slot = NULL;

+ if (unlikely(!kprobes_initialized))
+ return __get_insn_slot_early(c);
+
mutex_lock(&c->mutex);
retry:
list_for_each_entry(kip, &c->pages, list) {
@@ -249,6 +256,9 @@ void __free_insn_slot(struct kprobe_insn_cache *c,
{
struct kprobe_insn_page *kip;

+ if (unlikely(__free_insn_slot_early(c, slot)))
+ return;
+
mutex_lock(&c->mutex);
list_for_each_entry(kip, &c->pages, list) {
long idx = ((long)slot - (long)kip->insns) /
@@ -280,6 +290,10 @@ struct kprobe_insn_cache kprobe_optinsn_slots = {
.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
/* .insn_size is initialized later */
.nr_garbage = 0,
+#ifdef CONFIG_EARLY_KPROBES
+ .early_slots_start = __early_kprobes_code_area_start,
+ .early_slots_end = __early_kprobes_code_area_end,
+#endif
};
#endif
#endif
--
1.8.4


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