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Subject[RFC PATCH -tip 2/3] kprobes: Add functions to find instruction buffer entry address
Date
Add find_kprobe_{insn,optinsn}_slot_entry() functions to find
corresponding entry address of the kprobe instrurction buffer
which includes given address.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
include/linux/kprobes.h | 8 ++++++++
kernel/kprobes.c | 25 ++++++++++++++++++-------
2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index f530f82a046d..08adfd6cf562 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -305,6 +305,8 @@ extern void __free_insn_slot(struct kprobe_insn_cache *c,
/* sleep-less address checking routine */
extern bool __is_insn_slot_addr(struct kprobe_insn_cache *c,
unsigned long addr);
+extern unsigned long
+__find_insn_slot_entry(struct kprobe_insn_cache *c, unsigned long addr);

#define DEFINE_INSN_CACHE_OPS(__name) \
extern struct kprobe_insn_cache kprobe_##__name##_slots; \
@@ -322,6 +324,12 @@ static inline void free_##__name##_slot(kprobe_opcode_t *slot, int dirty)\
static inline bool is_kprobe_##__name##_slot(unsigned long addr) \
{ \
return __is_insn_slot_addr(&kprobe_##__name##_slots, addr); \
+} \
+ \
+static inline unsigned long \
+find_kprobe_##__name##_slot_entry(unsigned long addr) \
+{ \
+ return __find_insn_slot_entry(&kprobe_##__name##_slots, addr); \
}
#define KPROBE_INSN_PAGE_SYM "kprobe_insn_page"
#define KPROBE_OPTINSN_PAGE_SYM "kprobe_optinsn_page"
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 4ce3e6f5d28d..b62635969fa6 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -277,26 +277,37 @@ void __free_insn_slot(struct kprobe_insn_cache *c,
}

/*
- * Check given address is on the page of kprobe instruction slots.
- * This will be used for checking whether the address on a stack
- * is on a text area or not.
+ * Find the entry address of the kprobe instruction slots where the
+ * @addr points.
*/
-bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
+unsigned long
+__find_insn_slot_entry(struct kprobe_insn_cache *c, unsigned long addr)
{
struct kprobe_insn_page *kip;
- bool ret = false;
+ unsigned long entry = 0, index;

rcu_read_lock();
list_for_each_entry_rcu(kip, &c->pages, list) {
if (addr >= (unsigned long)kip->insns &&
addr < (unsigned long)kip->insns + PAGE_SIZE) {
- ret = true;
+ index = (addr - (unsigned long)kip->insns) / c->insn_size;
+ entry = (unsigned long)kip->insns + (index * c->insn_size);
break;
}
}
rcu_read_unlock();

- return ret;
+ return entry;
+}
+
+/*
+ * Check given address is on the page of kprobe instruction slots.
+ * This will be used for checking whether the address on a stack
+ * is on a text area or not.
+ */
+bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
+{
+ return __find_insn_slot_entry(c, addr) != 0;
}

int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
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