Add the new helper, is_swbp_at_addr_fast(), will be used by
find_active_uprobe().
It is almost the same as is_swbp_at_addr(), but since it plays
with current->mm it can avoid the slow get_user_pages() in the
likely case.
---
kernel/events/uprobes.c | 23 +++++++++++++++++++++++
1 files changed, 23 insertions(+), 0 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 3d0a4d6..2050b1a 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1474,6 +1474,29 @@ static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
return false;
}
+int __weak is_swbp_at_addr_fast(unsigned long vaddr)
+{
+ uprobe_opcode_t opcode;
+ int fault;
+
+ pagefault_disable();
+ fault = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
+ sizeof(opcode));
+ pagefault_enable();
+
+ if (unlikely(fault)) {
+ /*
+ * XXX: read_opcode() lacks FOLL_FORCE, it can fail if
+ * we race with another thread which does mprotect(NONE)
+ * after we hit bp.
+ */
+ if (read_opcode(current->mm, vaddr, &opcode))
+ return -EFAULT;
+ }
+
+ return is_swbp_insn(&opcode);
+}
+
static struct uprobe *find_active_uprobe(unsigned long bp_vaddr)
{
struct mm_struct *mm = current->mm;
--
1.5.5.1
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