diff options
| -rw-r--r-- | kernel/events/uprobes.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 62c14dffa1ba..daf4314961ab 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -2294,6 +2294,47 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) return is_trap_insn(&opcode); } +static struct uprobe *find_active_uprobe_speculative(unsigned long bp_vaddr) +{ + struct mm_struct *mm = current->mm; + struct uprobe *uprobe = NULL; + struct vm_area_struct *vma; + struct file *vm_file; + loff_t offset; + unsigned int seq; + + guard(rcu)(); + + if (!mmap_lock_speculate_try_begin(mm, &seq)) + return NULL; + + vma = vma_lookup(mm, bp_vaddr); + if (!vma) + return NULL; + + /* + * vm_file memory can be reused for another instance of struct file, + * but can't be freed from under us, so it's safe to read fields from + * it, even if the values are some garbage values; ultimately + * find_uprobe_rcu() + mmap_lock_speculation_end() check will ensure + * that whatever we speculatively found is correct + */ + vm_file = READ_ONCE(vma->vm_file); + if (!vm_file) + return NULL; + + offset = (loff_t)(vma->vm_pgoff << PAGE_SHIFT) + (bp_vaddr - vma->vm_start); + uprobe = find_uprobe_rcu(vm_file->f_inode, offset); + if (!uprobe) + return NULL; + + /* now double check that nothing about MM changed */ + if (mmap_lock_speculate_retry(mm, seq)) + return NULL; + + return uprobe; +} + /* assumes being inside RCU protected region */ static struct uprobe *find_active_uprobe_rcu(unsigned long bp_vaddr, int *is_swbp) { @@ -2301,6 +2342,10 @@ static struct uprobe *find_active_uprobe_rcu(unsigned long bp_vaddr, int *is_swb struct uprobe *uprobe = NULL; struct vm_area_struct *vma; + uprobe = find_active_uprobe_speculative(bp_vaddr); + if (uprobe) + return uprobe; + mmap_read_lock(mm); vma = vma_lookup(mm, bp_vaddr); if (vma) { |