diff options
Diffstat (limited to 'kernel/events/uprobes.c')
| -rw-r--r-- | kernel/events/uprobes.c | 60 |
1 files changed, 43 insertions, 17 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 24b7d6ca871b..b886a5e7d4ff 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -73,6 +73,17 @@ struct uprobe { struct inode *inode; /* Also hold a ref to inode */ loff_t offset; unsigned long flags; + + /* + * The generic code assumes that it has two members of unknown type + * owned by the arch-specific code: + * + * insn - copy_insn() saves the original instruction here for + * arch_uprobe_analyze_insn(). + * + * ixol - potentially modified instruction to execute out of + * line, copied to xol_area by xol_get_insn_slot(). + */ struct arch_uprobe arch; }; @@ -86,6 +97,29 @@ struct return_instance { }; /* + * Execute out of line area: anonymous executable mapping installed + * by the probed task to execute the copy of the original instruction + * mangled by set_swbp(). + * + * On a breakpoint hit, thread contests for a slot. It frees the + * slot after singlestep. Currently a fixed number of slots are + * allocated. + */ +struct xol_area { + wait_queue_head_t wq; /* if all slots are busy */ + atomic_t slot_count; /* number of in-use slots */ + unsigned long *bitmap; /* 0 = free slot */ + struct page *page; + + /* + * We keep the vma's vm_start rather than a pointer to the vma + * itself. The probed process or a naughty kernel module could make + * the vma go away, and we must handle that reasonably gracefully. + */ + unsigned long vaddr; /* Page(s) of instruction slots */ +}; + +/* * valid_vma: Verify if the specified vma is an executable vma * Relax restrictions while unregistering: vm_flags might have * changed after breakpoint was inserted. @@ -330,7 +364,7 @@ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned int __weak set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) { - return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); + return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn); } static int match_uprobe(struct uprobe *l, struct uprobe *r) @@ -529,8 +563,8 @@ static int copy_insn(struct uprobe *uprobe, struct file *filp) { struct address_space *mapping = uprobe->inode->i_mapping; loff_t offs = uprobe->offset; - void *insn = uprobe->arch.insn; - int size = MAX_UINSN_BYTES; + void *insn = &uprobe->arch.insn; + int size = sizeof(uprobe->arch.insn); int len, err = -EIO; /* Copy only available bytes, -EIO if nothing was read */ @@ -569,7 +603,7 @@ static int prepare_uprobe(struct uprobe *uprobe, struct file *file, goto out; ret = -ENOTSUPP; - if (is_trap_insn((uprobe_opcode_t *)uprobe->arch.insn)) + if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) goto out; ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); @@ -1264,7 +1298,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe) /* Initialize the slot */ copy_to_page(area->page, xol_vaddr, - uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); + &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); /* * We probably need flush_icache_user_range() but it needs vma. * This should work on supported architectures too. @@ -1403,12 +1437,10 @@ static void uprobe_warn(struct task_struct *t, const char *msg) static void dup_xol_work(struct callback_head *work) { - kfree(work); - if (current->flags & PF_EXITING) return; - if (!__create_xol_area(current->utask->vaddr)) + if (!__create_xol_area(current->utask->dup_xol_addr)) uprobe_warn(current, "dup xol area"); } @@ -1419,7 +1451,6 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags) { struct uprobe_task *utask = current->utask; struct mm_struct *mm = current->mm; - struct callback_head *work; struct xol_area *area; t->utask = NULL; @@ -1441,14 +1472,9 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags) if (mm == t->mm) return; - /* TODO: move it into the union in uprobe_task */ - work = kmalloc(sizeof(*work), GFP_KERNEL); - if (!work) - return uprobe_warn(t, "dup xol area"); - - t->utask->vaddr = area->vaddr; - init_task_work(work, dup_xol_work); - task_work_add(t, work, true); + t->utask->dup_xol_addr = area->vaddr; + init_task_work(&t->utask->dup_xol_work, dup_xol_work); + task_work_add(t, &t->utask->dup_xol_work, true); } /* |