diff options
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/core.c | 49 | ||||
| -rw-r--r-- | kernel/events/uprobes.c | 278 |
2 files changed, 310 insertions, 17 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 5a97f34bc14c..8c490130c4fb 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8376,30 +8376,39 @@ static struct pmu perf_tracepoint = { * * PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe * if not set, create kprobe/uprobe + * + * The following values specify a reference counter (or semaphore in the + * terminology of tools like dtrace, systemtap, etc.) Userspace Statically + * Defined Tracepoints (USDT). Currently, we use 40 bit for the offset. + * + * PERF_UPROBE_REF_CTR_OFFSET_BITS # of bits in config as th offset + * PERF_UPROBE_REF_CTR_OFFSET_SHIFT # of bits to shift left */ enum perf_probe_config { PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0, /* [k,u]retprobe */ + PERF_UPROBE_REF_CTR_OFFSET_BITS = 32, + PERF_UPROBE_REF_CTR_OFFSET_SHIFT = 64 - PERF_UPROBE_REF_CTR_OFFSET_BITS, }; PMU_FORMAT_ATTR(retprobe, "config:0"); +#endif -static struct attribute *probe_attrs[] = { +#ifdef CONFIG_KPROBE_EVENTS +static struct attribute *kprobe_attrs[] = { &format_attr_retprobe.attr, NULL, }; -static struct attribute_group probe_format_group = { +static struct attribute_group kprobe_format_group = { .name = "format", - .attrs = probe_attrs, + .attrs = kprobe_attrs, }; -static const struct attribute_group *probe_attr_groups[] = { - &probe_format_group, +static const struct attribute_group *kprobe_attr_groups[] = { + &kprobe_format_group, NULL, }; -#endif -#ifdef CONFIG_KPROBE_EVENTS static int perf_kprobe_event_init(struct perf_event *event); static struct pmu perf_kprobe = { .task_ctx_nr = perf_sw_context, @@ -8409,7 +8418,7 @@ static struct pmu perf_kprobe = { .start = perf_swevent_start, .stop = perf_swevent_stop, .read = perf_swevent_read, - .attr_groups = probe_attr_groups, + .attr_groups = kprobe_attr_groups, }; static int perf_kprobe_event_init(struct perf_event *event) @@ -8441,6 +8450,24 @@ static int perf_kprobe_event_init(struct perf_event *event) #endif /* CONFIG_KPROBE_EVENTS */ #ifdef CONFIG_UPROBE_EVENTS +PMU_FORMAT_ATTR(ref_ctr_offset, "config:32-63"); + +static struct attribute *uprobe_attrs[] = { + &format_attr_retprobe.attr, + &format_attr_ref_ctr_offset.attr, + NULL, +}; + +static struct attribute_group uprobe_format_group = { + .name = "format", + .attrs = uprobe_attrs, +}; + +static const struct attribute_group *uprobe_attr_groups[] = { + &uprobe_format_group, + NULL, +}; + static int perf_uprobe_event_init(struct perf_event *event); static struct pmu perf_uprobe = { .task_ctx_nr = perf_sw_context, @@ -8450,12 +8477,13 @@ static struct pmu perf_uprobe = { .start = perf_swevent_start, .stop = perf_swevent_stop, .read = perf_swevent_read, - .attr_groups = probe_attr_groups, + .attr_groups = uprobe_attr_groups, }; static int perf_uprobe_event_init(struct perf_event *event) { int err; + unsigned long ref_ctr_offset; bool is_retprobe; if (event->attr.type != perf_uprobe.type) @@ -8471,7 +8499,8 @@ static int perf_uprobe_event_init(struct perf_event *event) return -EOPNOTSUPP; is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE; - err = perf_uprobe_init(event, is_retprobe); + ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT; + err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe); if (err) return err; diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 2bf792d22087..96d4bee83489 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -73,6 +73,7 @@ struct uprobe { struct uprobe_consumer *consumers; struct inode *inode; /* Also hold a ref to inode */ loff_t offset; + loff_t ref_ctr_offset; unsigned long flags; /* @@ -88,6 +89,15 @@ struct uprobe { struct arch_uprobe arch; }; +struct delayed_uprobe { + struct list_head list; + struct uprobe *uprobe; + struct mm_struct *mm; +}; + +static DEFINE_MUTEX(delayed_uprobe_lock); +static LIST_HEAD(delayed_uprobe_list); + /* * Execute out of line area: anonymous executable mapping installed * by the probed task to execute the copy of the original instruction @@ -282,6 +292,166 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t return 1; } +static struct delayed_uprobe * +delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct delayed_uprobe *du; + + list_for_each_entry(du, &delayed_uprobe_list, list) + if (du->uprobe == uprobe && du->mm == mm) + return du; + return NULL; +} + +static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct delayed_uprobe *du; + + if (delayed_uprobe_check(uprobe, mm)) + return 0; + + du = kzalloc(sizeof(*du), GFP_KERNEL); + if (!du) + return -ENOMEM; + + du->uprobe = uprobe; + du->mm = mm; + list_add(&du->list, &delayed_uprobe_list); + return 0; +} + +static void delayed_uprobe_delete(struct delayed_uprobe *du) +{ + if (WARN_ON(!du)) + return; + list_del(&du->list); + kfree(du); +} + +static void delayed_uprobe_remove(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct list_head *pos, *q; + struct delayed_uprobe *du; + + if (!uprobe && !mm) + return; + + list_for_each_safe(pos, q, &delayed_uprobe_list) { + du = list_entry(pos, struct delayed_uprobe, list); + + if (uprobe && du->uprobe != uprobe) + continue; + if (mm && du->mm != mm) + continue; + + delayed_uprobe_delete(du); + } +} + +static bool valid_ref_ctr_vma(struct uprobe *uprobe, + struct vm_area_struct *vma) +{ + unsigned long vaddr = offset_to_vaddr(vma, uprobe->ref_ctr_offset); + + return uprobe->ref_ctr_offset && + vma->vm_file && + file_inode(vma->vm_file) == uprobe->inode && + (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && + vma->vm_start <= vaddr && + vma->vm_end > vaddr; +} + +static struct vm_area_struct * +find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct vm_area_struct *tmp; + + for (tmp = mm->mmap; tmp; tmp = tmp->vm_next) + if (valid_ref_ctr_vma(uprobe, tmp)) + return tmp; + + return NULL; +} + +static int +__update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d) +{ + void *kaddr; + struct page *page; + struct vm_area_struct *vma; + int ret; + short *ptr; + + if (!vaddr || !d) + return -EINVAL; + + ret = get_user_pages_remote(NULL, mm, vaddr, 1, + FOLL_WRITE, &page, &vma, NULL); + if (unlikely(ret <= 0)) { + /* + * We are asking for 1 page. If get_user_pages_remote() fails, + * it may return 0, in that case we have to return error. + */ + return ret == 0 ? -EBUSY : ret; + } + + kaddr = kmap_atomic(page); + ptr = kaddr + (vaddr & ~PAGE_MASK); + + if (unlikely(*ptr + d < 0)) { + pr_warn("ref_ctr going negative. vaddr: 0x%lx, " + "curr val: %d, delta: %d\n", vaddr, *ptr, d); + ret = -EINVAL; + goto out; + } + + *ptr += d; + ret = 0; +out: + kunmap_atomic(kaddr); + put_page(page); + return ret; +} + +static void update_ref_ctr_warn(struct uprobe *uprobe, + struct mm_struct *mm, short d) +{ + pr_warn("ref_ctr %s failed for inode: 0x%lx offset: " + "0x%llx ref_ctr_offset: 0x%llx of mm: 0x%pK\n", + d > 0 ? "increment" : "decrement", uprobe->inode->i_ino, + (unsigned long long) uprobe->offset, + (unsigned long long) uprobe->ref_ctr_offset, mm); +} + +static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm, + short d) +{ + struct vm_area_struct *rc_vma; + unsigned long rc_vaddr; + int ret = 0; + + rc_vma = find_ref_ctr_vma(uprobe, mm); + + if (rc_vma) { + rc_vaddr = offset_to_vaddr(rc_vma, uprobe->ref_ctr_offset); + ret = __update_ref_ctr(mm, rc_vaddr, d); + if (ret) + update_ref_ctr_warn(uprobe, mm, d); + + if (d > 0) + return ret; + } + + mutex_lock(&delayed_uprobe_lock); + if (d > 0) + ret = delayed_uprobe_add(uprobe, mm); + else + delayed_uprobe_remove(uprobe, mm); + mutex_unlock(&delayed_uprobe_lock); + + return ret; +} + /* * NOTE: * Expect the breakpoint instruction to be the smallest size instruction for @@ -302,9 +472,13 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t opcode) { + struct uprobe *uprobe; struct page *old_page, *new_page; struct vm_area_struct *vma; - int ret; + int ret, is_register, ref_ctr_updated = 0; + + is_register = is_swbp_insn(&opcode); + uprobe = container_of(auprobe, struct uprobe, arch); retry: /* Read the page with vaddr into memory */ @@ -317,6 +491,15 @@ retry: if (ret <= 0) goto put_old; + /* We are going to replace instruction, update ref_ctr. */ + if (!ref_ctr_updated && uprobe->ref_ctr_offset) { + ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1); + if (ret) + goto put_old; + + ref_ctr_updated = 1; + } + ret = anon_vma_prepare(vma); if (ret) goto put_old; @@ -337,6 +520,11 @@ put_old: if (unlikely(ret == -EAGAIN)) goto retry; + + /* Revert back reference counter if instruction update failed. */ + if (ret && is_register && ref_ctr_updated) + update_ref_ctr(uprobe, mm, -1); + return ret; } @@ -378,8 +566,15 @@ static struct uprobe *get_uprobe(struct uprobe *uprobe) static void put_uprobe(struct uprobe *uprobe) { - if (atomic_dec_and_test(&uprobe->ref)) + if (atomic_dec_and_test(&uprobe->ref)) { + /* + * If application munmap(exec_vma) before uprobe_unregister() + * gets called, we don't get a chance to remove uprobe from + * delayed_uprobe_list from remove_breakpoint(). Do it here. + */ + delayed_uprobe_remove(uprobe, NULL); kfree(uprobe); + } } static int match_uprobe(struct uprobe *l, struct uprobe *r) @@ -484,7 +679,18 @@ static struct uprobe *insert_uprobe(struct uprobe *uprobe) return u; } -static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) +static void +ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe) +{ + pr_warn("ref_ctr_offset mismatch. inode: 0x%lx offset: 0x%llx " + "ref_ctr_offset(old): 0x%llx ref_ctr_offset(new): 0x%llx\n", + uprobe->inode->i_ino, (unsigned long long) uprobe->offset, + (unsigned long long) cur_uprobe->ref_ctr_offset, + (unsigned long long) uprobe->ref_ctr_offset); +} + +static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, + loff_t ref_ctr_offset) { struct uprobe *uprobe, *cur_uprobe; @@ -494,6 +700,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) uprobe->inode = inode; uprobe->offset = offset; + uprobe->ref_ctr_offset = ref_ctr_offset; init_rwsem(&uprobe->register_rwsem); init_rwsem(&uprobe->consumer_rwsem); @@ -501,6 +708,12 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) cur_uprobe = insert_uprobe(uprobe); /* a uprobe exists for this inode:offset combination */ if (cur_uprobe) { + if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) { + ref_ctr_mismatch_warn(cur_uprobe, uprobe); + put_uprobe(cur_uprobe); + kfree(uprobe); + return ERR_PTR(-EINVAL); + } kfree(uprobe); uprobe = cur_uprobe; } @@ -895,7 +1108,7 @@ EXPORT_SYMBOL_GPL(uprobe_unregister); * else return 0 (success) */ static int __uprobe_register(struct inode *inode, loff_t offset, - struct uprobe_consumer *uc) + loff_t ref_ctr_offset, struct uprobe_consumer *uc) { struct uprobe *uprobe; int ret; @@ -912,9 +1125,12 @@ static int __uprobe_register(struct inode *inode, loff_t offset, return -EINVAL; retry: - uprobe = alloc_uprobe(inode, offset); + uprobe = alloc_uprobe(inode, offset, ref_ctr_offset); if (!uprobe) return -ENOMEM; + if (IS_ERR(uprobe)) + return PTR_ERR(uprobe); + /* * We can race with uprobe_unregister()->delete_uprobe(). * Check uprobe_is_active() and retry if it is false. @@ -938,10 +1154,17 @@ static int __uprobe_register(struct inode *inode, loff_t offset, int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { - return __uprobe_register(inode, offset, uc); + return __uprobe_register(inode, offset, 0, uc); } EXPORT_SYMBOL_GPL(uprobe_register); +int uprobe_register_refctr(struct inode *inode, loff_t offset, + loff_t ref_ctr_offset, struct uprobe_consumer *uc) +{ + return __uprobe_register(inode, offset, ref_ctr_offset, uc); +} +EXPORT_SYMBOL_GPL(uprobe_register_refctr); + /* * uprobe_apply - unregister an already registered probe. * @inode: the file in which the probe has to be removed. @@ -1060,6 +1283,35 @@ static void build_probe_list(struct inode *inode, spin_unlock(&uprobes_treelock); } +/* @vma contains reference counter, not the probed instruction. */ +static int delayed_ref_ctr_inc(struct vm_area_struct *vma) +{ + struct list_head *pos, *q; + struct delayed_uprobe *du; + unsigned long vaddr; + int ret = 0, err = 0; + + mutex_lock(&delayed_uprobe_lock); + list_for_each_safe(pos, q, &delayed_uprobe_list) { + du = list_entry(pos, struct delayed_uprobe, list); + + if (du->mm != vma->vm_mm || + !valid_ref_ctr_vma(du->uprobe, vma)) + continue; + + vaddr = offset_to_vaddr(vma, du->uprobe->ref_ctr_offset); + ret = __update_ref_ctr(vma->vm_mm, vaddr, 1); + if (ret) { + update_ref_ctr_warn(du->uprobe, vma->vm_mm, 1); + if (!err) + err = ret; + } + delayed_uprobe_delete(du); + } + mutex_unlock(&delayed_uprobe_lock); + return err; +} + /* * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. * @@ -1072,7 +1324,15 @@ int uprobe_mmap(struct vm_area_struct *vma) struct uprobe *uprobe, *u; struct inode *inode; - if (no_uprobe_events() || !valid_vma(vma, true)) + if (no_uprobe_events()) + return 0; + + if (vma->vm_file && + (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && + test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) + delayed_ref_ctr_inc(vma); + + if (!valid_vma(vma, true)) return 0; inode = file_inode(vma->vm_file); @@ -1246,6 +1506,10 @@ void uprobe_clear_state(struct mm_struct *mm) { struct xol_area *area = mm->uprobes_state.xol_area; + mutex_lock(&delayed_uprobe_lock); + delayed_uprobe_remove(NULL, mm); + mutex_unlock(&delayed_uprobe_lock); + if (!area) return; |
