diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 31 | ||||
| -rw-r--r-- | kernel/events/ring_buffer.c | 42 | ||||
| -rw-r--r-- | kernel/events/uprobes.c | 60 |
3 files changed, 96 insertions, 37 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index f5744010a8d2..56003c6edfd3 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -119,7 +119,8 @@ static int cpu_function_call(int cpu, int (*func) (void *info), void *info) #define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\ PERF_FLAG_FD_OUTPUT |\ - PERF_FLAG_PID_CGROUP) + PERF_FLAG_PID_CGROUP |\ + PERF_FLAG_FD_CLOEXEC) /* * branch priv levels that need permission checks @@ -3542,7 +3543,7 @@ static void perf_event_for_each(struct perf_event *event, static int perf_event_period(struct perf_event *event, u64 __user *arg) { struct perf_event_context *ctx = event->ctx; - int ret = 0; + int ret = 0, active; u64 value; if (!is_sampling_event(event)) @@ -3566,6 +3567,20 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg) event->attr.sample_period = value; event->hw.sample_period = value; } + + active = (event->state == PERF_EVENT_STATE_ACTIVE); + if (active) { + perf_pmu_disable(ctx->pmu); + event->pmu->stop(event, PERF_EF_UPDATE); + } + + local64_set(&event->hw.period_left, 0); + + if (active) { + event->pmu->start(event, PERF_EF_RELOAD); + perf_pmu_enable(ctx->pmu); + } + unlock: raw_spin_unlock_irq(&ctx->lock); @@ -6670,6 +6685,9 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, INIT_LIST_HEAD(&event->event_entry); INIT_LIST_HEAD(&event->sibling_list); INIT_LIST_HEAD(&event->rb_entry); + INIT_LIST_HEAD(&event->active_entry); + INIT_HLIST_NODE(&event->hlist_entry); + init_waitqueue_head(&event->waitq); init_irq_work(&event->pending, perf_pending_event); @@ -6980,6 +6998,7 @@ SYSCALL_DEFINE5(perf_event_open, int event_fd; int move_group = 0; int err; + int f_flags = O_RDWR; /* for future expandability... */ if (flags & ~PERF_FLAG_ALL) @@ -7008,7 +7027,10 @@ SYSCALL_DEFINE5(perf_event_open, if ((flags & PERF_FLAG_PID_CGROUP) && (pid == -1 || cpu == -1)) return -EINVAL; - event_fd = get_unused_fd(); + if (flags & PERF_FLAG_FD_CLOEXEC) + f_flags |= O_CLOEXEC; + + event_fd = get_unused_fd_flags(f_flags); if (event_fd < 0) return event_fd; @@ -7130,7 +7152,8 @@ SYSCALL_DEFINE5(perf_event_open, goto err_context; } - event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, O_RDWR); + event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, + f_flags); if (IS_ERR(event_file)) { err = PTR_ERR(event_file); goto err_context; diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index e8b168af135b..146a5792b1d2 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -61,19 +61,20 @@ again: * * kernel user * - * READ ->data_tail READ ->data_head - * smp_mb() (A) smp_rmb() (C) - * WRITE $data READ $data - * smp_wmb() (B) smp_mb() (D) - * STORE ->data_head WRITE ->data_tail + * if (LOAD ->data_tail) { LOAD ->data_head + * (A) smp_rmb() (C) + * STORE $data LOAD $data + * smp_wmb() (B) smp_mb() (D) + * STORE ->data_head STORE ->data_tail + * } * * Where A pairs with D, and B pairs with C. * - * I don't think A needs to be a full barrier because we won't in fact - * write data until we see the store from userspace. So we simply don't - * issue the data WRITE until we observe it. Be conservative for now. + * In our case (A) is a control dependency that separates the load of + * the ->data_tail and the stores of $data. In case ->data_tail + * indicates there is no room in the buffer to store $data we do not. * - * OTOH, D needs to be a full barrier since it separates the data READ + * D needs to be a full barrier since it separates the data READ * from the tail WRITE. * * For B a WMB is sufficient since it separates two WRITEs, and for C @@ -81,7 +82,7 @@ again: * * See perf_output_begin(). */ - smp_wmb(); + smp_wmb(); /* B, matches C */ rb->user_page->data_head = head; /* @@ -144,17 +145,26 @@ int perf_output_begin(struct perf_output_handle *handle, if (!rb->overwrite && unlikely(CIRC_SPACE(head, tail, perf_data_size(rb)) < size)) goto fail; + + /* + * The above forms a control dependency barrier separating the + * @tail load above from the data stores below. Since the @tail + * load is required to compute the branch to fail below. + * + * A, matches D; the full memory barrier userspace SHOULD issue + * after reading the data and before storing the new tail + * position. + * + * See perf_output_put_handle(). + */ + head += size; } while (local_cmpxchg(&rb->head, offset, head) != offset); /* - * Separate the userpage->tail read from the data stores below. - * Matches the MB userspace SHOULD issue after reading the data - * and before storing the new tail position. - * - * See perf_output_put_handle(). + * We rely on the implied barrier() by local_cmpxchg() to ensure + * none of the data stores below can be lifted up by the compiler. */ - smp_mb(); if (unlikely(head - local_read(&rb->wakeup) > rb->watermark)) local_add(rb->watermark, &rb->wakeup); 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); } /* |