From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753176AbZIYItx (ORCPT ); Fri, 25 Sep 2009 04:49:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752935AbZIYItw (ORCPT ); Fri, 25 Sep 2009 04:49:52 -0400 Received: from hera.kernel.org ([140.211.167.34]:41775 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752575AbZIYItt (ORCPT ); Fri, 25 Sep 2009 04:49:49 -0400 Date: Fri, 25 Sep 2009 08:49:06 GMT From: tip-bot for Peter Zijlstra Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, jens.axboe@oracle.com, davem@davemloft.net, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, davem@davemloft.net, jens.axboe@oracle.com, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/urgent] perf_event: Provide vmalloc() based mmap() backing Message-ID: Git-Commit-ID: 9c4bcf34b02533056f59f8d35fb5894c2f5b84bc X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Fri, 25 Sep 2009 08:49:08 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 9c4bcf34b02533056f59f8d35fb5894c2f5b84bc Gitweb: http://git.kernel.org/tip/9c4bcf34b02533056f59f8d35fb5894c2f5b84bc Author: Peter Zijlstra AuthorDate: Mon, 21 Sep 2009 16:08:49 +0200 Committer: Ingo Molnar CommitDate: Fri, 25 Sep 2009 10:42:44 +0200 perf_event: Provide vmalloc() based mmap() backing Some architectures such as Sparc, ARM and MIPS (basically everything with flush_dcache_page()) need to deal with dcache aliases by carefully placing pages in both kernel and user maps. These architectures typically have to use vmalloc_user() for this. However, on other architectures, vmalloc() is not needed and has the downsides of being more restricted and slower than regular allocations. Acked-by: David Miller Cc: Andrew Morton Cc: Jens Axboe Cc: Paul Mackerras LKML-Reference: Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- arch/sparc/Kconfig | 2 + include/linux/perf_event.h | 5 + init/Kconfig | 17 +++ kernel/perf_event.c | 248 +++++++++++++++++++++++++++++++++----------- tools/perf/design.txt | 3 + 5 files changed, 213 insertions(+), 62 deletions(-) diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 97fca46..5658826 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -26,6 +26,7 @@ config SPARC select RTC_CLASS select RTC_DRV_M48T59 select HAVE_PERF_EVENTS + select PERF_NEEDS_VMALLOC select HAVE_DMA_ATTRS select HAVE_DMA_API_DEBUG @@ -48,6 +49,7 @@ config SPARC64 select RTC_DRV_SUN4V select RTC_DRV_STARFIRE select HAVE_PERF_EVENTS + select PERF_NEEDS_VMALLOC config ARCH_DEFCONFIG string diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 3a9d36d..ae24947 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -442,6 +442,7 @@ enum perf_callchain_context { #include #include #include +#include #include #define PERF_MAX_STACK_DEPTH 255 @@ -513,6 +514,10 @@ struct file; struct perf_mmap_data { struct rcu_head rcu_head; +#ifdef CONFIG_PERF_WANTS_VMALLOC + struct work_struct work; +#endif + int data_order; int nr_pages; /* nr of data pages */ int writable; /* are we writable */ int nr_locked; /* nr pages mlocked */ diff --git a/init/Kconfig b/init/Kconfig index 0aa6579..b18c709 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -921,6 +921,11 @@ config HAVE_PERF_EVENTS help See tools/perf/design.txt for details. +config PERF_NEEDS_VMALLOC + bool + help + See tools/perf/design.txt for details + menu "Kernel Performance Events And Counters" config PERF_EVENTS @@ -976,6 +981,18 @@ config PERF_COUNTERS Say N if unsure. +config PERF_WANTS_VMALLOC + bool "Use vmalloc to back perf mmap() buffers" + default y if (PERF_NEEDS_VMALLOC) + depends on PERF_EVENTS + help + Use vmalloc memory to back perf mmap() buffers. + + Mostly useful for debugging the vmalloc code on platforms + that don't require it. + + Say N if unsure. + endmenu config VM_EVENT_COUNTERS diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 76ac4db..2f7c08f 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -2105,49 +2106,31 @@ unlock: rcu_read_unlock(); } -static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +static unsigned long perf_data_size(struct perf_mmap_data *data) { - struct perf_event *event = vma->vm_file->private_data; - struct perf_mmap_data *data; - int ret = VM_FAULT_SIGBUS; - - if (vmf->flags & FAULT_FLAG_MKWRITE) { - if (vmf->pgoff == 0) - ret = 0; - return ret; - } - - rcu_read_lock(); - data = rcu_dereference(event->data); - if (!data) - goto unlock; - - if (vmf->pgoff == 0) { - vmf->page = virt_to_page(data->user_page); - } else { - int nr = vmf->pgoff - 1; - - if ((unsigned)nr > data->nr_pages) - goto unlock; + return data->nr_pages << (PAGE_SHIFT + data->data_order); +} - if (vmf->flags & FAULT_FLAG_WRITE) - goto unlock; +#ifndef CONFIG_PERF_WANTS_VMALLOC - vmf->page = virt_to_page(data->data_pages[nr]); - } +/* + * Back perf_mmap() with regular GFP_KERNEL-0 pages. + */ - get_page(vmf->page); - vmf->page->mapping = vma->vm_file->f_mapping; - vmf->page->index = vmf->pgoff; +static struct page * +perf_mmap_to_page(struct perf_mmap_data *data, unsigned long pgoff) +{ + if (pgoff > data->nr_pages) + return NULL; - ret = 0; -unlock: - rcu_read_unlock(); + if (pgoff == 0) + return virt_to_page(data->user_page); - return ret; + return virt_to_page(data->data_pages[pgoff - 1]); } -static int perf_mmap_data_alloc(struct perf_event *event, int nr_pages) +static struct perf_mmap_data * +perf_mmap_data_alloc(struct perf_event *event, int nr_pages) { struct perf_mmap_data *data; unsigned long size; @@ -2172,19 +2155,10 @@ static int perf_mmap_data_alloc(struct perf_event *event, int nr_pages) goto fail_data_pages; } + data->data_order = 0; data->nr_pages = nr_pages; - atomic_set(&data->lock, -1); - - if (event->attr.watermark) { - data->watermark = min_t(long, PAGE_SIZE * nr_pages, - event->attr.wakeup_watermark); - } - if (!data->watermark) - data->watermark = max(PAGE_SIZE, PAGE_SIZE * nr_pages / 4); - rcu_assign_pointer(event->data, data); - - return 0; + return data; fail_data_pages: for (i--; i >= 0; i--) @@ -2196,7 +2170,7 @@ fail_user_page: kfree(data); fail: - return -ENOMEM; + return NULL; } static void perf_mmap_free_page(unsigned long addr) @@ -2207,28 +2181,169 @@ static void perf_mmap_free_page(unsigned long addr) __free_page(page); } -static void __perf_mmap_data_free(struct rcu_head *rcu_head) +static void perf_mmap_data_free(struct perf_mmap_data *data) { - struct perf_mmap_data *data; int i; - data = container_of(rcu_head, struct perf_mmap_data, rcu_head); - perf_mmap_free_page((unsigned long)data->user_page); for (i = 0; i < data->nr_pages; i++) perf_mmap_free_page((unsigned long)data->data_pages[i]); +} + +#else + +/* + * Back perf_mmap() with vmalloc memory. + * + * Required for architectures that have d-cache aliasing issues. + */ + +static struct page * +perf_mmap_to_page(struct perf_mmap_data *data, unsigned long pgoff) +{ + if (pgoff > (1UL << data->data_order)) + return NULL; + + return vmalloc_to_page((void *)data->user_page + pgoff * PAGE_SIZE); +} + +static void perf_mmap_unmark_page(void *addr) +{ + struct page *page = vmalloc_to_page(addr); + + page->mapping = NULL; +} + +static void perf_mmap_data_free_work(struct work_struct *work) +{ + struct perf_mmap_data *data; + void *base; + int i, nr; + + data = container_of(work, struct perf_mmap_data, work); + nr = 1 << data->data_order; + + base = data->user_page; + for (i = 0; i < nr + 1; i++) + perf_mmap_unmark_page(base + (i * PAGE_SIZE)); + + vfree(base); +} + +static void perf_mmap_data_free(struct perf_mmap_data *data) +{ + schedule_work(&data->work); +} + +static struct perf_mmap_data * +perf_mmap_data_alloc(struct perf_event *event, int nr_pages) +{ + struct perf_mmap_data *data; + unsigned long size; + void *all_buf; + WARN_ON(atomic_read(&event->mmap_count)); + + size = sizeof(struct perf_mmap_data); + size += sizeof(void *); + + data = kzalloc(size, GFP_KERNEL); + if (!data) + goto fail; + + INIT_WORK(&data->work, perf_mmap_data_free_work); + + all_buf = vmalloc_user((nr_pages + 1) * PAGE_SIZE); + if (!all_buf) + goto fail_all_buf; + + data->user_page = all_buf; + data->data_pages[0] = all_buf + PAGE_SIZE; + data->data_order = ilog2(nr_pages); + data->nr_pages = 1; + + return data; + +fail_all_buf: + kfree(data); + +fail: + return NULL; +} + +#endif + +static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + struct perf_event *event = vma->vm_file->private_data; + struct perf_mmap_data *data; + int ret = VM_FAULT_SIGBUS; + + if (vmf->flags & FAULT_FLAG_MKWRITE) { + if (vmf->pgoff == 0) + ret = 0; + return ret; + } + + rcu_read_lock(); + data = rcu_dereference(event->data); + if (!data) + goto unlock; + + if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE)) + goto unlock; + + vmf->page = perf_mmap_to_page(data, vmf->pgoff); + if (!vmf->page) + goto unlock; + + get_page(vmf->page); + vmf->page->mapping = vma->vm_file->f_mapping; + vmf->page->index = vmf->pgoff; + + ret = 0; +unlock: + rcu_read_unlock(); + + return ret; +} + +static void +perf_mmap_data_init(struct perf_event *event, struct perf_mmap_data *data) +{ + long max_size = perf_data_size(data); + + atomic_set(&data->lock, -1); + + if (event->attr.watermark) { + data->watermark = min_t(long, max_size, + event->attr.wakeup_watermark); + } + + if (!data->watermark) + data->watermark = max_t(long, PAGE_SIZE, max_size / 2); + + + rcu_assign_pointer(event->data, data); +} + +static void perf_mmap_data_free_rcu(struct rcu_head *rcu_head) +{ + struct perf_mmap_data *data; + + data = container_of(rcu_head, struct perf_mmap_data, rcu_head); + perf_mmap_data_free(data); kfree(data); } -static void perf_mmap_data_free(struct perf_event *event) +static void perf_mmap_data_release(struct perf_event *event) { struct perf_mmap_data *data = event->data; WARN_ON(atomic_read(&event->mmap_count)); rcu_assign_pointer(event->data, NULL); - call_rcu(&data->rcu_head, __perf_mmap_data_free); + call_rcu(&data->rcu_head, perf_mmap_data_free_rcu); } static void perf_mmap_open(struct vm_area_struct *vma) @@ -2244,11 +2359,12 @@ static void perf_mmap_close(struct vm_area_struct *vma) WARN_ON_ONCE(event->ctx->parent_ctx); if (atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) { + unsigned long size = perf_data_size(event->data); struct user_struct *user = current_user(); - atomic_long_sub(event->data->nr_pages + 1, &user->locked_vm); + atomic_long_sub((size >> PAGE_SHIFT) + 1, &user->locked_vm); vma->vm_mm->locked_vm -= event->data->nr_locked; - perf_mmap_data_free(event); + perf_mmap_data_release(event); mutex_unlock(&event->mmap_mutex); } } @@ -2266,6 +2382,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) unsigned long user_locked, user_lock_limit; struct user_struct *user = current_user(); unsigned long locked, lock_limit; + struct perf_mmap_data *data; unsigned long vma_size; unsigned long nr_pages; long user_extra, extra; @@ -2328,10 +2445,15 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) } WARN_ON(event->data); - ret = perf_mmap_data_alloc(event, nr_pages); - if (ret) + + data = perf_mmap_data_alloc(event, nr_pages); + ret = -ENOMEM; + if (!data) goto unlock; + ret = 0; + perf_mmap_data_init(event, data); + atomic_set(&event->mmap_count, 1); atomic_long_add(user_extra, &user->locked_vm); vma->vm_mm->locked_vm += extra; @@ -2519,7 +2641,7 @@ static bool perf_output_space(struct perf_mmap_data *data, unsigned long tail, if (!data->writable) return true; - mask = (data->nr_pages << PAGE_SHIFT) - 1; + mask = perf_data_size(data) - 1; offset = (offset - tail) & mask; head = (head - tail) & mask; @@ -2624,7 +2746,7 @@ void perf_output_copy(struct perf_output_handle *handle, const void *buf, unsigned int len) { unsigned int pages_mask; - unsigned int offset; + unsigned long offset; unsigned int size; void **pages; @@ -2633,12 +2755,14 @@ void perf_output_copy(struct perf_output_handle *handle, pages = handle->data->data_pages; do { - unsigned int page_offset; + unsigned long page_offset; + unsigned long page_size; int nr; nr = (offset >> PAGE_SHIFT) & pages_mask; - page_offset = offset & (PAGE_SIZE - 1); - size = min_t(unsigned int, PAGE_SIZE - page_offset, len); + page_size = 1UL << (handle->data->data_order + PAGE_SHIFT); + page_offset = offset & (page_size - 1); + size = min_t(unsigned int, page_size - page_offset, len); memcpy(pages[nr] + page_offset, buf, size); diff --git a/tools/perf/design.txt b/tools/perf/design.txt index f1946d1..97398b0 100644 --- a/tools/perf/design.txt +++ b/tools/perf/design.txt @@ -455,3 +455,6 @@ will need at least this: If your architecture does have hardware capabilities, you can override the weak stub hw_perf_event_init() to register hardware counters. + +Architectures that have d-cache aliassing issues, such as Sparc and ARM, +should select PERF_NEEDS_VMALLOC in order to avoid these for perf mmap().