From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7DA4C433F5 for ; Mon, 17 Jan 2022 15:37:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240530AbiAQPhE (ORCPT ); Mon, 17 Jan 2022 10:37:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237296AbiAQPhC (ORCPT ); Mon, 17 Jan 2022 10:37:02 -0500 Received: from mail-wm1-x349.google.com (mail-wm1-x349.google.com [IPv6:2a00:1450:4864:20::349]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FE20C061574 for ; Mon, 17 Jan 2022 07:37:02 -0800 (PST) Received: by mail-wm1-x349.google.com with SMTP id w5-20020a1cf605000000b0034b8cb1f55eso5190179wmc.0 for ; Mon, 17 Jan 2022 07:37:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=1thsq464ntZ1Q6hN1oNhhbpxlas4Ufptak2u+5NaEgg=; b=Mu/4nG9MsWYJC0F8RgjvHauRdNem04cKRH+xztrPCTh8xwBL3zS9lULs+kndSOLPeg DCY1B7EiOfqzKPw5+gzRCFB/kqf1/Et/m0GCDDjCDo1KKkYmkFqlBfmhol/1RO4PGsFX vQy2wtJu4HzXh/XG1T88ibpsyL3WkYqxxDegotZDOkoy4Kuo+Q4JUBj+xxxXkDXHX8o+ oWmfg+Ou3VNd9Rwlk6zCBxYsLyi+l7Fhn9N7jhCWMHMNVN0/Nf7Hicrr+Jjb7sRWm/oZ to02tjLEO5wgUISZBZwXTyP6AzT4h6LjKeNTeIQqlHAStRY89nm5+gNWCHzz6wdtjpBe RPtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=1thsq464ntZ1Q6hN1oNhhbpxlas4Ufptak2u+5NaEgg=; b=E8z51Rzyggk9LxFrArQ1TzxrAW9wyZV5G+QxH5WSy/vtPuuHzDVhhUWZLRI2oPfgsn tp7df144i/V5Nti5xwE7SKLq3LQwceni+yEhklMbEFGVNE2GbI9SrQNgdZR2I8Y4Y4UA zqWKo6SMHPLEPdM0af5qsbRRvABwCFO6ng/SZ614DZUwmsLjOLOnbzJGgligbgRLc/gz VboT8hH+C9mR7etUELI2/h1HuH3Px8/oL35LE8Tug+SFv37ju0r4CoZqrmNe4EDHJvMy itR9Zw6ElOfT/7hAdVk2OmdrL7iC56pp/sb0YVNIAFCO/rLygejXvZOKpQx/cE63BzsN Cu2A== X-Gm-Message-State: AOAM533+mJmYQzdHYNBLJCtykqczJVSUxY+t6H7h7BQMyJBE21uCmzSK lvYRWple/6mRSU9z6zv/rp10d32Er9A= X-Google-Smtp-Source: ABdhPJyeOOYVbaUb669nA1YMRKxEqaGjPJjSEmytoc6GRzTaslfSLpD5JOlE0QEasuDhzg3ORCJRsiGtLYc= X-Received: from nogikh-hp.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:200d]) (user=nogikh job=sendgmr) by 2002:a05:600c:33a7:: with SMTP id o39mr20091461wmp.6.1642433820772; Mon, 17 Jan 2022 07:37:00 -0800 (PST) Date: Mon, 17 Jan 2022 15:36:34 +0000 In-Reply-To: <20220117153634.150357-1-nogikh@google.com> Message-Id: <20220117153634.150357-3-nogikh@google.com> Mime-Version: 1.0 References: <20220117153634.150357-1-nogikh@google.com> X-Mailer: git-send-email 2.34.1.703.g22d0c6ccf7-goog Subject: [PATCH v3 2/2] kcov: properly handle subsequent mmap calls From: Aleksandr Nogikh To: kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: dvyukov@google.com, andreyknvl@gmail.com, elver@google.com, glider@google.com, tarasmadan@google.com, bigeasy@linutronix.de, nogikh@google.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Allocate the kcov buffer during KCOV_MODE_INIT in order to untie mmapping of a kcov instance and the actual coverage collection process. Modify kcov_mmap, so that it can be reliably used any number of times once KCOV_MODE_INIT has succeeded. These changes to the user-facing interface of the tool only weaken the preconditions, so all existing user space code should remain compatible with the new version. Signed-off-by: Aleksandr Nogikh --- kernel/kcov.c | 34 +++++++++++++++------------------- 1 file changed, 15 insertions(+), 19 deletions(-) diff --git a/kernel/kcov.c b/kernel/kcov.c index e1be7301500b..475524bd900a 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -459,37 +459,28 @@ void kcov_task_exit(struct task_struct *t) static int kcov_mmap(struct file *filep, struct vm_area_struct *vma) { int res = 0; - void *area; struct kcov *kcov = vma->vm_file->private_data; unsigned long size, off; struct page *page; unsigned long flags; - area = vmalloc_user(vma->vm_end - vma->vm_start); - if (!area) - return -ENOMEM; - spin_lock_irqsave(&kcov->lock, flags); size = kcov->size * sizeof(unsigned long); - if (kcov->mode != KCOV_MODE_INIT || vma->vm_pgoff != 0 || + if (kcov->area == NULL || vma->vm_pgoff != 0 || vma->vm_end - vma->vm_start != size) { res = -EINVAL; goto exit; } - if (!kcov->area) { - kcov->area = area; - vma->vm_flags |= VM_DONTEXPAND; - spin_unlock_irqrestore(&kcov->lock, flags); - for (off = 0; off < size; off += PAGE_SIZE) { - page = vmalloc_to_page(kcov->area + off); - if (vm_insert_page(vma, vma->vm_start + off, page)) - WARN_ONCE(1, "vm_insert_page() failed"); - } - return 0; + spin_unlock_irqrestore(&kcov->lock, flags); + vma->vm_flags |= VM_DONTEXPAND; + for (off = 0; off < size; off += PAGE_SIZE) { + page = vmalloc_to_page(kcov->area + off); + if (vm_insert_page(vma, vma->vm_start + off, page)) + WARN_ONCE(1, "vm_insert_page() failed"); } + return 0; exit: spin_unlock_irqrestore(&kcov->lock, flags); - vfree(area); return res; } @@ -674,6 +665,7 @@ static long kcov_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) unsigned int remote_num_handles; unsigned long remote_arg_size; unsigned long size, flags; + void *area; kcov = filep->private_data; switch (cmd) { @@ -683,17 +675,21 @@ static long kcov_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) * Must happen before anything else. * * First check the size argument - it must be at least 2 - * to hold the current position and one PC. Later we allocate - * size * sizeof(unsigned long) memory, that must not overflow. + * to hold the current position and one PC. */ size = arg; if (size < 2 || size > INT_MAX / sizeof(unsigned long)) return -EINVAL; + area = vmalloc_user(size * sizeof(unsigned long)); + if (area == NULL) + return -ENOMEM; spin_lock_irqsave(&kcov->lock, flags); if (kcov->mode != KCOV_MODE_DISABLED) { spin_unlock_irqrestore(&kcov->lock, flags); + vfree(area); return -EBUSY; } + kcov->area = area; kcov->size = size; kcov->mode = KCOV_MODE_INIT; spin_unlock_irqrestore(&kcov->lock, flags); -- 2.34.1.703.g22d0c6ccf7-goog