From patchwork Thu Feb 22 20:43:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Henderson X-Patchwork-Id: 774900 Delivered-To: patch@linaro.org Received: by 2002:adf:a356:0:b0:33b:4db1:f5b3 with SMTP id d22csp43854wrb; Thu, 22 Feb 2024 12:47:33 -0800 (PST) X-Forwarded-Encrypted: i=2; AJvYcCVkySM5N/qNzOLhdM3hcSPPGOm6OA92yja9RD1o15DtXIxsV6/w1MUOb6QgcOGFVidzt9Y83in15e536iZrUjN7 X-Google-Smtp-Source: AGHT+IG58qGRZP6tkvt6nraI+hP9vYGJ4d1z9gtRK7WWuZkq8C5hD5YscezshsaEGsAOgK4OFyPc X-Received: by 2002:a05:6830:9:b0:6e1:13a2:3948 with SMTP id c9-20020a056830000900b006e113a23948mr196109otp.5.1708634853436; Thu, 22 Feb 2024 12:47:33 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1708634853; cv=none; d=google.com; s=arc-20160816; b=OlV6hqkKtnSEhesr3ITm/r/RapgtooBVO3qaad78OrqZVnnG9XVNnPphU/fgJsrgFL /ImFSB31ZPoL9mJftakIT/m1jjC2fYf+DRVn4ZBtq/9ND8x9PuZstNvifOdlwbeo4Fvu tRw7O+qMFdwCuIHYO8hqlM3PS8zn4TdT4EyM1TYKBLVsh5cLICBY6TgTrcpfSiXHCsxG M7oBuRDSWHld+fSn1eP+0vW743gTiNU9FzujN6QWP1et5H/HWGt+O4fFV8A67we9FJtY Ah/95z/geGqa6pWbpsV3oCulfCCZpH8myXz+Zpa6vTEfBzd8JB8SmmtbfUsYJnXrmS75 JHYw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:list-subscribe:list-help:list-post:list-archive :list-unsubscribe:list-id:precedence:content-transfer-encoding :mime-version:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=I4UwZkIS26PhKHP+iY1jWw6KRSEUK2Dc0FNGbwDM3y4=; fh=akUSvRccVt8SjEp97fUPeSLjFmLWLgFk16EYqCeIvf8=; b=qipEqMQ4GlLr8a30y760ViUDu/S8fa8ioRH04Fw+WznnnAM+YkBfIxu9uPSqPrOzVF c3l2qsaWdXDhpSlGGvHzDsQy2Wx10PnLTv+v3UesKpSbrQdtOyWEWkVZhudL0f9f84ct S9XKbt0prJxAZThXc8bZzKXLB6CcKacAXh4n5Fj9V06ApMeHAiKnlP7zOkCo/QkXHKcH cecMrJsNnb5jVVRBj7OcfB9ubUg0ZRsK4rwjcaN/ZgVxYOehityc4hGlEXOJt6rUO9fx ncgk0yTVXvpMo371RKoDR3iz5be2LcHj8mIt60sLswvXjjBAvvG6quF+DN1Xngot4YG1 7dlQ==; dara=google.com ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=vYcoB7I+; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+patch=linaro.org@nongnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from lists.gnu.org (lists.gnu.org. [209.51.188.17]) by mx.google.com with ESMTPS id b24-20020ac85418000000b0042e50840471si1573313qtq.530.2024.02.22.12.47.33 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 22 Feb 2024 12:47:33 -0800 (PST) Received-SPF: pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=vYcoB7I+; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+patch=linaro.org@nongnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rdFvQ-0007gf-Fr; Thu, 22 Feb 2024 15:44:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rdFvO-0007f9-NN for qemu-devel@nongnu.org; Thu, 22 Feb 2024 15:44:10 -0500 Received: from mail-pl1-x62d.google.com ([2607:f8b0:4864:20::62d]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1rdFvM-0002kt-P2 for qemu-devel@nongnu.org; Thu, 22 Feb 2024 15:44:10 -0500 Received: by mail-pl1-x62d.google.com with SMTP id d9443c01a7336-1dba94f9201so2033125ad.0 for ; Thu, 22 Feb 2024 12:44:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1708634647; x=1709239447; darn=nongnu.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=I4UwZkIS26PhKHP+iY1jWw6KRSEUK2Dc0FNGbwDM3y4=; b=vYcoB7I+svat1gp4rABqsuXPL7k+lOamSGb8G5j4P25bOA9yiZv8V1cKvbpRcz7+I3 OVGgN+t7VUvMWtjICIH57xLuN30mv+PQRGgNCjkUFHkwl4pIxST2qOSTZcgvD6QxUjiS QCUV6fY1HgJ2QKvMMfO0Kvq/lThYiGkbUsnJmun4N72SYnVaT5TwOzrfWpGP4EZYqduJ e/vVL7TdF2WKzQB5jwuNyXdeIgB//2zajH9YA4wnbzBf3jUkusym84FvcwmFKUmcgiAu bUninxD2ghcTbD4n/Kt7olQkjX4smCSdWmhUvO7XXIvhruJp+kSNELsgm7Ap0uO9KST+ IJyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708634647; x=1709239447; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=I4UwZkIS26PhKHP+iY1jWw6KRSEUK2Dc0FNGbwDM3y4=; b=HUXX2vDcaWOJ4x+aNHm5VBCC9BuXd/XEV5CgLLD1UqvBi7JMGTGeRKrgUsYzx8BvhL 5HQSCMMjZN7jQHZ/PiMIOG26mZd2JLSxo4eFY5rOTXtpqdywYbgPF5bycBFXohsZZ3fu 0reK+aCMU3udl4m4dOGU7924y8YWK24Fp5CwXvTHCe1I4hrDPpafsDdvG/xI3QyFNrPx kWiOazmf8M5clQZusteW7cBf47sHlf4nuSim1j6YWRfKR29Lk0UNlLaUMNZ960JRkESh Gten/gwqNmby1QdauBJCxAcgeQZhB93EKH2HKu6peLxkdLchT/PLvn8W6nXhIDTrV3A1 oedw== X-Gm-Message-State: AOJu0Yyml2BX/GucMrDSo4hZLQDdXQaupQXqLHRn6y8ekP/VaO530XmI EtzPOsqL2oFSbyXFMq85tD4EftZCM6aiSEpySUKIkhg9I/RS7bCFT97MmT9NVeBqi8tTODiJIrJ R X-Received: by 2002:a17:902:ecc1:b0:1dc:673:1932 with SMTP id a1-20020a170902ecc100b001dc06731932mr13462931plh.38.1708634647523; Thu, 22 Feb 2024 12:44:07 -0800 (PST) Received: from stoup.. (173-197-098-125.biz.spectrum.com. [173.197.98.125]) by smtp.gmail.com with ESMTPSA id l12-20020a170902d34c00b001d8f81ecebesm10275500plk.192.2024.02.22.12.44.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Feb 2024 12:44:07 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Cc: Pierrick Bouvier , Helge Deller Subject: [PULL 27/39] linux-user: Split out mmap_h_lt_g Date: Thu, 22 Feb 2024 10:43:11 -1000 Message-Id: <20240222204323.268539-28-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240222204323.268539-1-richard.henderson@linaro.org> References: <20240222204323.268539-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::62d; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x62d.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: qemu-devel-bounces+patch=linaro.org@nongnu.org Work much harder to get alignment and mapping beyond the end of the file correct. Both of which are excercised by our test-mmap for alpha (8k pages) on any 4k page host. Signed-off-by: Richard Henderson Reviewed-by: Pierrick Bouvier Acked-by: Helge Deller Message-Id: <20240102015808.132373-23-richard.henderson@linaro.org> --- linux-user/mmap.c | 184 ++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 153 insertions(+), 31 deletions(-) diff --git a/linux-user/mmap.c b/linux-user/mmap.c index d3556bcc14..ff8f9f7ed0 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -569,6 +569,156 @@ static abi_long mmap_h_eq_g(abi_ulong start, abi_ulong len, return mmap_end(start, last, start, last, flags, page_flags); } +/* + * Special case host page size < target page size. + * + * The two special cases are increased guest alignment, and mapping + * past the end of a file. + * + * When mapping files into a memory area larger than the file, + * accesses to pages beyond the file size will cause a SIGBUS. + * + * For example, if mmaping a file of 100 bytes on a host with 4K + * pages emulating a target with 8K pages, the target expects to + * be able to access the first 8K. But the host will trap us on + * any access beyond 4K. + * + * When emulating a target with a larger page-size than the hosts, + * we may need to truncate file maps at EOF and add extra anonymous + * pages up to the targets page boundary. + * + * This workaround only works for files that do not change. + * If the file is later extended (e.g. ftruncate), the SIGBUS + * vanishes and the proper behaviour is that changes within the + * anon page should be reflected in the file. + * + * However, this case is rather common with executable images, + * so the workaround is important for even trivial tests, whereas + * the mmap of of a file being extended is less common. + */ +static abi_long mmap_h_lt_g(abi_ulong start, abi_ulong len, int host_prot, + int mmap_flags, int page_flags, int fd, + off_t offset, int host_page_size) +{ + void *p, *want_p = g2h_untagged(start); + off_t fileend_adj = 0; + int flags = mmap_flags; + abi_ulong last, pass_last; + + if (!(flags & MAP_ANONYMOUS)) { + struct stat sb; + + if (fstat(fd, &sb) == -1) { + return -1; + } + if (offset >= sb.st_size) { + /* + * The entire map is beyond the end of the file. + * Transform it to an anonymous mapping. + */ + flags |= MAP_ANONYMOUS; + fd = -1; + offset = 0; + } else if (offset + len > sb.st_size) { + /* + * A portion of the map is beyond the end of the file. + * Truncate the file portion of the allocation. + */ + fileend_adj = offset + len - sb.st_size; + } + } + + if (flags & (MAP_FIXED | MAP_FIXED_NOREPLACE)) { + if (fileend_adj) { + p = mmap(want_p, len, host_prot, flags | MAP_ANONYMOUS, -1, 0); + } else { + p = mmap(want_p, len, host_prot, flags, fd, offset); + } + if (p != want_p) { + if (p != MAP_FAILED) { + /* Host does not support MAP_FIXED_NOREPLACE: emulate. */ + do_munmap(p, len); + errno = EEXIST; + } + return -1; + } + + if (fileend_adj) { + void *t = mmap(p, len - fileend_adj, host_prot, + (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED, + fd, offset); + + if (t == MAP_FAILED) { + int save_errno = errno; + + /* + * We failed a map over the top of the successful anonymous + * mapping above. The only failure mode is running out of VMAs, + * and there's nothing that we can do to detect that earlier. + * If we have replaced an existing mapping with MAP_FIXED, + * then we cannot properly recover. It's a coin toss whether + * it would be better to exit or continue here. + */ + if (!(flags & MAP_FIXED_NOREPLACE) && + !page_check_range_empty(start, start + len - 1)) { + qemu_log("QEMU target_mmap late failure: %s", + strerror(save_errno)); + } + + do_munmap(want_p, len); + errno = save_errno; + return -1; + } + } + } else { + size_t host_len, part_len; + + /* + * Take care to align the host memory. Perform a larger anonymous + * allocation and extract the aligned portion. Remap the file on + * top of that. + */ + host_len = len + TARGET_PAGE_SIZE - host_page_size; + p = mmap(want_p, host_len, host_prot, flags | MAP_ANONYMOUS, -1, 0); + if (p == MAP_FAILED) { + return -1; + } + + part_len = (uintptr_t)p & (TARGET_PAGE_SIZE - 1); + if (part_len) { + part_len = TARGET_PAGE_SIZE - part_len; + do_munmap(p, part_len); + p += part_len; + host_len -= part_len; + } + if (len < host_len) { + do_munmap(p + len, host_len - len); + } + + if (!(flags & MAP_ANONYMOUS)) { + void *t = mmap(p, len - fileend_adj, host_prot, + flags | MAP_FIXED, fd, offset); + + if (t == MAP_FAILED) { + int save_errno = errno; + do_munmap(p, len); + errno = save_errno; + return -1; + } + } + + start = h2g(p); + } + + last = start + len - 1; + if (fileend_adj) { + pass_last = ROUND_UP(last - fileend_adj, host_page_size) - 1; + } else { + pass_last = last; + } + return mmap_end(start, last, start, pass_last, mmap_flags, page_flags); +} + static abi_long target_mmap__locked(abi_ulong start, abi_ulong len, int target_prot, int flags, int page_flags, int fd, off_t offset) @@ -613,37 +763,9 @@ static abi_long target_mmap__locked(abi_ulong start, abi_ulong len, if (host_page_size == TARGET_PAGE_SIZE) { return mmap_h_eq_g(start, len, host_prot, flags, page_flags, fd, offset); - } - - /* - * When mapping files into a memory area larger than the file, accesses - * to pages beyond the file size will cause a SIGBUS. - * - * For example, if mmaping a file of 100 bytes on a host with 4K pages - * emulating a target with 8K pages, the target expects to be able to - * access the first 8K. But the host will trap us on any access beyond - * 4K. - * - * When emulating a target with a larger page-size than the hosts, we - * may need to truncate file maps at EOF and add extra anonymous pages - * up to the targets page boundary. - */ - if (host_page_size < TARGET_PAGE_SIZE && !(flags & MAP_ANONYMOUS)) { - struct stat sb; - - if (fstat(fd, &sb) == -1) { - return -1; - } - - /* Are we trying to create a map beyond EOF?. */ - if (offset + len > sb.st_size) { - /* - * If so, truncate the file map at eof aligned with - * the hosts real pagesize. Additional anonymous maps - * will be created beyond EOF. - */ - len = ROUND_UP(sb.st_size - offset, host_page_size); - } + } else if (host_page_size < TARGET_PAGE_SIZE) { + return mmap_h_lt_g(start, len, host_prot, flags, + page_flags, fd, offset, host_page_size); } if (!(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) {