From patchwork Sat Jul 15 13:53:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Henderson X-Patchwork-Id: 1808160 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256 header.s=google header.b=wsEvgqE5; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4R38yJ2fvvz20c3 for ; Sat, 15 Jul 2023 23:56:08 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qKfjZ-00062M-Vm; Sat, 15 Jul 2023 09:54:54 -0400 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 1qKfia-00048V-1A for qemu-devel@nongnu.org; Sat, 15 Jul 2023 09:53:59 -0400 Received: from mail-wr1-x436.google.com ([2a00:1450:4864:20::436]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qKfiU-0001KB-3M for qemu-devel@nongnu.org; Sat, 15 Jul 2023 09:53:50 -0400 Received: by mail-wr1-x436.google.com with SMTP id ffacd0b85a97d-3090d3e9c92so3053009f8f.2 for ; Sat, 15 Jul 2023 06:53:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1689429225; x=1692021225; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:from:to:cc:subject:date:message-id :reply-to; bh=aO8i+PWWEj2wFULENv6+H9RCy3N3UL0z2bpJ1K4Mi2s=; b=wsEvgqE5JwG2oMXqSuKUyB74s//5oP3TdSjTQFzT8S8Hk0lKibidfY78ixLTyuEXZu 6UwEj3NuwsDcvNsVkj75tLGE4TQFVnkvV9x99ix2TAzfwXCaV/Ldwfv2/kPxDxPPE+cY qoeouKTOhWwkHAz1mXOBa749xFCmPBcXwc5tZw+2x0gifbbbn0ViwP9KQeHZ9y56lbrV RKxmaOij2b6ShkGf4r2QLEEiMoysOpsEAFb5Y7rUaQ9ksCv5JELS9/adU47Ye7dKQdb6 2sCc3LdY4QVvXzWLsP5SV2SYO9wLAIrjK1gPIredUJn0a9K9rPNuVdzy1WkFnvMcpGDc 9tMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689429225; x=1692021225; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=aO8i+PWWEj2wFULENv6+H9RCy3N3UL0z2bpJ1K4Mi2s=; b=HggP1hEKIjQHu2yg9mApvJUOANnghMPj+5m9RZU9J2+kFhi/56yDRqRhaox13eFuWZ JR7NPBYfEY1XaissTLoP6uR+cuO4t8fZZsVIk1QPxiNXi7Bkl2iJ+42ho0hX2Q+9El6S iRQW5oHujkbHUrHaUC4/gj1NCc8rau7W4B0AK/BWRTZiZUPQ91BIhOeGij30QEMegmUY IdXfs5Ik4xs3ji7O08df2aphkvpGVgMNv45n6EveULGTNchS2KjgQmVZIeBcn5xaSK4c tVg0nQV9hVXErKhjWLF31E/7BN1Q0ynFx8OoEcRvz8VN57AsKa83h1Cu2r44//ctVcil +kFw== X-Gm-Message-State: ABy/qLYOZWEl2pMBMcZ5fVgRda/FROtThOvZs41IpdOuSsv1ypR++qb8 g32yTVwWMY9/ryIFn8q/YjqmIsl9S+6X7g8fvZA6iw== X-Google-Smtp-Source: APBJJlHOZkgsoNINbGjpQ2VG+qhjQ9Xaaak80NB5eST1fQoYz3bMOSC6OWFoTyhR3Ch24uFPc/3YDQ== X-Received: by 2002:adf:fbc4:0:b0:316:e325:fd92 with SMTP id d4-20020adffbc4000000b00316e325fd92mr7014989wrs.55.1689429224759; Sat, 15 Jul 2023 06:53:44 -0700 (PDT) Received: from stoup.lan ([51.219.12.49]) by smtp.gmail.com with ESMTPSA id k10-20020a5d66ca000000b00313f9085119sm13838014wrw.113.2023.07.15.06.53.44 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 15 Jul 2023 06:53:44 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PULL 32/47] linux-user: Rewrite mmap_frag Date: Sat, 15 Jul 2023 14:53:02 +0100 Message-Id: <20230715135317.7219-33-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230715135317.7219-1-richard.henderson@linaro.org> References: <20230715135317.7219-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::436; envelope-from=richard.henderson@linaro.org; helo=mail-wr1-x436.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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Use 'last' variables instead of 'end' variables. Always zero MAP_ANONYMOUS fragments, which we previously failed to do if they were not writable; early exit in case we allocate a new page from the kernel, known zeros. Signed-off-by: Richard Henderson Message-Id: <20230707204054.8792-16-richard.henderson@linaro.org> --- linux-user/mmap.c | 123 +++++++++++++++++++++++----------------------- 1 file changed, 62 insertions(+), 61 deletions(-) diff --git a/linux-user/mmap.c b/linux-user/mmap.c index d02d74d279..c4b2515271 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -222,73 +222,76 @@ int target_mprotect(abi_ulong start, abi_ulong len, int target_prot) } /* map an incomplete host page */ -static int mmap_frag(abi_ulong real_start, - abi_ulong start, abi_ulong end, - int prot, int flags, int fd, off_t offset) +static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, + int prot, int flags, int fd, off_t offset) { - abi_ulong real_end, addr; + abi_ulong real_last; void *host_start; - int prot1, prot_new; + int prot_old, prot_new; + int host_prot_old, host_prot_new; - real_end = real_start + qemu_host_page_size; - host_start = g2h_untagged(real_start); - - /* get the protection of the target pages outside the mapping */ - prot1 = 0; - for (addr = real_start; addr < real_end; addr++) { - if (addr < start || addr >= end) { - prot1 |= page_get_flags(addr); - } + if (!(flags & MAP_ANONYMOUS) + && (flags & MAP_TYPE) == MAP_SHARED + && (prot & PROT_WRITE)) { + /* + * msync() won't work with the partial page, so we return an + * error if write is possible while it is a shared mapping. + */ + errno = EINVAL; + return false; } - if (prot1 == 0) { - /* no page was there, so we allocate one */ + real_last = real_start + qemu_host_page_size - 1; + host_start = g2h_untagged(real_start); + + /* Get the protection of the target pages outside the mapping. */ + prot_old = 0; + for (abi_ulong a = real_start; a < start; a += TARGET_PAGE_SIZE) { + prot_old |= page_get_flags(a); + } + for (abi_ulong a = real_last; a > last; a -= TARGET_PAGE_SIZE) { + prot_old |= page_get_flags(a); + } + + if (prot_old == 0) { + /* + * Since !(prot_old & PAGE_VALID), there were no guest pages + * outside of the fragment we need to map. Allocate a new host + * page to cover, discarding whatever else may have been present. + */ void *p = mmap(host_start, qemu_host_page_size, target_to_host_prot(prot), flags | MAP_ANONYMOUS, -1, 0); if (p == MAP_FAILED) { - return -1; + return false; } - prot1 = prot; + prot_old = prot; } - prot1 &= PAGE_BITS; + prot_new = prot | prot_old; - prot_new = prot | prot1; - if (!(flags & MAP_ANONYMOUS)) { - /* - * msync() won't work here, so we return an error if write is - * possible while it is a shared mapping. - */ - if ((flags & MAP_TYPE) == MAP_SHARED && (prot & PROT_WRITE)) { - return -1; - } + host_prot_old = target_to_host_prot(prot_old); + host_prot_new = target_to_host_prot(prot_new); - /* adjust protection to be able to read */ - if (!(prot1 & PROT_WRITE)) { - mprotect(host_start, qemu_host_page_size, - target_to_host_prot(prot1) | PROT_WRITE); - } + /* Adjust protection to be able to write. */ + if (!(host_prot_old & PROT_WRITE)) { + host_prot_old |= PROT_WRITE; + mprotect(host_start, qemu_host_page_size, host_prot_old); + } - /* read the corresponding file data */ - if (pread(fd, g2h_untagged(start), end - start, offset) == -1) { - return -1; - } - - /* put final protection */ - if (prot_new != (prot1 | PROT_WRITE)) { - mprotect(host_start, qemu_host_page_size, - target_to_host_prot(prot_new)); - } + /* Read or zero the new guest pages. */ + if (flags & MAP_ANONYMOUS) { + memset(g2h_untagged(start), 0, last - start + 1); } else { - if (prot_new != prot1) { - mprotect(host_start, qemu_host_page_size, - target_to_host_prot(prot_new)); - } - if (prot_new & PROT_WRITE) { - memset(g2h_untagged(start), 0, end - start); + if (pread(fd, g2h_untagged(start), last - start + 1, offset) == -1) { + return false; } } - return 0; + + /* Put final protection */ + if (host_prot_new != host_prot_old) { + mprotect(host_start, qemu_host_page_size, host_prot_new); + } + return true; } #if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64 @@ -681,27 +684,25 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot, if (start > real_start) { if (real_end == real_start + qemu_host_page_size) { /* one single host page */ - ret = mmap_frag(real_start, start, end, - target_prot, flags, fd, offset); - if (ret == -1) { + if (!mmap_frag(real_start, start, end - 1, + target_prot, flags, fd, offset)) { goto fail; } goto the_end1; } - ret = mmap_frag(real_start, start, real_start + qemu_host_page_size, - target_prot, flags, fd, offset); - if (ret == -1) { + if (!mmap_frag(real_start, start, + real_start + qemu_host_page_size - 1, + target_prot, flags, fd, offset)) { goto fail; } real_start += qemu_host_page_size; } /* handle the end of the mapping */ if (end < real_end) { - ret = mmap_frag(real_end - qemu_host_page_size, - real_end - qemu_host_page_size, end, - target_prot, flags, fd, - offset + real_end - qemu_host_page_size - start); - if (ret == -1) { + if (!mmap_frag(real_end - qemu_host_page_size, + real_end - qemu_host_page_size, end - 1, + target_prot, flags, fd, + offset + real_end - qemu_host_page_size - start)) { goto fail; } real_end -= qemu_host_page_size;