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[173.197.98.125]) by smtp.gmail.com with ESMTPSA id l12-20020a170902d34c00b001d8f81ecebesm10275500plk.192.2024.02.22.12.44.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); 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=1708634649; x=1709239449; 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=MfmBcNvAQcjDLvj9qNkCIuvVr8sl09md9gL9eOBPbro=; b=jmMKvmWF8WNZyVIOnP4VIOKJD5vEZbgdp5PXcTqmosoJpfgZgzcgLd4Yq8OfEgWZsb WXK3vrlkd9rS/HrfMgTDDkCpwMQ+wQxk1F6HMo7VPa06R7DmJgoCqQMd5O2DSqdiqrdb oeWmvHd/uAsB+NNmoOluDWVNanOOGcwEyd9Sw+Doa65UeVCOzdrLQYdBmOfYvmdsPdbG ZtWxYtuqenLvxBZZvnF1euG4XShhTSdV8318zYaHWUMCne1nghnWAsnc2t9OMAcZuEqq VrA996z7A+I+F65ov6BhS6mWoitEbtKxAtz6DkmBrPP31FYeLaDvHnU3+/bOKVXfBmgb sgjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708634649; x=1709239449; 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=MfmBcNvAQcjDLvj9qNkCIuvVr8sl09md9gL9eOBPbro=; b=FQwu9gQMBCoizy6tK6YT/dxUkQ1KHO0F3Pd4DyK2dGflSZauTqW6ltOHx7ubkf28kM B0bQeR7GcFysG39TCUdI6Hv6xfNuOCcBojPKfdyDUqckdQpyXOwd8POCV99tBMznacDv iIKO1ORiVMNdivk5dcwWe59nzi6HPZ6UrD/hZ952J+PWoKJEA5D2oWv5NMabNKgOPhi4 RNy2OLVf0TFeHmmOS9FxyFe2640d0p5uJv7yMt6SaXSJZHassHRcuhOxrsCm1nhEhzWu 9vDnBwCUHFAUpmK39a++nVLLMArYLAQQNhdiExFEq51RutoK/RTLifwjhjPdJGLFLAJw L/pQ== X-Gm-Message-State: AOJu0YzKDiaf3tVqPoJn2cxY68Xurutc8PqCx+AzLmmNclmQwPa/vklc 1ctyzAiBeLRh8o9nJH9ud9W0E+Ly0zDk3lNCJJYzqjfofZf5acSbe8NZ2RotmntqEAgprW/LiWH O X-Google-Smtp-Source: AGHT+IG98EL4HHBXS6w+XbrUxwDgWhGqzZUMIvX9dz2+dFc2k5Zz2ihjyu3RKI5CIekSCa3LTTKshA== X-Received: by 2002:a17:903:298b:b0:1db:be69:d02d with SMTP id lm11-20020a170903298b00b001dbbe69d02dmr23269427plb.32.1708634648954; Thu, 22 Feb 2024 12:44:08 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Cc: Pierrick Bouvier , Helge Deller Subject: [PULL 28/39] linux-user: Split out mmap_h_gt_g Date: Thu, 22 Feb 2024 10:43:12 -1000 Message-Id: <20240222204323.268539-29-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 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2607:f8b0:4864:20::633; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x633.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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @linaro.org) X-ZM-MESSAGEID: 1708635133040100001 Content-Type: text/plain; charset="utf-8" Signed-off-by: Richard Henderson Reviewed-by: Pierrick Bouvier Acked-by: Helge Deller Message-Id: <20240102015808.132373-24-richard.henderson@linaro.org> --- linux-user/mmap.c | 288 ++++++++++++++++++++++------------------------ 1 file changed, 139 insertions(+), 149 deletions(-) diff --git a/linux-user/mmap.c b/linux-user/mmap.c index ff8f9f7ed0..82f4026283 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -282,7 +282,16 @@ static int do_munmap(void *addr, size_t len) return munmap(addr, len); } =20 -/* map an incomplete host page */ +/* + * Map an incomplete host page. + * + * Here be dragons. This case will not work if there is an existing + * overlapping host page, which is file mapped, and for which the mapping + * is beyond the end of the file. In that case, we will see SIGBUS when + * trying to write a portion of this page. + * + * FIXME: Work around this with a temporary signal handler and longjmp. + */ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong las= t, int prot, int flags, int fd, off_t offset) { @@ -719,19 +728,138 @@ static abi_long mmap_h_lt_g(abi_ulong start, abi_ulo= ng len, int host_prot, return mmap_end(start, last, start, pass_last, mmap_flags, page_flags); } =20 +/* + * Special case host page size > target page size. + * + * The two special cases are address and file offsets that are valid + * for the guest that cannot be directly represented by the host. + */ +static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len, + int target_prot, int host_prot, + int flags, int page_flags, int fd, + off_t offset, int host_page_size) +{ + void *p, *want_p =3D g2h_untagged(start); + off_t host_offset =3D offset & -host_page_size; + abi_ulong last, real_start, real_last; + bool misaligned_offset =3D false; + size_t host_len; + + if (!(flags & (MAP_FIXED | MAP_FIXED_NOREPLACE))) { + /* + * Adjust the offset to something representable on the host. + */ + host_len =3D len + offset - host_offset; + p =3D mmap(want_p, host_len, host_prot, flags, fd, host_offset); + if (p =3D=3D MAP_FAILED) { + return -1; + } + + /* Update start to the file position at offset. */ + p +=3D offset - host_offset; + + start =3D h2g(p); + last =3D start + len - 1; + return mmap_end(start, last, start, last, flags, page_flags); + } + + if (!(flags & MAP_ANONYMOUS)) { + misaligned_offset =3D (start ^ offset) & (host_page_size - 1); + + /* + * The fallback for misalignment is a private mapping + read. + * This carries none of semantics required of MAP_SHARED. + */ + if (misaligned_offset && (flags & MAP_TYPE) !=3D MAP_PRIVATE) { + errno =3D EINVAL; + return -1; + } + } + + last =3D start + len - 1; + real_start =3D start & -host_page_size; + real_last =3D ROUND_UP(last, host_page_size) - 1; + + /* + * Handle the start and end of the mapping. + */ + if (real_start < start) { + abi_ulong real_page_last =3D real_start + host_page_size - 1; + if (last <=3D real_page_last) { + /* Entire allocation a subset of one host page. */ + if (!mmap_frag(real_start, start, last, target_prot, + flags, fd, offset)) { + return -1; + } + return mmap_end(start, last, -1, 0, flags, page_flags); + } + + if (!mmap_frag(real_start, start, real_page_last, target_prot, + flags, fd, offset)) { + return -1; + } + real_start =3D real_page_last + 1; + } + + if (last < real_last) { + abi_ulong real_page_start =3D real_last - host_page_size + 1; + if (!mmap_frag(real_page_start, real_page_start, last, + target_prot, flags, fd, + offset + real_page_start - start)) { + return -1; + } + real_last =3D real_page_start - 1; + } + + if (real_start > real_last) { + return mmap_end(start, last, -1, 0, flags, page_flags); + } + + /* + * Handle the middle of the mapping. + */ + + host_len =3D real_last - real_start + 1; + want_p +=3D real_start - start; + + if (flags & MAP_ANONYMOUS) { + p =3D mmap(want_p, host_len, host_prot, flags, -1, 0); + } else if (!misaligned_offset) { + p =3D mmap(want_p, host_len, host_prot, flags, fd, + offset + real_start - start); + } else { + p =3D mmap(want_p, host_len, host_prot | PROT_WRITE, + flags | MAP_ANONYMOUS, -1, 0); + } + if (p !=3D want_p) { + if (p !=3D MAP_FAILED) { + do_munmap(p, host_len); + errno =3D EEXIST; + } + return -1; + } + + if (misaligned_offset) { + /* TODO: The read could be short. */ + if (pread(fd, p, host_len, offset + real_start - start) !=3D host_= len) { + do_munmap(p, host_len); + return -1; + } + if (!(host_prot & PROT_WRITE)) { + mprotect(p, host_len, host_prot); + } + } + + return mmap_end(start, last, -1, 0, flags, page_flags); +} + static abi_long target_mmap__locked(abi_ulong start, abi_ulong len, int target_prot, int flags, int page_f= lags, int fd, off_t offset) { int host_page_size =3D qemu_real_host_page_size(); - abi_ulong ret, last, real_start, real_last, retaddr, host_len; - abi_ulong passthrough_start =3D -1, passthrough_last =3D 0; - off_t host_offset; int host_prot; =20 - real_start =3D start & -host_page_size; - host_offset =3D offset & -host_page_size; - /* * For reserved_va, we are in full control of the allocation. * Find a suitable hole and convert to MAP_FIXED. @@ -745,6 +873,8 @@ static abi_long target_mmap__locked(abi_ulong start, ab= i_ulong len, } flags =3D (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED; } else if (!(flags & MAP_FIXED)) { + abi_ulong real_start =3D start & -host_page_size; + off_t host_offset =3D offset & -host_page_size; size_t real_len =3D len + offset - host_offset; abi_ulong align =3D MAX(host_page_size, TARGET_PAGE_SIZE); =20 @@ -766,150 +896,10 @@ static abi_long target_mmap__locked(abi_ulong start,= abi_ulong len, } 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))) { - uintptr_t host_start; - void *p; - - host_len =3D len + offset - host_offset; - host_len =3D ROUND_UP(host_len, host_page_size); - - /* Note: we prefer to control the mapping address. */ - p =3D mmap(g2h_untagged(start), host_len, host_prot, - flags | MAP_FIXED | MAP_ANONYMOUS, -1, 0); - if (p =3D=3D MAP_FAILED) { - return -1; - } - /* update start so that it points to the file position at 'offset'= */ - host_start =3D (uintptr_t)p; - if (!(flags & MAP_ANONYMOUS)) { - p =3D mmap(g2h_untagged(start), len, host_prot, - flags | MAP_FIXED, fd, host_offset); - if (p =3D=3D MAP_FAILED) { - do_munmap(g2h_untagged(start), host_len); - return -1; - } - host_start +=3D offset - host_offset; - } - start =3D h2g(host_start); - last =3D start + len - 1; - passthrough_start =3D start; - passthrough_last =3D last; } else { - last =3D start + len - 1; - real_last =3D ROUND_UP(last, host_page_size) - 1; - - if (flags & MAP_FIXED_NOREPLACE) { - /* Validate that the chosen range is empty. */ - if (!page_check_range_empty(start, last)) { - errno =3D EEXIST; - return -1; - } - - /* - * With reserved_va, the entire address space is mmaped in the - * host to ensure it isn't accidentally used for something els= e. - * We have just checked that the guest address is not mapped - * within the guest, but need to replace the host reservation. - * - * Without reserved_va, despite the guest address check above, - * keep MAP_FIXED_NOREPLACE so that the guest does not overwri= te - * any host address mappings. - */ - if (reserved_va) { - flags =3D (flags & ~MAP_FIXED_NOREPLACE) | MAP_FIXED; - } - } - - /* - * worst case: we cannot map the file because the offset is not - * aligned, so we read it - */ - if (!(flags & MAP_ANONYMOUS) && - (offset & (host_page_size - 1)) !=3D (start & (host_page_size = - 1))) { - /* - * msync() won't work here, so we return an error if write is - * possible while it is a shared mapping - */ - if ((flags & MAP_TYPE) =3D=3D MAP_SHARED - && (target_prot & PROT_WRITE)) { - errno =3D EINVAL; - return -1; - } - retaddr =3D target_mmap(start, len, target_prot | PROT_WRITE, - (flags & (MAP_FIXED | MAP_FIXED_NOREPLAC= E)) - | MAP_PRIVATE | MAP_ANONYMOUS, - -1, 0); - if (retaddr =3D=3D -1) { - return -1; - } - if (pread(fd, g2h_untagged(start), len, offset) =3D=3D -1) { - return -1; - } - if (!(target_prot & PROT_WRITE)) { - ret =3D target_mprotect(start, len, target_prot); - assert(ret =3D=3D 0); - } - return mmap_end(start, last, -1, 0, flags, page_flags); - } - - /* handle the start of the mapping */ - if (start > real_start) { - if (real_last =3D=3D real_start + host_page_size - 1) { - /* one single host page */ - if (!mmap_frag(real_start, start, last, - target_prot, flags, fd, offset)) { - return -1; - } - return mmap_end(start, last, -1, 0, flags, page_flags); - } - if (!mmap_frag(real_start, start, - real_start + host_page_size - 1, - target_prot, flags, fd, offset)) { - return -1; - } - real_start +=3D host_page_size; - } - /* handle the end of the mapping */ - if (last < real_last) { - abi_ulong real_page =3D real_last - host_page_size + 1; - if (!mmap_frag(real_page, real_page, last, - target_prot, flags, fd, - offset + real_page - start)) { - return -1; - } - real_last -=3D host_page_size; - } - - /* map the middle (easier) */ - if (real_start < real_last) { - void *p, *want_p; - off_t offset1; - size_t len1; - - if (flags & MAP_ANONYMOUS) { - offset1 =3D 0; - } else { - offset1 =3D offset + real_start - start; - } - len1 =3D real_last - real_start + 1; - want_p =3D g2h_untagged(real_start); - - p =3D mmap(want_p, len1, host_prot, flags, fd, offset1); - if (p !=3D want_p) { - if (p !=3D MAP_FAILED) { - do_munmap(p, len1); - errno =3D EEXIST; - } - return -1; - } - passthrough_start =3D real_start; - passthrough_last =3D real_last; - } + return mmap_h_gt_g(start, len, target_prot, host_prot, flags, + page_flags, fd, offset, host_page_size); } - return mmap_end(start, last, passthrough_start, passthrough_last, - flags, page_flags); } =20 /* NOTE: all the constants are the HOST ones */ --=20 2.34.1