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[92.23.208.66]) by smtp.gmail.com with ESMTPSA id q10-20020a1ce90a000000b003fbb25da65bsm3337736wmc.30.2023.07.07.13.41.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Jul 2023 13:41:08 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Cc: laurent@vivier.eu, mjt@tls.msk.ru Subject: [PATCH v2 18/24] linux-user: Rewrite mmap_reserve Date: Fri, 7 Jul 2023 21:40:48 +0100 Message-Id: <20230707204054.8792-21-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230707204054.8792-1-richard.henderson@linaro.org> References: <20230707204054.8792-1-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; be careful about avoiding overflow. Assert that the mmap succeeded. Signed-off-by: Richard Henderson --- linux-user/mmap.c | 68 +++++++++++++++++++++++++++++------------------ 1 file changed, 42 insertions(+), 26 deletions(-) diff --git a/linux-user/mmap.c b/linux-user/mmap.c index 67a117823f..6b030dac42 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -722,47 +722,63 @@ fail: return -1; } -static void mmap_reserve(abi_ulong start, abi_ulong size) +static void mmap_reserve(abi_ulong start, abi_ulong len) { abi_ulong real_start; - abi_ulong real_end; - abi_ulong addr; - abi_ulong end; + abi_ulong real_last; + abi_ulong real_len; + abi_ulong last; + abi_ulong a; + void *host_start, *ptr; int prot; + last = start + len - 1; real_start = start & qemu_host_page_mask; - real_end = HOST_PAGE_ALIGN(start + size); - end = start + size; - if (start > real_start) { - /* handle host page containing start */ + real_last = HOST_PAGE_ALIGN(last) - 1; + + /* + * If guest pages remain on the first or last host pages, + * adjust the deallocation to retain those guest pages. + * The single page special case is required for the last page, + * lest real_start overflow to zero. + */ + if (real_last - real_start < qemu_host_page_size) { prot = 0; - for (addr = real_start; addr < start; addr += TARGET_PAGE_SIZE) { - prot |= page_get_flags(addr); + for (a = real_start; a < start; a += TARGET_PAGE_SIZE) { + prot |= page_get_flags(a); } - if (real_end == real_start + qemu_host_page_size) { - for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { - prot |= page_get_flags(addr); - } - end = real_end; + for (a = last; a < real_last; a += TARGET_PAGE_SIZE) { + prot |= page_get_flags(a + 1); + } + if (prot != 0) { + return; + } + } else { + for (prot = 0, a = real_start; a < start; a += TARGET_PAGE_SIZE) { + prot |= page_get_flags(a); } if (prot != 0) { real_start += qemu_host_page_size; } - } - if (end < real_end) { - prot = 0; - for (addr = end; addr < real_end; addr += TARGET_PAGE_SIZE) { - prot |= page_get_flags(addr); + + for (prot = 0, a = last; a < real_last; a += TARGET_PAGE_SIZE) { + prot |= page_get_flags(a + 1); } if (prot != 0) { - real_end -= qemu_host_page_size; + real_last -= qemu_host_page_size; + } + + if (real_last < real_start) { + return; } } - if (real_start != real_end) { - mmap(g2h_untagged(real_start), real_end - real_start, PROT_NONE, - MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE, - -1, 0); - } + + real_len = real_last - real_start + 1; + host_start = g2h_untagged(real_start); + + ptr = mmap(host_start, real_len, PROT_NONE, + MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE, -1, 0); + assert(ptr == host_start); } int target_munmap(abi_ulong start, abi_ulong len)