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Wed, 02 Aug 2023 01:27:47 +0200 From: Helge Deller To: qemu-devel@nongnu.org Cc: Richard Henderson , Laurent Vivier , Paolo Bonzini , Joel Stanley , Akihiko Odaki , Helge Deller Subject: [PATCH v6 3/8] linux-user: Use MAP_FIXED_NOREPLACE for do_brk() Date: Wed, 2 Aug 2023 01:27:40 +0200 Message-ID: <20230801232745.4125-4-deller@gmx.de> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230801232745.4125-1-deller@gmx.de> References: <20230801232745.4125-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:2zbxf4Mlm/sfRfMCxhUDsMmDMmpgR4UM56FXN4/Xnj4ZbT4C38u 2ydGFZ2GmTlK3BEdAPI8FOUf70MnDWYhypt2bT7HoovpI9wT+4BeQTE5yharYHzcoVRcwXH Meq5RUSwuuSO6SPBSoy7kqORAkULNtBi1mlmSSLLNEFG3tSvoAv1jbYbYOGPTGj30h4VtH8 WUW81iQPndRcfbsY18JNw== UI-OutboundReport: notjunk:1;M01:P0:vUQg5kBlA4w=;alQkAbN6aqIx1M49faYAsK8oKVp QLf1y3o3V9aMUppmo/vd23t0mW7XlyzmU2cgxUXWrTQCp7ONqSThcYtSPGmYnoKFmhQ/JasDh cP7txei3w/CgK1Jz/SxTHsnvd8sTl3ZuFT+Wyi3uWDWfxOMn4mmIakjOTsNMr+ioiN/SfKMRX 7/p7E+3BAKZFDdHD8yGArTQ+Yf/4XwMHD8d9boLKVrGV3Qvv3aBn0AE33oO6FVgh6X3CT0EKg /JRZAFqowvNFrc9Z+FIFnfL9gkjjqVmgvQpsMrJeiSouDoMe0gQ9xAARZxncympNikXo8szq/ 0T6VTT6sa9vqpdtMeNV50CvojPTR+eLqmPqrbb8RXLLJjAiqXTCGuW4KUDAbVc804RF0JSNk2 reU+H34upvgr/yjfr0WN1YDNozINWscfjY1AcG/SEC8wB36MMbtuswaGidZCtrqwkqtBI53M9 bk3ge1D8Ci+WQvIzI+hlNYSQackZa9gx/hthZfLf+UKZ6rXEVm7Fi1CU8CLLAtwBQ/6qtiTTs eGEqh+LHUoPnSx67bDZnJ7+WAmgpwLfl2HzTU2H7gnBqscw9bI/XpemDdj91H1zH/3JYy3NAT Em4o1tWjkOvHDJg9Qu4NY8jqV7Ya5mLrBCIzJPMKVEbmuFnXXc2qo1FGDr5eKOP4T2J2p0BQl VBLsDM/QBsBTigyHeWtjkYGtAjOcAa72o1DwrwKSImJyH+mI9k5Xrs/HRAfu+buU/fyHb8/aC YT91PGw2DBd+tbC+XiszHbHvakfNraVJe71pMZ74lCrKdqNbTqsmikm1GdANQkyXGBy5yznMi eCPzA9vkUN7S081mlYmYtG3D292FQnYsPJ+B7buWOqmUVxsp720PLvPv3a1DyLB14JwE/oU27 imfvLW8iTqkgGdpgICURAwRKzmMGH7r631qHHxl4GHuFHutHsw67zf0Idzq4WhTyFqTqRAycb d1UoQT6h/N+Gx/WZ3reDXyqoT1Q= Received-SPF: pass client-ip=212.227.17.20; envelope-from=deller@gmx.de; helo=mout.gmx.net X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_LOW=-0.7, 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 From: Akihiko Odaki MAP_FIXED_NOREPLACE can ensure the mapped address is fixed without concerning that the new mapping overwrites something else. Signed-off-by: Akihiko Odaki Reviewed-by: Helge Deller Signed-off-by: Helge Deller --- linux-user/syscall.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) -- 2.41.0 diff --git a/linux-user/syscall.c b/linux-user/syscall.c index b9d2ec02f9..ac429a185a 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -854,17 +854,12 @@ abi_long do_brk(abi_ulong brk_val) return target_brk; } - /* We need to allocate more memory after the brk... Note that - * we don't use MAP_FIXED because that will map over the top of - * any existing mapping (like the one with the host libc or qemu - * itself); instead we treat "mapped but at wrong address" as - * a failure and unmap again. - */ if (new_host_brk_page > brk_page) { new_alloc_size = new_host_brk_page - brk_page; mapped_addr = target_mmap(brk_page, new_alloc_size, - PROT_READ|PROT_WRITE, - MAP_ANON|MAP_PRIVATE, 0, 0); + PROT_READ | PROT_WRITE, + MAP_FIXED_NOREPLACE | MAP_ANON | MAP_PRIVATE, + 0, 0); } else { new_alloc_size = 0; mapped_addr = brk_page; @@ -883,12 +878,6 @@ abi_long do_brk(abi_ulong brk_val) target_brk = brk_val; brk_page = new_host_brk_page; return target_brk; - } else if (mapped_addr != -1) { - /* Mapped but at wrong address, meaning there wasn't actually - * enough space for this brk. - */ - target_munmap(mapped_addr, new_alloc_size); - mapped_addr = -1; } #if defined(TARGET_ALPHA)