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[97.113.2.170]) by smtp.gmail.com with ESMTPSA id x124-v6sm8999945pfx.72.2018.05.11.22.03.01 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 11 May 2018 22:03:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=0mECzgDVo12qmCSM432Ob3SIFDVRUdbq2Ys26U/zmIE=; b=UoiYZNKJXEhOeYi5bknN/SOO73/sVaiuhsla8R24GvCN0k89SA3w7/CTxSF26wXjcT PQv9QmldA8xD+bkWlosUm/j4ifVnHnFsokrfS/4c2X+xCPnahIigAUAhASMd0aI74w8y 0etSLBZvBVTCw13MKcz8Hu3OksFMcSdGaedac= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=0mECzgDVo12qmCSM432Ob3SIFDVRUdbq2Ys26U/zmIE=; b=M9uaDpWqSm5LIn2Aomwbo398KWxFwj2AFWgJG9bq+esvj0hVmxnISuEq0UmrYPZjAn QSWUnZYeWjpiQXCO8zWHBb9UCxwgmCCcPnr2jczhg8IE74IU8JvFzrbBcZXLa8DkuVIE IP1aDEg5H79Q3Xk4xWQ34vYvMaO8V1BvjLeVcPBvK3hCy0Mn1Y6IMoUseYnY7RQCAGWE APQTc/ReHSt6aNvLHGKtyK59v3qrgnxCXaChPH1/lFDasv9ddPlaki8kX0lIFmVdZAGQ ri38P7niDQBO9Oc5GovbJcNOr7EEQ6LpQVyPU+O112i3kJdq+tVliA75KUUoN5s3Cbxd AigQ== X-Gm-Message-State: ALKqPwfCVYYpsgF61Mk03P9HQE1turfIwiRWkSeW/EE9JIlsLscbk0kE bMYja1wG/5+4aMQyVYAQzK/zB3ASIFk= X-Google-Smtp-Source: AB8JxZobtcv1iB1WPWFpOvGsGzN9oFJzVS7R5TznxfVZ3j3eYgGLkkOnzK15lVqGvZlKmtVX6a1pfw== X-Received: by 2002:a17:902:82c3:: with SMTP id u3-v6mr1002638plz.83.1526101382367; Fri, 11 May 2018 22:03:02 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Date: Fri, 11 May 2018 22:02:49 -0700 Message-Id: <20180512050250.12774-9-richard.henderson@linaro.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180512050250.12774-1-richard.henderson@linaro.org> References: <20180512050250.12774-1-richard.henderson@linaro.org> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:400e:c01::241 Subject: [Qemu-devel] [PATCH 8/9] target/m68k: Improve ending TB at page boundaries X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: laurent@vivier.eu Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Rather than limit total TB size to PAGE-32 bytes, end the TB when near the end of a page. This should provide proper semantics of SIGSEGV when executing near the end of a page. Signed-off-by: Richard Henderson --- target/m68k/translate.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/target/m68k/translate.c b/target/m68k/translate.c index 0ab9ab1148..069558bc28 100644 --- a/target/m68k/translate.c +++ b/target/m68k/translate.c @@ -6105,9 +6105,25 @@ static void m68k_tr_translate_insn(DisasContextBase = *dcbase, CPUState *cpu) disas_m68k_insn(cpu->env_ptr, dc); dc->base.pc_next =3D dc->pc; =20 - if (dc->base.is_jmp =3D=3D DISAS_NEXT - && dc->pc - dc->base.pc_first >=3D TARGET_PAGE_SIZE - 32) { - dc->base.is_jmp =3D DISAS_TOO_MANY; + if (dc->base.is_jmp =3D=3D DISAS_NEXT) { + /* Stop translation when the next insn might touch a new page. + * This ensures that prefetch aborts at the right place. + * + * We cannot determine the size of the next insn without + * completely decoding it. However, the maximum insn size + * is 32 bytes, so end if we do not have that much remaining. + * This may produce several small TBs at the end of each page, + * but they will all be linked with goto_tb. + * + * ??? ColdFire maximum is 4 bytes; MC68000's maximum is also + * smaller than MC68020's. + */ + target_ulong start_page_offset + =3D dc->pc - (dc->base.pc_first & TARGET_PAGE_MASK); + + if (start_page_offset >=3D TARGET_PAGE_SIZE - 32) { + dc->base.is_jmp =3D DISAS_TOO_MANY; + } } } =20 --=20 2.17.0