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[174.21.76.141]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1f9eb323641sm46904215ad.101.2024.06.23.09.30.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 23 Jun 2024 09:30:49 -0700 (PDT) Message-ID: <7db4406b-a4f6-4aa3-ab69-3dc2b0f4e0c3@linaro.org> Date: Sun, 23 Jun 2024 09:30:47 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 02/23] Added CPU loop function To: Warner Losh Cc: Ajeet Singh , qemu-devel@nongnu.org, Ajeet Singh , Stacey Son , Kyle Evans , Sean Bruno , Jessica Clarke References: <20240617185804.25075-1-itachis@FreeBSD.org> <20240617185804.25075-3-itachis@FreeBSD.org> <3eed856e-51bf-4dd5-8665-60132adf01a3@linaro.org> Content-Language: en-US From: Richard Henderson In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::102b; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102b.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 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 6/22/24 11:49, Warner Losh wrote: > > > On Mon, Jun 17, 2024 at 10:24 PM Richard Henderson > wrote: > > On 6/17/24 11:57, Ajeet Singh wrote: > > +            /* > > +             * The carry bit is cleared for no error; set for error. > > +             * See arm64/arm64/vm_machdep.c cpu_set_syscall_retval() > > +             */ > > +            pstate = pstate_read(env); > > +            if (ret >= 0) { > > +                pstate &= ~PSTATE_C; > > +                env->xregs[0] = ret; > > +            } else if (ret == -TARGET_ERESTART) { > > +                env->pc -= 4; > > +                break; > > +            } else if (ret != -TARGET_EJUSTRETURN) { > > +                pstate |= PSTATE_C; > > +                env->xregs[0] = -ret; > > +            } > > +            pstate_write(env, pstate); > > No need for full pstate read/write: > >      env->CF = {0,1}; > > > If I understand what you're suggesting, the quoted code can be replaced > by the following, faster construct: > >             /* >              * The carry bit is cleared for no error; set for error. >              * See arm64/arm64/vm_machdep.c cpu_set_syscall_retval() >              */ >             if (ret >= 0) { >                 env->CF = 0; >                 env->xregs[0] = ret; >             } else if (ret == -TARGET_ERESTART) { >                 env->pc -= 4; >                 break; >             } else if (ret != -TARGET_EJUSTRETURN) { >                 env->CF = 1; >                 env->xregs[0] = -ret; >             } >             break; > > Is that what you're saying? Yes. > > > +            break; > > + > > +        case EXCP_INTERRUPT: > > +            /* Just indicate that signals should be handle ASAP. */ > > +            break; > > + > > +        case EXCP_UDEF: > > +            force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPN, env->pc); > > +            break; > > + > > + > > +        case EXCP_PREFETCH_ABORT: > > +        case EXCP_DATA_ABORT: > > +            /* We should only arrive here with EC in {DATAABORT, INSNABORT}. */ > > +            ec = syn_get_ec(env->exception.syndrome); > > Nevermind about my question about syndrome.h vs patch 1. > > > Ah, Since we have to re-roll this patch anyway, maybe moving it is a good idea? > Honestly, I'm good either way. Least effort is called for. :-) r~