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Tue, 06 Sep 2022 17:59:33 -0700 (PDT) X-Gm-Message-State: ACgBeo0W9VqXv5TXoKPsfKFGV61JfS6cqDh1ZepetPyAzcT7dX3Z1tgH rmJhU5vzdvHaggG/J1xXqcFU/9Ia6NXcJCi3ryc= X-Google-Smtp-Source: AA6agR4T+5pUb7afC0nbWNUE6t9rpyPvgc4usas9mXHv8gHcqGmB5W7iv8rmSa98jv8Ovc8tvPLbDXQ/sXx4rvotOG8= X-Received: by 2002:a05:6830:3482:b0:638:92b7:f09b with SMTP id c2-20020a056830348200b0063892b7f09bmr497235otu.140.1662512372833; Tue, 06 Sep 2022 17:59:32 -0700 (PDT) MIME-Version: 1.0 References: <20220906035423.634617-1-guoren@kernel.org> <20220906035423.634617-5-guoren@kernel.org> In-Reply-To: From: Guo Ren Date: Wed, 7 Sep 2022 08:59:20 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH V3 4/7] riscv: convert to generic entry To: Peter Zijlstra Cc: arnd@arndb.de, palmer@rivosinc.com, tglx@linutronix.de, luto@kernel.org, conor.dooley@microchip.com, heiko@sntech.de, jszhang@kernel.org, lazyparser@gmail.com, falcon@tinylab.org, chenhuacai@kernel.org, apatel@ventanamicro.com, atishp@atishpatra.org, palmer@dabbelt.com, paul.walmsley@sifive.com, bigeasy@linutronix.de, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Guo Ren X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220906_175935_486071_83FC05D5 X-CRM114-Status: GOOD ( 20.43 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Tue, Sep 6, 2022 at 5:20 PM Peter Zijlstra wrote: > > On Mon, Sep 05, 2022 at 11:54:20PM -0400, guoren@kernel.org wrote: > > > +asmlinkage void noinstr do_riscv_irq(struct pt_regs *regs) > > +{ > > + struct pt_regs *old_regs; > > + irqentry_state_t state = irqentry_enter(regs); > > + > > + irq_enter_rcu(); > > + old_regs = set_irq_regs(regs); > > + handle_arch_irq(regs); > > + set_irq_regs(old_regs); > > + irq_exit_rcu(); > > + > > + irqentry_exit(regs, state); > > +} > > The above is right in that everything that calls irqentry_enter() should > be noinstr; however all the below instances get it wrong: > > > #define DO_ERROR_INFO(name, signo, code, str) \ > > asmlinkage __visible __trap_section void name(struct pt_regs *regs) \ > > { \ > > + irqentry_state_t state = irqentry_enter(regs); \ > > do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ > > + irqentry_exit(regs, state); \ > > } > > > > DO_ERROR_INFO(do_trap_unknown, > > @@ -123,18 +126,22 @@ int handle_misaligned_store(struct pt_regs *regs); > > > > asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs) > > { > > + irqentry_state_t state = irqentry_enter(regs); > > if (!handle_misaligned_load(regs)) > > return; > > do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, > > "Oops - load address misaligned"); > > + irqentry_exit(regs, state); > > } > > > > asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs) > > { > > + irqentry_state_t state = irqentry_enter(regs); > > if (!handle_misaligned_store(regs)) > > return; > > do_trap_error(regs, SIGBUS, BUS_ADRALN, regs->epc, > > "Oops - store (or AMO) address misaligned"); > > + irqentry_exit(regs, state); > > } > > #endif > > DO_ERROR_INFO(do_trap_store_fault, > > @@ -158,6 +165,8 @@ static inline unsigned long get_break_insn_length(unsigned long pc) > > > > asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs) > > { > > + irqentry_state_t state = irqentry_enter(regs); > > + > > #ifdef CONFIG_KPROBES > > if (kprobe_single_step_handler(regs)) > > return; > > @@ -185,6 +194,8 @@ asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs) > > regs->epc += get_break_insn_length(regs->epc); > > else > > die(regs, "Kernel BUG"); > > + > > + irqentry_exit(regs, state); > > } > > NOKPROBE_SYMBOL(do_trap_break); > > > +asmlinkage void do_page_fault(struct pt_regs *regs) > > +{ > > + irqentry_state_t state = irqentry_enter(regs); > > + > > + __do_page_fault(regs); > > + > > + irqentry_exit(regs, state); > > +} > > NOKPROBE_SYMBOL(do_page_fault); > > Without noinstr the compiler is free to insert instrumentation (think > all the k*SAN, KCov, GCov, ftrace etc..) which can call code we're not > yet ready to run this early in the entry path, for instance it could > rely on RCU which isn't on yet, or expect lockdep state. I'll add a patch to fix it in the next version. Thx for pointing it out. > > -- Best Regards Guo Ren _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv