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Thu, 07 Jul 2022 08:00:46 -0700 (PDT) Received: from [10.4.255.21] ([139.177.225.235]) by smtp.gmail.com with ESMTPSA id h14-20020a170902f7ce00b0016be0d5483asm9622923plw.252.2022.07.07.08.00.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 07 Jul 2022 08:00:45 -0700 (PDT) Message-ID: <33a63e76-fb71-2b9e-3b3c-cc6f7a675cf3@bytedance.com> Date: Thu, 7 Jul 2022 23:00:37 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.0 Subject: Re: [RFC PATCH 2/2] arm64: support HAVE_IRQ_EXIT_ON_IRQ_STACK Content-Language: en-US To: Arnd Bergmann Cc: Catalin Marinas , Will Deacon , Linux ARM , Linux Kernel Mailing List References: <20220707110511.52129-1-zhengqi.arch@bytedance.com> <20220707110511.52129-3-zhengqi.arch@bytedance.com> <42bfd82c-b3fb-c942-d6f2-ae5adec90a26@bytedance.com> From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/7/7 22:41, Arnd Bergmann wrote: > On Thu, Jul 7, 2022 at 3:38 PM Qi Zheng wrote: >> On 2022/7/7 20:49, Arnd Bergmann wrote: >>> On Thu, Jul 7, 2022 at 1:05 PM Qi Zheng wrote: >> * Restore the SP from the FP, and restore the FP and LR from >> the frame >> * record. >> */ >> - mov sp, x29 >> +999: mov sp, x29 >> ldp x29, x30, [sp], #16 >> #ifdef CONFIG_SHADOW_CALL_STACK >> ldp scs_sp, xzr, [sp], #16 >> >> But this also requires a new parameter in do_interrupt_handler. >> >> I also considered implementing call_on_irq_stack() for nmi and irq >> separately, but later think it's unnecessary. > > What I had in mind was something along the lines of > > diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c > index 56cefd33eb8e..432042b91588 100644 > --- a/arch/arm64/kernel/entry-common.c > +++ b/arch/arm64/kernel/entry-common.c > @@ -270,10 +270,7 @@ static void do_interrupt_handler(struct pt_regs *regs, > { > struct pt_regs *old_regs = set_irq_regs(regs); > > - if (on_thread_stack()) > - call_on_irq_stack(regs, handler); > - else > - handler(regs); > + handler(regs); > > set_irq_regs(old_regs); > } > @@ -473,16 +470,31 @@ static void noinstr el1_interrupt(struct pt_regs *regs, > __el1_irq(regs, handler); > } > > -asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs) > +static void noinstr el1_irq(struct pt_regs *regs) > { > el1_interrupt(regs, handle_arch_irq); > } > > -asmlinkage void noinstr el1h_64_fiq_handler(struct pt_regs *regs) > +asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs) > +{ > + if (on_thread_stack()) > + call_on_irq_stack(regs, el1_irq); IMO, this can't work. Because el1_interrupt() will invoke arm64_preempt_schedule_irq(), which will cause scheduling on the IRQ stack. Thanks, Qi > + else > + el1_irq(regs); > +} > + > +static void noinstr el1_fiq(struct pt_regs *regs) > { > el1_interrupt(regs, handle_arch_fiq); > } > > +asmlinkage void noinstr el1h_64_fiq_handler(struct pt_regs *regs) > +{ > + if (on_thread_stack()) > + call_on_irq_stack(regs, el1_fiq); > + else > + el1_fiq(regs); > +} > + > asmlinkage void noinstr el1h_64_error_handler(struct pt_regs *regs) > { > unsigned long esr = read_sysreg(esr_el1); > @@ -713,7 +731,7 @@ static void noinstr > __el0_irq_handler_common(struct pt_regs *regs) > > asmlinkage void noinstr el0t_64_irq_handler(struct pt_regs *regs) > { > - __el0_irq_handler_common(regs); > + call_on_irq_stack(regs, __el0_irq_handler_common); > } > > static void noinstr __el0_fiq_handler_common(struct pt_regs *regs) > @@ -723,7 +741,7 @@ static void noinstr > __el0_fiq_handler_common(struct pt_regs *regs) > > asmlinkage void noinstr el0t_64_fiq_handler(struct pt_regs *regs) > { > - __el0_fiq_handler_common(regs); > + call_on_irq_stack(regs, __el0_fiq_handler_common); > } > > static void noinstr __el0_error_handler_common(struct pt_regs *regs) > @@ -807,12 +825,12 @@ asmlinkage void noinstr > el0t_32_sync_handler(struct pt_regs *regs) > > asmlinkage void noinstr el0t_32_irq_handler(struct pt_regs *regs) > { > - __el0_irq_handler_common(regs); > + call_on_irq_stack(regs, __el0_irq_handler_common); > } > > asmlinkage void noinstr el0t_32_fiq_handler(struct pt_regs *regs) > { > - __el0_fiq_handler_common(regs); > + call_on_irq_stack(regs, __el0_fiq_handler_common); > } > > asmlinkage void noinstr el0t_32_error_handler(struct pt_regs *regs) > > Not sure if that works. > > Arnd -- Thanks, Qi