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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kiMEG-0004JH-5G; Thu, 26 Nov 2020 18:42:52 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kiME3-0004D6-72 for linux-arm-kernel@lists.infradead.org; Thu, 26 Nov 2020 18:42:41 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7C504169C; Thu, 26 Nov 2020 10:42:37 -0800 (PST) Received: from [172.16.1.114] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 888573F23F; Thu, 26 Nov 2020 10:42:36 -0800 (PST) Subject: Re: [PATCHv4 14/17] arm64: uaccess: remove set_fs() To: Mark Rutland , linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, will@kernel.org References: <20201113124937.20574-1-mark.rutland@arm.com> <20201113124937.20574-15-mark.rutland@arm.com> From: James Morse Message-ID: <827c7b13-4a23-f68f-d9ac-ddfef9e1bd56@arm.com> Date: Thu, 26 Nov 2020 18:42:26 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201113124937.20574-15-mark.rutland@arm.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201126_134239_493133_6A38AF3A X-CRM114-Status: GOOD ( 15.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: robin.murphy@arm.com, hch@lst.de Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mark, On 13/11/2020 12:49, Mark Rutland wrote: > Now that the uaccess primitives dont take addr_limit into acccount, we (account) > #if defined(CONFIG_ARM64_64K_PAGES) && defined(CONFIG_KUSER_HELPERS) > diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h > index 2547d94634be..2bb53bc3c326 100644 > --- a/arch/arm64/include/asm/ptrace.h > +++ b/arch/arm64/include/asm/ptrace.h > @@ -193,8 +193,7 @@ struct pt_regs { > s32 syscallno; > u32 unused2; > #endif > - > - u64 orig_addr_limit; > + u64 sdei_ttbr1; > /* Only valid when ARM64_HAS_IRQ_PRIO_MASKING is enabled. */ > u64 pmr_save; > u64 stackframe[2]; Hmmm, > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index b295fb912b12..bdd3b57b12f5 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -999,10 +987,9 @@ SYM_CODE_START(__sdei_asm_entry_trampoline) > mov x4, xzr > > /* > - * Use reg->interrupted_regs.addr_limit to remember whether to unmap > - * the kernel on exit. > + * Remember whether to unmap the kernel on exit. > */ > -1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] > +1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] > > #ifdef CONFIG_RANDOMIZE_BASE > adr x4, tramp_vectors + PAGE_SIZE > @@ -1023,7 +1010,7 @@ NOKPROBE(__sdei_asm_entry_trampoline) > * x4: struct sdei_registered_event argument from registration time. > */ > SYM_CODE_START(__sdei_asm_exit_trampoline) > - ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] > + ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] > cbnz x4, 1f > > tramp_unmap_kernel tmp=x4 Ah, that. This was previously abusing orig_addr_limit as the space was already there, and if you squint.... Now it seems odd to waste that space in every pt_regs given its only needed in here, but its still needed for padding. If more padding ever turns up I'll add cleaning this up to my todo list. Acked-by: James Morse Thanks, James _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel