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spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=e0OEC7kQjBNzp0K1QDNb0Gtth/9+FCatyG1e7oy+zG0=; b=YXAX44gqZAl1nJYp3Ki/Kgj3A umaM3U5gqajCxeSelLZ9awAqFvrkgJTnq/eVfwJAusoDMDfRVxNRoD7E674SnrrDk8flTkBWIoQls aOxwj5DnSNicmHykJO/wrmo+W/23if/YYwM5kUwYYBaTD5UoCYzM7gyHYlWsMIiN3nTntNNO/3kTG 75heLByojh35g69fxIEDL+spcQkPNMiV6QCUSd6+aSrExSUv1uO/cZpf/z9EM0qZNwMw+thGYJzvC Xrs0Lxs5Xd7hXarfAKEDpFidtdcyMQbuZRvrBWJZzqRE70Z+CUoCBc6PpQFVmLHtdifsY4j4B4lo9 tX3QGAb7g==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6Zhl-0003LI-D4; Mon, 01 Feb 2021 13:57:25 +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 1l6Zhi-0003Kc-45 for linux-arm-kernel@lists.infradead.org; Mon, 01 Feb 2021 13:57:23 +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 DEE01101E; Mon, 1 Feb 2021 05:57:18 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.41.104]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 50AB83F71A; Mon, 1 Feb 2021 05:57:17 -0800 (PST) Date: Mon, 1 Feb 2021 13:57:14 +0000 From: Mark Rutland To: Russell King - ARM Linux admin Subject: Re: [PATCH] ARM: kexec: Fix panic after TLB are invalidated Message-ID: <20210201135714.GB66060@C02TD0UTHF1T.local> References: <1612140296-12546-1-git-send-email-giancarlo.ferrari89@gmail.com> <20210201124720.GA66060@C02TD0UTHF1T.local> <20210201130344.GF1463@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210201130344.GF1463@shell.armlinux.org.uk> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210201_085722_240837_A51902C5 X-CRM114-Status: GOOD ( 20.75 ) 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: linux-kernel@vger.kernel.org, penberg@kernel.org, geert@linux-m68k.org, rppt@kernel.org, Giancarlo Ferrari , akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org, giancarlo.ferrari@nokia.com 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 On Mon, Feb 01, 2021 at 01:03:45PM +0000, Russell King - ARM Linux admin wrote: > On Mon, Feb 01, 2021 at 12:47:20PM +0000, Mark Rutland wrote: > > 1. copy reloc code into buffer > > 2. alter variables in copy of reloc code > > 3. branch to buffer > > > > ... which would avoid this class of problem too. > > Yep, slightly messy to do though: > > diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c > index 5d84ad333f05..6058e0d3a40d 100644 > --- a/arch/arm/kernel/machine_kexec.c > +++ b/arch/arm/kernel/machine_kexec.c > @@ -174,18 +174,27 @@ void machine_kexec(struct kimage *image) > > reboot_code_buffer = page_address(image->control_code_page); > > - /* Prepare parameters for reboot_code_buffer*/ > - set_kernel_text_rw(); > - kexec_start_address = image->start; > - kexec_indirection_page = page_list; > - kexec_mach_type = machine_arch_type; > - kexec_boot_atags = image->arch.kernel_r2; > - > /* copy our kernel relocation code to the control code page */ > reboot_entry = fncpy(reboot_code_buffer, > &relocate_new_kernel, > relocate_new_kernel_size); > > +#define set(what, val) \ > + do { \ > + uintptr_t __funcp_address; \ > + int __offset; \ > + void *__ptr; \ > + asm("" : "=r" (__funcp_address) : "0" (&relocate_new_kernel)); \ > + __offset = (uintptr_t)&(what) - (__funcp_address & ~1); \ > + __ptr = reboot_code_buffer + __offset; \ > + *(__typeof__(&(what)))__ptr = val; \ > + } while (0) > + > + set(kexec_start_address, image->start); > + set(kexec_indirection_page, page_list); > + set(kexec_mach_type, machine_arch_type); > + set(kexec_boot_atags, image->arch.kernel_r2); We could simplify this slightly if we moved the kexec_& variables into a struct (using asm-offset KEXEC_VAR_* offsets and a KEXEC_VAR_SIZE region reserved in the asm), then here we could do something like: static struct kexec_vars *kexec_buffer_vars(void *buffer) { unsigned long code = ((unisigned long)relocate_new_kernel) & ~1; unsigned long vars - (unsigned long)relocate_vars; unsigned long offset = vars - code; return buffer + offset; } ... and in machine_kexec() do: struct kexec_vars *kv = kexec_buffer_vars(reboot_code_buffer); kv->start_address = image->start; kv->indirection_page = page_list; kv->mach_type = machine-arch_type; kv->boot_atags = arch.kernel_r2; ... if that looks any better to you? Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel