From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 11 May 2020 12:00:14 +0100 From: Catalin Marinas Subject: Re: [PATCH 02/31] arm64: fix the flush_icache_range arguments in machine_kexec Message-ID: <20200511110014.GA19176@gaia> References: <20200510075510.987823-1-hch@lst.de> <20200510075510.987823-3-hch@lst.de> <20200511075115.GA16134@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200511075115.GA16134@willie-the-truck> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+geert.uytterhoeven=gmail.com@lists.infradead.org To: Will Deacon Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Roman Zippel , linux-mips@vger.kernel.org, linux-mm@kvack.org, sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, Christoph Hellwig , linux-arch@vger.kernel.org, linux-c6x-dev@linux-c6x.org, linux-hexagon@vger.kernel.org, x86@kernel.org, linux-xtensa@linux-xtensa.org, Arnd Bergmann , Jessica Yu , linux-um@lists.infradead.org, linux-m68k@lists.linux-m68k.org, openrisc@lists.librecores.org, linux-arm-kernel@lists.infradead.org, Michal Simek , linux-kernel@vger.kernel.org, james.morse@arm.com, linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org List-ID: On Mon, May 11, 2020 at 08:51:15AM +0100, Will Deacon wrote: > On Sun, May 10, 2020 at 09:54:41AM +0200, Christoph Hellwig wrote: > > The second argument is the end "pointer", not the length. > > > > Signed-off-by: Christoph Hellwig > > --- > > arch/arm64/kernel/machine_kexec.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c > > index 8e9c924423b4e..a0b144cfaea71 100644 > > --- a/arch/arm64/kernel/machine_kexec.c > > +++ b/arch/arm64/kernel/machine_kexec.c > > @@ -177,6 +177,7 @@ void machine_kexec(struct kimage *kimage) > > * the offline CPUs. Therefore, we must use the __* variant here. > > */ > > __flush_icache_range((uintptr_t)reboot_code_buffer, > > + (uintptr_t)reboot_code_buffer + > > arm64_relocate_new_kernel_size); > > Urgh, well spotted. It's annoyingly different from __flush_dcache_area(). > > But now I'm wondering what this code actually does... the loop condition > in invalidate_icache_by_line works with 64-bit arithmetic, so we could > spend a /very/ long time here afaict. I think it goes through the loop only once. The 'b.lo' saves us here. OTOH, there is no I-cache maintenance done. > It's also a bit annoying that we do a bunch of redundant D-cache > maintenance too. Should we use invalidate_icache_range() here instead? Since we have the __flush_dcache_area() above it for cleaning to PoC, we could use invalidate_icache_range() here. We probably didn't have this function at the time, it was added for KVM (commit 4fee94736603cd6). > (and why does that thing need to toggle uaccess)? invalidate_icache_range() doesn't need to, it works on the kernel linear map. __flush_icache_range() doesn't need to either, that's a side-effect of the fall-through implementation. Anyway, I think Christoph's patch needs to go in with a fixes tag: Fixes: d28f6df1305a ("arm64/kexec: Add core kexec support") Cc: # 4.8.x- and we'll change these functions/helpers going forward for arm64. Happy to pick this up via the arm64 for-next/fixes branch. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel