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[209.85.221.177]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5347906c2fdsm2035896e0c.30.2025.07.09.02.36.39 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Jul 2025 02:36:40 -0700 (PDT) Received: by mail-vk1-f177.google.com with SMTP id 71dfb90a1353d-5344894a85aso2127297e0c.2 for ; Wed, 09 Jul 2025 02:36:39 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCU6YF4r1XYWYItGQxiYZRogIUTktNP+0u3z1XMxegOW89wxkwwRTy87TZuKXMGBRIFntU7phYFhZQ==@kvack.org X-Received: by 2002:a05:6102:5113:b0:4e4:5ed0:19b2 with SMTP id ada2fe7eead31-4f5414b7eaamr875062137.9.1752053799069; Wed, 09 Jul 2025 02:36:39 -0700 (PDT) MIME-Version: 1.0 References: <20250707080317.3791624-1-kirill.shutemov@linux.intel.com> <20250707080317.3791624-12-kirill.shutemov@linux.intel.com> In-Reply-To: From: Geert Uytterhoeven Date: Wed, 9 Jul 2025 11:36:27 +0200 X-Gmail-Original-Message-ID: X-Gm-Features: Ac12FXzhSGHLdm6kLZFXquKo1YsS99gZt-VKBXVubQkHxm__bRsl73xUeT8gKHo Message-ID: Subject: Re: [PATCHv9 11/16] x86/traps: Communicate a LASS violation in #GP message To: "Kirill A. Shutemov" Cc: Sohil Mehta , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Ard Biesheuvel , "Paul E. McKenney" , Josh Poimboeuf , Xiongwei Song , Xin Li , "Mike Rapoport (IBM)" , Brijesh Singh , Michael Roth , Tony Luck , Alexey Kardashevskiy , Alexander Shishkin , Jonathan Corbet , Ingo Molnar , Pawan Gupta , Daniel Sneddon , Kai Huang , Sandipan Das , Breno Leitao , Rick Edgecombe , Alexei Starovoitov , Hou Tao , Juergen Gross , Vegard Nossum , Kees Cook , Eric Biggers , Jason Gunthorpe , "Masami Hiramatsu (Google)" , Andrew Morton , Luis Chamberlain , Yuntao Wang , Rasmus Villemoes , Christophe Leroy , Tejun Heo , Changbin Du , Huang Shijie , Geert Uytterhoeven , Namhyung Kim , Arnaldo Carvalho de Melo , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 975404000C X-Stat-Signature: nop74oby61rugf4k85i8kg9o4nfwqfsk X-HE-Tag: 1752053804-477416 X-HE-Meta: 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 8/gHd3ay B1N542biryflgn3DZ/t9pvjLmXjCF8/9iB3z9vEu6PlIfhTcmixnhph/UIvSQbN4YfHnWrULP0S7biftQ+MBXQKLtLwX8OJyi+YBYFGYCNenjIzPna8hjYYft2XlknwTC1Z545jjFfSiQxe90NPZnb3OELTzFQskUVcq0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Kirill, On Wed, 9 Jul 2025 at 11:31, Kirill A. Shutemov wrote: > On Tue, Jul 08, 2025 at 07:40:35PM -0700, Sohil Mehta wrote: > > > @@ -664,14 +673,23 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs, > > > return GP_NO_HINT; > > > > > > #ifdef CONFIG_X86_64 > > > > Might as well get rid of the #ifdef in C code, if possible. > > > > if (!IS_ENABLED(CONFIG_X86_64) > > return GP_CANONICAL; > > > > or combine it with the next check. > > I tried this before. It triggers compiler error on 32-bit: > > arch/x86/kernel/traps.c:673:16: error: shift count >= width of type [-Werror,-Wshift-count-overflow] > 673 | if (*addr >= ~__VIRTUAL_MASK) > | ^~~~~~~~~~~~~~ > > __VIRTUAL_MASK is not usable on 32-bit configs. arch/x86/include/asm/page_32_types.h:#define __VIRTUAL_MASK_SHIFT 32 arch/x86/include/asm/page_32_types.h:#define __VIRTUAL_MASK_SHIFT 32 arch/x86/include/asm/page_64_types.h:#define __VIRTUAL_MASK_SHIFT (pgtable_l5_enabled() ? 56 : 47) arch/x86/include/asm/page_types.h:#define __VIRTUAL_MASK ((1UL << __VIRTUAL_MASK_SHIFT) - 1) Given __VIRTUAL_MASK_SHIFT is 32 on 32-bit platforms, perhaps __VIRTUAL_MASK should just be changed to shift 1ULL instead? Or better, use GENMASK(__VIRTUAL_MASK_SHIFT - 1, 0), so the resulting type is still unsigned long. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds