From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2553923D8 for ; Fri, 22 Dec 2023 04:33:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VNCGXFZF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703219595; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/dnfBu/fEgkmN9hsRGrX3Qh2OWxZhe8THfvYViPvNZA=; b=VNCGXFZFyZe3dz2Yzh3CYpBFLT+PTfzlgaW8f+PJ+kCqE5f8QtEYMVk09wfjcukL34wtsM LY72RkgqH6ln6Tdf9B2w2M5ePwna6t+Ht3E+KqAyfQ8cB9taKbxRU/5hmxNhCIxnPuj7IQ BJE7pKHaAxBaTB3c5ildvNxB90EnkVE= Received: from mail-pl1-f199.google.com (mail-pl1-f199.google.com [209.85.214.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-315-1ccVgsWKMLK_68NB2VVa2g-1; Thu, 21 Dec 2023 23:33:13 -0500 X-MC-Unique: 1ccVgsWKMLK_68NB2VVa2g-1 Received: by mail-pl1-f199.google.com with SMTP id d9443c01a7336-1d41d6055f6so1095275ad.0 for ; Thu, 21 Dec 2023 20:33:13 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703219592; x=1703824392; h=content-transfer-encoding:content-disposition:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=/dnfBu/fEgkmN9hsRGrX3Qh2OWxZhe8THfvYViPvNZA=; b=Gfty5waQaVbppp0IQ6gago9Rw6lOzUKqv18XYt9xtj4b8/nYGtfzwzt2Rt/VLarvKI 2AykRHgj4H+OcVXvvemhESv0PcWB/LPx0C3pRTIgtUJ/BDPjGEBVzKnZg1LWCQD1/zQm tHdmsiix1v4B6GX7x3XYLuOKYNCdPKKdAZsCLMQXPPLVKF2ELE8lRhr2JFZyDfKYOWnX yeUc9ha4P3DI6jBVejfxXfAn5aeWNswJ1THp/4DvDK+QBHTcZJavbwFwUJQxPV86nS9l OiDmHezv/6qHnv/P/DVIm1BgarK+moVu0cYjFnjC1uSP+MN6T9R9KuKGSkDqGhfCLwgA Njhg== X-Gm-Message-State: AOJu0YyfBkAR2AJunv4mB6aurj/6oGm1Pug/F3EEK/l27lQ1jmpMB3M+ xYnFDy2vRzKDrJynWf0AnbO5LRF22yCHI+osAtTaW2FlRQxuXzTKd1PnQY6I5yNdKY2vMVSBkl8 85oex9aMuM+pGYGVqjCQfUZCXorTiUz/y X-Received: by 2002:a17:903:2602:b0:1d3:e573:20ec with SMTP id jd2-20020a170903260200b001d3e57320ecmr390693plb.90.1703219592221; Thu, 21 Dec 2023 20:33:12 -0800 (PST) X-Google-Smtp-Source: AGHT+IGDVSGCaLDAAox1pQj6Gf9KxzIRJQl9Z4MY1pWe1L18FSa4/g4aAgyj/u/pm0pPnmWI+7vOLQ== X-Received: by 2002:a17:903:2602:b0:1d3:e573:20ec with SMTP id jd2-20020a170903260200b001d3e57320ecmr390684plb.90.1703219591881; Thu, 21 Dec 2023 20:33:11 -0800 (PST) Received: from localhost.localdomain ([2804:1b3:a802:7496:88a7:1b1a:a837:bebf]) by smtp.gmail.com with ESMTPSA id e21-20020a170902d39500b001d3f79f61fdsm2445115pld.211.2023.12.21.20.33.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 20:33:11 -0800 (PST) From: Leonardo Bras To: Charlie Jenkins Cc: Leonardo Bras , Guo Ren , linux-kernel@vger.kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com, alexghiti@rivosinc.com, xiao.w.wang@intel.com, david@redhat.com, panqinglin2020@iscas.ac.cn, rick.p.edgecombe@intel.com, willy@infradead.org, bjorn@rivosinc.com, conor.dooley@microchip.com, cleger@rivosinc.com, linux-riscv@lists.infradead.org, Guo Ren , stable@vger.kernel.org Subject: Re: [PATCH V2 1/4] riscv: mm: Fixup compat mode boot failure Date: Fri, 22 Dec 2023 01:32:56 -0300 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: References: <20231221154702.2267684-1-guoren@kernel.org> <20231221154702.2267684-2-guoren@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit On Thu, Dec 21, 2023 at 07:50:27PM -0800, Charlie Jenkins wrote: > On Fri, Dec 22, 2023 at 10:57:16AM +0800, Guo Ren wrote: > > On Fri, Dec 22, 2023 at 9:51 AM Leonardo Bras wrote: > > > > > > Hello Guo Ren, > > > > > > On Thu, Dec 21, 2023 at 10:46:58AM -0500, guoren@kernel.org wrote: > > > > From: Guo Ren > > > > > > > > In COMPAT mode, the STACK_TOP is 0x80000000, but the TASK_SIZE is > > > > 0x7fff000. When the user stack is upon 0x7fff000, it will cause a user > > > > segment fault. Sometimes, it would cause boot failure when the whole > > > > rootfs is rv32. > > > > > > Checking if I get the scenario: > > > > > > In pgtable.h: > > > #ifdef CONFIG_64BIT > > > #define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2) > > > #define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2) > > > > > > #ifdef CONFIG_COMPAT > > > #define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE) > > > #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \ > > > TASK_SIZE_32 : TASK_SIZE_64) > > > #else > > > [...] > > > > > > Meaning CONFIG_COMPAT is only available in CONFIG_64BIT, and TASK_SIZE in > > > compat mode is either TASK_SIZE_32 or TASK_SIZE_64 depending on the thread_flag. > > > > > > from processor.h: > > > #ifdef CONFIG_64BIT > > > #define DEFAULT_MAP_WINDOW (UL(1) << (MMAP_VA_BITS - 1)) > > > #define STACK_TOP_MAX TASK_SIZE_64 > > > [...] > > > #define STACK_TOP DEFAULT_MAP_WINDOW > > > > > > > > > where: > > > #define MMAP_VA_BITS (is_compat_task() ? VA_BITS_SV32 : MMAP_VA_BITS_64) > > > with MMAP_VA_BITS_64 being either 48 or 37. > > > > > > In compat mode, > > > STACK_TOP = 1 << (32 - 1) -> 0x80000000 > > > TASK_SIZE = 0x8000000 - 4k -> 0x7ffff000 > > > > > > IIUC, your suggestion is to make TASK_SIZE = STACK_TOP in compat mode only. > > Yes, it causes the problem, which causes the boot to fail. > > I think what Leonardo is getting at is that it is odd that it would > cause boot issues if TASK_SIZE is not equal STACK_TOP. This seems > indicative of a different problem. While this may fix the issue, it > should be valid for TASK_SIZE to be less than STACK_TOP. > > - Charlie > That is also a good point, but I am not that acquainted to this to actually propose this. I was thinking more on these questions: Is TASK_SIZE and STACK_TOP related somehow? If so, would not be better to describe one in terms of the other, like #define TASK_SIZE (STACK_TOP - PAGE_SIZE) Or the other way around. I mean, if they have any relation it would be much easier to represent them that way, and it would avoid having two magical numbers. Thanks! Leo > > > > > > > > Then why not: > > > #ifdef CONFIG_COMPAT > > > #define TASK_SIZE_32 STACK_TOP > > Yes, it's the solution that I think at first. But I didn't find any > > problem with 0x7ffff000 ~ 0x80000000, and then I removed this gap to > > unify it with Sv39 and Sv48. > > > > > > > > With some comments explaining why there is no need to reserve a PAGE_SIZE > > > in the TASK_SIZE_32. > > At first, I wanted to put a invalid page between the user & kernel > > space, but it seems useless. > > > > > > > > Does that make sense? > > > > > > Thanks! > > > Leo > > > > > > > > > > > Freeing unused kernel image (initmem) memory: 2236K > > > > Run /sbin/init as init process > > > > Starting init: /sbin/init exists but couldn't execute it (error -14) > > > > Run /etc/init as init process > > > > ... > > > > > > > > Cc: stable@vger.kernel.org > > > > Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57") > > > > Signed-off-by: Guo Ren > > > > Signed-off-by: Guo Ren > > > > --- > > > > arch/riscv/include/asm/pgtable.h | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > > > > index ab00235b018f..74ffb2178f54 100644 > > > > --- a/arch/riscv/include/asm/pgtable.h > > > > +++ b/arch/riscv/include/asm/pgtable.h > > > > @@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte) > > > > #define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2) > > > > > > > > #ifdef CONFIG_COMPAT > > > > -#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE) > > > > +#define TASK_SIZE_32 (_AC(0x80000000, UL)) > > > > > > > > > > > > > > > > #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \ > > > > TASK_SIZE_32 : TASK_SIZE_64) > > > > #else > > > > -- > > > > 2.40.1 > > > > > > > > > > > > > -- > > Best Regards > > Guo Ren >