From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7A568C433EF for ; Wed, 25 May 2022 15:22:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238583AbiEYPWU (ORCPT ); Wed, 25 May 2022 11:22:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231238AbiEYPWR (ORCPT ); Wed, 25 May 2022 11:22:17 -0400 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6CBAAFAF0 for ; Wed, 25 May 2022 08:22:14 -0700 (PDT) Received: from ip5b412258.dynamic.kabel-deutschland.de ([91.65.34.88] helo=diego.localnet) by gloria.sntech.de with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1ntspm-0006gP-1A; Wed, 25 May 2022 17:22:02 +0200 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: Alexandre Ghiti Cc: palmer@dabbelt.com, paul.walmsley@sifive.com, aou@eecs.berkeley.edu, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, wefu@redhat.com, liush@allwinnertech.com, guoren@kernel.org, atishp@atishpatra.org, anup@brainfault.org, drew@beagleboard.org, hch@lst.de, arnd@arndb.de, wens@csie.org, maxime@cerno.tech, gfavor@ventanamicro.com, andrea.mondelli@huawei.com, behrensj@mit.edu, xinhaoqu@huawei.com, mick@ics.forth.gr, allen.baum@esperantotech.com, jscheid@ventanamicro.com, rtrauben@gmail.com, samuel@sholland.org, cmuellner@linux.com, philipp.tomsich@vrull.eu Subject: Re: [PATCH 08/12] riscv: Fix accessing pfn bits in PTEs for non-32bit variants Date: Wed, 25 May 2022 17:22:00 +0200 Message-ID: <2545779.7s5MMGUR32@diego> In-Reply-To: References: <20220511192921.2223629-1-heiko@sntech.de> <20220511192921.2223629-9-heiko@sntech.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alexandre, Am Montag, 23. Mai 2022, 16:03:10 CEST schrieb Alexandre Ghiti: > Hi Heiko, > > On Wed, May 11, 2022 at 9:31 PM Heiko Stuebner wrote: > > > > On rv32 the PFN part of PTEs is defined to use bits [xlen-1:10] > > while on rv64 it is defined to use bits [53:10], leaving [63:54] > > as reserved. > > > > With upcoming optional extensions like svpbmt these previously > > reserved bits will get used so simply right-shifting the PTE > > to get the PFN won't be enough. > > > > So introduce a _PAGE_PFN_MASK constant to mask the correct bits > > for both rv32 and rv64 before shifting. > > > > Signed-off-by: Heiko Stuebner > > Reviewed-by: Philipp Tomsich > > --- > > arch/riscv/include/asm/pgtable-32.h | 8 ++++++++ > > arch/riscv/include/asm/pgtable-64.h | 14 +++++++++++--- > > arch/riscv/include/asm/pgtable-bits.h | 6 ------ > > arch/riscv/include/asm/pgtable.h | 8 +++++--- > > 4 files changed, 24 insertions(+), 12 deletions(-) > > > > diff --git a/arch/riscv/include/asm/pgtable-32.h b/arch/riscv/include/asm/pgtable-32.h > > index 5b2e79e5bfa5..e266a4fe7f43 100644 > > --- a/arch/riscv/include/asm/pgtable-32.h > > +++ b/arch/riscv/include/asm/pgtable-32.h > > @@ -7,6 +7,7 @@ > > #define _ASM_RISCV_PGTABLE_32_H > > > > #include > > +#include > > #include > > > > /* Size of region mapped by a page global directory */ > > @@ -16,4 +17,11 @@ > > > > #define MAX_POSSIBLE_PHYSMEM_BITS 34 > > > > +/* > > + * rv32 PTE format: > > + * | XLEN-1 10 | 9 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 > > + * PFN reserved for SW D A G U X W R V > > + */ > > +#define _PAGE_PFN_MASK GENMASK(31, 10) > > + > > #endif /* _ASM_RISCV_PGTABLE_32_H */ > > diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h > > index 7e246e9f8d70..15f3ad5aee4f 100644 > > --- a/arch/riscv/include/asm/pgtable-64.h > > +++ b/arch/riscv/include/asm/pgtable-64.h > > @@ -6,6 +6,7 @@ > > #ifndef _ASM_RISCV_PGTABLE_64_H > > #define _ASM_RISCV_PGTABLE_64_H > > > > +#include > > #include > > > > extern bool pgtable_l4_enabled; > > @@ -65,6 +66,13 @@ typedef struct { > > > > #define PTRS_PER_PMD (PAGE_SIZE / sizeof(pmd_t)) > > > > +/* > > + * rv64 PTE format: > > + * | 63 | 62 61 | 60 54 | 53 10 | 9 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 > > + * N MT RSV PFN reserved for SW D A G U X W R V > > + */ > > +#define _PAGE_PFN_MASK GENMASK(53, 10) > > + > > static inline int pud_present(pud_t pud) > > { > > return (pud_val(pud) & _PAGE_PRESENT); > > @@ -108,12 +116,12 @@ static inline unsigned long _pud_pfn(pud_t pud) > > > > static inline pmd_t *pud_pgtable(pud_t pud) > > { > > - return (pmd_t *)pfn_to_virt(pud_val(pud) >> _PAGE_PFN_SHIFT); > > + return (pmd_t *)pfn_to_virt(__page_val_to_pfn(pud_val(pud))); > > } > > > > static inline struct page *pud_page(pud_t pud) > > { > > - return pfn_to_page(pud_val(pud) >> _PAGE_PFN_SHIFT); > > + return pfn_to_page(__page_val_to_pfn(pud_val(pud))); > > } > > > > #define mm_p4d_folded mm_p4d_folded > > @@ -143,7 +151,7 @@ static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot) > > > > static inline unsigned long _pmd_pfn(pmd_t pmd) > > { > > - return pmd_val(pmd) >> _PAGE_PFN_SHIFT; > > + return __page_val_to_pfn(pmd_val(pmd)); > > } > > > > #define mk_pmd(page, prot) pfn_pmd(page_to_pfn(page), prot) > > diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h > > index a6b0c89824c2..e571fa954afc 100644 > > --- a/arch/riscv/include/asm/pgtable-bits.h > > +++ b/arch/riscv/include/asm/pgtable-bits.h > > @@ -6,12 +6,6 @@ > > #ifndef _ASM_RISCV_PGTABLE_BITS_H > > #define _ASM_RISCV_PGTABLE_BITS_H > > > > -/* > > - * PTE format: > > - * | XLEN-1 10 | 9 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 > > - * PFN reserved for SW D A G U X W R V > > - */ > > - > > #define _PAGE_ACCESSED_OFFSET 6 > > > > #define _PAGE_PRESENT (1 << 0) > > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > > index 046b44225623..faba543e2b08 100644 > > --- a/arch/riscv/include/asm/pgtable.h > > +++ b/arch/riscv/include/asm/pgtable.h > > @@ -108,6 +108,8 @@ > > #include > > #include > > > > +#define __page_val_to_pfn(_val) (((_val) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT) > > + > > #ifdef CONFIG_64BIT > > #include > > #else > > @@ -261,12 +263,12 @@ static inline unsigned long _pgd_pfn(pgd_t pgd) > > > > static inline struct page *pmd_page(pmd_t pmd) > > { > > - return pfn_to_page(pmd_val(pmd) >> _PAGE_PFN_SHIFT); > > + return pfn_to_page(__page_val_to_pfn(pmd_val(pmd))); > > } > > > > static inline unsigned long pmd_page_vaddr(pmd_t pmd) > > { > > - return (unsigned long)pfn_to_virt(pmd_val(pmd) >> _PAGE_PFN_SHIFT); > > + return (unsigned long)pfn_to_virt(__page_val_to_pfn(pmd_val(pmd))); > > } > > > > static inline pte_t pmd_pte(pmd_t pmd) > > @@ -282,7 +284,7 @@ static inline pte_t pud_pte(pud_t pud) > > /* Yields the page frame number (PFN) of a page table entry */ > > static inline unsigned long pte_pfn(pte_t pte) > > { > > - return (pte_val(pte) >> _PAGE_PFN_SHIFT); > > + return __page_val_to_pfn(pte_val(pte)); > > } > > > > #define pte_page(x) pfn_to_page(pte_pfn(x)) > > -- > > 2.35.1 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv > > I had this weird bug and it took some time to figure out that _pgd_pfn > is missing the "& _PAGE_PFN_MASK" here. > > And then I grepped _PAGE_PFN_SHIFT and saw that _pud_pfn, p4d_pgtable, > __pmd_to_phys and stage2_pte_page_vaddr are also missing this mask. I > agree that we need something similar to your helper __page_val_to_pfn > (even if __page prefix is a bit weird to me) but I think we should go > further: forbid the use of _PAGE_PFN_SHIFT and contain this in a > single function that should be used to access the pfn minus the upper > bits, that would avoid future oversights. > > I can come up with something if needs be, up to you! as you seem to be stuck in the topic already, you might be faster than me with that I guess?