From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 19197811E2 for ; Wed, 7 Aug 2024 22:37:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723070247; cv=none; b=YrB4w1+U59P2MxNlO7MfcAIQ1jQwR7tznGJBrGrIx6HI9YRlcoCMSz/Mgd9SjqHVUMrAcN01FlBT71fwnkz47bZj4Umn7t9ashvX/U1y63gELR5PVl+ZeHaOAStVeNqRk9bc029kydoQUampt1w9UeZSvZSeRIZeoehbAEgHsUw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723070247; c=relaxed/simple; bh=I+nh1RcrayyOe4E6ICcgBqkW0+LUwAubE2kU08fGfRY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=NOm9Xj1s//xzxEAsSme3uq1rywnJEYrCyVEsBX5hE83+ggx583ipSw9ISKHapISoMncaBTpjxaiquWQspUNeI2CtiC7/H6+jLnuMAT9SU+29hN1dwGhMCZMOHGsVqaijd6Tn3SGrOtqyEQe3QyMgqGWbO6tLDS7nZsBo1jsoijQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=2guZOYZ9; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=IB5N8gDs; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="2guZOYZ9"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="IB5N8gDs" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1723070242; 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: in-reply-to:in-reply-to:references:references; bh=ijzboojuY5XpUno0lk+35UbNznLU2ucd6kpR6qcMWxg=; b=2guZOYZ99eyTcewCEP8xSZxwsHPHCJoQsL15+KAEcO68JB85EE+Hd6SCbExGA8OqLINdLh mX32IGFpl1TmhRwBqJ+dF0jiQHcEBoZBV+AltYSVcbizerrFhRVdNW9OkKsHUlLl/RpVL9 iyJoFp1hsL/2Izml40cfR4Bgi2fluswxwsvarN4ZmHFECUAurABZ5b6xRyopii7S45bIcd FEtgLFzszmtb4INfqVZrUIR9w6gSju9DqSiPuZF37VxavgThej1oJKme+a1nQ2rLwmKD82 RoYUBkCzU/T/WzNZWB+ndNEBkuWHKIi+tMWb5a+GNDneBs2LwmGEj77sWmPIfQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1723070242; 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: in-reply-to:in-reply-to:references:references; bh=ijzboojuY5XpUno0lk+35UbNznLU2ucd6kpR6qcMWxg=; b=IB5N8gDs6FBpyO8gAD9i3Vzt37QlGsQG8iqeySMgtnjM8GKUrJWBMjTtXMeWMZFSrrqVIv yXjA4dOnrV6rqPBg== To: Peter Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: "Aneesh Kumar K . V" , Michael Ellerman , Oscar Salvador , Dan Williams , James Houghton , Matthew Wilcox , Nicholas Piggin , Rik van Riel , Dave Jiang , Andrew Morton , x86@kernel.org, Ingo Molnar , Rick P Edgecombe , "Kirill A . Shutemov" , peterx@redhat.com, linuxppc-dev@lists.ozlabs.org, Mel Gorman , Hugh Dickins , Borislav Petkov , David Hildenbrand , Vlastimil Babka , Dave Hansen , Christophe Leroy , Huang Ying Subject: Re: [PATCH v4 6/7] mm/x86: Add missing pud helpers In-Reply-To: <20240807194812.819412-7-peterx@redhat.com> References: <20240807194812.819412-1-peterx@redhat.com> <20240807194812.819412-7-peterx@redhat.com> Date: Thu, 08 Aug 2024 00:37:21 +0200 Message-ID: <875xsc0xjy.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Wed, Aug 07 2024 at 15:48, Peter Xu wrote: > These new helpers will be needed for pud entry updates soon. Introduce > these helpers by referencing the pmd ones. Namely: > > - pudp_invalidate() > - pud_modify() Zero content about what these helpers do and why they are needed. That's not how it works, really. > +static inline pud_t pud_mkinvalid(pud_t pud) > +{ > + return pfn_pud(pud_pfn(pud), > + __pgprot(pud_flags(pud) & ~(_PAGE_PRESENT|_PAGE_PROTNONE))); 100 characters... > +} > + > static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask); > > static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) > @@ -834,14 +840,8 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) > pmd_result = __pmd(val); > > /* > - * To avoid creating Write=0,Dirty=1 PMDs, pte_modify() needs to avoid: > - * 1. Marking Write=0 PMDs Dirty=1 > - * 2. Marking Dirty=1 PMDs Write=0 > - * > - * The first case cannot happen because the _PAGE_CHG_MASK will filter > - * out any Dirty bit passed in newprot. Handle the second case by > - * going through the mksaveddirty exercise. Only do this if the old > - * value was Write=1 to avoid doing this on Shadow Stack PTEs. > + * Avoid creating shadow stack PMD by accident. See comment in > + * pte_modify(). The changelog is utterly silent about this comment update. > */ > if (oldval & _PAGE_RW) > pmd_result = pmd_mksaveddirty(pmd_result); > @@ -851,6 +851,29 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) > return pmd_result; > } > > +static inline pud_t pud_modify(pud_t pud, pgprot_t newprot) > +{ > + pudval_t val = pud_val(pud), oldval = val; > + pud_t pud_result; > + > + val &= _HPAGE_CHG_MASK; > + val |= check_pgprot(newprot) & ~_HPAGE_CHG_MASK; > + val = flip_protnone_guard(oldval, val, PHYSICAL_PUD_PAGE_MASK); > + > + pud_result = __pud(val); > + > + /* > + * Avoid creating shadow stack PUD by accident. See comment in > + * pte_modify(). > + */ > + if (oldval & _PAGE_RW) > + pud_result = pud_mksaveddirty(pud_result); > + else > + pud_result = pud_clear_saveddirty(pud_result); > + > + return pud_result; > +} > + > /* > * mprotect needs to preserve PAT and encryption bits when updating > * vm_page_prot > @@ -1389,10 +1412,26 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, > } > #endif > > +static inline pud_t pudp_establish(struct vm_area_struct *vma, > + unsigned long address, pud_t *pudp, pud_t pud) Random line break alignment.... See documentation. > +{ > + page_table_check_pud_set(vma->vm_mm, pudp, pud); > + if (IS_ENABLED(CONFIG_SMP)) { > + return xchg(pudp, pud); > + } else { > + pud_t old = *pudp; > + WRITE_ONCE(*pudp, pud); Lacks a newline between variable declaration and code. But seriously, why optimizing for !SMP? That's a pointless exercise and a guarantee for bitrot. > + return old; > + } > +} > + > #define __HAVE_ARCH_PMDP_INVALIDATE_AD > extern pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, > unsigned long address, pmd_t *pmdp); > > +pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, > + pud_t *pudp); While 'extern' is not required, please keep the file style consistent and use the 100 characters... > --- a/arch/x86/mm/pgtable.c > +++ b/arch/x86/mm/pgtable.c > @@ -641,6 +641,18 @@ pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address, > } > #endif > > +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ > + defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) > +pud_t pudp_invalidate(struct vm_area_struct *vma, unsigned long address, > + pud_t *pudp) > +{ > + VM_WARN_ON_ONCE(!pud_present(*pudp)); > + pud_t old = pudp_establish(vma, address, pudp, pud_mkinvalid(*pudp)); > + flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE); > + return old; Your keyboard clearly lacks a newline key ... Thanks, tglx