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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gRZT5Aycj8nb9nzE9CkfCAmO1Pk+zt96vwJ0a+6cKk6Wn/mIV1tYxcrUG/53HkHzj hn2MLdJulVDpzweQyjtnhqxSXAs3RDgKOuCTNjnCpg+4zOinXDuxDvU/Xyloz5ww/k V36SggskoTyyC6c++z8jGDd4uZBRW8buLuFGqQZY= Message-ID: <1ef238fd-232c-4b8a-b28d-cd20db57bcfc@arm.com> Date: Fri, 3 Jul 2026 11:00:32 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 6/6] mm/mprotect: use huge_ptep_get() for hugetlb To: "David Hildenbrand (Arm)" , muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org Cc: riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcampbell@nvidia.com, apopple@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, j-nomura@ce.jp.nec.com, nao.horiguchi@gmail.com, ak@linux.intel.com, mel@csn.ul.ie, pfalcato@suse.de, jpoimboe@kernel.org, dave.hansen@intel.com, tglx@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260702051341.126509-1-dev.jain@arm.com> <20260702051341.126509-7-dev.jain@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: dqpybaxwudzhz3j6mfa4ocah9up15gpu X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: E5200100009 X-HE-Tag: 1783056645-415404 X-HE-Meta: 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 zxmBoWli /D6c1mpeKQfCEGKmiz/NKFK2N829avdKmpK6E2ZRLo/h0IaqCbvtyqhfUqAt6Goy/NLfsgTfZinC2277ARj03Vsgm7SgKDP3Pf8UzOromQME0GzJUGBGkxmVRuVnwpO/60Vn41+quCXjVgyWucn58lYshWfzbAI5UUcNuxVbG8gPb1p0uSGya/3BVIIcGp0dTa1NfBbpVBscShItiQ3DJLrCzuEWyHkpRNap/CtHYc0vbU1BFbeW2Uh+onWRQUiEUPV6y6hjsCOMOM9JV/fkzrkuUox+sGOPZv4ByemyPmUm2Vqq8/pR1ED5gWUq7e8dVwITRq/PD6TEZ8GLqM0w5ShhYZSbPv2nImjFynr+d/JcGsn+Juwp3nbYjji06VB07gUsbA+zD2PAq7daFVap8WikaxncmNyuXakq5 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 02/07/26 9:17 pm, David Hildenbrand (Arm) wrote: > On 7/2/26 07:13, Dev Jain wrote: >> prot_none_hugetlb_entry() is the hugetlb callback for the early >> mprotect(PROT_NONE) PFN permission walk on x86. >> >> The callback passes the decoded PFN to pfn_modify_allowed(). For a >> hugetlb callback, the pte pointer refers to a hugetlb entry. On >> architectures where hugetlb entries need huge_ptep_get(), reading that >> entry with ptep_get() can make the permission check use the wrong PFN. >> >> Use huge_ptep_get() before decoding the hugetlb PFN. >> >> Currently there is no path which can trigger a bug: huge_ptep_get() is a >> simple ptep_get() for x86, and the prot_none walk occurs only for x86. >> >> So no need to backport - use the correct helper anyways. >> >> Fixes: 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings") >> Signed-off-by: Dev Jain >> --- >> mm/mprotect.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/mm/mprotect.c b/mm/mprotect.c >> index 9cbf932b028cf..23779632d18bf 100644 >> --- a/mm/mprotect.c >> +++ b/mm/mprotect.c >> @@ -699,14 +699,20 @@ static int prot_none_pte_entry(pte_t *pte, unsigned long addr, >> 0 : -EACCES; >> } >> >> +#ifdef CONFIG_HUGETLB_PAGE >> static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, >> unsigned long addr, unsigned long next, >> struct mm_walk *walk) >> { >> - return pfn_modify_allowed(pte_pfn(ptep_get(pte)), >> + pte_t entry = huge_ptep_get(walk->mm, addr, pte); > > Nit: can be const :) > >> + >> + return pfn_modify_allowed(pte_pfn(entry), >> *(pgprot_t *)(walk->private)) ? >> 0 : -EACCES; > > Indentation is odd. > > Can we just make this readable? > > if (pfn_modify_allowed ...) > return 0 > return -EACCESS; > Sure I'll do this. >