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Fri, 25 Sep 2026 13:42:24 +0000 (GMT) Received: from osiris (unknown [9.111.31.68]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTPS; Fri, 25 Sep 2026 13:42:24 +0000 (GMT) Date: Fri, 25 Sep 2026 15:42:23 +0200 From: Heiko Carstens To: "Mike Rapoport (Microsoft)" Cc: Andrew Morton , Albert Ou , Alexander Gordeev , Alexandre Ghiti , Borislav Petkov , Catalin Marinas , "Christophe Leroy (CS GROUP)" , Christian Borntraeger , Dave Hansen , David Hildenbrand , Gerald Schaefer , Ingo Molnar , "Liam R. Howlett" , Lorenzo Stoakes , Madhavan Srinivasan , Mark Rutland , Michael Ellerman , Michal Hocko , Nicholas Piggin , Palmer Dabbelt , Paul Walmsley , "H. Peter Anvin" , Ritesh Harjani , Russell King , Shrikanth Hegde , Suren Baghdasaryan , Sven Schnelle , Thomas Gleixner , Vasily Gorbik , Vlastimil Babka , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org Subject: Re: [PATCH] arch, mm: promote DEBUG_WX to CHECK_WX Message-ID: <20260925134223.23528E0e-hca@linux.ibm.com> References: <20260925-direct-map-verify-wx-v1-1-7fd2f7d6d23b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260925-direct-map-verify-wx-v1-1-7fd2f7d6d23b@kernel.org> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: az6V2wRZNTPsfcgPJvRvBbZTbbclocGz X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI1MDA1NCBTYWx0ZWRfX8eL1fhw8Wcuz gwW3tmVcEwpUDvML7GILF9tAuDr0VlXZUr5Wt11Sb6FgeUgSArMjIqmr7nGQy57VhoNxjcdb1nB xgUIIMHQV/ped6lC1/jiVHQShjl212s= 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engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-25_02,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 phishscore=0 spamscore=0 clxscore=1015 suspectscore=0 bulkscore=0 lowpriorityscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609250054 X-Stat-Signature: kjdgohethckej8k64depyn4seibzkkxp X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 641CEC0002 X-HE-Tag: 1790343788-558742 X-HE-Meta: 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 lDt10kTJ KBUM7af39KSk7Ax+COtdjPESyHLtFaWXmwdo4hlvTXD3Qf0pFBxirhIsaY5VoBQbeQxzb5VQP0dEkLGW6/nhn+e80GB1Ln2zMRGl8fu8Qjqm8L2r0wLxCEmG4UHal7EFMp1w1UGYvv1reuK3d+KtLsVGl7mBBDak4nWORCIO9m2ETWrlAnPtfixDXQa+f9uGoHunMZc1/871Uk/Y9JzcXkyLHQHZHUQxZLXuemtnhKix0RsE7KWHZkNSDgrJ8ZLloDoLAg7FowsvG9QLNWdoTzlDGrz3T3go5W9nBR735N9vvtZlTgOvkbIovsu6JUefxTwe4HjDI4hlCCDCXNACkuhBJ3Zz7E0W8k2M0a8mYZBjphXvj/lubdRujCqy6awGKR91sV3NYJfOLmtjyoSwoPzYkTO/VB3XCx1bn Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Sep 25, 2026 at 12:53:46PM +0300, Mike Rapoport (Microsoft) wrote: > Verification that the kernel does not have writable + executable > mappings is about detecting security risks rather than a pure debug > feature. > > Major distribution configurations enable it in their kernels as well as > defconfigs of most architectures that have ARCH_HAS_DEBUG_WX. > > Rename relevant generic configuration options to use CHECK_WX and move > their definitions from mm/Kconfig.debug to mm/Kconfig. > > For arm that does not widely enable it, only rename its variants of the > config options. > > Enabling CHECK_WX adds a few kilobytes to the kernel binary and while > the added size can be slightly reduced with churny updates of > architecture implementations of ptdump, the core functionality takes > most of the added size. It cannot be moved to .init.text because the > verification has to happen after init sections are freed. > > With this, make generic CHECK_WX default to STRICT_KERNEL_RWX while > still leaving users targeting small kernels the possibility to opt-out. > > Suggested-by: Dave Hansen > Signed-off-by: Mike Rapoport (Microsoft) > --- ... > arch/s390/Kconfig | 2 +- > arch/s390/configs/debug_defconfig | 2 +- > arch/s390/configs/defconfig | 2 +- > arch/s390/mm/dump_pagetables.c | 2 +- Acked-by: Heiko Carstens # s390 > diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c > index 89badbe72ae7..a23a0bd4d8a8 100644 > --- a/arch/s390/mm/dump_pagetables.c > +++ b/arch/s390/mm/dump_pagetables.c > @@ -86,7 +86,7 @@ static void note_prot_wx(struct pg_state *st, unsigned long addr) > */ > if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !cpu_has_bear())) > return; > - WARN_ONCE(IS_ENABLED(CONFIG_DEBUG_WX), > + WARN_ONCE(IS_ENABLED(CONFIG_CHECK_WX), Hm... looks like there is bug with relocated lowcore handling in the if condition above the WARN_ONCE(). I'm going to address that, but that has nothing to do with your patch.