From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D3221511E64 for ; Tue, 8 Sep 2026 09:27:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788859668; cv=none; b=Sz+DHLYRy1dS2rvzUIfGPOKbMJjB5fJ2ZhZwnzZhLTmsb+3O8W46VVLsa23C9Hl9mutr+IrHbD17Y9/NJSMKBi2JD+G/5ON8S0SbqDHAmmeHwR5oTotSf4oVhWOat8zVJx1t8KMXUHKTPSzNOIoO3B4OXO02d4srb+q+uxyV2Zw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788859668; c=relaxed/simple; bh=7Ly2HKur9qtOXtjzPcloCvSUgsrmkjerkiQ66e2gqyc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=H8yWbodU0qOgwjPC3RcTOSUDoOR0mDbt3AJ+AGWF8HFd1ON+yz6UNQAON5frxPTQXe16hWb9TP+peRjDVWK6tsSL9AM2mI0OILMfYB6gL7U1AlJIinUu+jCpe6I0WxhomsnNZF+kDOChG2H4TbCEHTtsN7PLeFmSZtiLu3I/N6A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=moKBq+kj; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="moKBq+kj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B761D1F00A3A; Tue, 8 Sep 2026 09:27:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788859666; bh=fAPpGCdN95bGFO91E5DBtBDsmutoxakUFDAMgvaJoL4=; h=From:To:Cc:Subject:Date; b=moKBq+kj1uOJPnH2aWvQkgnuZpb3BZquJGzkKCHgqM6JpVSiHxth6Pjln262SJoVV 8KNSkcJbOYJs7z2tbzqQYvhHklHGqJjVJ0riHVypApu+Ort/t47GbgCMFzWpL+u8KO BwgiQZMf4KadzSpOtcRrD/+9uI00dFiHs3nry+KeRpxBgXrzOxd44cWeeDAO6te8K1 cXQK2DwJYgiCSGGWNlaOgxc3rEzeDPqPbMowtvwHz7CFfviMG4wd01aUmk8/3d5nFv roKwmYmm/cwUV1rKpLQ9LVHDZpFHrB8bdKcK69Rw+NDkcHkW2tXL3DAQtVOhvDYMB7 RkJsypg5LZvzQ== From: Mike Rapoport To: Dave Hansen Cc: Andy Lutomirski , Borislav Petkov , Ingo Molnar , Mike Rapoport , Nathan Chancellor , "H. Peter Anvin" , Peter Zijlstra , Thomas Gleixner , linux-kernel@vger.kernel.org, x86@kernel.org Subject: [PATCH] x86/mm/pat: skip RWX verification until kernel text is set to read only Date: Tue, 8 Sep 2026 12:27:30 +0300 Message-ID: <20260908092730.4002628-1-rppt@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Mike Rapoport (Microsoft)" Nathan Chancellor reports the following warning: CPA detected W^X violation: 8000000000000123 -> 0000000000000123 range: 0xffffffffc0400000 - 0xffffffffc0400fff PFN 100e00 WARNING: arch/x86/mm/pat/set_memory.c:722 at __change_page_attr_set_clr+0xde7/0x1290, CPU#0: swapper/0/0 Modules linked in: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.3.0-rc1-debug-00006-g453e78594434 #1 PREEMPT(full) 2950d432dd3910251071a66f3134fe0875432786 Hardware name: ASUS System Product Name/PRIME Z590M-PLUS, BIOS 1801 12/26/2022 RIP: 0010:__change_page_attr_set_clr+0xdff/0x1290 Code: 80 7c 24 42 00 0f 85 3a 04 00 00 48 8d 3d 19 8d 79 02 49 89 d9 4c 89 e1 4c 89 d2 4c 89 f6 4d 8d 84 24 ff 0f 00 00 4c 89 14 24 <67> 48 0f b9 3a 4c 8b 14 24 48 8b 0d 81 44 bf 01 41 f6 c2 01 RSP: 0000:ffffffff87003c60 EFLAGS: 00010246 RAX: 0000000000000002 RBX: 0000000000100e00 RCX: ffffffffc0400000 RDX: 0000000000000123 RSI: 8000000000000123 RDI: ffffffff872e50c0 RBP: 8000000100e00123 R08: ffffffffc0400fff R09: 0000000000100e00 R10: 0000000000000123 R11: 0000000000000001 R12: ffffffffc0400000 R13: 0000000100e00123 R14: 8000000000000123 R15: ffffffff87003d58 FS: 0000000000000000(0000) GS:ffff8ad1777a7000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff8ad0a4201000 CR3: 00000007e3022001 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: ? _vm_unmap_aliases+0x219/0x280 change_page_attr_set_clr+0x161/0x250 ? events_sysfs_show+0x5d/0x80 set_memory_x+0x39/0x50 apply_retpolines+0x656/0x6d0 ? events_sysfs_show+0x5d/0x80 ? events_sysfs_show+0x6c/0x80 ? events_sysfs_show+0x62/0x80 alternative_instructions+0x3c/0xd0 arch_cpu_finalize_init+0x130/0x190 start_kernel+0x97d/0xa10 x86_64_start_reservations+0x24/0x30 x86_64_start_kernel+0xda/0xe0 common_startup_64+0x13e/0x151 ---[ end trace 0000000000000000 ]--- The warning appears because commit 038176c21617f ("x86/mm/pat: fix effective RW computation in lookup_address_in_pgd_attr()") fixed the effective RW checked by verify_rwx() and it exposed that pages used for ITS trampolines temporarily have RWX permissions. The permissions are updated in its_fini_core() after all the ITS trampolines are generated, but since verify_rwx() detects invalid transitions, it warns when its_alloc() makes RW memory executable. At the time of alternatives patching the entire kernel text is mapped RWX, so the warning is bogus anyway. Skip verification of W^X violations in verify_rwx() when they are triggered by transitions happening before the kernel text is remapped as read-only. Reported-by: Nathan Chancellor Closes: https://lore.kernel.org/all/20260905044253.GA3816371@ax162 Signed-off-by: Mike Rapoport (Microsoft) --- arch/x86/mm/pat/set_memory.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 226660973d515..2eecb76703bb4 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -708,6 +708,10 @@ static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long star if (!(__supported_pte_mask & _PAGE_NX)) return new; + /* skip verification until kernel text is set to read only */ + if (!kernel_set_to_readonly) + return new; + if (!((pgprot_val(old) ^ pgprot_val(new)) & (_PAGE_RW | _PAGE_NX))) return new; base-commit: 038176c21617fcc03ccc1ca43230ffedb712c047 -- 2.53.0