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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47aa0f213e8sm48543085f8f.34.2026.07.09.04.12.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Jul 2026 04:13:01 -0700 (PDT) Message-ID: <835e2f62-3b66-45d4-a614-dc2198a715ad@oss.qualcomm.com> Date: Thu, 9 Jul 2026 13:12:57 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [patch 01/18] powerpc: Move stack randomization after syscall_enter_from_user_mode() Content-Language: en-US To: Thomas Gleixner , LKML Cc: Peter Zijlstra , Michael Ellerman , Shrikanth Hegde , linuxppc-dev@lists.ozlabs.org, Kees Cook , Huacai Chen , loongarch@lists.linux.dev, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Sven Schnelle , linux-s390@vger.kernel.org, x86@kernel.org, Mark Rutland , Jinjie Ruan , Andy Lutomirski , Oleg Nesterov , Richard Henderson , Russell King , Catalin Marinas , Guo Ren , Geert Uytterhoeven , Thomas Bogendoerfer , Helge Deller , Yoshinori Sato , Richard Weinberger , Chris Zankel , linux-arm-kernel@lists.infradead.org, linux-alpha@vger.kernel.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-um@lists.infradead.org, Arnd Bergmann , Vineet Gupta , Will Deacon , Brian Cain , Michal Simek , Dinh Nguyen , "David S. Miller" , Andreas Larsson , linux-snps-arc@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-openrisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, =?UTF-8?Q?Michal_Such=C3=A1nek?= , Jonathan Corbet , linux-doc@vger.kernel.org References: <20260707181957.433213175@kernel.org> <20260707190253.718191130@kernel.org> From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: <20260707190253.718191130@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA5MDEwOCBTYWx0ZWRfXxXvF6qSVCpQK +dst5Z/th90GbjclZgtuL7p0r87vkeE525w8GzSpzLM5MKuIGk0B2onRxb/AUvylI79SapFvUXC eeXBc8PEGBmGnXV+9sVYYPqtZzlVJ2E= X-Proofpoint-GUID: 1tpPGLEPwXRhAQOqy6BiCyVqRLKB8N8_ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA5MDEwOCBTYWx0ZWRfXwNbLwDtTCAo0 Tgg9d/Lxt1IubrtMlsrp2uXo1FQ6yGPadO+SYKYv3zYB6f0uTMdqyERYS29MbYqunNqqaDd++SK RMsPKMQSfCq/RECJDWAYTp8A2oKU8Dj1S8fqB698BFRBtGFHHRxDMMfGhkvz2PtJcgy3OuIKUDN zMq+jxAtkbzo1bjR8atKYtRLWQLirewguQdQVXhnkQaFARjAdOiKNnDX5/ZO8Te+szspA9+2P0h kAFgRruxQKhoDIfJfunIo3Un2hJxNrh5oLYP2OEbZwFeqeSac7edU9qUoxZPOWmPBPgdaxtXViA OyUohMclbpkVLbDT4KbVhd+kkHyx5xcyr5gZaE97i9MpA+KUkrEF5eJUQiBfSHZlQc/GaBhMJ8L c+Au9k3ynAgds7K9C4pe40jbp5nfN6jJFicU+nT8HlNeBD+WlfG5X7f/uJ8hpnfioomq4HJD9D5 /FqBVAgHgUtVkkb79Ng== X-Authority-Analysis: v=2.4 cv=Sv2gLvO0 c=1 sm=1 tr=0 ts=6a4f823f cx=c_pps a=50t2pK5VMbmlHzFWWp8p/g==:117 a=4s3hRJSeHn4rkQlkrse1kQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=M51BFTxLslgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_glEPmIy2e8OvE2BGh3C:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=voM4FWlXAAAA:8 a=EUspDBNiAAAA:8 a=63ny2n9c4_t8xnV3ltYA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=IoWCM6iH3mJn3m4BftBB:22 a=IC2XNlieTeVoXbcui8wp:22 X-Proofpoint-ORIG-GUID: 1tpPGLEPwXRhAQOqy6BiCyVqRLKB8N8_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-09_02,2026-07-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 priorityscore=1501 suspectscore=0 malwarescore=0 impostorscore=0 lowpriorityscore=0 clxscore=1015 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607090108 On 7/7/26 21:05, Thomas Gleixner wrote: > add_random_kstack_offset() is invoked before syscall_enter_from_user_mode() > establishes state. That's wrong because add_random_kstack_offset() calls > into instrumentable code. > > Move it after syscall_enter_from_user_mode() to ensure that state is > correctly established. > > Signed-off-by: Thomas Gleixner > Cc: Michael Ellerman > Cc: Shrikanth Hegde > Cc: linuxppc-dev@lists.ozlabs.org > --- > arch/powerpc/kernel/syscall.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/arch/powerpc/kernel/syscall.c > +++ b/arch/powerpc/kernel/syscall.c > @@ -19,8 +19,8 @@ notrace long system_call_exception(struc > long ret; > syscall_fn f; > > - add_random_kstack_offset(); > r0 = syscall_enter_from_user_mode(regs, r0); > + add_random_kstack_offset(); > > if (unlikely(r0 >= NR_syscalls)) { > if (unlikely(trap_is_unsupported_scv(regs))) { > Reviewed-by: Philippe Mathieu-Daudé