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Tue, 18 Mar 2025 05:38:47 +0000 (GMT) Message-ID: <67bff00d-eca7-41bd-ad9c-7ee6d5dac040@linux.ibm.com> Date: Tue, 18 Mar 2025 11:08:45 +0530 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 v13 00/11] Support page table check on PowerPC To: Andrew Donnellan , linuxppc-dev@lists.ozlabs.org Cc: x86@kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, pasha.tatashin@soleen.com, sweettea-kernel@dorminy.me References: <20250211161404.850215-1-ajd@linux.ibm.com> Content-Language: en-US From: Madhavan Srinivasan In-Reply-To: <20250211161404.850215-1-ajd@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 9pxqW5-JFDH7ipa2HtNalmErx99yR2nv X-Proofpoint-GUID: 9pxqW5-JFDH7ipa2HtNalmErx99yR2nv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-18_02,2025-03-17_03,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 bulkscore=0 mlxlogscore=999 priorityscore=1501 adultscore=0 suspectscore=0 impostorscore=0 mlxscore=0 lowpriorityscore=0 clxscore=1011 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503180037 On 2/11/25 9:43 PM, Andrew Donnellan wrote: > Support page table check on all PowerPC platforms. This works by > serialising assignments, reassignments and clears of page table > entries at each level in order to ensure that anonymous mappings > have at most one writable consumer, and likewise that file-backed > mappings are not simultaneously also anonymous mappings. > > In order to support this infrastructure, a number of stubs must be > defined for all powerpc platforms. Additionally, seperate set_pte_at() > and set_pte_at_unchecked(), to allow for internal, uninstrumented mappings. > > (This series was written by Rohan McLure, who has left IBM and is no longer > working on powerpc - I've taken far too long to pick this up and finally > send it.) > For powerpc changes Acked-by: Madhavan Srinivasan > v13: > * Rebase on mainline > * Don't use set_pte_at_unchecked() for early boot purposes (Pasha) > > v12: > * Rename commits that revert changes to instead reflect that we are > reinstating old behaviour due to it providing more flexibility > * Add return line to pud_pfn() stub > * Instrument ptep_get_and_clear() for nohash > Link: https://lore.kernel.org/linuxppc-dev/20240402051154.476244-1-rmclure@linux.ibm.com/ > > v11: > * The pud_pfn() stub, which previously had no legitimate users on any > powerpc platform, now has users in Book3s64 with transparent pages. > Include a stub of the same name for each platform that does not > define their own. > * Drop patch that standardised use of p*d_leaf(), as already included > upstream in v6.9. > * Provide fallback definitions of p{m,u}d_user_accessible_page() that > do not reference p*d_leaf(), p*d_pte(), as they are defined after > powerpc/mm headers by linux/mm headers. > * Ensure that set_pte_at_unchecked() has the same checks as > set_pte_at(). > Link: https://lore.kernel.org/linuxppc-dev/20240328045535.194800-14-rmclure@linux.ibm.com/ > > v10: > * Revert patches that removed address and mm parameters from page table > check routines, including consuming code from arm64, x86_64 and > riscv. > * Implement *_user_accessible_page() routines in terms of pte_user() > where available (64-bit, book3s) but otherwise by checking the > address (on platforms where the pte does not imply whether the > mapping is for user or kernel) > * Internal set_pte_at() calls replaced with set_pte_at_unchecked(), which > is identical, but prevents double instrumentation. > Link: https://lore.kernel.org/linuxppc-dev/20240313042118.230397-9-rmclure@linux.ibm.com/T/ > > v9: > * Adapt to using the set_ptes() API, using __set_pte_at() where we need > must avoid instrumentation. > * Use the logic of *_access_permitted() for implementing > *_user_accessible_page(), which are required routines for page table > check. > * Even though we no longer need p{m,u,4}d_leaf(), still default > implement these to assist in refactoring out extant > p{m,u,4}_is_leaf(). > * Add p{m,u}_pte() stubs where asm-generic does not provide them, as > page table check wants all *user_accessible_page() variants, and we > would like to default implement the variants in terms of > pte_user_accessible_page(). > * Avoid the ugly pmdp_collapse_flush() macro nonsense! Just instrument > its constituent calls instead for radix and hash. > Link: https://lore.kernel.org/linuxppc-dev/20231130025404.37179-2-rmclure@linux.ibm.com/ > > v8: > * Fix linux/page_table_check.h include in asm/pgtable.h breaking > 32-bit. > Link: https://lore.kernel.org/linuxppc-dev/20230215231153.2147454-1-rmclure@linux.ibm.com/ > > v7: > * Remove use of extern in set_pte prototypes > * Clean up pmdp_collapse_flush macro > * Replace set_pte_at with static inline function > * Fix commit message for patch 7 > Link: https://lore.kernel.org/linuxppc-dev/20230215020155.1969194-1-rmclure@linux.ibm.com/ > > v6: > * Support huge pages and p{m,u}d accounting. > * Remove instrumentation from set_pte from kernel internal pages. > * 64s: Implement pmdp_collapse_flush in terms of __pmdp_collapse_flush > as access to the mm_struct * is required. > Link: https://lore.kernel.org/linuxppc-dev/20230214015939.1853438-1-rmclure@linux.ibm.com/ > > v5: > Link: https://lore.kernel.org/linuxppc-dev/20221118002146.25979-1-rmclure@linux.ibm.com/ > > Rohan McLure (11): > mm/page_table_check: Reinstate address parameter in > [__]page_table_check_pud_set() > mm/page_table_check: Reinstate address parameter in > [__]page_table_check_pmd_set() > mm/page_table_check: Provide addr parameter to > page_table_check_pte_set() > mm/page_table_check: Reinstate address parameter in > [__]page_table_check_pud_clear() > mm/page_table_check: Reinstate address parameter in > [__]page_table_check_pmd_clear() > mm/page_table_check: Reinstate address parameter in > [__]page_table_check_pte_clear() > mm: Provide address parameter to p{te,md,ud}_user_accessible_page() > powerpc: mm: Add pud_pfn() stub > powerpc: mm: Implement *_user_accessible_page() for ptes > powerpc: mm: Use set_pte_at_unchecked() for internal usages > powerpc: mm: Support page table check > > arch/arm64/include/asm/pgtable.h | 18 +++--- > arch/powerpc/Kconfig | 1 + > arch/powerpc/include/asm/book3s/32/pgtable.h | 12 +++- > arch/powerpc/include/asm/book3s/64/pgtable.h | 62 +++++++++++++++--- > arch/powerpc/include/asm/nohash/pgtable.h | 13 +++- > arch/powerpc/include/asm/pgtable.h | 19 ++++++ > arch/powerpc/mm/book3s64/hash_pgtable.c | 4 ++ > arch/powerpc/mm/book3s64/pgtable.c | 17 +++-- > arch/powerpc/mm/book3s64/radix_pgtable.c | 9 ++- > arch/powerpc/mm/pgtable.c | 12 ++++ > arch/riscv/include/asm/pgtable.h | 18 +++--- > arch/x86/include/asm/pgtable.h | 20 +++--- > include/linux/page_table_check.h | 67 ++++++++++++-------- > include/linux/pgtable.h | 10 +-- > mm/page_table_check.c | 39 +++++++----- > 15 files changed, 225 insertions(+), 96 deletions(-) >