[PATCH v11 00/11] Support page table check PowerPC

Rohan McLure
2024-03-28T04:57:18Z

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.

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().

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):
Revert "mm/page_table_check: remove unused parameter in
[__]page_table_check_pud_set"
Revert "mm/page_table_check: remove unused parameter in
[__]page_table_check_pmd_set"
mm: Provide addr parameter to page_table_check_pte_set()
Revert "mm/page_table_check: remove unused parameter in
[__]page_table_check_pud_clear"
Revert "mm/page_table_check: remove unused parameter in
[__]page_table_check_pmd_clear"
Revert "mm/page_table_check: remove unused 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
poweprc: mm: Implement *_user_accessible_page() for ptes
powerpc: mm: Use set_pte_at_unchecked() for early-boot / 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 | 5 ++
arch/powerpc/include/asm/pgtable.h | 18 ++++++
arch/powerpc/mm/book3s64/hash_pgtable.c | 6 +-
arch/powerpc/mm/book3s64/pgtable.c | 17 +++--
arch/powerpc/mm/book3s64/radix_pgtable.c | 11 ++--
arch/powerpc/mm/nohash/book3e_pgtable.c | 2 +-
arch/powerpc/mm/pgtable.c | 12 ++++
arch/powerpc/mm/pgtable_32.c | 2 +-
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 | 8 +--
mm/page_table_check.c | 39 +++++++-----
17 files changed, 220 insertions(+), 98 deletions(-)