From: Ryan Roberts <ryan.roberts@arm.com> mainline inclusion from mainline-v6.18-rc6 commit 53357f14f924a06cced46069755bb10c2a6891c1 category: feature bugzilla: https://atomgit.com/openeuler/kernel/issues/9850 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... ------------------------------------------- Tidy up the implementation of force_pte_mapping() to make it easier to read and introduce the split_leaf_mapping_possible() helper to reduce code duplication in split_kernel_leaf_mapping() and arch_kfence_init_pool(). Suggested-by: David Hildenbrand (Red Hat) <david@kernel.org> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Reviewed-by: David Hildenbrand (Red Hat) <david@kernel.org> Reviewed-by: Yang Shi <yang@os.amperecomputing.com> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- arch/arm64/mm/mmu.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 635743da6e17..792ef9491280 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -653,12 +653,26 @@ static int split_kernel_leaf_mapping_locked(unsigned long addr) static inline bool force_pte_mapping(void) { - bool bbml2 = system_capabilities_finalized() ? + const bool bbml2 = system_capabilities_finalized() ? system_supports_bbml2_noabort() : cpu_supports_bbml2_noabort(); - return (!bbml2 && (rodata_full || arm64_kfence_can_set_direct_map() || - is_realm_world())) || - debug_pagealloc_enabled(); + if (debug_pagealloc_enabled()) + return true; + if (bbml2) + return false; + return rodata_full || arm64_kfence_can_set_direct_map() || is_realm_world(); +} + +static inline bool split_leaf_mapping_possible(void) +{ + /* + * !BBML2_NOABORT systems should never run into scenarios where we would + * have to split. So exit early and let calling code detect it and raise + * a warning. + */ + if (!system_supports_bbml2_noabort()) + return false; + return !force_pte_mapping(); } static DEFINE_MUTEX(pgtable_split_lock); @@ -668,22 +682,11 @@ int split_kernel_leaf_mapping(unsigned long start, unsigned long end) int ret; /* - * !BBML2_NOABORT systems should not be trying to change permissions on - * anything that is not pte-mapped in the first place. Just return early - * and let the permission change code raise a warning if not already - * pte-mapped. - */ - if (!system_supports_bbml2_noabort()) - return 0; - - /* - * If the region is within a pte-mapped area, there is no need to try to - * split. Additionally, CONFIG_DEBUG_PAGEALLOC and CONFIG_KFENCE may - * change permissions from atomic context so for those cases (which are - * always pte-mapped), we must not go any further because taking the - * mutex below may sleep. + * Exit early if the region is within a pte-mapped area or if we can't + * split. For the latter case, the permission change code will raise a + * warning if not already pte-mapped. */ - if (force_pte_mapping() || is_kfence_address((void *)start)) + if (!split_leaf_mapping_possible() || is_kfence_address((void *)start)) return 0; /* @@ -987,7 +990,7 @@ bool arch_kfence_init_pool(void) int ret; /* Exit early if we know the linear map is already pte-mapped. */ - if (!system_supports_bbml2_noabort() || force_pte_mapping()) + if (!split_leaf_mapping_possible()) return true; /* Kfence pool is already pte-mapped for the early init case. */ -- 2.43.0