The behaviour of pXdp_get() will change with generic compile-time folded page tables. To prepare for that, rework effective_prot() to ignore any folded page tables entries, as it will unconditionally get called by ptdump core with pXd_val(pXdp_get()), and the value for folded entries really should be ignored.
For this, introduce mm_first_pgtable_level() to identify the first real page-table level, move mm_pXd_folded() in !__ASSEMBLER__ and update effective_prot with higher_prot only when the current entry is not folded nor the first level. There should be no functional change. Signed-off-by: Yeoreum Yun <[email protected]> --- arch/x86/mm/dump_pagetables.c | 6 +++-- include/linux/pgtable.h | 61 ++++++++++++++++++++++++++++++++----------- 2 files changed, 50 insertions(+), 17 deletions(-) diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index a18a61e732c3..2acbe41eb58f 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -38,6 +38,7 @@ struct pg_state { bool check_wx; unsigned long wx_pages; struct seq_file *seq; + struct mm_struct *mm; }; struct addr_marker { @@ -254,7 +255,7 @@ static void effective_prot(struct ptdump_state *pt_st, enum pgtable_level level, pgprotval_t prot = val & PTE_FLAGS_MASK; pgprotval_t effective; - if (level > PGTABLE_LEVEL_PGD) { + if (level > mm_first_pgtable_level(st->mm)) { pgprotval_t higher_prot = st->prot_levels[level - 1]; effective = (higher_prot & prot & (_PAGE_USER | _PAGE_RW)) | @@ -452,7 +453,8 @@ bool ptdump_walk_pgd_level_core(struct seq_file *m, .level = -1, .to_dmesg = dmesg, .check_wx = checkwx, - .seq = m + .seq = m, + .mm = mm, }; ptdump_walk_pgd(&st.ptdump, mm, pgd); diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 3186096a6e13..ed7101a13ce9 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -392,6 +392,22 @@ static inline void lazy_mmu_mode_pause(void) {} static inline void lazy_mmu_mode_resume(void) {} #endif +/* + * On some architectures it depends on the mm if the p4d/pud or pmd + * layer of the page table hierarchy is folded or not. + */ +#ifndef mm_p4d_folded +#define mm_p4d_folded(mm) __is_defined(__PAGETABLE_P4D_FOLDED) +#endif + +#ifndef mm_pud_folded +#define mm_pud_folded(mm) __is_defined(__PAGETABLE_PUD_FOLDED) +#endif + +#ifndef mm_pmd_folded +#define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) +#endif + #ifndef pte_batch_hint /** * pte_batch_hint - Number of pages that can be added to batch without scanning. @@ -2313,6 +2329,36 @@ static inline const char *pgtable_level_to_str(enum pgtable_level level) } } +#ifdef CONFIG_MMU +/** + * mm_first_pgtable_level - return the first non-folded page-table level + * @mm: The mm structure. + * + * With runtime- or compile-time folded page tables, page-table walkers + * effectively skip the folded top-level page tables, treating them as + * always-present entries pointing to the next lower-level page table. + * + * Return the first page-table level in @mm that is not folded. + * + * Return: the first non-folded page-table level. + */ +static inline enum pgtable_level mm_first_pgtable_level(struct mm_struct *mm) +{ + /* + * "PMD folded" actually means "PMD is folded into PUD", and + * pud_present() etc. are hard-coded to look like present page table + * levels, whereby pmd_present() etc. contain real logic. + */ + if (mm_pmd_folded(mm)) + return PGTABLE_LEVEL_PMD; + if (mm_pud_folded(mm)) + return PGTABLE_LEVEL_PUD; + if (mm_p4d_folded(mm)) + return PGTABLE_LEVEL_P4D; + return PGTABLE_LEVEL_PGD; +} +#endif /* CONFIG_MMU */ + void ptval_bytes_to_hex_str(char *buf, size_t buf_size, const void *entry, size_t entry_size); #define ptval_to_str(buf, val) \ @@ -2349,21 +2395,6 @@ void ptval_bytes_to_hex_str(char *buf, size_t buf_size, const void *entry, size_ #ifndef has_transparent_pud_hugepage #define has_transparent_pud_hugepage() IS_BUILTIN(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) #endif -/* - * On some architectures it depends on the mm if the p4d/pud or pmd - * layer of the page table hierarchy is folded or not. - */ -#ifndef mm_p4d_folded -#define mm_p4d_folded(mm) __is_defined(__PAGETABLE_P4D_FOLDED) -#endif - -#ifndef mm_pud_folded -#define mm_pud_folded(mm) __is_defined(__PAGETABLE_PUD_FOLDED) -#endif - -#ifndef mm_pmd_folded -#define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) -#endif #ifndef p4d_offset_lockless #define p4d_offset_lockless(pgdp, pgd, address) p4d_offset(&(pgd), address) -- 2.43.0
