[PATCH v7 19/20] x86: mm: Convert ptdump_walk_pgd_level_core() to take an mm_struct
From: Steven Price <steven.price@arm.com>
Date: 2019-03-28 15:23:10
Also in:
linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
An mm_struct is needed to enable x86 to use of the generic walk_page_range() function. In the case of walking the user page tables (when CONFIG_PAGE_TABLE_ISOLATION is enabled), it is necessary to create a fake_mm structure because there isn't an mm_struct with a pointer to the pgd of the user page tables. This fake_mm structure is initialised with the minimum necessary for the generic page walk code. Signed-off-by: Steven Price <steven.price@arm.com> --- arch/x86/mm/dump_pagetables.c | 36 ++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-)
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 40b3f1da6e15..c0fbb9e5a790 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c@@ -111,8 +111,6 @@ static struct addr_marker address_markers[] = { [END_OF_SPACE_NR] = { -1, NULL } }; -#define INIT_PGD ((pgd_t *) &init_top_pgt) - #else /* CONFIG_X86_64 */ enum address_markers_idx {
@@ -147,8 +145,6 @@ static struct addr_marker address_markers[] = { [END_OF_SPACE_NR] = { -1, NULL } }; -#define INIT_PGD (swapper_pg_dir) - #endif /* !CONFIG_X86_64 */ /* Multipliers for offsets within the PTEs */
@@ -522,10 +518,10 @@ static inline bool is_hypervisor_range(int idx) #endif } -static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd, +static void ptdump_walk_pgd_level_core(struct seq_file *m, struct mm_struct *mm, bool checkwx, bool dmesg) { - pgd_t *start = pgd; + pgd_t *start = mm->pgd; pgprotval_t prot, eff; int i; struct pg_state st = {};
@@ -572,39 +568,49 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd, void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm) { - ptdump_walk_pgd_level_core(m, mm->pgd, false, true); + ptdump_walk_pgd_level_core(m, mm, false, true); } +#ifdef CONFIG_PAGE_TABLE_ISOLATION +static void ptdump_walk_pgd_level_user_core(struct seq_file *m, + struct mm_struct *mm, + bool checkwx, bool dmesg) +{ + struct mm_struct fake_mm = { + .pgd = kernel_to_user_pgdp(mm->pgd) + }; + init_rwsem(&fake_mm.mmap_sem); + ptdump_walk_pgd_level_core(m, &fake_mm, checkwx, dmesg); +} +#endif + void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm, bool user) { - pgd_t *pgd = mm->pgd; #ifdef CONFIG_PAGE_TABLE_ISOLATION if (user && static_cpu_has(X86_FEATURE_PTI)) - pgd = kernel_to_user_pgdp(pgd); + ptdump_walk_pgd_level_user_core(m, mm, false, false); + else #endif - ptdump_walk_pgd_level_core(m, pgd, false, false); + ptdump_walk_pgd_level_core(m, mm, false, false); } EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs); void ptdump_walk_user_pgd_level_checkwx(void) { #ifdef CONFIG_PAGE_TABLE_ISOLATION - pgd_t *pgd = INIT_PGD; - if (!(__supported_pte_mask & _PAGE_NX) || !static_cpu_has(X86_FEATURE_PTI)) return; pr_info("x86/mm: Checking user space page tables\n"); - pgd = kernel_to_user_pgdp(pgd); - ptdump_walk_pgd_level_core(NULL, pgd, true, false); + ptdump_walk_pgd_level_user_core(NULL, &init_mm, true, false); #endif } void ptdump_walk_pgd_level_checkwx(void) { - ptdump_walk_pgd_level_core(NULL, INIT_PGD, true, false); + ptdump_walk_pgd_level_core(NULL, &init_mm, true, false); } static int __init pt_dump_init(void)
--
2.20.1
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