From: Steven Price <steven.price@xxxxxxx> Subject: x86: mm: convert ptdump_walk_pgd_level_core() to take an mm_struct 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. Link: http://lkml.kernel.org/r/20191028135910.33253-19-steven.price@xxxxxxx Signed-off-by: Steven Price <steven.price@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Alexandre Ghiti <alex@xxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Dave Jiang <dave.jiang@xxxxxxxxx> Cc: David S. Miller <davem@xxxxxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Cc: James Hogan <jhogan@xxxxxxxxxx> Cc: James Morse <james.morse@xxxxxxx> Cc: "Liang, Kan" <kan.liang@xxxxxxxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxx> Cc: Paul Burton <paul.burton@xxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxx> Cc: Shiraz Hashim <shashim@xxxxxxxxxxxxxx> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Zong Li <zong.li@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/mm/dump_pagetables.c | 36 ++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 15 deletions(-) --- a/arch/x86/mm/dump_pagetables.c~x86-mm-convert-ptdump_walk_pgd_level_core-to-take-an-mm_struct +++ a/arch/x86/mm/dump_pagetables.c @@ -107,8 +107,6 @@ static struct addr_marker address_marker [END_OF_SPACE_NR] = { -1, NULL } }; -#define INIT_PGD ((pgd_t *) &init_top_pgt) - #else /* CONFIG_X86_64 */ enum address_markers_idx { @@ -143,8 +141,6 @@ static struct addr_marker address_marker [END_OF_SPACE_NR] = { -1, NULL } }; -#define INIT_PGD (swapper_pg_dir) - #endif /* !CONFIG_X86_64 */ /* Multipliers for offsets within the PTEs */ @@ -515,10 +511,10 @@ static inline bool is_hypervisor_range(i #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 = {}; @@ -565,39 +561,49 @@ static void ptdump_walk_pgd_level_core(s 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 && boot_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) || !boot_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) _
