diff options
| author | Andy Lutomirski | 2018-01-25 13:12:15 -0800 |
|---|---|---|
| committer | Thomas Gleixner | 2018-01-26 15:56:23 +0100 |
| commit | 36b3a7726886f24c4209852a58e64435bde3af98 (patch) | |
| tree | b7138f27cf51076b3d2c05ca9b6d268d5e3bce62 | |
| parent | 5beda7d54eafece4c974cfa9fbb9f60fb18fd20a (diff) | |
x86/mm/64: Tighten up vmalloc_fault() sanity checks on 5-level kernels
On a 5-level kernel, if a non-init mm has a top-level entry, it needs to
match init_mm's, but the vmalloc_fault() code skipped over the BUG_ON()
that would have checked it.
While we're at it, get rid of the rather confusing 4-level folded "pgd"
logic.
Cleans-up: b50858ce3e2a ("x86/mm/vmalloc: Add 5-level paging support")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Neil Berrington <neil.berrington@datacore.com>
Link: https://lkml.kernel.org/r/2ae598f8c279b0a29baf75df207e6f2fdddc0a1b.1516914529.git.luto@kernel.org
| -rw-r--r-- | arch/x86/mm/fault.c | 22 |
1 files changed, 9 insertions, 13 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index b3e40773dce0..800de815519c 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -439,18 +439,13 @@ static noinline int vmalloc_fault(unsigned long address) if (pgd_none(*pgd_ref)) return -1; - if (pgd_none(*pgd)) { - set_pgd(pgd, *pgd_ref); - arch_flush_lazy_mmu_mode(); - } else if (CONFIG_PGTABLE_LEVELS > 4) { - /* - * With folded p4d, pgd_none() is always false, so the pgd may - * point to an empty page table entry and pgd_page_vaddr() - * will return garbage. - * - * We will do the correct sanity check on the p4d level. - */ - BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); + if (CONFIG_PGTABLE_LEVELS > 4) { + if (pgd_none(*pgd)) { + set_pgd(pgd, *pgd_ref); + arch_flush_lazy_mmu_mode(); + } else { + BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); + } } /* With 4-level paging, copying happens on the p4d level. */ @@ -459,7 +454,7 @@ static noinline int vmalloc_fault(unsigned long address) if (p4d_none(*p4d_ref)) return -1; - if (p4d_none(*p4d)) { + if (p4d_none(*p4d) && CONFIG_PGTABLE_LEVELS == 4) { set_p4d(p4d, *p4d_ref); arch_flush_lazy_mmu_mode(); } else { @@ -470,6 +465,7 @@ static noinline int vmalloc_fault(unsigned long address) * Below here mismatches are bugs because these lower tables * are shared: */ + BUILD_BUG_ON(CONFIG_PGTABLE_LEVELS < 4); pud = pud_offset(p4d, address); pud_ref = pud_offset(p4d_ref, address); |