Commit-ID: 36b3a7726886f24c4209852a58e64435bde3af98
Gitweb: https://git.kernel.org/tip/36b3a7726886f24c4209852a58e64435bde3af98
Author: Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Thu, 25 Jan 2018 13:12:15 -0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 26 Jan 2018 15:56:23 +0100
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@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Neil Berrington <neil.berrington@xxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/2ae598f8c279b0a29baf75df207e6f2fdddc0a1b.1516914529.git.luto@xxxxxxxxxx
---
arch/x86/mm/fault.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index b3e4077..800de81 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);
--
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