free_ldt_pgtables() uses the MMU gather API for batching TLB flushes
over the call to free_pgd_range(). However, tlb_gather_mmu() expects
to operate on user addresses and so passing LDT_{BASE,END}_ADDR will
confuse the range setting logic in __tlb_adjust_range(), causing the
gather to identify a range starting at TASK_SIZE. Such a large range
will be converted into a 'fullmm' flush by the low-level invalidation
code, so change the caller to invoke tlb_gather_mmu_fullmm() directly.
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
arch/x86/kernel/ldt.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 7ad9834e0d95..aa15132228da 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -398,7 +398,13 @@ static void free_ldt_pgtables(struct mm_struct *mm)
if (!boot_cpu_has(X86_FEATURE_PTI))
return;
- tlb_gather_mmu(&tlb, mm);
+ /*
+ * Although free_pgd_range() is intended for freeing user
+ * page-tables, it also works out for kernel mappings on x86.
+ * We use tlb_gather_mmu_fullmm() to avoid confusing the
+ * range-tracking logic in __tlb_adjust_range().
+ */
+ tlb_gather_mmu_fullmm(&tlb, mm);
free_pgd_range(&tlb, start, end, start, end);
tlb_finish_mmu(&tlb);
#endif
--
2.30.0.365.g02bc693789-goog
