Commit 8cf55f24 authored by Will Deacon's avatar Will Deacon Committed by Peter Zijlstra
Browse files

x86/ldt: Use tlb_gather_mmu_fullmm() when freeing LDT page-tables 



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.

Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarYu Zhao <yuzhao@google.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20210127235347.1402-7-will@kernel.org
parent c7bd8010

arch/x86/kernel/ldt.c

+7 −1
Original line number Diff line number Diff line
@@ -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