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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: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20210127235347.1402-7-will@kernel.org
This commit is contained in:
Will Deacon 2021-01-27 23:53:47 +00:00 committed by Peter Zijlstra
parent c7bd8010a3
commit 8cf55f24ce
1 changed files with 7 additions and 1 deletions
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8
arch/x86/kernel/ldt.c
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@ -398,7 +398,13 @@ static void free_ldt_pgtables(struct mm_struct *mm)
if (!boot_cpu_has(X86_FEATURE_PTI)) if (!boot_cpu_has(X86_FEATURE_PTI))
return; 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); free_pgd_range(&tlb, start, end, start, end);
tlb_finish_mmu(&tlb); tlb_finish_mmu(&tlb);
#endif #endif