Re: [RFC PATCH 13/16] arm64: mm: Reset pkey in __tlb_remove_table()

Kevin Brodsky
2024-12-10T09:28:53Z

On 09/12/2024 11:29, Peter Zijlstra wrote:
> On Fri, Dec 06, 2024 at 10:11:07AM +0000, Kevin Brodsky wrote:
>> [...]
>>
>> diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
>> index a947c6e784ed..d1611ffa6d91 100644
>> --- a/arch/arm64/include/asm/tlb.h
>> +++ b/arch/arm64/include/asm/tlb.h
>> @@ -10,10 +10,14 @@
>>
>> #include <linux/pagemap.h>
>> #include <linux/swap.h>
>> +#include <linux/kpkeys.h>
>>
>> static inline void __tlb_remove_table(void *_table)
>> {
>> - free_page_and_swap_cache((struct page *)_table);
>> + struct page *page = (struct page *)_table;
>> +
>> + kpkeys_unprotect_pgtable_memory((unsigned long)page_address(page), 1);
>> + free_page_and_swap_cache(page);
>> }
> Same as for the others, perhaps stick this in generic code instead of in
> the arch code?

This should be doable, with some refactoring. __tlb_remove_table() is
currently called from two functions in mm/mmu_gather.c, I suppose I
could create a wrapper there that calls
kpkeys_unprotect_pgtable_memory() and then __tlb_remove_table(). Like in
the p4d case I do however wonder how robust this is, as
__tlb_remove_table() could end up being called from other places.

- Kevin