Messages in this thread Patch in this message | | | From | David Laight <> | Subject | RE: [PATCH 09/11] x86: remove address space overrides using set_fs() | Date | Mon, 17 Aug 2020 08:23:11 +0000 |
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From: Christoph Hellwig > Sent: 17 August 2020 08:32 > > Stop providing the possibility to override the address space using > set_fs() now that there is no need for that any more. To properly > handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on > x86 a new alternative is introduced, which just like the one in > entry_64.S has to use the hardcoded virtual address bits to escape > the fact that TASK_SIZE_MAX isn't actually a constant when 5-level > page tables are enabled. .... > @@ -93,7 +69,7 @@ static inline bool pagefault_disabled(void); > #define access_ok(addr, size) \ > ({ \ > WARN_ON_IN_IRQ(); \ > - likely(!__range_not_ok(addr, size, user_addr_max())); \ > + likely(!__range_not_ok(addr, size, TASK_SIZE_MAX)); \ > })
Can't that always compare against a constant even when 5-levl page tables are enabled on x86-64?
On x86-64 it can (probably) reduce to (addr | (addr + size)) < 0.
David
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