Re: [PATCH v8 11/27] x86/mm: Introduce _PAGE_DIRTY_SW
flat view
From: Peter Zijlstra <peterz@infradead.org>
Date: 2019-08-23 14:02:55
Also in:
linux-arch, linux-doc, linux-mm, lkml
On Tue, Aug 13, 2019 at 01:52:09PM -0700, Yu-cheng Yu wrote:
quoted hunk ↗ jump to hunk
+static inline pte_t pte_move_flags(pte_t pte, pteval_t from, pteval_t to) +{ + if (pte_flags(pte) & from) + pte = pte_set_flags(pte_clear_flags(pte, from), to); + return pte; +}
Aside of the whole conditional thing (I agree it would be better to have this unconditionally); the function doesn't really do as advertised. That is, if @from is clear, it doesn't endeavour to make sure @to is also clear. Now it might be sufficient, but in that case it really needs a comment and or different name. An implementation that actually moves the bit is something like: pteval_t a,b; a = native_pte_value(pte); b = (a >> from_bit) & 1; a &= ~((1ULL << from_bit) | (1ULL << to_bit)); a |= b << to_bit; return make_native_pte(a);