Messages in this thread | | | From | "Bae, Chang Seok" <> | Subject | Re: [PATCH v9 10/26] x86/fpu/xstate: Update the XSTATE buffer address finder to support dynamic states | Date | Wed, 18 Aug 2021 19:47:04 +0000 |
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On Aug 18, 2021, at 04:33, Borislav Petkov <bp@alien8.de> wrote: > On Fri, Jul 30, 2021 at 07:59:41AM -0700, Chang S. Bae wrote: >> >> + * @feature_nr: The feature number >> + * >> + * Returns: The offset value >> + */ >> +static unsigned int get_xstate_comp_offset(u64 mask, int feature_nr) >> +{ >> + u64 xmask = BIT_ULL(feature_nr + 1) - 1; >> + unsigned int next_offset, offset = 0; >> + int i; >> + >> + if ((xfeatures_mask_all & xmask) == (mask & xmask)) >> + return xstate_comp_offsets[feature_nr]; >> + >> + /* >> + * With the given mask, no relevant size is found. Calculate it by >> + * summing up each state size. >> + */ >> + for (next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE, i = FIRST_EXTENDED_XFEATURE; >> + i <= feature_nr; i++) { >> + if (!(mask & BIT_ULL(i))) >> + continue; >> + >> + offset = xstate_aligns[i] ? ALIGN(next_offset, 64) : next_offset; >> + next_offset += xstate_sizes[i]; > > Why is this more complex than it has to be? > > IOW, why can't you simply do: > > offset = FXSAVE_SIZE + XSAVE_HDR_SIZE; > for (i = FIRST_EXTENDED_XFEATURE; i <= feature_nr; i++) { > if (!(mask & BIT_ULL(i))) > continue; > > if (xstate_aligns[i]) > offset = ALIGN(offset, 64); > > offset += xstate_sizes[i]; > } > return offset; > > like it was before?
It was refactored to use in the new helper to find feature_nr’s start point. If the size is added up here, it is not ‘i’'s start point anymore.
Thanks, Chang
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