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SubjectRe: [PATCH Bugfix v2 2/4] x86/xsaves: Define and use user_xstate_size for xstate size in signal context
On 04/21/2015 09:51 PM, Fenghua Yu wrote:
> + /*
> + * Copy rest of xstates in compact format to user.
> + */
> + for (i = 2; i < xstate_features; i++) {
> + if (test_bit(i, (unsigned long *)&pcntxt_mask)) {
> + int user_offset, kernel_offset;
> + int size;
> +
> + user_offset = xstate_offsets[i];
> + kernel_offset = xstate_comp_offsets[i];
> + size = xstate_sizes[i];
> +
> + if (__copy_to_user(buf_fx + user_offset,
> + xsave + kernel_offset, size))
> + return -1;
> + }
> + }

Is this checking the right bitmap?

The 'xsaves' documentation says: "If RFBM[i] = 1, XSTATE_BV[i] is set to
the value of XINUSE[i]". Where "XINUSE denotes the state-component
bitmap corresponding to the init optimization".

So shouldn't this be checking xsave->xsave_hdr.xstate_bv instead of
pcntxt_mask? The will be equal unless the "init optimization" is in play.


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