x86/fpu/xstate: Fix up bad get_xsave_addr() assumptions

 * This is the API that is called to get xstate address in either

 * standard format or compacted format of xsave area.

 *

 * Note that if there is no data for the field in the xsave buffer

 * this will return NULL.

 *

 * Inputs:

 *	xsave: base address of the xsave area;

 *	xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE,

 *	etc.)

 *	xstate: the thread's storage area for all FPU data

 *	xstate_feature: state which is defined in xsave.h (e.g.

 *	XSTATE_FP, XSTATE_SSE, etc...)

 * Output:

 *	address of the state in the xsave area.

 *	address of the state in the xsave area, or NULL if the

 *	field is not present in the xsave buffer.

 */

void *get_xsave_addr(struct xregs_state *xsave, int xstate)

void *get_xsave_addr(struct xregs_state *xsave, int xstate_feature)

{

	int feature = fls64(xstate) - 1;

	if (!test_bit(feature, (unsigned long *)&xfeatures_mask))

	int feature_nr = fls64(xstate_feature) - 1;

	/*

	 * Do we even *have* xsave state?

	 */

	if (!boot_cpu_has(X86_FEATURE_XSAVE))

		return NULL;

	xsave = &current->thread.fpu.state.xsave;

	/*

	 * We should not ever be requesting features that we

	 * have not enabled.  Remember that pcntxt_mask is

	 * what we write to the XCR0 register.

	 */

	WARN_ONCE(!(xfeatures_mask & xstate_feature),

		  "get of unsupported state");

	/*

	 * This assumes the last 'xsave*' instruction to

	 * have requested that 'xstate_feature' be saved.

	 * If it did not, we might be seeing and old value

	 * of the field in the buffer.

	 *

	 * This can happen because the last 'xsave' did not

	 * request that this feature be saved (unlikely)

	 * or because the "init optimization" caused it

	 * to not be saved.

	 */

	if (!(xsave->header.xfeatures & xstate_feature))

		return NULL;

	return (void *)xsave + xstate_comp_offsets[feature];

	return (void *)xsave + xstate_comp_offsets[feature_nr];

}

EXPORT_SYMBOL_GPL(get_xsave_addr);