Commit d6d6d50f authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov
Browse files

x86/fpu/xstate: Consolidate size calculations 



Use the offset calculation to do the size calculation which avoids yet
another series of CPUID instructions for each invocation.

  [ Fix the FP/SSE only case which missed to take the xstate
    header into account, as
    Reported-by: kernel test robot <oliver.sang@intel.com> ]

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/87o81pgbp2.ffs@tglx
parent 781c64bf

arch/x86/kernel/fpu/xstate.c

+8 −41
Original line number Diff line number Diff line
@@ -385,25 +385,6 @@ static void __init setup_init_fpu_buf(void) 
	fxsave(&init_fpstate.regs.fxsave);

}



static int xfeature_uncompacted_offset(int xfeature_nr)

{

	u32 eax, ebx, ecx, edx;



	/*

	 * Only XSAVES supports supervisor states and it uses compacted

	 * format. Checking a supervisor state's uncompacted offset is

	 * an error.

	 */

	if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) {

		WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);

		return -1;

	}



	CHECK_XFEATURE(xfeature_nr);

	cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);

	return ebx;

}



int xfeature_size(int xfeature_nr)

{

	u32 eax, ebx, ecx, edx;
@@ -581,29 +562,15 @@ static bool __init check_xstate_against_struct(int nr) 


static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)

{

	unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;

	int i;

	unsigned int topmost = fls64(xfeatures) -  1;

	unsigned int offset = xstate_offsets[topmost];



	for_each_extended_xfeature(i, xfeatures) {

		/* Align from the end of the previous feature */

		if (xfeature_is_aligned64(i))

			size = ALIGN(size, 64);

		/*

		 * In compacted format the enabled features are packed,

		 * i.e. disabled features do not occupy space.

		 *

		 * In non-compacted format the offsets are fixed and

		 * disabled states still occupy space in the memory buffer.

		 */

		if (!compacted)

			size = xfeature_uncompacted_offset(i);

		/*

		 * Add the feature size even for non-compacted format

		 * to make the end result correct

		 */

		size += xfeature_size(i);

	}

	return size;

	if (topmost <= XFEATURE_SSE)

		return sizeof(struct xregs_state);



	if (compacted)

		offset = xfeature_get_offset(xfeatures, topmost);

	return offset + xstate_sizes[topmost];

}



/*