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x86/fpu/xstate: Consolidate size calculations

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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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/87o81pgbp2.ffs@tglx
This commit is contained in:
Thomas Gleixner 2022-03-28 20:43:21 +02:00 committed by Borislav Petkov
parent 781c64bfcb
commit d6d6d50f1e
1 changed files with 8 additions and 41 deletions
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49
arch/x86/kernel/fpu/xstate.c
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@ -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];
}
/*