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x86/fpu/xstate: Provide xstate_calculate_size()

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Split out the size calculation from the paranoia check so it can be used
for recalculating buffer sizes when dynamically enabled features are
supported.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
[ tglx: Adopted to changed base code ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-4-chang.seok.bae@intel.com
This commit is contained in:
Chang S. Bae
2021-10-21 15:55:07 -07:00
committed by Borislav Petkov
parent 3aac3ebea0
commit 84e4dccc8f
1 changed files with 28 additions and 18 deletions
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46
arch/x86/kernel/fpu/xstate.c
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@@ -549,6 +549,33 @@ static bool __init check_xstate_against_struct(int nr)
return true;
}
static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
{
unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
int i;
for_each_extended_xfeature(i, xfeatures) {
/* Align from the end of the previous feature */
if (xfeature_is_aligned(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;
}
/*
* This essentially double-checks what the cpu told us about
* how large the XSAVE buffer needs to be. We are recalculating
@@ -575,25 +602,8 @@ static bool __init paranoid_xstate_size_valid(unsigned int kernel_size)
XSTATE_WARN_ON(1);
return false;
}
/* Align from the end of the previous feature */
if (xfeature_is_aligned(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);
}
size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);
XSTATE_WARN_ON(size != kernel_size);
return size == kernel_size;
}