[tip: x86/fpu] x86/fpu/xstate: Provide xstate_calculate_size()

From: tip-bot2 for Chang S. Bae
Date: Tue Oct 26 2021 - 12:17:38 EST


The following commit has been merged into the x86/fpu branch of tip:

Commit-ID: 84e4dccc8fce20b497388d756e12de5c9006eb48
Gitweb: https://git.kernel.org/tip/84e4dccc8fce20b497388d756e12de5c9006eb48
Author: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
AuthorDate: Thu, 21 Oct 2021 15:55:07 -07:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Tue, 26 Oct 2021 10:18:09 +02:00

x86/fpu/xstate: Provide xstate_calculate_size()

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@xxxxxxxxx>
[ tglx: Adopted to changed base code ]
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20211021225527.10184-4-chang.seok.bae@xxxxxxxxx
---
arch/x86/kernel/fpu/xstate.c | 46 +++++++++++++++++++++--------------
1 file changed, 28 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index cbba381..310c420 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -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;
}