linux-kernel - [RFC PATCH 08/10] x86/fpu: Don't keep state

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Date:   Fri,  3 Dec 2021 00:36:34 +0000
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     x86@...nel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com,
        chang.seok.bae@...el.com, linux-kernel@...r.kernel.org,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Jiaxun Yang <j.yang-87@....ed.ac.uk>
Subject: [RFC PATCH 08/10] x86/fpu: Don't keep state_size in perm struct

As we are now calculating kernel fpstate size accroading
to features actually in use, there is no need to keep the
size of states permitted.

Signed-off-by: Jiaxun Yang <j.yang-87@....ed.ac.uk>
---
 arch/x86/include/asm/fpu/types.h | 8 --------
 arch/x86/kernel/fpu/core.c       | 1 -
 arch/x86/kernel/fpu/xstate.c     | 8 ++------
 3 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 3c06c82ab355..a2cadaa9c305 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -409,14 +409,6 @@ struct fpu_state_perm {
 	 */
 	u64				__state_perm;
 
-	/*
-	 * @__state_size:
-	 *
-	 * The size required for @__state_perm. Only valid to access
-	 * with sighand locked.
-	 */
-	unsigned int			__state_size;
-
 	/*
 	 * @__user_state_size:
 	 *
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 861cbfc51c17..b257e2dac39a 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -473,7 +473,6 @@ void fpstate_reset(struct fpu *fpu)
 
 	/* Initialize the permission related info in fpu */
 	fpu->perm.__state_perm		= fpu_kernel_cfg.default_features;
-	fpu->perm.__state_size		= fpu_kernel_cfg.default_size;
 	fpu->perm.__user_state_size	= fpu_user_cfg.default_size;
 }
 
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 8519a6286d0d..4621b51d1b20 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1590,9 +1590,8 @@ static int __xstate_request_perm(u64 permitted, u64 requested)
 	 * vendors into extending XFD for the pre AMX states, especially
 	 * AVX512.
 	 */
-	bool compacted = cpu_feature_enabled(X86_FEATURE_XSAVES);
 	struct fpu *fpu = &current->group_leader->thread.fpu;
-	unsigned int ksize, usize;
+	unsigned int usize;
 	u64 mask;
 	int ret;
 
@@ -1602,7 +1601,6 @@ static int __xstate_request_perm(u64 permitted, u64 requested)
 
 	/* Calculate the resulting kernel state size */
 	mask = permitted | requested;
-	ksize = xstate_calculate_size(mask, compacted);
 
 	/* Calculate the resulting user state size */
 	mask &= XFEATURE_MASK_USER_SUPPORTED;
@@ -1615,7 +1613,6 @@ static int __xstate_request_perm(u64 permitted, u64 requested)
 	/* Pairs with the READ_ONCE() in xstate_get_group_perm() */
 	WRITE_ONCE(fpu->perm.__state_perm, requested);
 	/* Protected by sighand lock */
-	fpu->perm.__state_size = ksize;
 	fpu->perm.__user_state_size = usize;
 	return ret;
 }
@@ -1663,7 +1660,7 @@ static int xstate_request_perm(unsigned long idx)
 int xfd_enable_feature(u64 xfd_err)
 {
 	u64 xfd_event = xfd_err & XFEATURE_MASK_USER_DYNAMIC;
-	unsigned int ksize, usize;
+	unsigned int usize;
 	struct fpu *fpu;
 
 	if (!xfd_event) {
@@ -1681,7 +1678,6 @@ int xfd_enable_feature(u64 xfd_err)
 	}
 
 	fpu = &current->group_leader->thread.fpu;
-	ksize = fpu->perm.__state_size;
 	usize = fpu->perm.__user_state_size;
 	/*
 	 * The feature is permitted. State size is sufficient.  Dropping
-- 
2.30.2