linux-kernel - [PATCH 2/6] x86/fpu: regset: introduce get

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Message-ID: <20250814101418.GA17349@redhat.com>
Date: Thu, 14 Aug 2025 12:14:18 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	Jens Axboe <axboe@...nel.dk>, Peter Zijlstra <peterz@...radead.org>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Sohil Mehta <sohil.mehta@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [PATCH 2/6] x86/fpu: regset: introduce get_fpstate() helper

After the previous change the regset get() functions do not really need
"struct fpu *", they can use "struct fpstate *" returned by the new helper
which also does sync_fpstate().

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 arch/x86/kernel/fpu/regset.c | 42 ++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index d280d415b171..f5a803774e1c 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -49,6 +49,13 @@ static void sync_fpstate(struct fpu *fpu)
 		fpu_sync_fpstate(fpu);
 }
 
+static struct fpstate *get_fpstate(struct task_struct *task)
+{
+	struct fpu *fpu = x86_task_fpu(task);
+	sync_fpstate(fpu);
+	return fpu->fpstate;
+}
+
 /*
  * Invalidate cached FPU registers before modifying the stopped target
  * task's fpstate.
@@ -71,19 +78,19 @@ static void fpu_force_restore(struct fpu *fpu)
 int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
 		struct membuf to)
 {
-	struct fpu *fpu = x86_task_fpu(target);
+	struct fpstate *fpstate;
 
 	if (!cpu_feature_enabled(X86_FEATURE_FXSR))
 		return -ENODEV;
 
-	sync_fpstate(fpu);
+	fpstate = get_fpstate(target);
 
 	if (!use_xsave()) {
-		return membuf_write(&to, &fpu->fpstate->regs.fxsave,
-				    sizeof(fpu->fpstate->regs.fxsave));
+		return membuf_write(&to, &fpstate->regs.fxsave,
+				    sizeof(fpstate->regs.fxsave));
 	}
 
-	copy_xstate_to_uabi_buf(to, fpu->fpstate, target->thread.pkru, XSTATE_COPY_FX);
+	copy_xstate_to_uabi_buf(to, fpstate, target->thread.pkru, XSTATE_COPY_FX);
 	return 0;
 }
 
@@ -130,14 +137,13 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
 int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
 		struct membuf to)
 {
-	struct fpu *fpu = x86_task_fpu(target);
+	struct fpstate *fpstate;
 
 	if (!cpu_feature_enabled(X86_FEATURE_XSAVE))
 		return -ENODEV;
 
-	sync_fpstate(fpu);
-
-	copy_xstate_to_uabi_buf(to, fpu->fpstate, target->thread.pkru, XSTATE_COPY_XSAVE);
+	fpstate = get_fpstate(target);
+	copy_xstate_to_uabi_buf(to, fpstate, target->thread.pkru, XSTATE_COPY_XSAVE);
 	return 0;
 }
 
@@ -189,15 +195,15 @@ int ssp_active(struct task_struct *target, const struct user_regset *regset)
 int ssp_get(struct task_struct *target, const struct user_regset *regset,
 	    struct membuf to)
 {
-	struct fpu *fpu = x86_task_fpu(target);
+	struct fpstate *fpstate;
 	struct cet_user_state *cetregs;
 
 	if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK) ||
 	    !ssp_active(target, regset))
 		return -ENODEV;
 
-	sync_fpstate(fpu);
-	cetregs = get_xsave_addr(&fpu->fpstate->regs.xsave, XFEATURE_CET_USER);
+	fpstate = get_fpstate(target);
+	cetregs = get_xsave_addr(&fpstate->regs.xsave, XFEATURE_CET_USER);
 	if (WARN_ON(!cetregs)) {
 		/*
 		 * This shouldn't ever be NULL because shadow stack was
@@ -403,17 +409,17 @@ void convert_to_fxsr(struct fxregs_state *fxsave,
 int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 	       struct membuf to)
 {
-	struct fpu *fpu = x86_task_fpu(target);
+	struct fpstate *fpstate;
 	struct user_i387_ia32_struct env;
 	struct fxregs_state fxsave, *fx;
 
-	sync_fpstate(fpu);
-
 	if (!cpu_feature_enabled(X86_FEATURE_FPU))
 		return fpregs_soft_get(target, regset, to);
 
+	fpstate = get_fpstate(target);
+
 	if (!cpu_feature_enabled(X86_FEATURE_FXSR)) {
-		return membuf_write(&to, &fpu->fpstate->regs.fsave,
+		return membuf_write(&to, &fpstate->regs.fsave,
 				    sizeof(struct fregs_state));
 	}
 
@@ -421,10 +427,10 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 		struct membuf mb = { .p = &fxsave, .left = sizeof(fxsave) };
 
 		/* Handle init state optimized xstate correctly */
-		copy_xstate_to_uabi_buf(mb, fpu->fpstate, target->thread.pkru, XSTATE_COPY_FP);
+		copy_xstate_to_uabi_buf(mb, fpstate, target->thread.pkru, XSTATE_COPY_FP);
 		fx = &fxsave;
 	} else {
-		fx = &fpu->fpstate->regs.fxsave;
+		fx = &fpstate->regs.fxsave;
 	}
 
 	__convert_from_fxsr(&env, target, fx);
-- 
2.25.1.362.g51ebf55