linux-kernel - [PATCH 1/6] x86/fpu: change copy_xstate_to_uabi_buf() to accept fpstate + pkru instead of task

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250814101411.GA17341@redhat.com>
Date: Thu, 14 Aug 2025 12:14:11 +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 1/6] x86/fpu: change copy_xstate_to_uabi_buf() to accept
 fpstate + pkru instead of task_struct

Preparation for the next change.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 arch/x86/kernel/fpu/regset.c | 10 ++++++----
 arch/x86/kernel/fpu/xstate.c | 12 ++++++------
 arch/x86/kernel/fpu/xstate.h |  4 ++--
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index 0986c2200adc..d280d415b171 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -83,7 +83,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
 				    sizeof(fpu->fpstate->regs.fxsave));
 	}
 
-	copy_xstate_to_uabi_buf(to, target, XSTATE_COPY_FX);
+	copy_xstate_to_uabi_buf(to, fpu->fpstate, target->thread.pkru, XSTATE_COPY_FX);
 	return 0;
 }
 
@@ -130,12 +130,14 @@ 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);
+
 	if (!cpu_feature_enabled(X86_FEATURE_XSAVE))
 		return -ENODEV;
 
-	sync_fpstate(x86_task_fpu(target));
+	sync_fpstate(fpu);
 
-	copy_xstate_to_uabi_buf(to, target, XSTATE_COPY_XSAVE);
+	copy_xstate_to_uabi_buf(to, fpu->fpstate, target->thread.pkru, XSTATE_COPY_XSAVE);
 	return 0;
 }
 
@@ -419,7 +421,7 @@ 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, target, XSTATE_COPY_FP);
+		copy_xstate_to_uabi_buf(mb, fpu->fpstate, target->thread.pkru, XSTATE_COPY_FP);
 		fx = &fxsave;
 	} else {
 		fx = &fpu->fpstate->regs.fxsave;
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 12ed75c1b567..2bd5974d5f0e 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1256,7 +1256,8 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
 /**
  * copy_xstate_to_uabi_buf - Copy kernel saved xstate to a UABI buffer
  * @to:		membuf descriptor
- * @tsk:	The task from which to copy the saved xstate
+ * @fpstate:	The fpstate buffer from which to copy
+ * @pkru_val:	The PKRU value to store in the PKRU component
  * @copy_mode:	The requested copy mode
  *
  * Converts from kernel XSAVE or XSAVES compacted format to UABI conforming
@@ -1265,12 +1266,11 @@ void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
  *
  * It supports partial copy but @to.pos always starts from zero.
  */
-void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
-			     enum xstate_copy_mode copy_mode)
+void copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
+			     u32 pkru_val, enum xstate_copy_mode copy_mode)
 {
-	__copy_xstate_to_uabi_buf(to, x86_task_fpu(tsk)->fpstate,
-				  x86_task_fpu(tsk)->fpstate->user_xfeatures,
-				  tsk->thread.pkru, copy_mode);
+	__copy_xstate_to_uabi_buf(to, fpstate, fpstate->user_xfeatures,
+				  pkru_val, copy_mode);
 }
 
 static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h
index 52ce19289989..9d76ded84cdd 100644
--- a/arch/x86/kernel/fpu/xstate.h
+++ b/arch/x86/kernel/fpu/xstate.h
@@ -46,8 +46,8 @@ struct membuf;
 extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
 				      u64 xfeatures, u32 pkru_val,
 				      enum xstate_copy_mode copy_mode);
-extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk,
-				    enum xstate_copy_mode mode);
+extern void copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate,
+				    u32 pkru_val, enum xstate_copy_mode copy_mode);
 extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru);
 extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void __user *ubuf);
 
-- 
2.25.1.362.g51ebf55