linux-kernel - [patch 13/21] x86/process: Move arch_thread_struct

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Date:   Wed, 13 Oct 2021 16:55:45 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, "Chang S. Bae" <chang.seok.bae@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Subject: [patch 13/21] x86/process: Move arch_thread_struct_whitelist() out of line

In preparation for dynamic enabled FPU features move the function out of
line as the goal is to expose less and not more information.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/include/asm/processor.h |    9 +++------
 arch/x86/kernel/fpu/core.c       |   10 ++++++++++
 arch/x86/kernel/fpu/internal.h   |    2 ++
 3 files changed, 15 insertions(+), 6 deletions(-)

--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -461,9 +461,6 @@ DECLARE_PER_CPU(struct irq_stack *, hard
 DECLARE_PER_CPU(struct irq_stack *, softirq_stack_ptr);
 #endif	/* !X86_64 */
 
-extern unsigned int fpu_kernel_xstate_size;
-extern unsigned int fpu_user_xstate_size;
-
 struct perf_event;
 
 struct thread_struct {
@@ -537,12 +534,12 @@ struct thread_struct {
 	 */
 };
 
-/* Whitelist the FPU register state from the task_struct for hardened usercopy. */
+extern void fpu_thread_struct_whitelist(unsigned long *offset, unsigned long *size);
+
 static inline void arch_thread_struct_whitelist(unsigned long *offset,
 						unsigned long *size)
 {
-	*offset = offsetof(struct thread_struct, fpu.__fpstate.regs);
-	*size = fpu_kernel_xstate_size;
+	fpu_thread_struct_whitelist(offset, size);
 }
 
 static inline void
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -405,6 +405,16 @@ int fpu_clone(struct task_struct *dst)
 }
 
 /*
+ * Whitelist the FPU register state embedded into task_struct for hardened
+ * usercopy.
+ */
+void fpu_thread_struct_whitelist(unsigned long *offset, unsigned long *size)
+{
+	*offset = offsetof(struct thread_struct, fpu.__fpstate.regs);
+	*size = fpu_kernel_xstate_size;
+}
+
+/*
  * Drops current FPU state: deactivates the fpregs and
  * the fpstate. NOTE: it still leaves previous contents
  * in the fpregs in the eager-FPU case.
--- a/arch/x86/kernel/fpu/internal.h
+++ b/arch/x86/kernel/fpu/internal.h
@@ -2,6 +2,8 @@
 #ifndef __X86_KERNEL_FPU_INTERNAL_H
 #define __X86_KERNEL_FPU_INTERNAL_H
 
+extern unsigned int fpu_kernel_xstate_size;
+extern unsigned int fpu_user_xstate_size;
 extern struct fpstate init_fpstate;
 
 /* CPU feature check wrappers */