[patch 13/21] x86/process: Move arch_thread_struct_whitelist() out of line

Thomas Gleixner
2021-10-13T14:56:01Z

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@linutronix.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 */