Introduce the x86 kernel interfaces to allow kernel code to use

FPU/SSE hardware. Caller should provide a save area that is chained
into the stack of the areas; pcb save_area for usermode FPU state is
on top. The pcb now contains a pointer to the current FPU saved area,
used during FPUDNA handling and context switches.  There is also a
facility to allow the kernel thread to use pcb save_area.

Change the dreaded warnings "npxdna in kernel mode!" into the panics
when FPU usage is not registered.

KPI discussed with:	fabient
Tested by:    pho, fabient
Hardware provided by:	Sentex Communications
MFC after:    1 month

1 files changed, 24 insertions, 0 deletions

diff --git a/sys/amd64/include/fpu.h b/sys/amd64/include/fpu.h
index 272f94a..ca0ac8f 100644
--- a/sys/amd64/include/fpu.h
+++ b/sys/amd64/include/fpu.h
@@ -73,6 +73,17 @@ struct  savefpu {
 	u_char sv_pad[96];
 } __aligned(16);
 
+#ifdef _KERNEL
+struct fpu_kern_ctx {
+	struct savefpu hwstate;
+	struct savefpu *prev;
+	uint32_t flags;
+};
+#define	FPU_KERN_CTX_FPUINITDONE 0x01
+
+#define	PCB_USER_FPU(pcb) (((pcb)->pcb_flags & PCB_KERNFPU) == 0)
+#endif
+
 /*
  * The hardware default control word for i387's and later coprocessors is
  * 0x37F, giving:
@@ -102,9 +113,22 @@ void	fpudrop(void);
 void	fpuexit(struct thread *td);
 int	fpuformat(void);
 int	fpugetregs(struct thread *td, struct savefpu *addr);
+int	fpugetuserregs(struct thread *td, struct savefpu *addr);
 void	fpuinit(void);
 void	fpusetregs(struct thread *td, struct savefpu *addr);
+void	fpusetuserregs(struct thread *td, struct savefpu *addr);
 int	fputrap(void);
+int	fpu_kern_enter(struct thread *td, struct fpu_kern_ctx *ctx,
+	    u_int flags);
+int	fpu_kern_leave(struct thread *td, struct fpu_kern_ctx *ctx);
+int	fpu_kern_thread(u_int flags);
+int	is_fpu_kern_thread(u_int flags);
+
+/*
+ * Flags for fpu_kern_enter() and fpu_kern_thread().
+ */
+#define	FPU_KERN_NORMAL	0x0000
+
 #endif
 
 #endif /* !_MACHINE_FPU_H_ */