Add support for the extended FPU states on amd64, both for native

64bit and 32bit ABIs.  As a side-effect, it enables AVX on capable
CPUs.

In particular:

- Query the CPU support for XSAVE, list of the supported extensions
  and the required size of FPU save area. The hw.use_xsave tunable is
  provided for disabling XSAVE, and hw.xsave_mask may be used to
  select the enabled extensions.

- Remove the FPU save area from PCB and dynamically allocate the
  (run-time sized) user save area on the top of the kernel stack,
  right above the PCB. Reorganize the thread0 PCB initialization to
  postpone it after BSP is queried for save area size.

- The dumppcb, stoppcbs and susppcbs now do not carry the FPU state as
  well. FPU state is only useful for suspend, where it is saved in
  dynamically allocated suspfpusave area.

- Use XSAVE and XRSTOR to save/restore FPU state, if supported and
  enabled.

- Define new mcontext_t flag _MC_HASFPXSTATE, indicating that
  mcontext_t has a valid pointer to out-of-struct extended FPU
  state. Signal handlers are supplied with stack-allocated fpu
  state. The sigreturn(2) and setcontext(2) syscall honour the flag,
  allowing the signal handlers to inspect and manipilate extended
  state in the interrupted context.

- The getcontext(2) never returns extended state, since there is no
  place in the fixed-sized mcontext_t to place variable-sized save
  area. And, since mcontext_t is embedded into ucontext_t, makes it
  impossible to fix in a reasonable way.  Instead of extending
  getcontext(2) syscall, provide a sysarch(2) facility to query
  extended FPU state.

- Add ptrace(2) support for getting and setting extended state; while
  there, implement missed PT_I386_{GET,SET}XMMREGS for 32bit binaries.

- Change fpu_kern KPI to not expose struct fpu_kern_ctx layout to
  consumers, making it opaque. Internally, struct fpu_kern_ctx now
  contains a space for the extended state. Convert in-kernel consumers
  of fpu_kern KPI both on i386 and amd64.

First version of the support for AVX was submitted by Tim Bird
<tim.bird am sony com> on behalf of Sony. This version was written
from scratch.

Tested by:	pho (previous version), Yamagi Burmeister <lists yamagi org>
MFC after:	1 month

1 files changed, 14 insertions, 8 deletions

diff --git a/sys/amd64/include/fpu.h b/sys/amd64/include/fpu.h
index 1e7103e..d208789 100644
--- a/sys/amd64/include/fpu.h
+++ b/sys/amd64/include/fpu.h
@@ -101,14 +101,13 @@ struct savefpu_ymm {
 } __aligned(64);
 
 #ifdef _KERNEL
-struct fpu_kern_ctx {
-	struct savefpu hwstate;
-	struct savefpu *prev;
-	uint32_t flags;
-};
-#define	FPU_KERN_CTX_FPUINITDONE 0x01
+
+struct fpu_kern_ctx;
 
 #define	PCB_USER_FPU(pcb) (((pcb)->pcb_flags & PCB_KERNFPU) == 0)
+
+#define	XSAVE_AREA_ALIGN	64
+
 #endif
 
 /*
@@ -141,9 +140,15 @@ void	fpuexit(struct thread *td);
 int	fpuformat(void);
 int	fpugetregs(struct thread *td);
 void	fpuinit(void);
-void	fpusetregs(struct thread *td, struct savefpu *addr);
+void	fpusave(void *addr);
+int	fpusetregs(struct thread *td, struct savefpu *addr,
+	    char *xfpustate, size_t xfpustate_size);
+int	fpusetxstate(struct thread *td, char *xfpustate,
+	    size_t xfpustate_size);
 int	fputrap(void);
 void	fpuuserinited(struct thread *td);
+struct fpu_kern_ctx *fpu_kern_alloc_ctx(u_int flags);
+void	fpu_kern_free_ctx(struct fpu_kern_ctx *ctx);
 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);
@@ -151,9 +156,10 @@ int	fpu_kern_thread(u_int flags);
 int	is_fpu_kern_thread(u_int flags);
 
 /*
- * Flags for fpu_kern_enter() and fpu_kern_thread().
+ * Flags for fpu_kern_alloc_ctx(), fpu_kern_enter() and fpu_kern_thread().
  */
 #define	FPU_KERN_NORMAL	0x0000
+#define	FPU_KERN_NOWAIT	0x0001
 
 #endif