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, 11 insertions, 3 deletions

diff --git a/sys/i386/include/ucontext.h b/sys/i386/include/ucontext.h
index d8ffc4b..79aabd7 100644
--- a/sys/i386/include/ucontext.h
+++ b/sys/i386/include/ucontext.h
@@ -31,6 +31,12 @@
 #ifndef _MACHINE_UCONTEXT_H_
 #define	_MACHINE_UCONTEXT_H_
 
+/* Keep _MC_* values similar to amd64 */
+#define	_MC_HASSEGS	0x1
+#define	_MC_HASBASES	0x2
+#define	_MC_HASFPXSTATE	0x4
+#define	_MC_FLAG_MASK	(_MC_HASSEGS | _MC_HASBASES | _MC_HASFPXSTATE)
+
 typedef struct __mcontext {
 	/*
 	 * The definition of mcontext_t must match the layout of
@@ -68,7 +74,7 @@ typedef struct __mcontext {
 #define	_MC_FPOWNED_FPU		0x20001	/* FP state came from FPU */
 #define	_MC_FPOWNED_PCB		0x20002	/* FP state came from PCB */
 	int	mc_ownedfp;
-	int	mc_spare1[1];		/* align next field to 16 bytes */
+	__register_t mc_flags;
 	/*
 	 * See <machine/npx.h> for the internals of mc_fpstate[].
 	 */
@@ -77,11 +83,13 @@ typedef struct __mcontext {
 	__register_t mc_fsbase;
 	__register_t mc_gsbase;
 
-	int	mc_spare2[6];
+	__register_t mc_xfpustate;
+	__register_t mc_xfpustate_len;
+
+	int	mc_spare2[4];
 } mcontext_t;
 
 #if defined(_KERNEL) && defined(COMPAT_FREEBSD4)
-
 struct mcontext4 {
 	__register_t	mc_onstack;	/* XXX - sigcontext compat. */
 	__register_t	mc_gs;		/* machine state (struct trapframe) */