Revamp of the syscall path, exception and context handling. The

prime objectives are:
o  Implement a syscall path based on the epc inststruction (see
   sys/ia64/ia64/syscall.s).
o  Revisit the places were we need to save and restore registers
   and define those contexts in terms of the register sets (see
   sys/ia64/include/_regset.h).

Secundairy objectives:
o  Remove the requirement to use contigmalloc for kernel stacks.
o  Better handling of the high FP registers for SMP systems.
o  Switch to the new cpu_switch() and cpu_throw() semantics.
o  Add a good unwinder to reconstruct contexts for the rare
   cases we need to (see sys/contrib/ia64/libuwx)

Many files are affected by this change. Functionally it boils
down to:
o  The EPC syscall doesn't preserve registers it does not need
   to preserve and places the arguments differently on the stack.
   This affects libc and truss.
o  The address of the kernel page directory (kptdir) had to
   be unstaticized for use by the nested TLB fault handler.
   The name has been changed to ia64_kptdir to avoid conflicts.
   The renaming affects libkvm.
o  The trapframe only contains the special registers and the
   scratch registers. For syscalls using the EPC syscall path
   no scratch registers are saved. This affects all places where
   the trapframe is accessed. Most notably the unaligned access
   handler, the signal delivery code and the debugger.
o  Context switching only partly saves the special registers
   and the preserved registers. This affects cpu_switch() and
   triggered the move to the new semantics, which additionally
   affects cpu_throw().
o  The high FP registers are either in the PCB or on some
   CPU. context switching for them is done lazily. This affects
   trap().
o  The mcontext has room for all registers, but not all of them
   have to be defined in all cases. This mostly affects signal
   delivery code now. The *context syscalls are as of yet still
   unimplemented.

Many details went into the removal of the requirement to use
contigmalloc for kernel stacks. The details are mostly CPU
specific and limited to exception_save() and exception_restore().
The few places where we create, destroy or switch stacks were
mostly simplified by not having to construct physical addresses
and additionally saving the virtual addresses for later use.

Besides more efficient context saving and restoring, which of
course yields a noticable speedup, this also fixes the dreaded
SMP bootup problem as a side-effect. The details of which are
still not fully understood.

This change includes all the necessary backward compatibility
code to have it handle older userland binaries that use the
break instruction for syscalls. Support for break-based syscalls
has been pessimized in favor of a clean implementation. Due to
the overall better performance of the kernel, this will still
be notived as an improvement if it's noticed at all.

Approved by: re@ (jhb)

1 files changed, 6 insertions, 75 deletions

diff --git a/sys/ia64/include/frame.h b/sys/ia64/include/frame.h
index a66345d..262a8bf 100644
--- a/sys/ia64/include/frame.h
+++ b/sys/ia64/include/frame.h
@@ -29,87 +29,18 @@
 #ifndef _MACHINE_FRAME_H_
 #define	_MACHINE_FRAME_H_
 
-#include <machine/reg.h>
+#include <machine/_regset.h>
 
 /*
  * Software trap, exception, and syscall frame.
  */
 struct trapframe {
-	u_int64_t		tf_flags;
+	uint64_t		tf_length;
+	uint64_t		tf_flags;
 #define FRAME_SYSCALL		1	/* syscalls use a partial trapframe */
-
-	u_int64_t		tf_cr_iip;
-	u_int64_t		tf_cr_ipsr;
-	u_int64_t		tf_cr_isr;
-	u_int64_t		tf_cr_ifa;
-	u_int64_t		tf_pr;
-	u_int64_t		tf_ar_rsc;
-	u_int64_t		tf_ar_pfs;
-	u_int64_t		tf_cr_ifs;
-	u_int64_t		tf_ar_bspstore;
-	u_int64_t		tf_ar_rnat;
-	u_int64_t		tf_ndirty;
-	u_int64_t		tf_ar_unat;
-	u_int64_t		tf_ar_ccv;
-	u_int64_t		tf_ar_fpsr;
-	u_int64_t		tf_ar_lc;
-	u_int64_t		tf_ar_ec;
-
-	u_int64_t		tf_b[8];
-
-	u_int64_t		tf_r[31];	/* don't need to save r0 */
-#define FRAME_R1		0
-#define FRAME_R2		1
-#define FRAME_R3		2
-#define FRAME_R4		3
-#define FRAME_R5		4
-#define FRAME_R6		5
-#define FRAME_R7		6
-#define FRAME_R8		7
-#define FRAME_R9		8
-#define FRAME_R10		9
-#define FRAME_R11		10
-#define FRAME_R12		11
-#define FRAME_R13		12
-#define FRAME_R14		13
-#define FRAME_R15		14
-#define FRAME_R16		15
-#define FRAME_R17		16
-#define FRAME_R18		17
-#define FRAME_R19		18
-#define FRAME_R20		19
-#define FRAME_R21		20
-#define FRAME_R22		21
-#define FRAME_R23		22
-#define FRAME_R24		23
-#define FRAME_R25		24
-#define FRAME_R26		25
-#define FRAME_R27		26
-#define FRAME_R28		27
-#define FRAME_R29		28
-#define FRAME_R30		29
-#define FRAME_R31		30
-
-#define FRAME_GP		FRAME_R1
-#define FRAME_SP		FRAME_R12
-#define FRAME_TP		FRAME_R13
-
-	/*
-	 * We rely on the compiler to save/restore f2-f5 and
-	 * f16-f31. We also tell the compiler to avoid f32-f127
-	 * completely so we don't worry about them at all.
-	 */
-	struct ia64_fpreg	tf_f[10];
-#define FRAME_F6		0
-#define FRAME_F7		1
-#define FRAME_F8		2
-#define FRAME_F9		3
-#define FRAME_F10		4
-#define FRAME_F11		5
-#define FRAME_F12		6
-#define FRAME_F13		7
-#define FRAME_F14		8
-#define FRAME_F15		9
+	struct _special		tf_special;
+	struct _caller_saved	tf_scratch;
+	struct _caller_saved_fp	tf_scratch_fp;
 };
 
 #endif /* _MACHINE_FRAME_H_ */