Add BASIC i386 binary support for the amd64 kernel. This is largely

stolen from the ia64/ia32 code (indeed there was a repocopy), but I've
redone the MD parts and added and fixed a few essential syscalls.  It
is sufficient to run i386 binaries like /bin/ls, /usr/bin/id (dynamic)
and p4.  The ia64 code has not implemented signal delivery, so I had
to do that.

Before you say it, yes, this does need to go in a common place.  But
we're in a freeze at the moment and I didn't want to risk breaking ia64.
I will sort this out after the freeze so that the common code is in a
common place.

On the AMD64 side, this required adding segment selector context switch
support and some other support infrastructure.  The %fs/%gs etc code
is hairy because loading %gs will clobber the kernel's current MSR_GSBASE
setting.  The segment selectors are not used by the kernel, so they're only
changed at context switch time or when changing modes.  This still needs
to be optimized.

Approved by:	re (amd64/* blanket)

5 files changed, 35 insertions, 4 deletions

diff --git a/sys/amd64/include/cpufunc.h b/sys/amd64/include/cpufunc.h
index 1e1df33..21257dd 100644
--- a/sys/amd64/include/cpufunc.h
+++ b/sys/amd64/include/cpufunc.h
@@ -447,7 +447,6 @@ invlpg(u_long addr)
 	__asm __volatile("invlpg %0" : : "m" (*(char *)addr) : "memory");
 }
 
-/* XXX these are replaced with rdmsr/wrmsr */
 static __inline u_int
 rfs(void)
 {
@@ -465,6 +464,18 @@ rgs(void)
 }
 
 static __inline void
+load_ds(u_int sel)
+{
+	__asm __volatile("movl %0,%%ds" : : "rm" (sel));
+}
+
+static __inline void
+load_es(u_int sel)
+{
+	__asm __volatile("movl %0,%%es" : : "rm" (sel));
+}
+
+static __inline void
 load_fs(u_int sel)
 {
 	__asm __volatile("movl %0,%%fs" : : "rm" (sel));
diff --git a/sys/amd64/include/elf.h b/sys/amd64/include/elf.h
index 3883d49..b675859 100644
--- a/sys/amd64/include/elf.h
+++ b/sys/amd64/include/elf.h
@@ -33,9 +33,12 @@
  * ELF definitions for the AMD64 architecture.
  */
 
-#include <sys/elf64.h>	/* Definitions common to all 64 bit architectures. */
 
+#ifndef __ELF_WORD_SIZE
 #define	__ELF_WORD_SIZE	64	/* Used by <sys/elf_generic.h> */
+#endif
+#include <sys/elf32.h>	/* Definitions common to all 32 bit architectures. */
+#include <sys/elf64.h>	/* Definitions common to all 64 bit architectures. */
 #include <sys/elf_generic.h>
 
 #define	ELF_ARCH	EM_X86_64
@@ -48,6 +51,13 @@
  * The i386 supplement to the SVR4 ABI specification names this "auxv_t",
  * but POSIX lays claim to all symbols ending with "_t".
  */
+typedef struct {	/* Auxiliary vector entry on initial stack */
+	int	a_type;			/* Entry type. */
+	union {
+		int	a_val;		/* Integer value. */
+	} a_un;
+} Elf32_Auxinfo;
+
 
 typedef struct {	/* Auxiliary vector entry on initial stack */
 	long	a_type;			/* Entry type. */
@@ -118,7 +128,11 @@ __ElfType(Auxinfo);
 #define	R_X86_64_COUNT	16	/* Count of defined relocation types. */
 
 /* Define "machine" characteristics */
-#define	ELF_TARG_CLASS	ELFCLASS64
+#if __ELF_WORD_SIZE == 32
+#define ELF_TARG_CLASS  ELFCLASS32
+#else
+#define ELF_TARG_CLASS  ELFCLASS64
+#endif
 #define	ELF_TARG_DATA	ELFDATA2LSB
 #define	ELF_TARG_MACH	EM_X86_64
 #define	ELF_TARG_VER	1
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
index ad35173..63e9b2b 100644
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -69,5 +69,6 @@ void	pagezero(void *addr);
 int	is_physical_memory(vm_offset_t addr);
 void	setidt(int idx, alias_for_inthand_t *func, int typ, int dpl, int ist);
 void	swi_vm(void *);
+void	fpstate_drop(struct thread *td);
 
 #endif /* !_MACHINE_MD_VAR_H_ */
diff --git a/sys/amd64/include/pcb.h b/sys/amd64/include/pcb.h
index c17709b..5bfb41f 100644
--- a/sys/amd64/include/pcb.h
+++ b/sys/amd64/include/pcb.h
@@ -59,6 +59,11 @@ struct pcb {
 	register_t	pcb_rflags;
 	register_t	pcb_fsbase;
 	register_t	pcb_gsbase;
+	register_t	pcb_kgsbase;
+	u_int32_t	pcb_ds;
+	u_int32_t	pcb_es;
+	u_int32_t	pcb_fs;
+	u_int32_t	pcb_gs;
 
 	struct	savefpu	pcb_save;
 	u_long	pcb_flags;
diff --git a/sys/amd64/include/segments.h b/sys/amd64/include/segments.h
index 0f9a59b..919eeff 100644
--- a/sys/amd64/include/segments.h
+++ b/sys/amd64/include/segments.h
@@ -166,7 +166,7 @@ struct region_descriptor {
 /*
  * Size of IDT table
  */
-#define	NIDT	129		/* 32 reserved, 16 h/w, 0 s/w, linux's 0x80 */
+#define	NIDT	256		/* 32 reserved, 16 h/w, 0 s/w, linux's 0x80 */
 #define	NRSVIDT	32		/* reserved entries for cpu exceptions */
 
 /*