vx32

commit d310b6b9fb6a6310f566a854538a05f269a27080
parent f042e1f5454c68291e03d96be8a4e2f19cbdf1b3
Author: Russ Cox <rsc@swtch.com>
Date:   Sat, 28 Jun 2008 21:37:44 -0400

libvx32/Linux: switch to vx32_getcontext

Diffstat:
src/libvx32/Makefrag
 | 
4
++++
src/libvx32/emu.c
 | 
4
++--
src/libvx32/linux-asm.S
 | 
51
+++++++++++++++++++++++++++++++++++++++++++++++++++
src/libvx32/linux.c
 | 
12
++++--------
src/libvx32/vx32impl.h
 | 
5
++++-

5 files changed, 65 insertions(+), 11 deletions(-)
diff --git a/src/libvx32/Makefrag b/src/libvx32/Makefrag
@@ -8,6 +8,10 @@ ifeq ($(OS),darwin)
 VX32_RUN := $(VX32_RUN) darwin-asm.o
 endif
 
+ifeq ($(OS),linux)
+VX32_RUN := $(VX32_RUN) linux-asm.o
+endif
+
 VX32_OBJS = \
 	$(addprefix libvx32/, \
 		chunk.o \
diff --git a/src/libvx32/emu.c b/src/libvx32/emu.c
@@ -1801,9 +1801,9 @@ int vxproc_run(struct vxproc *vxp)
 	emu->trapenv = &env;
 	if(vx32_getcontext(&env)){
 #else
-	sigjmp_buf env;
+	mcontext_t env;
 	emu->trapenv = &env;
-	if(sigsetjmp(env, 1)){
+	if(vx32_getcontext(&env)){
 #endif
 		if(vx32_debugxlate) vxprint("VX trap %x err %x va %08x "
 				"veip %08x veflags %08x\n",
diff --git a/src/libvx32/linux-asm.S b/src/libvx32/linux-asm.S
@@ -0,0 +1,51 @@
+// Context routines for Linux
+
+// vx32_getcontext(struct mcontext_t *ss);  
+// see /usr/include/sys/ucontext.h for layout.
+// notice that we don't set the floating-point state.
+// notice also that unlike the linux getcontext,
+// we *do* copy the segment registers
+
+.globl vx32_getcontext
+vx32_getcontext:
+	movl 4(%esp), %eax
+	
+	movl %ecx, 40(%eax)
+	movl $0, %ecx
+	movw %gs, %cx
+	movl %ecx, 0(%eax)
+	movw %fs, %cx
+	movl %ecx, 4(%eax)
+	movw %es, %cx
+	movl %ecx, 8(%eax)
+	movw %ds, %cx
+	movl %ecx, 12(%eax)
+	movl %edi, 16(%eax)
+	movl %esi, 20(%eax)
+	movl %ebp, 24(%eax)
+	/* 28(%eax) is esp */
+	movl %ebx, 32(%eax)
+	movl %edx, 36(%eax)
+	/* 40(%eax) is ecx, saved above */
+	movl $1, 44(%eax)	/* eax */
+	movl $0, 48(%eax)	/* trapno */
+	movl $0, 52(%eax)	/* err */
+	/* 56(%eax) is eip */
+	movw %cs, %cx
+	movl %ecx, 60(%eax)
+	pushfl
+	popl 64(%eax)
+	/* 68(%eax) is another esp */
+	movw %ss, %cx
+	movl %ecx, 72(%eax)
+	
+	movl 0(%esp), %ecx		/* %eip */
+	movl %ecx, 56(%eax)
+	leal 4(%esp), %ecx		/* %esp */
+	movl %ecx, 28(%eax)
+	movl %ecx, 68(%eax)
+	
+	movl 40(%eax), %ecx		/* restore %ecx */
+	movl $0, %eax
+	ret
+
diff --git a/src/libvx32/linux.c b/src/libvx32/linux.c
@@ -1,10 +1,12 @@
 // Code specific to x86 hosts running Linux.
 
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <string.h>
 #include <signal.h>
 #include <assert.h>
 #include <ucontext.h>
+#include <sys/ucontext.h>
 #include <asm/ldt.h>
 
 #include "vx32.h"
@@ -319,14 +321,8 @@ int vx32_sighandler(int signo, siginfo_t *si, void *v)
 			return 0;
 		emu->cpu.traperr = ctx->err;
 		emu->cpu.trapva = ctx->cr2;
-
-		/*
-		 * Linux helpfully reset the floating point state
-		 * before entering the signal hander, so change it back.
-		  */
-		if(ctx->fpstate)
-			fprestore(ctx->fpstate);
-		siglongjmp(*emu->trapenv, 1);
+		memmove(mc->gregs, emu->trapenv->gregs, 19*4);
+		return 1;
 	}
 
 	// The signal handler is confused; so are we.
diff --git a/src/libvx32/vx32impl.h b/src/libvx32/vx32impl.h
@@ -119,6 +119,9 @@ typedef struct vxentry {
 struct i386_thread_state;
 int vx32_getcontext(struct i386_thread_state*);
 #endif
+#ifdef __linux__
+int vx32_getcontext(mcontext_t*);
+#endif
 
 // Emulation state for vx32-to-x86 translation.
 // This is the header for a variable-length structure;
@@ -156,7 +159,7 @@ struct vxemu {
 	uint32_t	saved_trap;	// trap to trigger after single-step
 	int	nsinglestep;
 
-#if defined(__FreeBSD__)
+#if defined(__FreeBSD__) || defined(__linux__)
 	mcontext_t		*trapenv;
 #elif defined(__APPLE__)
 	struct i386_thread_state *trapenv;