From ab9f27b2279f3bd28afb65050a9c4339d0b9961d Mon Sep 17 00:00:00 2001
From: Rob Pike <r@golang.org>
Date: Fri, 12 Sep 2008 12:35:06 -0700
Subject: [PATCH] fix up linux trap handling - INTB 5 gives SEGV

R=rsc
OCL=15244
CL=15244
---
 src/runtime/rt1_amd64_darwin.c | 34 +++++++++++++++++++++++++++++++---
 src/runtime/rt1_amd64_linux.c  | 33 +++++++++++++++++++++++++++++----
 src/runtime/rt2_amd64.c        | 29 -----------------------------
 src/runtime/runtime.h          |  2 --
 4 files changed, 60 insertions(+), 38 deletions(-)

diff --git a/src/runtime/rt1_amd64_darwin.c b/src/runtime/rt1_amd64_darwin.c
index 2cbc7f61346..f6f49ccbcdb 100644
--- a/src/runtime/rt1_amd64_darwin.c
+++ b/src/runtime/rt1_amd64_darwin.c
@@ -6,9 +6,6 @@
 #include "amd64_darwin.h"
 #include "signals.h"
 
-extern void _rt0_amd64_darwin();
-byte* startsym = (byte*)_rt0_amd64_darwin;
-
 typedef uint64 __uint64_t;
 
 /* From /usr/include/mach/i386/_structs.h */
@@ -133,6 +130,37 @@ typedef struct  sigaction {
 	int32 sa_flags;			/* see signal options below */
 } sigaction;
 
+/*
+ * For trace traps, disassemble instruction to see if it's INTB of known type.
+ */
+int32
+inlinetrap(int32 sig, byte* pc)
+{
+	extern void etext();
+	extern void _rt0_amd64_darwin();
+
+	if(sig != 5)	/* INTB 5 looks like TRAP */
+		return 0;
+	pc -= 2;	// mac steps across INTB
+	if(pc < (byte*)_rt0_amd64_darwin || pc+2 >= (byte*)etext)
+		return 0;
+	if(pc[0] != 0xcd)  /* INTB */
+		return 0;
+	switch(pc[1]) {
+	case 5:
+		prints("\nTRAP: array out of bounds\n");
+		break;
+	case 6:
+		prints("\nTRAP: leaving function with returning a value\n");
+		break;
+	default:
+		prints("\nTRAP: unknown run-time trap ");
+		sys·printint(pc[1]);
+		prints("\n");
+	}
+	return 1;
+}
+
 void
 sighandler(int32 sig, siginfo *info, void *context)
 {
diff --git a/src/runtime/rt1_amd64_linux.c b/src/runtime/rt1_amd64_linux.c
index 14cdf63e0b6..8c131d29202 100644
--- a/src/runtime/rt1_amd64_linux.c
+++ b/src/runtime/rt1_amd64_linux.c
@@ -6,9 +6,6 @@
 #include "amd64_linux.h"
 #include "signals.h"
 
-extern void _rt0_amd64_linux();
-byte* startsym = (byte*)_rt0_amd64_linux;
-
 /* From /usr/include/asm-x86_64/sigcontext.h */
 struct _fpstate {
   uint16   cwd;
@@ -137,6 +134,35 @@ typedef struct sigaction {
 	void (*sa_restorer) (void);	/* unused here; needed to return from trap? */
 } sigaction;
 
+/*
+ * For trace traps, disassemble instruction to see if it's INTB of known type.
+ */
+int32
+inlinetrap(int32 sig, byte* pc)
+{
+	extern void etext();
+	extern void _rt0_amd64_linux();
+
+	if(sig != 5 && sig != 11)	/* 5 is for trap, but INTB 5 looks like SEGV */
+		return 0;
+	if(pc < (byte*)_rt0_amd64_linux || pc+2 >= (byte*)etext)
+		return 0;
+	if(pc[0] != 0xcd)  /* INTB */
+		return 0;
+	switch(pc[1]) {
+	case 5:
+		prints("\nTRAP: array out of bounds\n");
+		break;
+	case 6:
+		prints("\nTRAP: leaving function with returning a value\n");
+		break;
+	default:
+		prints("\nTRAP: unknown run-time trap ");
+		sys·printint(pc[1]);
+		prints("\n");
+	}
+	return 1;
+}
 
 void
 sighandler(int32 sig, siginfo* info, void** context)
@@ -167,7 +193,6 @@ sighandler(int32 sig, siginfo* info, void** context)
 	sys·exit(2);
 }
 
-
 static sigaction a;
 
 void
diff --git a/src/runtime/rt2_amd64.c b/src/runtime/rt2_amd64.c
index b7c3b11109e..91bef543406 100644
--- a/src/runtime/rt2_amd64.c
+++ b/src/runtime/rt2_amd64.c
@@ -86,32 +86,3 @@ traceback(uint8 *pc, uint8 *sp, void* r15)
 		prints(", ...)\n");
 	}
 }
-
-/*
- * For trace traps, disassemble instruction to see if it's INTB of known type.
- */
-int32
-inlinetrap(int32 sig, byte* pc)
-{
-	extern void etext();
-
-	if(sig != 5)	/* SIGTRAP */
-		return 0;
-	if(pc-2 < startsym || pc >= (byte*)etext)
-		return 0;
-	if(pc[-2] != 0xcd)  /* INTB */
-		return 0;
-	switch(pc[-1]) {
-	case 5:
-		prints("\nTRAP: array out of bounds\n");
-		break;
-	case 6:
-		prints("\nTRAP: leaving function with returning a value\n");
-		break;
-	default:
-		prints("\nTRAP: unknown run-time trap ");
-		sys·printint(pc[-1]);
-		prints("\n");
-	}
-	return 1;
-}
diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h
index e786b78ecff..022789234d2 100644
--- a/src/runtime/runtime.h
+++ b/src/runtime/runtime.h
@@ -208,7 +208,6 @@ G*	allg;
 int32	goidgen;
 extern	int32	gomaxprocs;
 extern	int32	panicking;
-extern	byte	*startsym;
 
 /*
  * common functions and data
@@ -238,7 +237,6 @@ uint32	cmpstring(string, string);
 void	initsig(void);
 void	traceback(uint8 *pc, uint8 *sp, G* gp);
 void	tracebackothers(G*);
-int32	inlinetrap(int32 sig, byte* pc);
 int32	open(byte*, int32, ...);
 int32	read(int32, void*, int32);
 int32	write(int32, void*, int32);