Fix stack on FreeBSD / add stack check across the board

FreeBSD was passing stk as the new thread's stack base, while
stk is the top of the stack in go. The added check should cause
a trap if this ever comes up in any new ports, or regresses
in current ones.

R=rsc
CC=golang-dev
http://codereview.appspot.com/167055

Committer: Russ Cox <rsc@golang.org>

8 files changed, 36 insertions, 10 deletions

diff --git a/src/pkg/runtime/386/asm.s b/src/pkg/runtime/386/asm.s
index bd88f0fdc..7ec62161d 100644
--- a/src/pkg/runtime/386/asm.s
+++ b/src/pkg/runtime/386/asm.s
@@ -323,6 +323,17 @@ TEXT	runcgo(SB),7,$16
 	MOVL	4(SP), SP
 	RET
 
+// check that SP is in range [g->stackbase, g->stackguard)
+TEXT stackcheck(SB), 7, $0
+	MOVL g, AX
+	CMPL g_stackbase(AX), SP
+	JHI 2(PC)
+	INT $3
+	CMPL SP, g_stackguard(AX)
+	JHI 2(PC)
+	INT $3
+	RET
+
 
 GLOBL m0(SB), $1024
 GLOBL g0(SB), $1024
diff --git a/src/pkg/runtime/amd64/asm.s b/src/pkg/runtime/amd64/asm.s
index aee4e9a3f..3bd63ad15 100644
--- a/src/pkg/runtime/amd64/asm.s
+++ b/src/pkg/runtime/amd64/asm.s
@@ -301,3 +301,13 @@ TEXT runcgo(SB),7,$32
 	MOVQ	8(SP), SP
 	RET
 
+// check that SP is in range [g->stackbase, g->stackguard)
+TEXT stackcheck(SB), 7, $0
+	CMPQ g_stackbase(g), SP
+	JHI 2(PC)
+	INT $3
+	CMPQ SP, g_stackguard(g)
+	JHI 2(PC)
+	INT $3
+	RET
+
diff --git a/src/pkg/runtime/darwin/386/sys.s b/src/pkg/runtime/darwin/386/sys.s
index 445f53002..38459447f 100644
--- a/src/pkg/runtime/darwin/386/sys.s
+++ b/src/pkg/runtime/darwin/386/sys.s
@@ -153,6 +153,7 @@ TEXT bsdthread_start(SB),7,$0
 	MOVL	AX, g
 	MOVL	DX, m
 	MOVL	BX, m_procid(DX)	// m->procid = thread port (for debuggers)
+	CALL	stackcheck(SB)		// smashes AX
 	CALL	CX	// fn()
 	CALL	exit1(SB)
 	RET
diff --git a/src/pkg/runtime/freebsd/386/sys.s b/src/pkg/runtime/freebsd/386/sys.s
index 1c0eaead5..651ccb234 100644
--- a/src/pkg/runtime/freebsd/386/sys.s
+++ b/src/pkg/runtime/freebsd/386/sys.s
@@ -9,13 +9,13 @@
 #include "386/asm.h"
 	
 TEXT sys_umtx_op(SB),7,$-4
-	MOVL $454, AX
-	INT $0x80
+	MOVL	$454, AX
+	INT	$0x80
 	RET
 
 TEXT thr_new(SB),7,$-4
-	MOVL $455, AX
-	INT $0x80
+	MOVL	$455, AX
+	INT	$0x80
 	RET
 
 TEXT thr_start(SB),7,$0
@@ -33,10 +33,11 @@ TEXT thr_start(SB),7,$0
 	POPL	AX
 	POPL	AX
 	POPAL
-	MOVL BX, g
-	MOVL AX, m
-	CALL mstart(SB)
-	MOVL 0, AX			// crash (not reached)
+	MOVL	BX, g
+	MOVL	AX, m
+	CALL	stackcheck(SB)		// smashes AX
+	CALL	mstart(SB)
+	MOVL	0, AX			// crash (not reached)
 
 // Exit the entire program (like C exit)
 TEXT exit(SB),7,$-4
diff --git a/src/pkg/runtime/freebsd/amd64/sys.s b/src/pkg/runtime/freebsd/amd64/sys.s
index 1b6246810..30184e297 100644
--- a/src/pkg/runtime/freebsd/amd64/sys.s
+++ b/src/pkg/runtime/freebsd/amd64/sys.s
@@ -28,6 +28,7 @@ TEXT thr_new(SB),7,$0
 TEXT thr_start(SB),7,$0
 	MOVQ DI, m
 	MOVQ m_g0(m), g
+	CALL stackcheck(SB)
 	CALL mstart(SB)
 	MOVQ 0, AX			// crash (not reached)
 
diff --git a/src/pkg/runtime/freebsd/thread.c b/src/pkg/runtime/freebsd/thread.c
index 5f4402236..bf891e980 100644
--- a/src/pkg/runtime/freebsd/thread.c
+++ b/src/pkg/runtime/freebsd/thread.c
@@ -139,8 +139,8 @@ newosproc(M *m, G *g, void *stk, void (*fn)(void))
 
 	param.start_func = thr_start;
 	param.arg = m;
-	param.stack_base = stk;
-	param.stack_size = g->stackbase - g->stackguard + 256;
+	param.stack_base = (int8*)g->stackbase;
+	param.stack_size = (byte*)stk - (byte*)g->stackbase;
 	param.child_tid = (intptr*)&m->procid;
 	param.parent_tid = nil;
 	param.tls_base = (int8*)&m->tls[0];
diff --git a/src/pkg/runtime/linux/386/sys.s b/src/pkg/runtime/linux/386/sys.s
index 097dfe915..72882cb9d 100644
--- a/src/pkg/runtime/linux/386/sys.s
+++ b/src/pkg/runtime/linux/386/sys.s
@@ -152,6 +152,7 @@ TEXT clone(SB),7,$0
 	MOVL	DX, g
 	MOVL	BX, m
 
+	CALL	stackcheck(SB)	// smashes AX
 	MOVL	0(DX), DX	// paranoia; check they are not nil
 	MOVL	0(BX), BX
 
diff --git a/src/pkg/runtime/linux/amd64/sys.s b/src/pkg/runtime/linux/amd64/sys.s
index 238a423b1..6565d86de 100644
--- a/src/pkg/runtime/linux/amd64/sys.s
+++ b/src/pkg/runtime/linux/amd64/sys.s
@@ -149,6 +149,7 @@ TEXT clone(SB),7,$0
 	MOVQ	SI, SP
 	MOVQ	R8, m
 	MOVQ	R9, g
+	CALL	stackcheck(SB)
 
 	// Initialize m->procid to Linux tid
 	MOVL	$186, AX	// gettid