all: enable c-shared/c-archive support for freebsd/amd64

Fixes #14327
Much of the code is based on the linux/amd64 code that implements these
build modes, and code is shared where possible.

Change-Id: Ia510f2023768c0edbc863aebc585929ec593b332
Reviewed-on: https://go-review.googlesource.com/93875
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 93 insertions, 3 deletions

diff --git a/src/runtime/sys_freebsd_amd64.s b/src/runtime/sys_freebsd_amd64.s
index c2c71784dd..4d3e88b482 100644
--- a/src/runtime/sys_freebsd_amd64.s
+++ b/src/runtime/sys_freebsd_amd64.s
@@ -26,6 +26,7 @@ TEXT runtime·thr_new(SB),NOSPLIT,$0
 	MOVL size+8(FP), SI
 	MOVL $455, AX
 	SYSCALL
+	MOVL	AX, ret+16(FP)
 	RET
 
 TEXT runtime·thr_start(SB),NOSPLIT,$0
@@ -169,14 +170,27 @@ TEXT runtime·nanotime(SB), NOSPLIT, $32
 	MOVQ	AX, ret+0(FP)
 	RET
 
-TEXT runtime·sigaction(SB),NOSPLIT,$-8
-	MOVL	sig+0(FP), DI		// arg 1 sig
+TEXT runtime·asmSigaction(SB),NOSPLIT,$0
+	MOVQ	sig+0(FP), DI		// arg 1 sig
 	MOVQ	new+8(FP), SI		// arg 2 act
 	MOVQ	old+16(FP), DX		// arg 3 oact
 	MOVL	$416, AX
 	SYSCALL
 	JCC	2(PC)
-	MOVL	$0xf1, 0xf1  // crash
+	MOVL	$-1, AX
+	MOVL	AX, ret+24(FP)
+	RET
+
+TEXT runtime·callCgoSigaction(SB),NOSPLIT,$16
+	MOVQ	sig+0(FP), DI		// arg 1 sig
+	MOVQ	new+8(FP), SI		// arg 2 act
+	MOVQ	old+16(FP), DX		// arg 3 oact
+	MOVQ	_cgo_sigaction(SB), AX
+	MOVQ	SP, BX			// callee-saved
+	ANDQ	$~15, SP		// alignment as per amd64 psABI
+	CALL	AX
+	MOVQ	BX, SP
+	MOVL	AX, ret+24(FP)
 	RET
 
 TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
@@ -216,6 +230,82 @@ TEXT runtime·sigtramp(SB),NOSPLIT,$72
 	MOVQ	bx-8(SP),   BX
 	RET
 
+// Used instead of sigtramp in programs that use cgo.
+// Arguments from kernel are in DI, SI, DX.
+TEXT runtime·cgoSigtramp(SB),NOSPLIT,$0
+	// If no traceback function, do usual sigtramp.
+	MOVQ	runtime·cgoTraceback(SB), AX
+	TESTQ	AX, AX
+	JZ	sigtramp
+
+	// If no traceback support function, which means that
+	// runtime/cgo was not linked in, do usual sigtramp.
+	MOVQ	_cgo_callers(SB), AX
+	TESTQ	AX, AX
+	JZ	sigtramp
+
+	// Figure out if we are currently in a cgo call.
+	// If not, just do usual sigtramp.
+	get_tls(CX)
+	MOVQ	g(CX),AX
+	TESTQ	AX, AX
+	JZ	sigtrampnog     // g == nil
+	MOVQ	g_m(AX), AX
+	TESTQ	AX, AX
+	JZ	sigtramp        // g.m == nil
+	MOVL	m_ncgo(AX), CX
+	TESTL	CX, CX
+	JZ	sigtramp        // g.m.ncgo == 0
+	MOVQ	m_curg(AX), CX
+	TESTQ	CX, CX
+	JZ	sigtramp        // g.m.curg == nil
+	MOVQ	g_syscallsp(CX), CX
+	TESTQ	CX, CX
+	JZ	sigtramp        // g.m.curg.syscallsp == 0
+	MOVQ	m_cgoCallers(AX), R8
+	TESTQ	R8, R8
+	JZ	sigtramp        // g.m.cgoCallers == nil
+	MOVL	m_cgoCallersUse(AX), CX
+	TESTL	CX, CX
+	JNZ	sigtramp	// g.m.cgoCallersUse != 0
+
+	// Jump to a function in runtime/cgo.
+	// That function, written in C, will call the user's traceback
+	// function with proper unwind info, and will then call back here.
+	// The first three arguments, and the fifth, are already in registers.
+	// Set the two remaining arguments now.
+	MOVQ	runtime·cgoTraceback(SB), CX
+	MOVQ	$runtime·sigtramp(SB), R9
+	MOVQ	_cgo_callers(SB), AX
+	JMP	AX
+
+sigtramp:
+	JMP	runtime·sigtramp(SB)
+
+sigtrampnog:
+	// Signal arrived on a non-Go thread. If this is SIGPROF, get a
+	// stack trace.
+	CMPL	DI, $27 // 27 == SIGPROF
+	JNZ	sigtramp
+
+	// Lock sigprofCallersUse.
+	MOVL	$0, AX
+	MOVL	$1, CX
+	MOVQ	$runtime·sigprofCallersUse(SB), R11
+	LOCK
+	CMPXCHGL	CX, 0(R11)
+	JNZ	sigtramp  // Skip stack trace if already locked.
+
+	// Jump to the traceback function in runtime/cgo.
+	// It will call back to sigprofNonGo, which will ignore the
+	// arguments passed in registers.
+	// First three arguments to traceback function are in registers already.
+	MOVQ	runtime·cgoTraceback(SB), CX
+	MOVQ	$runtime·sigprofCallers(SB), R8
+	MOVQ	$runtime·sigprofNonGo(SB), R9
+	MOVQ	_cgo_callers(SB), AX
+	JMP	AX
+
 TEXT runtime·mmap(SB),NOSPLIT,$0
 	MOVQ	addr+0(FP), DI		// arg 1 addr
 	MOVQ	n+8(FP), SI		// arg 2 len