1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// +build darwin dragonfly freebsd linux netbsd openbsd
6
7package runtime
8
9import "unsafe"
10
11func dumpregs(c *sigctxt) {
12	print("trap    ", hex(c.trap()), "\n")
13	print("error   ", hex(c.error()), "\n")
14	print("oldmask ", hex(c.oldmask()), "\n")
15	print("r0      ", hex(c.r0()), "\n")
16	print("r1      ", hex(c.r1()), "\n")
17	print("r2      ", hex(c.r2()), "\n")
18	print("r3      ", hex(c.r3()), "\n")
19	print("r4      ", hex(c.r4()), "\n")
20	print("r5      ", hex(c.r5()), "\n")
21	print("r6      ", hex(c.r6()), "\n")
22	print("r7      ", hex(c.r7()), "\n")
23	print("r8      ", hex(c.r8()), "\n")
24	print("r9      ", hex(c.r9()), "\n")
25	print("r10     ", hex(c.r10()), "\n")
26	print("fp      ", hex(c.fp()), "\n")
27	print("ip      ", hex(c.ip()), "\n")
28	print("sp      ", hex(c.sp()), "\n")
29	print("lr      ", hex(c.lr()), "\n")
30	print("pc      ", hex(c.pc()), "\n")
31	print("cpsr    ", hex(c.cpsr()), "\n")
32	print("fault   ", hex(c.fault()), "\n")
33}
34
35//go:nosplit
36//go:nowritebarrierrec
37func (c *sigctxt) sigpc() uintptr { return uintptr(c.pc()) }
38
39func (c *sigctxt) sigsp() uintptr { return uintptr(c.sp()) }
40func (c *sigctxt) siglr() uintptr { return uintptr(c.lr()) }
41
42// preparePanic sets up the stack to look like a call to sigpanic.
43func (c *sigctxt) preparePanic(sig uint32, gp *g) {
44	// We arrange lr, and pc to pretend the panicking
45	// function calls sigpanic directly.
46	// Always save LR to stack so that panics in leaf
47	// functions are correctly handled. This smashes
48	// the stack frame but we're not going back there
49	// anyway.
50	sp := c.sp() - 4
51	c.set_sp(sp)
52	*(*uint32)(unsafe.Pointer(uintptr(sp))) = c.lr()
53
54	pc := gp.sigpc
55
56	if shouldPushSigpanic(gp, pc, uintptr(c.lr())) {
57		// Make it look the like faulting PC called sigpanic.
58		c.set_lr(uint32(pc))
59	}
60
61	// In case we are panicking from external C code
62	c.set_r10(uint32(uintptr(unsafe.Pointer(gp))))
63	c.set_pc(uint32(funcPC(sigpanic)))
64}
65
66// TODO(issue 35439): enabling async preemption causes failures on darwin/arm.
67// Disable for now.
68const pushCallSupported = GOOS != "darwin"
69
70func (c *sigctxt) pushCall(targetPC uintptr) {
71	// Push the LR to stack, as we'll clobber it in order to
72	// push the call. The function being pushed is responsible
73	// for restoring the LR and setting the SP back.
74	// This extra slot is known to gentraceback.
75	sp := c.sp() - 4
76	c.set_sp(sp)
77	*(*uint32)(unsafe.Pointer(uintptr(sp))) = c.lr()
78	// Set up PC and LR to pretend the function being signaled
79	// calls targetPC at the faulting PC.
80	c.set_lr(c.pc())
81	c.set_pc(uint32(targetPC))
82}
83