1// Copyright 2016 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
5package runtime
6
7import (
8	"internal/abi"
9	"internal/goarch"
10	"runtime/internal/sys"
11	"unsafe"
12)
13
14type sigctxt struct {
15	info *siginfo
16	ctxt unsafe.Pointer
17}
18
19//go:nosplit
20//go:nowritebarrierrec
21func (c *sigctxt) regs() *sigcontext {
22	return (*sigcontext)(unsafe.Pointer(&(*ucontext)(c.ctxt).uc_mcontext))
23}
24
25func (c *sigctxt) r0() uint64   { return c.regs().gregs[0] }
26func (c *sigctxt) r1() uint64   { return c.regs().gregs[1] }
27func (c *sigctxt) r2() uint64   { return c.regs().gregs[2] }
28func (c *sigctxt) r3() uint64   { return c.regs().gregs[3] }
29func (c *sigctxt) r4() uint64   { return c.regs().gregs[4] }
30func (c *sigctxt) r5() uint64   { return c.regs().gregs[5] }
31func (c *sigctxt) r6() uint64   { return c.regs().gregs[6] }
32func (c *sigctxt) r7() uint64   { return c.regs().gregs[7] }
33func (c *sigctxt) r8() uint64   { return c.regs().gregs[8] }
34func (c *sigctxt) r9() uint64   { return c.regs().gregs[9] }
35func (c *sigctxt) r10() uint64  { return c.regs().gregs[10] }
36func (c *sigctxt) r11() uint64  { return c.regs().gregs[11] }
37func (c *sigctxt) r12() uint64  { return c.regs().gregs[12] }
38func (c *sigctxt) r13() uint64  { return c.regs().gregs[13] }
39func (c *sigctxt) r14() uint64  { return c.regs().gregs[14] }
40func (c *sigctxt) r15() uint64  { return c.regs().gregs[15] }
41func (c *sigctxt) link() uint64 { return c.regs().gregs[14] }
42func (c *sigctxt) sp() uint64   { return c.regs().gregs[15] }
43
44//go:nosplit
45//go:nowritebarrierrec
46func (c *sigctxt) pc() uint64 { return c.regs().psw_addr }
47
48func (c *sigctxt) sigcode() uint32 { return uint32(c.info.si_code) }
49func (c *sigctxt) sigaddr() uint64 { return c.info.si_addr }
50
51func (c *sigctxt) set_r0(x uint64)      { c.regs().gregs[0] = x }
52func (c *sigctxt) set_r13(x uint64)     { c.regs().gregs[13] = x }
53func (c *sigctxt) set_link(x uint64)    { c.regs().gregs[14] = x }
54func (c *sigctxt) set_sp(x uint64)      { c.regs().gregs[15] = x }
55func (c *sigctxt) set_pc(x uint64)      { c.regs().psw_addr = x }
56func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
57func (c *sigctxt) set_sigaddr(x uint64) {
58	*(*uintptr)(add(unsafe.Pointer(c.info), 2*goarch.PtrSize)) = uintptr(x)
59}
60
61func dumpregs(c *sigctxt) {
62	print("r0   ", hex(c.r0()), "\t")
63	print("r1   ", hex(c.r1()), "\n")
64	print("r2   ", hex(c.r2()), "\t")
65	print("r3   ", hex(c.r3()), "\n")
66	print("r4   ", hex(c.r4()), "\t")
67	print("r5   ", hex(c.r5()), "\n")
68	print("r6   ", hex(c.r6()), "\t")
69	print("r7   ", hex(c.r7()), "\n")
70	print("r8   ", hex(c.r8()), "\t")
71	print("r9   ", hex(c.r9()), "\n")
72	print("r10  ", hex(c.r10()), "\t")
73	print("r11  ", hex(c.r11()), "\n")
74	print("r12  ", hex(c.r12()), "\t")
75	print("r13  ", hex(c.r13()), "\n")
76	print("r14  ", hex(c.r14()), "\t")
77	print("r15  ", hex(c.r15()), "\n")
78	print("pc   ", hex(c.pc()), "\t")
79	print("link ", hex(c.link()), "\n")
80}
81
82//go:nosplit
83//go:nowritebarrierrec
84func (c *sigctxt) sigpc() uintptr { return uintptr(c.pc()) }
85
86func (c *sigctxt) sigsp() uintptr { return uintptr(c.sp()) }
87func (c *sigctxt) siglr() uintptr { return uintptr(c.link()) }
88func (c *sigctxt) fault() uintptr { return uintptr(c.sigaddr()) }
89
90// preparePanic sets up the stack to look like a call to sigpanic.
91func (c *sigctxt) preparePanic(sig uint32, gp *g) {
92	// We arrange link, and pc to pretend the panicking
93	// function calls sigpanic directly.
94	// Always save LINK to stack so that panics in leaf
95	// functions are correctly handled. This smashes
96	// the stack frame but we're not going back there
97	// anyway.
98	sp := c.sp() - sys.MinFrameSize
99	c.set_sp(sp)
100	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
101
102	pc := uintptr(gp.sigpc)
103
104	if shouldPushSigpanic(gp, pc, uintptr(c.link())) {
105		// Make it look the like faulting PC called sigpanic.
106		c.set_link(uint64(pc))
107	}
108
109	// In case we are panicking from external C code
110	c.set_r0(0)
111	c.set_r13(uint64(uintptr(unsafe.Pointer(gp))))
112	c.set_pc(uint64(abi.FuncPCABIInternal(sigpanic)))
113}
114
115func (c *sigctxt) pushCall(targetPC, resumePC uintptr) {
116	// Push the LR to stack, as we'll clobber it in order to
117	// push the call. The function being pushed is responsible
118	// for restoring the LR and setting the SP back.
119	// This extra slot is known to gentraceback.
120	sp := c.sp() - 8
121	c.set_sp(sp)
122	*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
123	// Set up PC and LR to pretend the function being signaled
124	// calls targetPC at resumePC.
125	c.set_link(uint64(resumePC))
126	c.set_pc(uint64(targetPC))
127}
128