1/* $NetBSD: __sigtramp2.S,v 1.7 2021/11/23 02:49:56 thorpej Exp $ */
2
3/*-
4 * Copyright (c) 2014 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Matt Thomas of 3am Software Foundry.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include "SYS.h"
33#include "assym.h"
34
35/*
36 * The ARM64 signal trampoline is invoked only to return from
37 * the signal; the kernel calls the signal handler directly.
38 *
39 * On entry, the stack looks like:
40 *
41 *                  ucontext structure
42 *        sp->      siginfo structure
43 * and x28 points to the ucontext
44 *
45 * A DWARF pseudo-register is used for the return address from the
46 * signal trampoline.
47 */
48
49#if defined(__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__)
50#define   DWARF_SIGRETURN_REG           __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
51#else
52#define   DWARF_SIGRETURN_REG           96
53#endif
54
55#define   CFI_OFFSET_DWARF_REG(d, r)    .cfi_offset d, r * 8
56#define   CFI_OFFSET(r)                           CFI_OFFSET_DWARF_REG(r, r)
57
58          .text
59          .cfi_startproc simple
60          .cfi_signal_frame
61          .cfi_def_cfa _REG_X28, _UC_GREGS
62          CFI_OFFSET(_REG_X0)
63          CFI_OFFSET(_REG_X1)
64          CFI_OFFSET(_REG_X2)
65          CFI_OFFSET(_REG_X3)
66          CFI_OFFSET(_REG_X4)
67          CFI_OFFSET(_REG_X5)
68          CFI_OFFSET(_REG_X6)
69          CFI_OFFSET(_REG_X7)
70          CFI_OFFSET(_REG_X8)
71          CFI_OFFSET(_REG_X9)
72          CFI_OFFSET(_REG_X10)
73          CFI_OFFSET(_REG_X11)
74          CFI_OFFSET(_REG_X12)
75          CFI_OFFSET(_REG_X13)
76          CFI_OFFSET(_REG_X14)
77          CFI_OFFSET(_REG_X15)
78          CFI_OFFSET(_REG_X16)
79          CFI_OFFSET(_REG_X17)
80          CFI_OFFSET(_REG_X18)
81          CFI_OFFSET(_REG_X19)
82          CFI_OFFSET(_REG_X20)
83          CFI_OFFSET(_REG_X21)
84          CFI_OFFSET(_REG_X22)
85          CFI_OFFSET(_REG_X23)
86          CFI_OFFSET(_REG_X24)
87          CFI_OFFSET(_REG_X25)
88          CFI_OFFSET(_REG_X26)
89          CFI_OFFSET(_REG_X27)
90          CFI_OFFSET(_REG_X28)
91          CFI_OFFSET(_REG_X29)
92          CFI_OFFSET(_REG_X30)          /* a.k.a. _REG_LR */
93          CFI_OFFSET(_REG_X31)          /* a.k.a. _REG_SP */
94          .cfi_return_column DWARF_SIGRETURN_REG
95          CFI_OFFSET_DWARF_REG(DWARF_SIGRETURN_REG, _REG_PC)
96
97/*
98 * The unwind entry includes the one instruction prior to the trampoline
99 * because the unwinder will look up (return PC - 1) while unwinding.
100 * Normally this would be the jump / branch, but since there isn't one in
101 * this case, we place an explicit nop there instead.
102 */
103          nop
104
105ENTRY_NP(__sigtramp_siginfo_2)
106          mov       x0, x28                                 /* set the arg         */
107          SYSTRAP(setcontext)                     /* and call setcontext */
108
109          /* If that failed, exit with the error code. */
110          SYSTRAP(exit)
111          .cfi_endproc
112END(__sigtramp_siginfo_2)
113