1/* Copyright (C) 1991-2021 Free Software Foundation, Inc.
2   This file is part of the GNU C Library.
3
4   The GNU C Library is free software; you can redistribute it and/or
5   modify it under the terms of the GNU Lesser General Public
6   License as published by the Free Software Foundation; either
7   version 2.1 of the License, or (at your option) any later version.
8
9   The GNU C Library is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   Lesser General Public License for more details.
13
14   You should have received a copy of the GNU Lesser General Public
15   License along with the GNU C Library; if not, see
16   <https://www.gnu.org/licenses/>.  */
17
18#include <sysdep.h>
19
20#include <jmpbuf-offsets.h>
21#define ENV(base,reg) [%base + (reg * 4)]
22#define ST_FLUSH_WINDOWS 3
23
24ENTRY(__longjmp)
25	/* Store our arguments in global registers so we can still
26	   use them while unwinding frames and their register windows.  */
27
28	ld ENV(o0,JB_FP), %g3	/* Cache target FP in register %g3.  */
29#ifdef PTR_DEMANGLE
30	PTR_DEMANGLE (%g3, %g3, %g4)
31#endif
32	mov %o0, %g1		/* ENV in %g1 */
33	orcc %o1, %g0, %g2	/* VAL in %g2 */
34	be,a 0f			/* Branch if zero; else skip delay slot.  */
35	 mov 1, %g2		/* Delay slot only hit if zero: VAL = 1.  */
360:
37	xor %fp, %g3, %o0
38	add %fp, 512, %o1
39	andncc %o0, 4095, %o0
40	bne LOC(thread)
41	 cmp %o1, %g3
42	bl LOC(thread)
43
44	/* Now we will loop, unwinding the register windows up the stack
45	   until the restored %fp value matches the target value in %g3.  */
46
47LOC(loop):
48	cmp %fp, %g3		/* Have we reached the target frame? */
49	bl,a LOC(loop)		/* Loop while current fp is below target.  */
50	 restore		/* Unwind register window in delay slot.  */
51	be,a LOC(found)		/* Better have hit it exactly.  */
52	 ld ENV(g1,JB_SP), %o0	/* Delay slot: extract target SP.  */
53
54LOC(thread):
55	save	%sp, -96, %sp
56	/*
57	 * Do a "flush register windows trap".  The trap handler in the
58	 * kernel writes all the register windows to their stack slots, and
59	 * marks them all as invalid (needing to be sucked up from the
60	 * stack when used).  This ensures that all information needed to
61	 * unwind to these callers is in memory, not in the register
62	 * windows.
63	 */
64	ta	ST_FLUSH_WINDOWS
65#ifdef PTR_DEMANGLE
66	ld	ENV(g1,JB_PC), %g5 /* Set return PC. */
67	ld	ENV(g1,JB_SP), %g1 /* Set saved SP on restore below. */
68	PTR_DEMANGLE2 (%i7, %g5, %g4)
69	PTR_DEMANGLE2 (%fp, %g1, %g4)
70#else
71	ld	ENV(g1,JB_PC), %i7 /* Set return PC. */
72	ld	ENV(g1,JB_SP), %fp /* Set saved SP on restore below. */
73#endif
74	jmp	%i7 + 8
75	 restore %g2, 0, %o0	/* Restore values from above register frame. */
76
77LOC(found):
78	/* We have unwound register windows so %fp matches the target.  */
79#ifdef PTR_DEMANGLE
80	PTR_DEMANGLE2 (%sp, %o0, %g4)
81#else
82	mov %o0, %sp		/* OK, install new SP.  */
83#endif
84
85LOC(sp_ok):
86	ld ENV(g1,JB_PC), %o0	/* Extract target return PC.  */
87#ifdef PTR_DEMANGLE
88	PTR_DEMANGLE2 (%o0, %o0, %g4)
89#endif
90	jmp %o0 + 8		/* Return there.  */
91	 mov %g2, %o0		/* Delay slot: set return value.  */
92
93END(__longjmp)
94