1 /* Copyright (C) 1991-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
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/>. */
19 #include <pointer_guard.h>
21 #include <jmpbuf-offsets.h>
22 #define ENV(base,reg) [%base + (reg * 4)]
23 #define ST_FLUSH_WINDOWS 3
26 /* Store our arguments in global registers so we can still
27 use them while unwinding frames and their register windows. */
29 ld ENV(o0,JB_FP), %g3 /* Cache target FP in register %g3. */
31 PTR_DEMANGLE (%g3, %g3, %g4)
33 mov %o0, %g1 /* ENV in %g1 */
34 orcc %o1, %g0, %g2 /* VAL in %g2 */
35 be,a 0f /* Branch if zero; else skip delay slot. */
36 mov 1, %g2 /* Delay slot only hit if zero: VAL = 1. */
45 /* Now we will loop, unwinding the register windows up the stack
46 until the restored %fp value matches the target value in %g3. */
49 cmp %fp, %g3 /* Have we reached the target frame? */
50 bl,a LOC(loop) /* Loop while current fp is below target. */
51 restore /* Unwind register window in delay slot. */
52 be,a LOC(found) /* Better have hit it exactly. */
53 ld ENV(g1,JB_SP), %o0 /* Delay slot: extract target SP. */
58 * Do a "flush register windows trap". The trap handler in the
59 * kernel writes all the register windows to their stack slots, and
60 * marks them all as invalid (needing to be sucked up from the
61 * stack when used). This ensures that all information needed to
62 * unwind to these callers is in memory, not in the register
67 ld ENV(g1,JB_PC), %g5 /* Set return PC. */
68 ld ENV(g1,JB_SP), %g1 /* Set saved SP on restore below. */
69 PTR_DEMANGLE2 (%i7, %g5, %g4)
70 PTR_DEMANGLE2 (%fp, %g1, %g4)
72 ld ENV(g1,JB_PC), %i7 /* Set return PC. */
73 ld ENV(g1,JB_SP), %fp /* Set saved SP on restore below. */
76 restore %g2, 0, %o0 /* Restore values from above register frame. */
79 /* We have unwound register windows so %fp matches the target. */
81 PTR_DEMANGLE2 (%sp, %o0, %g4)
83 mov %o0, %sp /* OK, install new SP. */
87 ld ENV(g1,JB_PC), %o0 /* Extract target return PC. */
89 PTR_DEMANGLE2 (%o0, %o0, %g4)
91 jmp %o0 + 8 /* Return there. */
92 mov %g2, %o0 /* Delay slot: set return value. */