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1 | /* Assembly functions for libgcc2. |
2 | Copyright (C) 2001 Free Software Foundation, Inc. | |
3 | Contributed by Bob Wilson (bwilson@tensilica.com) at Tensilica. | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 2, or (at your option) any later | |
10 | version. | |
11 | ||
e2fb85da BW |
12 | In addition to the permissions in the GNU General Public License, the |
13 | Free Software Foundation gives you unlimited permission to link the | |
14 | compiled version of this file into combinations with other programs, | |
15 | and to distribute those combinations without any restriction coming | |
16 | from the use of this file. (The General Public License restrictions | |
17 | do apply in other respects; for example, they cover modification of | |
18 | the file, and distribution when not linked into a combine | |
19 | executable.) | |
20 | ||
03984308 BW |
21 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
22 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
23 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
24 | for more details. | |
25 | ||
26 | You should have received a copy of the GNU General Public License | |
27 | along with GCC; see the file COPYING. If not, write to the Free | |
39d14dda KC |
28 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
29 | 02110-1301, USA. */ | |
03984308 | 30 | |
e677f70c | 31 | #include "xtensa-config.h" |
03984308 | 32 | |
57174693 BW |
33 | /* __xtensa_libgcc_window_spill: This function flushes out all but the |
34 | current register window. This is used to set up the stack so that | |
ff482c8d | 35 | arbitrary frames can be accessed. */ |
03984308 | 36 | |
57174693 BW |
37 | .align 4 |
38 | .global __xtensa_libgcc_window_spill | |
39 | .type __xtensa_libgcc_window_spill,@function | |
03984308 | 40 | __xtensa_libgcc_window_spill: |
57174693 BW |
41 | entry sp, 32 |
42 | movi a2, 0 | |
43 | syscall | |
03984308 | 44 | retw |
57174693 | 45 | .size __xtensa_libgcc_window_spill,.-__xtensa_libgcc_window_spill |
03984308 BW |
46 | |
47 | ||
48 | /* __xtensa_nonlocal_goto: This code does all the hard work of a | |
49 | nonlocal goto on Xtensa. It is here in the library to avoid the | |
50 | code size bloat of generating it in-line. There are two | |
51 | arguments: | |
52 | ||
53 | a2 = frame pointer for the procedure containing the label | |
54 | a3 = goto handler address | |
55 | ||
56 | This function never returns to its caller but instead goes directly | |
57 | to the address of the specified goto handler. */ | |
58 | ||
59 | .align 4 | |
60 | .global __xtensa_nonlocal_goto | |
61 | .type __xtensa_nonlocal_goto,@function | |
62 | __xtensa_nonlocal_goto: | |
63 | entry sp, 32 | |
64 | ||
65 | /* flush registers */ | |
57174693 BW |
66 | mov a5, a2 |
67 | movi a2, 0 | |
68 | syscall | |
69 | mov a2, a5 | |
03984308 BW |
70 | |
71 | /* Because the save area for a0-a3 is stored one frame below | |
72 | the one identified by a2, the only way to restore those | |
73 | registers is to unwind the stack. If alloca() were never | |
74 | called, we could just unwind until finding the sp value | |
75 | matching a2. However, a2 is a frame pointer, not a stack | |
76 | pointer, and may not be encountered during the unwinding. | |
77 | The solution is to unwind until going _past_ the value | |
78 | given by a2. This involves keeping three stack pointer | |
79 | values during the unwinding: | |
80 | ||
81 | next = sp of frame N-1 | |
82 | cur = sp of frame N | |
83 | prev = sp of frame N+1 | |
84 | ||
85 | When next > a2, the desired save area is stored relative | |
86 | to prev. At this point, cur will be the same as a2 | |
87 | except in the alloca() case. | |
88 | ||
89 | Besides finding the values to be restored to a0-a3, we also | |
90 | need to find the current window size for the target | |
91 | function. This can be extracted from the high bits of the | |
92 | return address, initially in a0. As the unwinding | |
93 | proceeds, the window size is taken from the value of a0 | |
ff482c8d | 94 | saved _two_ frames below the current frame. */ |
03984308 BW |
95 | |
96 | addi a5, sp, -16 # a5 = prev - save area | |
97 | l32i a6, a5, 4 | |
98 | addi a6, a6, -16 # a6 = cur - save area | |
99 | mov a8, a0 # a8 = return address (for window size) | |
100 | j .Lfirstframe | |
101 | ||
102 | .Lnextframe: | |
103 | l32i a8, a5, 0 # next return address (for window size) | |
104 | mov a5, a6 # advance prev | |
105 | addi a6, a7, -16 # advance cur | |
106 | .Lfirstframe: | |
107 | l32i a7, a6, 4 # a7 = next | |
108 | bge a2, a7, .Lnextframe | |
109 | ||
110 | /* At this point, prev (a5) points to the save area with the saved | |
111 | values of a0-a3. Copy those values into the save area at the | |
112 | current sp so they will be reloaded when the return from this | |
113 | function underflows. We don't have to worry about exceptions | |
114 | while updating the current save area, because the windows have | |
ff482c8d | 115 | already been flushed. */ |
03984308 BW |
116 | |
117 | addi a4, sp, -16 # a4 = save area of this function | |
118 | l32i a6, a5, 0 | |
119 | l32i a7, a5, 4 | |
120 | s32i a6, a4, 0 | |
121 | s32i a7, a4, 4 | |
122 | l32i a6, a5, 8 | |
123 | l32i a7, a5, 12 | |
124 | s32i a6, a4, 8 | |
125 | s32i a7, a4, 12 | |
126 | ||
127 | /* Set return address to goto handler. Use the window size bits | |
ff482c8d | 128 | from the return address two frames below the target. */ |
03984308 BW |
129 | extui a8, a8, 30, 2 # get window size from return addr. |
130 | slli a3, a3, 2 # get goto handler addr. << 2 | |
131 | ssai 2 | |
132 | src a0, a8, a3 # combine them with a funnel shift | |
133 | ||
134 | retw | |
135 | .size __xtensa_nonlocal_goto,.-__xtensa_nonlocal_goto | |
136 | ||
137 | ||
138 | /* __xtensa_sync_caches: This function is called after writing a trampoline | |
139 | on the stack to force all the data writes to memory and invalidate the | |
140 | instruction cache. a2 is the address of the new trampoline. | |
141 | ||
142 | After the trampoline data is written out, it must be flushed out of | |
143 | the data cache into memory. We use DHWB in case we have a writeback | |
144 | cache. At least one DHWB instruction is needed for each data cache | |
145 | line which may be touched by the trampoline. An ISYNC instruction | |
146 | must follow the DHWBs. | |
147 | ||
148 | We have to flush the i-cache to make sure that the new values get used. | |
149 | At least one IHI instruction is needed for each i-cache line which may | |
150 | be touched by the trampoline. An ISYNC instruction is also needed to | |
151 | make sure that the modified instructions are loaded into the instruction | |
ff482c8d | 152 | fetch buffer. */ |
13fb3a61 | 153 | |
f42f5a1b | 154 | #define TRAMPOLINE_SIZE 59 |
03984308 BW |
155 | |
156 | .text | |
157 | .align 4 | |
158 | .global __xtensa_sync_caches | |
159 | .type __xtensa_sync_caches,@function | |
160 | __xtensa_sync_caches: | |
161 | entry sp, 32 | |
1839841c | 162 | #if XCHAL_DCACHE_SIZE > 0 |
03984308 BW |
163 | # Flush the trampoline from the data cache |
164 | extui a4, a2, 0, XCHAL_DCACHE_LINEWIDTH | |
165 | addi a4, a4, TRAMPOLINE_SIZE | |
166 | addi a4, a4, (1 << XCHAL_DCACHE_LINEWIDTH) - 1 | |
167 | srli a4, a4, XCHAL_DCACHE_LINEWIDTH | |
168 | mov a3, a2 | |
169 | .Ldcache_loop: | |
170 | dhwb a3, 0 | |
171 | addi a3, a3, (1 << XCHAL_DCACHE_LINEWIDTH) | |
172 | addi a4, a4, -1 | |
173 | bnez a4, .Ldcache_loop | |
174 | isync | |
175 | #endif | |
176 | #if XCHAL_ICACHE_SIZE > 0 | |
177 | # Invalidate the corresponding lines in the instruction cache | |
178 | extui a4, a2, 0, XCHAL_ICACHE_LINEWIDTH | |
179 | addi a4, a4, TRAMPOLINE_SIZE | |
180 | addi a4, a4, (1 << XCHAL_ICACHE_LINEWIDTH) - 1 | |
181 | srli a4, a4, XCHAL_ICACHE_LINEWIDTH | |
182 | .Licache_loop: | |
183 | ihi a2, 0 | |
184 | addi a2, a2, (1 << XCHAL_ICACHE_LINEWIDTH) | |
185 | addi a4, a4, -1 | |
186 | bnez a4, .Licache_loop | |
187 | isync | |
188 | #endif | |
189 | retw | |
190 | .size __xtensa_sync_caches,.-__xtensa_sync_caches |