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comparison src/trap_asm.S @ 0:83c23a36980d

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Init
author Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp>
date Fri, 26 May 2017 23:11:05 +0900
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-1:000000000000 0:83c23a36980d
1 //low-level trap handler glue code
2 #include "arm.h"
3
4 .text
5 .code 32
6
7 .global trap_swi
8 .global trap_irq
9 .global trap_reset
10 .global trap_und
11 .global trap_iabort
12 .global trap_dabort
13 .global trap_na
14 .global trap_fiq
15 .global trapret
16
17
18 # handle SWI, we allow nested SWI
19 trap_swi:
20 # build trapframe on the stack
21 STMFD sp!, {r0-r12, r14} // save context
22 MRS r2, spsr // copy spsr to r2
23 STMFD r13!, {r2} // save r2(spsr) to the stack
24 STMFD r13!, {r14} // save r14 again to have one uniform trapframe
25 STMFD r13, {sp, lr}^ // save user mode sp and lr
26 SUB r13, r13, #8
27
28 # call traps (trapframe *fp)
29 MOV r0, r13 // copy r13_svc to r0
30 BL swi_handler // branch to the isr_swi
31
32 # restore states
33 trapret:
34 LDMFD r13, {sp, lr}^ // restore user mode sp and lr
35 ADD r13, r13, #8
36 LDMFD r13!, {r14} // restore r14
37 LDMFD r13!, {r2} // restore spsr
38 MSR spsr_cxsf, r2
39 LDMFD r13!,{r0-r12, pc}^ // restore context and return
40
41
42 # handle IRQ, we allow nested IRQs
43 trap_irq:
44 # save a few registers to the irq stack to provide scratch regs.
45 # r14 (lr_irq) contains the instruction (pc) to return to, need to
46 # save it on the stack as r14 is banked
47 SUB r14, r14, #4 // r14 (lr) contains the interrupted PC
48 STMFD r13!, {r0-r2, r14} //
49 MRS r1, spsr // save spsr_irq
50 MOV r0, r13 // save stack stop (r13_irq)
51 ADD r13, r13, #16 // reset the IRQ stack
52
53 # switch to the SVC mode
54 MRS r2, cpsr
55 BIC r2, r2, #MODE_MASK
56 ORR r2, r2, #SVC_MODE
57 MSR cpsr_cxsf, r2
58
59 # now, in SVC mode, sp, lr, pc (r13, r14, r15) are all banked
60 # build the trap frame
61 LDR r2, [r0, #12] // read the r14_irq, then save it
62 STMFD r13!, {r2}
63 STMFD r13!, {r3-r12} // r4-r12 are preserved (non-banked)
64 LDMFD r0, {r3-r5} // copy r0-r2 over from irq stack
65 STMFD r13!, {r3-r5}
66 STMFD r13!, {r1} // save spsr
67 STMFD r13!, {lr} // save r14_svc
68
69 STMFD r13, {sp, lr}^ // save user mode sp and lr
70 SUB r13, r13, #8
71
72 # get the parameters, then call the handler
73 MOV r0, r13 // points to
74 BL irq_handler
75
76 # restore the previous status
77 B trapret
78
79 # handle reset/undefine instruction/abort/not-assigned/fiq
80 # these handler does not allow nested handling
81 trap_reset:
82 MOV r14, #0 // lr: not defined on reset
83 STMFD r13!, {r0-r12, r14}
84 MRS r2, spsr // copy spsr to r2
85 STMFD r13!, {r2} // save r2(spsr) to the stack
86 STMFD r13!, {r14} // save r14 again (it is not really correct)
87 STMFD r13, {sp, lr}^ // save user mode sp and lr
88 SUB r13, r13, #8
89
90 # call traps (trapframe *fp)
91 MOV r0, r13 // copy r13_svc to r0
92 BL reset_handler
93 B .
94
95 trap_und:
96 STMFD r13!, {r0-r12, r14} // lr: instruction after the undefined
97 MRS r2, spsr // copy spsr to r2
98 STMFD r13!, {r2} // save r2(spsr) to the stack
99 STMFD r13!, {r14} // save r14 again (it is not really correct)
100 STMFD r13, {sp, lr}^ // save user mode sp and lr
101 SUB r13, r13, #8
102
103 # call traps (trapframe *fp)
104 MOV r0, r13 // save trapframe as the first parameter
105 BL und_handler
106 B .
107
108 trap_iabort:
109 SUB r14, r14, #4 // lr: instruction causing the abort
110 STMFD r13!, {r0-r12, r14}
111 MRS r2, spsr // copy spsr to r2
112 STMFD r13!, {r2} // save r2(spsr) to the stack
113 STMFD r13!, {r14} // save r14 again (it is not really correct)
114 STMFD r13, {sp, lr}^ // save user mode sp and lr
115 SUB r13, r13, #8
116
117 # call traps (trapframe *fp)
118 MOV r0, r13 // save trapframe as the first parameter
119 BL iabort_handler
120 B .
121
122 trap_dabort:
123 SUB r14, r14, #8 // lr: instruction causing the abort
124 STMFD r13!, {r0-r12, r14}
125 MRS r2, spsr // copy spsr to r2
126 STMFD r13!, {r2} // save r2(spsr) to the stack
127 STMFD r13!, {r14} // save r14 again (it is not really correct)
128 STMFD r13, {sp, lr}^ // save user mode sp and lr
129 SUB r13, r13, #8
130
131 # call traps (trapframe *fp)
132 MOV r0, r13 // save trapframe as the first parameter
133 BL dabort_handler
134 MOV r0, #2 // #SYS_exit
135 SWI 0x00
136 B exit
137 #B . // trapret
138
139 trap_na:
140 STMFD r13!, {r0-r12, r14} // should never happen, hardware error
141 MRS r2, spsr // copy spsr to r2
142 STMFD r13!, {r2} // save r2(spsr) to the stack
143 STMFD r13!, {r14} // save r14 again (it is not really correct)
144 STMFD r13, {sp, lr}^ // save user mode sp and lr
145 SUB r13, r13, #8
146
147 # call traps (trapframe *fp)
148 MOV r0, r13 // save trapframe as the first parameter
149 BL na_handler
150 B .
151
152 trap_fiq:
153 SUB r14, r14, #4 // lr: return address after the fiq handler
154 STMFD r13!, {r0-r12, r14}
155 MRS r2, spsr // copy spsr to r2
156 STMFD r13!, {r2} // save r2(spsr) to the stack
157 STMFD r13!, {r14} // save r14 again (it is not really correct)
158 STMFD r13, {sp, lr}^ // save user mode sp and lr
159 SUB r13, r13, #8
160
161 # call traps (trapframe *fp)
162 MOV r0, r13 // save trapframe as the first parameter
163 BL fiq_handler
164 B .
165