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Line 61... Line 61...
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/** Switches to kernel stack and saves all registers there.
 61 
/** Switches to kernel stack and saves all registers there.
62 
 *
 62 
 *
63 
 * Temporary exception stack is used to save a few registers
 63 
 * Temporary exception stack is used to save a few registers
64 
 * before stack switch takes place.
 64 
 * before stack switch takes place.
65 
 *
 65 
 *
- 
 
 66 
 *  The stack fram created by the function looks like:
- 
 
 67 
 *
- 
 
 68 
 *      |_________________|
- 
 
 69 
 *      |                 |
- 
 
 70 
 *      |     SPSR        |
- 
 
 71 
 *      |                 |
- 
 
 72 
 *      |_________________|
- 
 
 73 
 *      | Stack Pointer   |
- 
 
 74 
 *      |      of         |
- 
 
 75 
 *      | Previous Mode   |
- 
 
 76 
 *      |_________________|
- 
 
 77 
 *      | Return address  |
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 78 
 *      |      of         |
- 
 
 79 
 *      | Previous Mode   |
- 
 
 80 
 *      |_________________|
- 
 
 81 
 *      |   R0  - R12     |
- 
 
 82 
 *      |      of         |
- 
 
 83 
 *      | Previous Mode   |
- 
 
 84 
 *      |_________________|
- 
 
 85 
 *      | Return address  |
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 *      |     from        |
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 87 
 *      |Exception Handler|
- 
 
 88 
 *      |_________________|
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 89 
 *      |                 |
- 
 
 90 
 *
66 
 */
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 */
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inline static void setup_stack_and_save_regs()
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inline static void setup_stack_and_save_regs()
68 
{
 93 
{
69 
    asm volatile (
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    asm volatile (
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        "ldr r13, =exc_stack\n"
 95 
        "ldr r13, =exc_stack\n"
71 
        "stmfd r13!, {r0}\n"
 96 
        "stmfd r13!, {r0-r3}\n"
- 
 
 97 
        "mrs r1, cpsr\n"
- 
 
 98 
        "bic r1, r1, #0x1f\n"
72 
        "mrs r0, spsr\n"
 99 
        "mrs r2, spsr\n"
73 
        "and r0, r0, #0x1f\n"
 100 
        "and r0, r2, #0x1f\n"
74 
        "cmp r0, #0x10\n"
 101 
        "cmp r0, #0x10\n"
75 
        "bne 1f\n"
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        "bne 1f\n"
76 
       
 103 
       
77 
        /* prev mode was usermode */
 104 
        /* prev mode was usermode */
- 
 
 105 
        "mov r0, sp\n"
78 
        "ldmfd r13!, {r0}\n"
 106 
        "mov r3, lr\n"
- 
 
 107 
 
- 
 
 108 
        /* Switch to supervisor mode */
- 
 
 109 
        "orr r1, r1, #0x13\n"
- 
 
 110 
        "msr cpsr_c, r1\n"
- 
 
 111 
 
- 
 
 112 
        /* Load sp with [supervisor_sp] */
79 
        "ldr r13, =supervisor_sp\n"
 113 
        "ldr r13, =supervisor_sp\n"
80 
        "ldr r13, [r13]\n"
 114 
        "ldr r13, [r13]\n"
- 
 
 115 
 
- 
 
 116 
        /* Populate the stack frame */
- 
 
 117 
        "msr spsr, r2\n"
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 118 
        "mov lr, r3\n"
81 
        "stmfd r13!, {lr}\n"
 119 
        "stmfd r13!, {lr}\n"
82 
        "stmfd r13!, {r0-r12}\n"
 120 
        "stmfd r13!, {r4-r12}\n"
- 
 
 121 
        "ldmfd r0!, {r4-r7}\n"
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 122 
        "stmfd r13!, {r4-r7}\n"
83 
        "stmfd r13!, {r13, lr}^\n"
 123 
        "stmfd r13!, {r13, lr}^\n"
84 
        "mrs r0, spsr\n"
 - 
 
85 
        "stmfd r13!, {r0}\n"
 124 
        "stmfd r13!, {r2}\n"
86 
        "b 2f\n"
 125 
        "b 2f\n"
- 
 
 126 
 
87 
       
 127 
   
88 
        /* mode was not usermode */
 128 
        /* mode was not usermode */
89 
        "1:\n"
 129 
        "1:\n"
90 
            "stmfd r13!, {r1, r2, r3}\n"
 130 
            /* Switch to previous mode which is undoubtedly the supervisor mode */
91 
            "mrs r1, cpsr\n"
 - 
 
92 
            "mov r2, lr\n"
 - 
 
93 
            "bic r1, r1, #0x1f\n"
 - 
 
94 
            "orr r1, r1, r0\n"
 131 
            "orr r1, r1, r0\n"
95 
            "mrs r0, cpsr\n"
 132 
            "mov r0, lr\n"
- 
 
 133 
            "mov r3, sp\n"
96 
            "msr cpsr_c, r1\n"
 134 
            "msr cpsr_c, r1\n"
97 
           
 135 
 
- 
 
 136 
            /* Populate the stack frame */
98 
            "mov r3, r13\n"
 137 
            "mov r1, sp\n"
99 
            "stmfd r13!, {r2}\n"
 138 
            "stmfd r13!, {r0}\n"
100 
            "mov r2, lr\n"
 - 
 
101 
            "stmfd r13!, {r4-r12}\n"
 139 
            "stmfd r13!, {r4-r12}\n"
102 
            "mov r1, r13\n"
 - 
 
103 
 
 140 
 
104 
            /* the following two lines are for debugging */
 141 
            /* Store r0-r3 in r4-r7 and then push it on to stack */
105 
            "mov sp, #0\n"
 142 
            "ldmfd r3!, {r4-r7}\n"
106 
            "mov lr, #0\n"
 - 
 
107 
            "msr cpsr_c, r0\n"
 143 
            "stmfd r13!, {r4-r7}\n"
108 
           
 144 
 
109 
            "ldmfd r13!, {r4, r5, r6, r7}\n"
 145 
            /* Push return address and stack pointer on to stack */
110 
            "stmfd r1!, {r4, r5, r6}\n"
 - 
 
111 
            "stmfd r1!, {r7}\n"
 146 
            "stmfd r13!, {lr}\n"
112 
            "stmfd r1!, {r2}\n"
 147 
            "stmfd r13!, {r1}\n"
113 
            "stmfd r1!, {r3}\n"
 148 
            "mov lr, r0\n"
114 
            "mrs r0, spsr\n"
 149 
            "msr spsr, r2\n"
115 
            "stmfd r1!, {r0}\n"
 150 
            "stmfd r13!, {r2}\n"
116 
            "mov r13, r1\n"
 - 
 
117 
           
 151 
 
118 
        "2:\n"
 152 
        "2:\n"
119 
    );
 153 
    );
120 
}
 154 
}
121 
 
 155 
 
122 
/** Returns from exception mode.
 156 
/** Returns from exception mode.
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144 
        "bic r3, r3, #0x1f      \n"
 178 
        "bic r3, r3, #0x1f      \n"
145 
        "orr r3, r3, r0         \n"
 179 
        "orr r3, r3, r0         \n"
146 
        "mrs r0, cpsr           \n"
 180 
        "mrs r0, cpsr           \n"
147 
        "msr cpsr_c, r3         \n"
 181 
        "msr cpsr_c, r3         \n"
148 
 
 182 
 
149 
        "mov r13, r1            \n"
 - 
 
150 
        "mov lr, r2         \n"
 183 
        "mov lr, r2         \n"
151 
        "msr cpsr_c, r0         \n"
 184 
        "msr cpsr_c, r0         \n"
152 
 
 185 
 
153 
        /* actual return */
 186 
        /* actual return */
154 
    "2:\n"
 187 
    "2:\n"
155 
        "ldmfd r13!, {r0-r12, pc}^\n"
 188 
        "ldmfd r13!, {r0-r12, pc}^\n"
156 
    );
 189 
    );
157 
}
 190 
}
158 
 
 191 
 
159 
 
 192 
 
160 
/** Switch CPU to mode in which interrupts are serviced (currently it
 - 
 
161 
 * is Undefined mode).
 - 
 
162 
 *
 - 
 
163 
 * The default mode for interrupt servicing (Interrupt Mode)
 - 
 
164 
 * can not be used because of nested interrupts (which can occur
 - 
 
165 
 * because interrupts are enabled in higher levels of interrupt handler).
 - 
 
166 
 */
 - 
 
167 
inline static void switch_to_irq_servicing_mode()
 - 
 
168 
{
 - 
 
169 
    /* switch to Undefined mode */
 - 
 
170 
    asm volatile(
 - 
 
171 
        /* save regs used during switching */
 - 
 
172 
        "stmfd sp!, {r0-r3}     \n"
 - 
 
173 
 
 - 
 
174 
        /* save stack pointer and link register to r1, r2 */
 - 
 
175 
        "mov r1, sp         \n"
 - 
 
176 
        "mov r2, lr         \n"
 - 
 
177 
 
 - 
 
178 
        /* mode switch */
 - 
 
179 
        "mrs r0, cpsr           \n"
 - 
 
180 
        "bic r0, r0, #0x1f      \n"
 - 
 
181 
        "orr r0, r0, #0x1b      \n"
 - 
 
182 
        "msr cpsr_c, r0         \n"
 - 
 
183 
 
 - 
 
184 
        /* restore saved sp and lr */
 - 
 
185 
        "mov sp, r1         \n"
 - 
 
186 
        "mov lr, r2         \n"
 - 
 
187 
 
 - 
 
188 
        /* restore original regs */
 - 
 
189 
        "ldmfd sp!, {r0-r3}     \n"
 - 
 
190 
    );
 - 
 
191 
}
 - 
 
192 
 
 - 
 
193 
/** Calls exception dispatch routine. */
 193 
/** Calls exception dispatch routine. */
194 
#define CALL_EXC_DISPATCH(exception) \
 194 
#define CALL_EXC_DISPATCH(exception) \
195 
    asm volatile ( \
 195 
    asm volatile ( \
196 
        "mov r0, %[exc]\n" \
 196 
        "mov r0, %[exc]\n" \
197 
        "mov r1, r13\n" \
 197 
        "mov r1, r13\n" \
Line 286... Line 286...
286 
{
 286 
{
287 
    asm volatile (
 287 
    asm volatile (
288 
        "sub lr, lr, #4"
 288 
        "sub lr, lr, #4"
289 
    );
 289 
    );
290 
   
 290 
   
291 
    setup_stack_and_save_regs();
 - 
 
292 
   
 - 
 
293 
    switch_to_irq_servicing_mode();
 - 
 
294 
   
 - 
 
295 
    CALL_EXC_DISPATCH(EXC_IRQ)
 291 
    PROCESS_EXCEPTION(EXC_IRQ)
296 
 
 - 
 
297 
    load_regs();
 - 
 
298 
}
 292 
}
299 
 
 293 
 
300 
/** Software Interrupt handler.
 294 
/** Software Interrupt handler.
301 
 *
 295 
 *
302 
 * Dispatches the syscall.
 296 
 * Dispatches the syscall.