39 lines
872 B
ArmAsm
39 lines
872 B
ArmAsm
#include "arm.s"
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/*
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* This is the first jump from kernel to user mode.
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* Fake a return from interrupt.
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*
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* Enter with R0 containing the user stack pointer.
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* UTZERO + 0x20 is always the entry point.
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*
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*/
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TEXT touser(SB), 1, $-4
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/* store the user stack pointer into the USR_r13 */
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MOVM.DB.W [R0], (R13)
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/* avoid the ambiguity described in notes/movm.w. */
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MOVM.S (R13), [R13]
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ADD $4, R13 /* pop new user SP */
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/* set up a PSR for user level */
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MOVW $(PsrMusr), R0
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MOVW R0, SPSR
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/* push new user PSR */
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MOVM.DB.W [R0], (R13)
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/* push the new user PC on the stack */
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MOVW $(UTZERO+0x20), R0
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MOVM.DB.W [R0], (R13)
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RFEV7W(13)
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/*
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* here to jump to a newly forked process
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*/
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TEXT forkret(SB), 1, $-4
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ADD $(4*NREGS), R13 /* make r13 point to ureg->type */
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MOVW 8(R13), R14 /* restore link */
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MOVW 4(R13), R0 /* restore SPSR */
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B rfue(SB)
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