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| author | Taru Karttunen <taruti@taruti.net> | 2011-03-30 15:46:40 +0300 |
|---|---|---|
| committer | Taru Karttunen <taruti@taruti.net> | 2011-03-30 15:46:40 +0300 |
| commit | e5888a1ffdae813d7575f5fb02275c6bb07e5199 (patch) | |
| tree | d8d51eac403f07814b9e936eed0c9a79195e2450 /sys/src/9/omap/lproc.s | |
Import sources from 2011-03-30 iso image
Diffstat (limited to 'sys/src/9/omap/lproc.s')
| -rwxr-xr-x | sys/src/9/omap/lproc.s | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/sys/src/9/omap/lproc.s b/sys/src/9/omap/lproc.s new file mode 100755 index 000000000..0b4eac238 --- /dev/null +++ b/sys/src/9/omap/lproc.s @@ -0,0 +1,47 @@ +#include "mem.h" +#include "arm.h" + +/* + * This is the first jump from kernel to user mode. + * Fake a return from interrupt. + * + * Enter with R0 containing the user stack pointer. + * UTZERO + 0x20 is always the entry point. + * + */ +TEXT touser(SB), 1, $-4 + /* store the user stack pointer into the USR_r13 */ + MOVM.DB.W [R0], (R13) + /* avoid the ambiguity described in notes/movm.w. */ +// MOVM.S.IA.W (R13), [R13] + MOVM.S (R13), [R13] + ADD $4, R13 + + /* set up a PSR for user level */ + MOVW $(PsrMusr), R0 + MOVW R0, SPSR + + /* save the PC on the stack */ + MOVW $(UTZERO+0x20), R0 + MOVM.DB.W [R0], (R13) + + /* + * note that 5a's RFE is not the v6 arch. instruction (0xe89d0a00, + * I think), which loads CPSR from the word after the PC at (R13), + * but rather the pre-v6 simulation `MOVM.IA.S.W (R13), [R15]' + * (0xe8fd8000 since MOVM is LDM in this case), which loads CPSR + * not from memory but from SPSR due to `.S'. + */ + RFE + +/* + * here to jump to a newly forked process + */ +TEXT forkret(SB), 1, $-4 + ADD $(4*15), R13 /* make r13 point to ureg->type */ + MOVW 8(R13), R14 /* restore link */ + MOVW 4(R13), R0 /* restore SPSR */ + MOVW R0, SPSR /* ... */ + MOVM.DB.S (R13), [R0-R14] /* restore registers */ + ADD $8, R13 /* pop past ureg->{type+psr} */ + RFE /* MOVM.IA.S.W (R13), [R15] */ |