ref: a5db044fd3ccb8f021d4deb07b3dc732ed41d699
dir: /sys/src/9/teg2/rebootcode.s/
/*
* arm v7 reboot code
*
* must fit in 11K to avoid stepping on PTEs; see mem.h.
* cache parameters are at CACHECONF.
*/
#include "arm.s"
/*
* All caches but L1 should be off before calling this.
* Turn off MMU, then copy the new kernel to its correct location
* in physical memory. Then jump to the start of the kernel.
*/
/* main(PADDR(entry), PADDR(code), size); */
TEXT main(SB), 1, $-4
MOVW $setR12(SB), R12
MOVW R0, p1+0(FP) /* destination, passed in R0 */
CPSID /* splhi */
PUTC('R')
BL cachesoff(SB)
/* now back in 29- or 26-bit addressing, mainly for SB */
/* double mapping of PHYSDRAM & KZERO now in effect */
PUTC('e')
/* before turning MMU off, switch to PHYSDRAM-based addresses */
DMB
MOVW $KSEGM, R7 /* clear segment bits */
MOVW $PHYSDRAM, R0 /* set dram base bits */
BIC R7, R12 /* adjust SB */
ORR R0, R12
BL _r15warp(SB)
/* don't care about saving R14; we're not returning */
/*
* now running in PHYSDRAM segment, not KZERO.
*/
PUTC('b')
/* invalidate mmu mappings */
MOVW $KZERO, R0 /* some valid virtual address */
MTCP CpSC, 0, R0, C(CpTLB), C(CpTLBinvu), CpTLBinv
BARRIERS
PUTC('o')
/*
* turn the MMU off
*/
MFCP CpSC, 0, R0, C(CpCONTROL), C(0)
BIC $CpCmmu, R0
MTCP CpSC, 0, R0, C(CpCONTROL), C(0)
BARRIERS
PUTC('o')
/* copy in arguments from stack frame before moving stack */
MOVW p2+4(FP), R4 /* phys source */
MOVW n+8(FP), R5 /* byte count */
MOVW p1+0(FP), R6 /* phys destination */
/* set up a new stack for local vars and memmove args */
MOVW R6, SP /* tiny trampoline stack */
SUB $(0x20 + 4), SP /* back up before a.out header */
// MOVW R14, -48(SP) /* store return addr */
SUB $48, SP /* allocate stack frame */
MOVW R5, 40(SP) /* save count */
MOVW R6, 44(SP) /* save dest/entry */
/* copy the new kernel into place */
DELAY(printloop2, 2)
PUTC('t')
MOVW 40(SP), R5 /* restore count */
MOVW 44(SP), R6 /* restore dest/entry */
MOVW R6, 0(SP) /* normally saved LR goes here */
MOVW R6, 4(SP) /* push dest */
MOVW R6, R0
MOVW R4, 8(SP) /* push src */
MOVW R5, 12(SP) /* push size */
BL memmove(SB)
PUTC('-')
PUTC('>')
DELAY(printloopret, 1)
PUTC('\r')
DELAY(printloopnl, 1)
PUTC('\n')
/*
* jump to kernel entry point. Note the true kernel entry point is
* the virtual address KZERO|R6, but this must wait until
* the MMU is enabled by the kernel in l.s
*/
MOVW 44(SP), R6 /* restore R6 (dest/entry) */
ORR R6, R6 /* NOP: avoid link bug */
B (R6)
PUTC('?')
PUTC('?')
B 0(PC)
/*
* turn the caches off, double map PHYSDRAM & KZERO, invalidate TLBs, revert
* to tiny addresses. upon return, it will be safe to turn off the mmu.
*/
TEXT cachesoff(SB), 1, $-4
MOVM.DB.W [R14,R1-R10], (R13) /* save regs on stack */
CPSID
BARRIERS
SUB $12, SP /* paranoia */
BL cacheuwbinv(SB)
ADD $12, SP /* paranoia */
MFCP CpSC, 0, R0, C(CpCONTROL), C(0)
BIC $(CpCicache|CpCdcache), R0
MTCP CpSC, 0, R0, C(CpCONTROL), C(0) /* caches off */
BARRIERS
/*
* caches are off
*/
/* invalidate stale TLBs before changing them */
MOVW $KZERO, R0 /* some valid virtual address */
MTCP CpSC, 0, R0, C(CpTLB), C(CpTLBinvu), CpTLBinv
BARRIERS
/* redo double map of PHYSDRAM, KZERO */
MOVW $PHYSDRAM, R3
CMP $KZERO, R3
BEQ noun2map
MOVW $(L1+L1X(PHYSDRAM)), R4 /* address of PHYSDRAM's PTE */
MOVW $PTEDRAM, R2 /* PTE bits */
MOVW $DOUBLEMAPMBS, R5
_ptrdbl:
ORR R3, R2, R1 /* first identity-map 0 to 0, etc. */
MOVW R1, (R4)
ADD $4, R4 /* bump PTE address */
ADD $MiB, R3 /* bump pa */
SUB.S $1, R5
BNE _ptrdbl
noun2map:
/*
* flush stale TLB entries
*/
BARRIERS
MOVW $KZERO, R0 /* some valid virtual address */
MTCP CpSC, 0, R0, C(CpTLB), C(CpTLBinvu), CpTLBinv
BARRIERS
/* switch back to PHYSDRAM addressing, mainly for SB */
MOVW $KSEGM, R7 /* clear segment bits */
MOVW $PHYSDRAM, R0 /* set dram base bits */
BIC R7, R12 /* adjust SB */
ORR R0, R12
BIC R7, SP
ORR R0, SP
MOVM.IA.W (R13), [R14,R1-R10] /* restore regs from stack */
MOVW $KSEGM, R0 /* clear segment bits */
BIC R0, R14 /* adjust link */
MOVW $PHYSDRAM, R0 /* set dram base bits */
ORR R0, R14
RET
TEXT _r15warp(SB), 1, $-4
BIC R7, R14 /* link */
ORR R0, R14
BIC R7, R13 /* SP */
ORR R0, R13
RET
TEXT panic(SB), 1, $-4 /* stub */
PUTC('?')
PUTC('!')
RET
TEXT pczeroseg(SB), 1, $-4 /* stub */
RET
#include "cache.v7.s"
/* modifies R0, R3—R6 */
TEXT printhex(SB), 1, $-4
MOVW R0, R3
MOVW $(32-4), R5 /* bits to shift right */
nextdig:
SRA R5, R3, R4
AND $0xf, R4
ADD $'0', R4
CMP.S $'9', R4
BLE nothex /* if R4 <= 9, jump */
ADD $('a'-('9'+1)), R4
nothex:
PUTC(R4)
SUB.S $4, R5
BGE nextdig
PUTC('\r')
PUTC('\n')
DELAY(proct, 50)
RET