查看64位多核 MIPS 异常和中断内核代码分析 (1)的源代码

===== RMI XLR732 =====

<source lang=c>
@0xFFFF FFFF 8000 0000                       
   c:    07610005     bgez    k1,24 <0x24>  /* if vaddr[61] != 1 (0xc000 0000 0000 0000 ~ 0xDFFF FFFF FFFF FFFF), branch */   
10:          3c1bc000     lui    k1,0xc000        -----> at delay slot, commit new value to k1 after reading k1 (bgez)
                                           
# vaddr is at 0xE000000000000000 ~ 0xFFFF FFFF FFFF FFFF，这个地址段里被 64 bit Linux 内核使用且又要经过 TLB 的就是 kseg2 了，内核的模块默认使用这个地址
14:    035bd02f     dsubu    k0,k0,k1        /* k0 = vaddr - 0xFFFF FFFF C0000000 */
18:    3c1b8396     lui    k1,0x8396
1c:    10000023     b    ac <0xac>        ----> @@@         
20:    277ba000     addiu    k1,k1,-24576    /* 0xFFFF FFFF 8395A000 = module_pg_dir , using the module_pg_dir as the PGD entry */
 
# vaddr is at 0xC000000000000000 ~ 0xDFFF FFFF FFFF FFFF
24:    001bd83c     dsll32    k1,k1,0x0        /* (0xFFFF FFFF C0000000 << 32) */
28:    035bd02f     dsubu    k0,k0,k1        /* k0 = vaddr - 0xC000000000000000 */
2c:    1000001f     b    ac <0xac>        ----> @@@
30:    3c1b8396     lui    k1,0x8396            /* 0xFFFF FFFF 83960000 = swapper_pg_current, using the swapper_pg_current as the PGD entry */
34:    00000000
38:    00000000 <repeat>
......

@0xFFFF FFFF 8000 0080 （xTLB Refill 入口）
8c:    403a4000     dmfc0    k0,c0_badvaddr        

90:    0740001a     bltz    k0,fc <0xfc>    /* if badvaddr >= 0x80000000 00000000 branch */
 
# vaddr is < 0x8000 0000 0000 000, so it's at kuseg
94:   403b2000    dmfc0   k1,c0_context
98:   001bddfa    dsrl    k1,k1,0x17      /* get (smp_processor_id() << 3) (26-23), see asm/mmu_context.h */
9c:   3c1a8396    lui k0,0x8396           /* swapper_pg_current = 0xFFFF FFFF 83960000 */
a0:   037ad82d    daddu   k1,k1,k0        /* k1 = swapper_pg_current[smp_processor_id()] */
a4:   403a4000    dmfc0   k0,c0_badvaddr
a8:   df7b2000    ld k1,8192(k1)        /*
                                             * pgd = *((void *)(k1 + 8192), 8 bytes per pgd entry, pgd_current = 0xFFFF FFFF 8396 2000,
                                             * 0x2000 = 8192
                                             * actually it's pgd = pgd_current[smp_processor_id()]
                                             */

@@@
ac:    001ad6fa     dsrl    k0,k0,0x1b        # >> 27
b0:    335a1ff8     andi    k0,k0,0x1ff8    /* get (vaddr[39:30] << 3), for indexing pgd */
b4:    037ad82d     daddu    k1,k1,k0        /* index pgd */

b8:    403a4000     dmfc0    k0,c0_badvaddr
bc:    df7b0000     ld    k1,0(k1)            /* get p_pmd */
c0:    001ad4ba     dsrl    k0,k0,0x12
c4:    335a0ff8     andi    k0,k0,0xff8        /* get (vaddr[29:21] << 3), for indexing pmd */
c8:    037ad82d     daddu    k1,k1,k0        /* index pmd */

cc:    403aa000     dmfc0    k0,c0_xcontext   
d0:    df7b0000     ld    k1,0(k1)            /* get p_pt */       
d4:    335a0ff0     andi    k0,k0,0xff0        /* get (va[20:13] << 4), actually use va[20:12] index the pt, va[12]=0, for indexing pt */
d8:    037ad82d     daddu    k1,k1,k0        /* index pt */

dc:    df7a0000     ld    k0,0(k1)            /* get even page addr */    <-------------
e0:    df7b0008     ld    k1,8(k1)            /* get odd page addr */

e4:    001ad1ba     dsrl    k0,k0,0x6        /* ignore the low 6 bits, it's for os */
e8:    409a1000     mtc0    k0,c0_entrylo0    /* tlb even page entry */
ec:    001bd9ba     dsrl    k1,k1,0x6        /* same as above */
f0:    409b1800     mtc0    k1,c0_entrylo1    /* tlb odd page entry */
f4:    42000006     tlbwr                    /* random write tlb */
f8:    42000018     eret                   
 
# go here, vaddr is >=0x8000 0000 0000 0000, so it's in xkphys or xkseg; and 0x8000 0000 0000 0000 ~ 0xBFFF FFFF FFFF FFFF is xkphys, unmapped, do not index TLB, so vaddr is at 0xc000 0000 0000 0000
fc:    001ad8b8     dsll    k1,k0,0x2        # vaddr << 2, will be test the vaddr[61]
100:    1000ffc2     b    c <0xc>

104:    00000000     nop
108:    00000000     nop
</source>

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