Re: [PATCH] arch: metag: lib: add "umoddi3.S" file for __umoddi3()

From: Chen Gang
Date: Thu Dec 19 2013 - 08:38:33 EST

On 12/19/2013 08:17 PM, James Hogan wrote:
> On 19/12/13 12:05, Chen Gang wrote:
>> Use objdump to get "umoddi3.S" for __umoddi3(), the original binary
>> file is "gcc-4.2.4-final/gcc/libgcc/umoddi3.o" which is generated by
>> "gcc-4.2.4/gcc/libgcc2.c".
>>
>> The relate error with allmodconfig:
>>
>> MODPOST 2909 modules
>> ERROR: "__umoddi3" [drivers/target/target_core_mod.ko] undefined!
>
> _umoddi3 is a 64bit division, which should be using the proper division
> functions provided by the kernel in <linux/math64.h>.
>
> It needs fixing wherever it comes from in drivers/target/target_core_mod.ko.
>

After disassemble target_core_mod.ko, for me, the compiler will use
___umoddi3 for '%' operator and use ___udivsi3 for '/' operator.

If what I guess is correct, we need use/copy the "system library" which
compiler provides, so just use its ".o" file is OK (just like another
"arch/metag/lib/*.S" have done).


The related C code is below:

463 static inline int core_alua_state_lba_dependent(
464 struct se_cmd *cmd,
465 struct t10_alua_tg_pt_gp *tg_pt_gp,
466 u8 *alua_ascq)
467 {
468 struct se_device *dev = cmd->se_dev;
469 u32 segment_size, segment_mult, sectors;
470 u64 lba;
471
472 /* Only need to check for cdb actually containing LBAs */
473 if (!cmd->se_cmd_flags & SCF_SCSI_DATA_CDB)
474 return 0;
475
476 spin_lock(&dev->t10_alua.lba_map_lock);
477 segment_size = dev->t10_alua.lba_map_segment_size;
478 segment_mult = dev->t10_alua.lba_map_segment_multiplier;
479 sectors = cmd->data_length / dev->dev_attrib.block_size; /* use ___udivsi3 */
480
481 lba = cmd->t_task_lba;
482 while (lba < cmd->t_task_lba + sectors) {
483 struct t10_alua_lba_map *cur_map = NULL, *map;
484 struct t10_alua_lba_map_member *map_mem;
485
486 list_for_each_entry(map, &dev->t10_alua.lba_map_list,
487 lba_map_list) {
488 u64 start_lba, last_lba;
489 u64 first_lba = map->lba_map_first_lba;
490
491 if (segment_mult) {
492 start_lba = lba % (segment_size * segment_mult); /* use ___umoddi3 */
493 last_lba = first_lba + segment_size - 1;
494 if (start_lba >= first_lba &&
495 start_lba <= last_lba) {
...



The related disassemble code is below:

280: ed 06 18 a7 GETD D0Ar2,[A0FrP+#52]
284: 24 d5 38 c6 GETD D1.7,[D0Ar2+#84]
288: 04 0e 18 01 MOV D1Ar1,D1.7
28c: 20 1c 18 03 ADD D1Ar1,D1Ar1,#0x384
290: f5 05 18 a5 SETD [A0FrP+#44],D1Ar1
294: 14 00 00 ab CALLR D1RtP,294 <__raw_spin_lock+0x294>
298: ed 06 20 a7 GETD D0FrT,[A0FrP+#52]
29c: 05 1e 08 00 MOV D0Ar6,D1.7
2a0: 24 0a 19 c6 GETD D1Ar1,[D0FrT+#40]
2a4: ad 9c 18 a7 GETD D0Ar2,[D0Ar6+#1252]
2a8: 35 76 08 a7 GETD D1Ar5,[D0Ar6+#944]
2ac: ad 75 28 a7 GETD D0.5,[D0Ar6+#940]
2b0: 75 05 08 a5 SETD [A0FrP+#40],D1Ar5
2b4: 14 00 00 ab CALLR D1RtP,2b4 <___udivsi3+0x2b4>
2b8: ed 06 10 a7 GETD D0Ar4,[A0FrP+#52]
2bc: 6d 05 18 a7 GETD D0Ar2,[A0FrP+#40]
2c0: 04 00 00 03 MOV D1Re0,#0
2c4: 22 9c 30 c7 GETL D0.6,D1.6,[D0Ar4+#224]
2c8: 40 ca 20 60 MULD D0FrT,D0Ar2,D0.5
2cc: 00 0c 00 08 ADDS D0Re0,D0Re0,D0.6
2d0: 04 0e 18 01 MOV D1Ar1,D1.7
2d4: 00 0c 00 01 ADD D1Re0,D1Re0,D1.6
2d8: a0 1d 18 03 ADD D1Ar1,D1Ar1,#0x3b4
2dc: 46 00 00 07 ADDCS D1Re0,D1Re0,#0x1
2e0: 04 08 08 00 MOV D0Ar6,D0FrT
2e4: 04 00 08 03 MOV D1Ar5,#0
2e8: 04 0a 10 00 MOV D0Ar4,D0.5
2ec: 04 00 10 03 MOV D1Ar3,#0
2f0: 75 08 18 a5 SETD [A0FrP+#64],D1Ar1
2f4: ef 03 00 a5 SETL [A0FrP+#56],D0Re0,D1Re0
2f8: 6f 02 08 a5 SETL [A0FrP+#32],D0Ar6,D1Ar5
2fc: ef 04 10 a5 SETL [A0FrP+#72],D0Ar4,D1Ar3
300: 40 0b 00 a0 B 468 <_target_alua_state_check+0x468>
304: 05 1e 08 00 MOV D0Ar6,D1.7
308: ad 76 20 a7 GETD D0FrT,[D0Ar6+#948]
30c: a0 06 00 a0 B 3e0 <_target_alua_state_check+0x3e0>
310: 75 05 08 a7 GETD D1Ar5,[A0FrP+#40]
314: 22 c0 29 c7 GETL D0.5,D1.5,[D0.7]
318: 00 00 08 73 CMP D1Ar5,#0
31c: c2 03 00 a0 BEQ 394 <_target_alua_state_check+0x394>
320: 6f 02 10 a7 GETL D0Ar4,D1Ar3,[A0FrP+#32]
324: 04 0c 18 00 MOV D0Ar2,D0.6
328: 04 0c 18 01 MOV D1Ar1,D1.6
32c: 14 00 00 ab CALLR D1RtP,32c <___umoddi3+0x32c>
330: 00 40 01 71 CMP D1.5,D1Re0
334: 52 05 00 a0 BHI 3dc <_target_alua_state_check+0x3dc>
338: 00 40 01 71 CMP D1.5,D1Re0
33c: 64 00 00 a0 BNE 348 <_target_alua_state_check+0x348>
340: 00 40 01 70 CMP D0.5,D0Re0
344: d2 04 00 a0 BHI 3dc <_target_alua_state_check+0x3dc>
348: ef 04 08 a7 GETL D0Ar6,D1Ar5,[A0FrP+#72]
34c: fe ff 1f 02 MOV D0Ar2,#-1
350: fe ff 1f 03 MOV D1Ar1,#-1
...


Thanks.
--
Chen Gang

Open, share and attitude like air, water and life which God blessed
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