On Sat, 13 Jun 2015 08:52:09 +1000, Dave Chinner wrote: > Yup, that's looking like a toolchain bug. Thread about arm directory > read corruption: I think that this is not a toolchain bug, this is related to Subject: [PATCH v2 1/1] ARM : missing corrupted reg in __do_div_asm http://www.spinics.net/lists/arm-kernel/msg426684.html -- The problematic line in xfs is: irecs->br_startblock = XFS_DADDR_TO_FSB(mp, mappedbno) in xfs_dabuf_map()/fs/xfs/xfs_da_btree.c. The expansion of it is: ld = mappedbno >> mp->m_blkbb_log; do_div(ld, mp->m_sb.sb_agblocks); startblock = ld << mp->m_sb.sb_agblklog; ld = mappedbno >> mp->m_blkbb_log; startblock |= do_div(ld, mp->m_sb.sb_agblocks); irecs->br_startblock = startblock; The assembler of these are: : bl __do_div64 ldr r1, [sp, #44] subs r3, r7, #32 orr r1, r1, r2, lsr r5 add r5, sp, #80 str r5, [sp, #64] ldr r5, [sp, #60] movpl r1, r2, asl r3 mov r2, r2, asl r7 str r2, [sp, #40] str r1, [sp, #44] mov r1, r9 str r5, [sp, #96] mov r7, #0 ldr r2, [sp, #96] mov r5, #1 ldr fp, [sp, #64] str r7, [sp, #84] mov r9, r2, asr #31 str r7, [sp, #104] bl __do_div64 : by GCC 4.7.2 with -O2 option. Because a result of do_div is stored in the 1st arg (r0), r0, which is "ld" in the C, must be reloaded after the 1st call of do_div, before the 2nd call of do_div. But it is not reloaded in the above assembler. The problem is macro __do_div_asm, as the patch describes. I confirmed that the patch fixed this problem. mov r1, sl str r2, [sp, #56] mov r0, fp bl __do_div64 ldr ip, [sp, #36] rsb r6, r5, #32 subs r3, r5, #32 ldr r1, [sp, #56] orr ip, ip, r2, lsr r6 str r7, [sp, #96] mov r6, #1 str r8, [sp, #80] mov r0, ip str r1, [sp, #52] movpl r0, r2, asl r3 mov r2, r2, asl r5 str r0, [sp, #36] mov r1, sl str r2, [sp, #32] mov r0, fp bl __do_div64 by GCC 4.7.2 with -O2 option and the patch. Thank you, -- UWATOKO _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
