PROBLEM: XFS on ARM corruption 'Structure needs cleaning'

[katsuki.uwatoko at toshiba.co.jp]

On Wed, 12 Aug 2015 13:14:07 +1000, Dave Chinner wrote:

> To close the loop, what code do the other versions GCC produce for
> this macro?  Evidence so far says that the result depends on the
> compiler version, so I would like to have confirmation that other
> versions of the compiler generate working code.  There are other
> XFS_DADDR_TO_FSB() calls in the XFS code, too - do they demonstrate
> the same problem, maybe with different compiler versions?
> 
> Basically I'm asking what is the scope of the problem you've found?
> i.e. when was the bug introduced, what compilers expose it, etc
> so that when ARM users report XFS corruptions we have some idea of
> whether their kernel/compiler combination might have caused the
> issue they are seeing...

I have the following versions of GCC now.
	4.5.1
	4.6.4
	4.7.2
# Sorry I don't have the recent versions of GCC.

And the results are:
	4.5.1 (-O2)	OK.
	4.6.4 (-O2)	BAD.
	4.7.2 (-O2)	BAD.

But even using gcc 4.7, this bug does not happen with -Os instead of -O2.
It means that when CONFIG_CC_OPTIMIZE_FOR_SIZE Kernel option is used, it does not happen.

As for the version of kernel, I am using 3.10 now. At least. it is the same as 2.6.32.

--
The following are codes generated by GCCs.

GCC 4.5.1 with -O2 (OK)
     178:       41a00003        movmi   r0, r3
     17c:       51a00057        asrpl   r0, r7, r0
     180:       e58da02c        str     sl, [sp, #44]   ; 0x2c
     184:       ebfffffe        bl      0 <__do_div64>
     188:       e1cd26f8        strd    r2, [sp, #104]  ; 0x68
     18c:       e3a08000        mov     r8, #0
     190:       e5d51175        ldrb    r1, [r5, #373]  ; 0x175
     194:       e59d2068        ldr     r2, [sp, #104]  ; 0x68
     198:       e251e020        subs    lr, r1, #32
     19c:       e5d5308c        ldrb    r3, [r5, #140]  ; 0x8c
     1a0:       e261c020        rsb     ip, r1, #32
     1a4:       e1a00136        lsr     r0, r6, r1
     1a8:       e1800c17        orr     r0, r0, r7, lsl ip
     1ac:       e2634020        rsb     r4, r3, #32
     1b0:       51a00e57        asrpl   r0, r7, lr
     1b4:       e253c020        subs    ip, r3, #32
     1b8:       e1a0b432        lsr     fp, r2, r4
     1bc:       e1a0a312        lsl     sl, r2, r3
     1c0:       51a0bc12        lslpl   fp, r2, ip
     1c4:       e59dc024        ldr     ip, [sp, #36]   ; 0x24
     1c8:       e5954064        ldr     r4, [r5, #100]  ; 0x64
     1cc:       e1a01157        asr     r1, r7, r1
     1d0:       e58d804c        str     r8, [sp, #76]   ; 0x4c
     1d4:       e58dc048        str     ip, [sp, #72]   ; 0x48
     1d8:       ebfffffe        bl      0 <__do_div64>

GCC 4.6.4 with -O2 (BAD)
     19c:       51a0025e        asrpl   r0, lr, r2
     1a0:       e3a0a001        mov     sl, #1
     1a4:       ebfffffe        bl      0 <__do_div64>
     1a8:       e1a0bb32        lsr     fp, r2, fp
     1ac:       e2553020        subs    r3, r5, #32
     1b0:       e1a01008        mov     r1, r8
     1b4:       e58d704c        str     r7, [sp, #76]   ; 0x4c
     1b8:       e1a0800b        mov     r8, fp
     1bc:       e58d7060        str     r7, [sp, #96]   ; 0x60
     1c0:       51a08312        lslpl   r8, r2, r3
     1c4:       e1a02512        lsl     r2, r2, r5
     1c8:       e58d8034        str     r8, [sp, #52]   ; 0x34
     1cc:       e1a0500a        mov     r5, sl
     1d0:       e58d2030        str     r2, [sp, #48]   ; 0x30
     1d4:       e28d8048        add     r8, sp, #72     ; 0x48
     1d8:       ebfffffe        bl      0 <__do_div64>

GCC 4.7.2 with -Os (OK)
     1a0:       e1cd02d8        ldrd    r0, [sp, #40]   ; 0x28
     1a4:       e1a0200b        mov     r2, fp
     1a8:       ebfffffe        bl      0 <__aeabi_lasr>
     1ac:       e5954064        ldr     r4, [r5, #100]  ; 0x64
     1b0:       ebfffffe        bl      0 <__do_div64>
     1b4:       e3a01000        mov     r1, #0
     1b8:       e1a00002        mov     r0, r2
     1bc:       e5d5208c        ldrb    r2, [r5, #140]  ; 0x8c
     1c0:       ebfffffe        bl      0 <__aeabi_llsl>
     1c4:       e1a0200b        mov     r2, fp
     1c8:       e1a06000        mov     r6, r0
     1cc:       e1a07001        mov     r7, r1
     1d0:       e1cd02d8        ldrd    r0, [sp, #40]   ; 0x28
     1d4:       ebfffffe        bl      0 <__aeabi_lasr>
     1d8:       e58da040        str     sl, [sp, #64]   ; 0x40
     1dc:       ebfffffe        bl      0 <__do_div64>

Thank you,
-- 
UWATOKO