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SubjectRe: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3)
Mathieu Desnoyers wrote:
> Can you also give us
>
> objdump -S --start-address=0xC00BB724 vmlinux | head 20
>
> ?
>
> Then we could compare the result with the OOPS instruction dump :
>
> 7c0802a6 bf61000c 3f60c038 7c3f0b78 90010024 7c7c1b78 7c9d2378 83db32a0
> 73c00001 7f83e378 7fa4eb78 4082002f <00000000> 2f830000 409e0030 801b32a0
>
> Mathieu
>
>

to give you more context I have run:
> powerpc-linux-gnu-objdump -S --start-address=0xC00BB700 vmlinux |
head -n 60

the discrepancy starts at address:
c00bb720: 40 82 00 30 <=> 40 82 00 2f
c00bb724: 4b ff fe 61 <=> 00 00 00 00

vmlinux: file format elf32-powerpc

Disassembly of section .text:

c00bb700 <d_lookup+0x1c>:
* d_lookup() is protected against the concurrent renames in some unrelated
* directory using the seqlockt_t rename_lock.
*/

struct dentry * d_lookup(struct dentry * parent, struct qstr * name)
{
c00bb700: 7c 3f 0b 78 mr r31,r1
c00bb704: 90 01 00 24 stw r0,36(r1)
c00bb708: 7c 7c 1b 78 mr r28,r3
c00bb70c: 7c 9d 23 78 mr r29,r4
c00bb710: 83 db 32 a0 lwz r30,12960(r27)
{
unsigned ret;

repeat:
ret = sl->sequence;
smp_rmb();
c00bb714: 73 c0 00 01 andi. r0,r30,1
struct dentry * dentry = NULL;
unsigned long seq;

do {
seq = read_seqbegin(&rename_lock);
dentry = __d_lookup(parent, name);
c00bb718: 7f 83 e3 78 mr r3,r28
c00bb71c: 7f a4 eb 78 mr r4,r29
if (unlikely(ret & 1)) {
c00bb720: 40 82 00 30 bne- c00bb750 <d_lookup+0x6c>
c00bb724: 4b ff fe 61 bl c00bb584 <__d_lookup>
if (dentry)
c00bb728: 2f 83 00 00 cmpwi cr7,r3,0
c00bb72c: 40 9e 00 30 bne- cr7,c00bb75c <d_lookup+0x78>
*
* If sequence value changed then writer changed data while in section.
*/
static __always_inline int read_seqretry(const seqlock_t *sl, unsigned
start)
{
smp_rmb();
c00bb730: 80 1b 32 a0 lwz r0,12960(r27)
break;
} while (read_seqretry(&rename_lock, seq));
c00bb734: 7f 80 f0 00 cmpw cr7,r0,r30
c00bb738: 41 9e 00 24 beq- cr7,c00bb75c <d_lookup+0x78>
/* Start of read calculation -- fetch last complete writer token */
static __always_inline unsigned read_seqbegin(const seqlock_t *sl)
{
unsigned ret;

repeat:
c00bb73c: 7c 1e 03 78 mr r30,r0
ret = sl->sequence;
smp_rmb();
c00bb740: 73 c0 00 01 andi. r0,r30,1
struct dentry * dentry = NULL;



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