----- Original Message -----
> From: chru...@suse.cz
> To: "Jan Stancek" <jstan...@redhat.com>
> Cc: ltp-list@lists.sourceforge.net
> Sent: Monday, 25 August, 2014 2:48:38 PM
> Subject: Re: [LTP] [PATCH] sendmsg02: fix parameter passed to semctl(SETVAL)
>
> Hi!
> > The fourth has the type union semun.
>
> The change looks good. I guess that this may have been failing on some
> big endian machine where sizeof(void*) != sizeof(int), am I right?
You're right it was big endian machine, but with sizeof(void *) == 4 and
sizeof(int) == 4.
Fourth parameter is expected to be passed by reference,
so it was actually crashing on RHEL5.10 ppc:
void func()
{
union semun a;
a.val = 0;
semctl(123, 456, SETVAL, a);
}
(gdb) disassemble func
Dump of assembler code for function func:
0x1000047c <func+0>: stwu r1,-48(r1)
0x10000480 <func+4>: mflr r0
0x10000484 <func+8>: stw r31,44(r1)
0x10000488 <func+12>: stw r0,52(r1)
0x1000048c <func+16>: mr r31,r1
0x10000490 <func+20>: li r0,0
0x10000494 <func+24>: stw r0,8(r31)
0x10000498 <func+28>: lwz r0,8(r31)
0x1000049c <func+32>: stw r0,24(r31)
0x100004a0 <func+36>: addi r0,r31,24
0x100004a4 <func+40>: li r3,123
0x100004a8 <func+44>: li r4,456
0x100004ac <func+48>: li r5,16
0x100004b0 <func+52>: mr r6,r0
0x100004b4 <func+56>: crclr 4*cr1+eq
0x100004b8 <func+60>: bl 0x10000870 <semctl@plt>
0x100004bc <func+64>: lwz r11,0(r1)
0x100004c0 <func+68>: lwz r0,4(r11)
0x100004c4 <func+72>: mtlr r0
0x100004c8 <func+76>: lwz r31,-4(r11)
0x100004cc <func+80>: mr r1,r11
0x100004d0 <func+84>: blr
End of assembler dump.
(gdb) b *0x100004b8
Breakpoint 1 at 0x100004b8: file a.c, line 18.
(gdb) r
Starting program:
/mnt/tests/scratch/jstancek2/ltp-full-20140820/testcases/kernel/syscalls/sendmsg/a.out
Breakpoint 1, 0x100004b8 in func () at a.c:18
18 semctl(123, 456, SETVAL, a);
(gdb) p &a
$1 = (union semun *) 0xffacf488
(gdb) p/x $r6
$2 = 0xffacf498
Regards,
Jan
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