Khem Raj wrote:
On Wed, Jun 16, 2010 at 12:02 PM, Khem Raj <[email protected]> wrote:
On Wed, Jun 9, 2010 at 6:15 PM, Daniel Ng <[email protected]> wrote:
Hi,
I'm using Linux kernel 2.6.30.3 with uClibc 0.9.30.1, on a powerpc (mpc8272)
platform.
It looks like the prctl parameters are not being passed to the kernel properly,
regardless of the the prctl operation I specify.
For example, in the kernel (kernel/sys.c), I have inserted a printk to print out
arg2:
case PR_SET_PDEATHSIG:
printk("PR_SET_PDEATHSIG: 0x%lx\n", arg2);
if (!valid_signal(arg2)) {
error = -EINVAL;
break;
}
-but arg2 always seems to be 0.
This is how I call prctl in userspace:
status = prctl(PR_SET_PDEATHSIG, SIGHUP, NULL, NULL, NULL);
I've also tried the following:
status = prctl(PR_SET_PDEATHSIG, 1, NULL, NULL, NULL);
status = prctl(PR_SET_PDEATHSIG, SIGHUP);
status = prctl(PR_SET_PDEATHSIG, 1);
-they all result in the kernel seeing arg2 as 0.
Is there something I'm missing, or is this a genuine uClibc bug,
or something else?
OK I had a chance to have ppc qemu system to look into it using uclibc
git/linux 2.6.34
the registers before the sc (system call) look correct to me
(gdb) i registers
r0 0xab 171
r1 0xbfeba0d0 3219890384
r2 0x4800f440 1208022080
r3 0x1 1
r4 0x1 1
r5 0x0 0
r6 0x0 0
r7 0x0 0
here r0 contains the syscall number which is 171 = __NR_prctl
and the arguments start from r3 onwards which means r4 contains are
second argument
and seems to be ok.
This is the lame test I executed
#include <sys/prctl.h>
#include <stdio.h>
int main ()
{
return prctl(PR_SET_PDEATHSIG, 1, NULL, NULL, NULL);
}
so as you can see r4 contains the second argument which is 1
I did the same on a sh4 box which runs a 2.6.32-based kernel and got
param correctly passed.
I only tried it on mips arch here and uclibc seems to pass correct
parameters to the syscall. I dont
have ppc system handy so cant test it right now however I would ask
you to reproduce it on latest
master on git if you could do that it will help.
Thanks
-Khem
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