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Date: Tue, 29 Mar 2005 20:01:06 -0500
From: ashwin tanugula <ashwin.tanugula@gmail.com>
To: linuxppc-dev@ozlabs.org
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Subject: ptrace and ORIG_EAX on ppc
Reply-To: ashwin tanugula <ashwin.tanugula@gmail.com>
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Hi!
Can somebody tell me how to set references to ORIG_EAX in ppc kernel.
We know ORIG_EAX is defined in unistd.h of i386. How do i make the
following program print two same pids in ppc?

#include <stdio.h>

#include <signal.h>

#include <sys/wait.h>

#include <sys/ptrace.h>

#include <asm/ptrace.h>

#include <asm/unistd.h>



static char stack[65536];



int child(void *arg)

{

if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){

perror("ptrace");

exit(1);

}

kill(getpid(), SIGSTOP);

while(1){

printf("getpid() returned %d\n", getpid());

sleep(3);

}

return(0);

}



int main(int argc, char **argv)

{

int pid, status, syscall;



printf("Parent pid = %d\n", getpid());

if((pid = clone(child, &stack[65532], SIGCHLD, NULL)) < 0){

perror("clone");

exit(1);

}

if((pid = waitpid(pid, &status, WUNTRACED)) < 0){

perror("Waiting for stop");

exit(1);

}

if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0){

perror("continuing");

exit(1);

}

while(1){

if((pid = waitpid(-1, &status, WUNTRACED)) <= 0){

perror("wait");

exit(1);

}

if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)){

syscall = ptrace(PTRACE_PEEKUSER, pid, 4 * ORIG_EAX, 0);

if(syscall == __NR_getpid){

if(ptrace(PTRACE_POKEUSER, pid, 4 * ORIG_EAX, __NR_getppid) < 0){

perror("ptrace");

exit(1);

}

}

if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0){

perror("continuing");

exit(1);

}

}

else printf("wait failed - pid = %d, status = %d\n", pid, status);

}

}



Note: References to ORIG_EAX have to be set here.
Thanks,
Ashwin.