Re: [uml-devel] 2.4.22-[67] problems

[Matt Zimmerman <mdz@debian.org>]

On Sun, Dec 28, 2003 at 01:51:15AM -0800, Matt Zimmerman wrote:

> This is making less and less sense.  handle_trap has this code:
> 
> 	syscall_nr = PT_SYSCALL_NR(regs->skas.regs);
> 	UPT_SYSCALL_NR(regs) = syscall_nr;
> 	if(syscall_nr < 1){
> 		relay_signal(SIGTRAP, regs);
> 		return;
> 	}
> 
> As I understand it, PT_SYSCALL_NR refers to ORIG_EAX, and UPT_SYSCALL_NR
> refers to skas.syscall.  i.e., syscall=0 can't happen.  So either things are
> not as they seem, or something is happening to regs between here and
> execute_syscall_skas.

[a few hundred printf's later]

So, the sequence of events in handle_trap is this:

1. UPT_SYSCALL_NR(regs) == 78

2. ptrace(PTRACE_POKEUSER,...)

3. UPT_SYSCALL_NR(regs) == 78 (still OK)

4. ptrace(PTRACE_SYSCALL,...)

5. UPT_SYSCALL_NR(regs) == 78 (still OK)

6. waitpid(pid,...)

7. UPT_SYSCALL_NR(regs) == 0 (boom)

I have no idea why.

-- 
 - mdz


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