Hi Wenji,
while I cannot comment on your kernel code analysis the testcase was definitely
broken since 2008-02-03 - it never PASSed. It should be fixed now.
/* We must set PC to our new function as the current PC stays in the glibc
function RAISE no matter which part of the code called it - we would have
to save and restore the whole stack for a proper restart of the code. */
I was not sure of its correctness, sorry for the delay.
Regards,
Jan
On Thu, 13 Mar 2008 10:25:04 +0100, Wenji Huang wrote:
> Hi,
>
> I made tests of step-jump-cont (utrace wiki page) on i686 and x86_64 with
> upstream 2.6.24 kernel. They have different behaviors.
>
> With help of assert statement and stap script, I got the following
> understandings:
>
> For i686:
> 1. Wait child stop upon SIGUSR1
> 2. Set singlestep on child : child->ptrace |= PT_DTRACE &&
> regs->eflags |= TRAP_FLAG
> 3. Change child regs->eflags |= TRAP_FLAG
> 4. Continue the child and clear child->ptrace and regs->eflags due to
> passed checking child->ptrace
> 5. Wait child stop, got signal SIGUSR2
> 6. Change the child regs->eflags |= TRAP_FLAG
> 7. Continue the child, but couldn't clear regs->eflags due to failed
> checking child->ptrace
> 8. Wait child, but got signal SIGTRAP due to eflags (Child stop on
> sending SIGUSR2)
>
> For x86_64:
> 1. Wait child stop upon SIGUSR1
> 2. Set singlestep on child : child->ptrace |= PT_DTRACE &&
> regs->eflags |= TRAP_FLAG.
> (*** But these are missing after the syscall ***)
> 3. Change child regs->eflags |= TRAP_FLAG
> 4. Continue the child, but couldn't clear regs->eflags due to failed
> checking child->ptrace
> 5. Wait child, but got signal SIGTRAP due to eflags (Child stop on
> sending SIGUSR1).
>
> So I think it may be correct in i686 case, just need to change testcase.
> But it looks like there are some problems in x86_64 code.
>
> Regards,
> Wenji
