Re: force_successful_syscall_return() buggy?

David Mosberger
2003-06-17T18:47:29Z

>>>>> On Tue, 17 Jun 2003 12:24:23 +0530, "Aneesh Kumar K.V" <aneesh.kumar@digital.com> said:

Aneesh> I was facing a simillar problem with ptrace on Alpha (ptrace
Aneesh> on alpha expect the pt_regs at current + 2*PAGE_SIZE for
Aneesh> 2.4. kernel ) w.r.t www.openssi.org project. What i found
Aneesh> was that even after we return to user space subsequent
Aneesh> syscalls are not putting pt_regs at that offset. I guess
Aneesh> while entering the kernel kernel stack pointer always point
Aneesh> to value stored in thread_struct.ksp ?

If a platform doesn't start with an empty kernel stack on entry from
user-space, that platform will be wasting (precious) stack space and
ptrace() most likely won't work reliably. Personally, I'd consider
such behavior a bug, but I suppose it is to some degree a
platform-choice.

--david