Re: No PTRACE_READDATA for archs other than SPARC?

David S. Miller (davem@redhat.com)
Sun, 19 May 2002 21:40:53 -0700 (PDT)


From: Pradeep Padala <ppadala@cise.ufl.edu>
Date: Sun, 19 May 2002 23:08:36 -0400 (EDT)

I was trying to understand ptrace code in kernel. It seems there's
no PTRACE_READDATA for architectures other than sparc and sparc64.
There's a function named ptrace_readdata() in kernel/ptrace.c but I
couldn't find a way to invoke it from user space. Is the feature
missing? or Is it intended?

Only Sparc implements this, that is correct.

If other platforms added PTRACE_READDATA support, they would
also need to add some way to do a feature test for it's presence
so that GDB and other debugging code could actually make use
of it portably.

Another thing I noticed, the prototype for do_ptrace() in
arch/sparc/kernel/ptrace.c is

asmlinkage void do_ptrace(struct pt_regs *regs)

I thought it should be some thing like
asmlinkage int sys_ptrace(long request, long pid, long addr, long
data)

The return values are set directly in the user's pt_regs.
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