Messages in this thread | | | Date | Tue, 22 Jun 2010 11:14:29 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH v5 3/14] User Space Breakpoint Assistance Layer |
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> > +/** > > + * user_bkpt_write_data - Write @nbytes from @kbuf at @vaddr in @tsk. > > + * Can be used to write to stack or data VM areas, but not instructions. > > + * Not exported, but available for use by arch-specific user_bkpt code. > > + * @tsk: The probed task > > + * @vaddr: Destination address, in user space. > > + * @kbuf: Source address, in kernel space to be read. > > I'm curious. Anything prevent this from being called on instructions, or > is this just "Don't do that?". >
Both, copy_to_user doesnt work on writes to text. And if I am right, copy_to_user isnt preferred while writing to text pages too.
> > + > > + memcpy(vaddr_new, vaddr_old, PAGE_SIZE); > > + /* poke the new insn in, ASSUMES we don't cross page boundary */ > > + vaddr = vaddr & (PAGE_SIZE - 1); > > This should probably be vaddr = vaddr & ~PAGE_MASK;
Okay, I will make the corresponding change. > >
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