Messages in this thread | | | Date | Fri, 19 Feb 2010 23:28:59 +0530 | From | "K.Prasad" <> | Subject | Re: [PATCH 2/2] hw-breakpoint: Keep track of dr7 local enable bits |
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On Fri, Feb 19, 2010 at 04:34:03PM +0100, Frederic Weisbecker wrote: > 2010/2/19 K.Prasad <prasad@linux.vnet.ibm.com>: > > So, the thread's copy of DR7 (in thread->ptrace_dr7) stores the > > requested data even if the 'write' onto DR7 i.e. ptrace_write_dr7() > > failed. This can be the other way round i.e. populate the thread's copy > > of DR7 only if the write was successful. > > > > No. We store the new dr7 value only if ptrace_set_dr7() didn't fail. > > > > > I think it will be in consonance with the v2.6.32 behaviour as well. For > > instance, in the code snippet from ptrace_set_debugreg() in v2.6.32 > > below: > > for (i = 0; i < 4; i++) > > if ((DR7_MASK >> ((data >> (16 + 4*i)) & 0xf)) & 1) > > return -EIO; > > child->thread.debugreg7 = data; > > > > The thread's copy of DR7 is populated only if the incoming data is > > found to be valid. > > > This is also what does this patch. thread->ptrace_dr7 is only > changed if ptrace_set_dr7() succeeded. > > Thanks.
hmmh...I see...looks like I experienced single-bit ECC as I read the patch :-) Yes, let debugreg7 store values only when a valid bkpt request comes in.
Thanks, K.Prasad
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