From: "K.Prasad" <prasad@linux•vnet.ibm.com>
To: Alan Stern <stern@rowland•harvard.edu>
Cc: Michael Neuling <mikey@neuling•org>,
Benjamin Herrenschmidt <benh@au1•ibm.com>,
linuxppc-dev@ozlabs•org, paulus@samba•org,
Roland McGrath <roland@redhat•com>
Subject: Re: [RFC Patch 2/6] Introduce PPC64 specific Hardware Breakpointinterfaces
Date: Thu, 21 May 2009 12:45:05 +0530 [thread overview]
Message-ID: <20090521071505.GB9344@in.ibm.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0905181227180.3136-100000@iolanthe.rowland.org>
On Mon, May 18, 2009 at 12:30:41PM -0400, Alan Stern wrote:
> On Mon, 18 May 2009, K.Prasad wrote:
>
> > > > > > +int __kprobes hw_breakpoint_handler(struct die_args *args)
> > > > > > +{
> > > > > > + int rc = NOTIFY_STOP;
> > > > > > + struct hw_breakpoint *bp;
> > > > > > + struct pt_regs *regs = args->regs;
> > > > > > + unsigned long dar;
> > > > > > + int cpu, stepped, is_kernel;
> > > > > > +
> > > > > > + /* Disable breakpoints during exception handling */
> > > > > > + set_dabr(0);
> > > > > > +
> > > > > > + dar = regs->dar & (~HW_BREAKPOINT_ALIGN);
> > > > > > + is_kernel = (dar >= TASK_SIZE) ? 1 : 0;
> > > > >
> > > > > is_kernel_addr() ?
> > > > >
> > > >
> > > > Ok.
> > >
> > > Shouldn't this test hbp_kernel_pos instead?
> > >
> >
> > Testing hbp_kernel_pos should be sufficient for PPC64 with just one
> > breakpoint register. However the above code is more extensible to other
> > PowerPC implementations which have more than one breakpoint register.
>
> Then maybe you don't want to test this at all. Just compare the dar
> value with each of the breakpoint addresses. That's more like what the
> x86 code does.
>
> Alan Stern
>
Comparing the DAR register value with each breakpoint address is
required to determine if the exception is the cause of a breakpoint hit
and I've added the code to hw_breakpoint_handler(). With this check in
place, I find that using hbp_kernel_pos to determine kernel/user space
origin is much easier (as you suggested) and the code is modified
accordingly.
Please find the changes in the new patchset being sent.
Thanks,
K.Prasad
next prev parent reply other threads:[~2009-05-21 7:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20090514133312.360702378@prasadkr_t60p.in.ibm.com>
2009-05-14 13:43 ` [RFC Patch 1/6] Prepare the PowerPC platform for HW Breakpoint infrastructure K.Prasad
2009-05-18 3:35 ` Benjamin Herrenschmidt
2009-05-18 16:15 ` K.Prasad
2009-05-14 13:44 ` [RFC Patch 2/6] Introduce PPC64 specific Hardware Breakpoint interfaces K.Prasad
2009-05-14 14:50 ` Michael Ellerman
2009-05-14 19:50 ` [RFC Patch 2/6] Introduce PPC64 specific Hardware Breakpointinterfaces K.Prasad
2009-05-14 20:20 ` Alan Stern
2009-05-18 16:10 ` K.Prasad
2009-05-18 16:30 ` Alan Stern
2009-05-21 7:15 ` K.Prasad [this message]
2009-05-14 13:45 ` [RFC Patch 3/6] Modify ptrace code to use Hardware Breakpoint interfaces K.Prasad
2009-05-14 13:45 ` [RFC Patch 4/6] Modify process handling code to handle hardware debug registers K.Prasad
2009-05-14 14:54 ` Michael Ellerman
2009-05-14 13:45 ` [RFC Patch 5/6] Modify Data storage exception code to recognise DABR match first K.Prasad
2009-05-14 13:46 ` [RFC Patch 6/6] Adapt kexec and samples code to recognise PPC64 hardware breakpoint usage K.Prasad
2009-05-14 13:59 ` Geert Uytterhoeven
2009-05-14 14:11 ` Michael Ellerman
2009-05-14 14:18 ` Geert Uytterhoeven
2009-05-14 14:55 ` Michael Ellerman
2009-05-14 19:15 ` [RFC Patch 6/6] Adapt kexec and samples code to recognise PPC64hardware " K.Prasad
2009-05-14 20:21 ` [RFC Patch 6/6] Adapt kexec and samples code to recognise PPC64 hardware " Alan Stern
2009-05-18 16:11 ` [RFC Patch 6/6] Adapt kexec and samples code to recognise PPC64hardware " K.Prasad
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090521071505.GB9344@in.ibm.com \
--to=prasad@linux$(echo .)vnet.ibm.com \
--cc=benh@au1$(echo .)ibm.com \
--cc=linuxppc-dev@ozlabs$(echo .)org \
--cc=mikey@neuling$(echo .)org \
--cc=paulus@samba$(echo .)org \
--cc=roland@redhat$(echo .)com \
--cc=stern@rowland$(echo .)harvard.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox