On Wed, Dec 01, 2010 at 10:07:58AM +0530, K.Prasad wrote:
> On Mon, Nov 29, 2010 at 11:15:51AM +0100, Andreas Schwab wrote:
> > "K.Prasad" <pra...@linux.vnet.ibm.com> writes:
> >
> > > Although ppc_set_hwdebug() can set DABR through set_dabr() in
> > > arch/powerpc/kernel/process.c, it is good to have it converted to use
> > > register_user_hw_breakpoint().
> >
> > What do you mean with "good to have"? It doesn't work without it unless
> > I disable PERF_EVENTS (which is the only way to disable
> > HAVE_HW_BREAKPOINT).
> >
> > Andreas.
> >
>
> Let me see if I can cook up a patch for this i.e. make set_dabr() invoke
> register_user_hw_breakpoint() when CONFIG_PPC_BOOK3S is defined; before I
> head out on my vacation (starting second week of this month).
>
> Thanks,
> K.Prasad
>
Hi,
Can you check if the following patch (compile tested only) works
for you?
Thanks,
K.Prasad
Signed-off-by: K.Prasad <pra...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/ptrace.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
Index: linux-2.6.set_hwdebug/arch/powerpc/kernel/ptrace.c
===================================================================
--- linux-2.6.set_hwdebug.orig/arch/powerpc/kernel/ptrace.c
+++ linux-2.6.set_hwdebug/arch/powerpc/kernel/ptrace.c
@@ -1316,6 +1316,11 @@ static int set_dac_range(struct task_str
static long ppc_set_hwdebug(struct task_struct *child,
struct ppc_hw_breakpoint *bp_info)
{
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ struct perf_event *bp;
+ struct perf_event_attr attr;
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
if (bp_info->version != 1)
return -ENOTSUPP;
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
@@ -1362,10 +1367,29 @@ static long ppc_set_hwdebug(struct task_
if (child->thread.dabr)
return -ENOSPC;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ if (child->thread->ptrace_bps[0])
+ return -ENOSPC;
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
if ((unsigned long)bp_info->addr >= TASK_SIZE)
return -EIO;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ /* Create a new breakpoint request if one doesn't exist already */
+ hw_breakpoint_init(&attr);
+ attr.bp_addr = bp_info->addr & ~HW_BREAKPOINT_ALIGN;
+ arch_bp_generic_fields(bp_info->addr &
+ (DABR_DATA_WRITE | DABR_DATA_READ),
+ &attr.bp_type);
+
+ bp = register_user_hw_breakpoint(&attr, ptrace_triggered, task);
+ if (IS_ERR(bp))
+ return PTR_ERR(bp);
+
+ child->thread.ptrace_bps[0] = bp;
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
child->thread.dabr = (unsigned long)bp_info->addr;
return 1;
@@ -1395,6 +1419,16 @@ static long ppc_del_hwdebug(struct task_
return -EINVAL;
if (child->thread.dabr == 0)
return -ENOENT;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ /*
+ * There is no way by which address in ptrace_bps[0] and thread.dabr
+ * can be different. So we don't explicitly check if they're the same
+ */
+ if (child->thread.ptrace_bps[0]) {
+ unregister_hw_breakpoint(child->thread.ptrace_bps[0]);
+ child->thread.ptrace_bps[0] = NULL;
+ }
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
child->thread.dabr = 0;
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