On Mon, Dec 13, 2010 at 08:05:36PM +0100, Andreas Schwab wrote:
> "K.Prasad" <pra...@linux.vnet.ibm.com> writes:
>
> > +#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;
>
> That cannot work, see
> <http://permalink.gmane.org/gmane.linux.ports.ppc64.devel/71418>.
>
Ok. The above patch makes it a bit easy.
How about the revised patch below? It is only compile-tested; have you
got a quick test case that I can run?
Enable PPC_PTRACE_SETHWDEBUG and PPC_PTRACE_DELHWDEBUG to use the generic
hardware breakpoint interfaces. This helps prevent conflict for the use of
DABR register in the absence of CONFIG_PPC_ADV_DEBUG_REGS and when
PTRACE_SET_DEBUGREG/PTRACE_GET_DEBUGREG flags are used by ptrace.
Signed-off-by: K.Prasad <pra...@linux.vnet.ibm.com>
---
arch/powerpc/kernel/ptrace.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 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 +1316,10 @@ 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 */
#ifndef CONFIG_PPC_ADV_DEBUG_REGS
unsigned long dabr;
#endif
@@ -1365,6 +1369,10 @@ 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;
@@ -1376,6 +1384,20 @@ static long ppc_set_hwdebug(struct task_
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
dabr |= DABR_DATA_WRITE;
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ /* Create a new breakpoint request if one doesn't exist already */
+ hw_breakpoint_init(&attr);
+ attr.bp_addr = dabr & ~HW_BREAKPOINT_ALIGN;
+ arch_bp_generic_fields(dabr & (DABR_DATA_WRITE | DABR_DATA_READ),
+ &attr.bp_type);
+
+ bp = register_user_hw_breakpoint(&attr, ptrace_triggered, child);
+ if (IS_ERR(bp))
+ return PTR_ERR(bp);
+
+ child->thread.ptrace_bps[0] = bp;
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
child->thread.dabr = dabr;
return 1;
@@ -1405,6 +1427,16 @@ 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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