[Patch 3/6] Modify ptrace code to use Hardware Breakpoint interfaces
K.Prasad
prasad at linux.vnet.ibm.com
Wed Jun 10 19:08:13 EST 2009
Modify the ptrace code to use the hardware breakpoint interfaces for user-space.
Signed-off-by: K.Prasad <prasad at linux.vnet.ibm.com>
---
arch/powerpc/kernel/ptrace.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
Index: linux-2.6-tip.hbkpt/arch/powerpc/kernel/ptrace.c
===================================================================
--- linux-2.6-tip.hbkpt.orig/arch/powerpc/kernel/ptrace.c
+++ linux-2.6-tip.hbkpt/arch/powerpc/kernel/ptrace.c
@@ -37,6 +37,7 @@
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/system.h>
+#include <asm/hw_breakpoint.h>
/*
* does not yet catch signals sent when the child dies.
@@ -737,11 +738,24 @@ void user_disable_single_step(struct tas
void ptrace_triggered(struct hw_breakpoint *bp, struct pt_regs *regs)
{
+ /*
+ * Unregister the breakpoint request here since ptrace has defined a
+ * one-shot behaviour for breakpoint exceptions in PPC64.
+ * The SIGTRAP signal is generated automatically for us in do_dabr().
+ * We don't have to do anything here
+ */
+ unregister_user_hw_breakpoint(current, bp);
+ kfree(bp);
}
int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
unsigned long data)
{
+#ifdef CONFIG_PPC64
+ struct thread_struct *thread = &(task->thread);
+ struct hw_breakpoint *bp;
+ int ret;
+#endif
/* For ppc64 we support one DABR and no IABR's at the moment (ppc64).
* For embedded processors we support one DAC and no IAC's at the
* moment.
@@ -771,6 +785,35 @@ int ptrace_set_debugreg(struct task_stru
if (data && !(data & DABR_TRANSLATION))
return -EIO;
+#ifdef CONFIG_PPC64
+ bp = thread->hbp[0];
+ if (data == 0) {
+ if (bp) {
+ unregister_user_hw_breakpoint(task, bp);
+ kfree(bp);
+ }
+ return 0;
+ }
+
+ if (bp) {
+ bp->info.type = data & HW_BREAKPOINT_RW;
+ task->thread.dabr = bp->info.address = data;
+ return modify_user_hw_breakpoint(task, bp);
+ }
+ bp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL);
+ if (!bp)
+ return -ENOMEM;
+
+ /* Store the type of breakpoint */
+ bp->info.type = data & HW_BREAKPOINT_RW;
+ bp->triggered = ptrace_triggered;
+ task->thread.dabr = bp->info.address = data;
+
+ ret = register_user_hw_breakpoint(task, bp);
+ if (ret)
+ return ret;
+#endif /* CONFIG_PPC64 */
+
/* Move contents to the DABR register */
task->thread.dabr = data;
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