| Message ID | 20090727001324.GD13562@in.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | David Gibson |
| Headers | show |
On Mon, Jul 27, 2009 at 05:48:27AM +0530, K.Prasad wrote: > Modify the ptrace code to use the hardware breakpoint interfaces for user-space. > > Signed-off-by: K.Prasad <prasad@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. > @@ -757,11 +758,24 @@ 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); This unregisters the breakpoint, but doesn't actually abort the current breakpoint handling sequence it's invoked from. So, if your breakpoint handler was invoked at all, which as previously mentioned, I don't think it is, wouldn't this result in *two* SIGTRAPs from a ptrace breakpoint: one issued before the trapping instruction from do_dabr() and another afterwards from your step-over code. > } > > 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. > @@ -791,6 +805,35 @@ 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; > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >
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. @@ -757,11 +758,24 @@ 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. @@ -791,6 +805,35 @@ 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;
Modify the ptrace code to use the hardware breakpoint interfaces for user-space. Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com> --- arch/powerpc/kernel/ptrace.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+)