Commit 1b788400 authored by K.Prasad's avatar K.Prasad Committed by Benjamin Herrenschmidt
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powerpc/hw-breakpoint: Use generic hw-breakpoint interfaces for new PPC ptrace flags 



PPC_PTRACE_GETHWDBGINFO, PPC_PTRACE_SETHWDEBUG and PPC_PTRACE_DELHWDEBUG are
PowerPC specific ptrace flags that use the watchpoint register. While they are
targeted primarily towards BookE users, user-space applications such as GDB
have started using them for BookS too. This patch enables the use of generic
hardware breakpoint interfaces for these new flags.

Apart from the usual benefits of using generic hw-breakpoint interfaces, these
changes allow debuggers (such as GDB) to use a common set of ptrace flags for
their watchpoint needs and allow more precise breakpoint specification (length
of the variable can be specified).

Signed-off-by: default avatarK.Prasad <prasad@linux.vnet.ibm.com>
Acked-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 404e32e4

Documentation/powerpc/ptrace.txt

+16 −0
Original line number Diff line number Diff line
@@ -127,6 +127,22 @@ Some examples of using the structure to: 
  p.addr2           = (uint64_t) end_range;

  p.condition_value = 0;



- set a watchpoint in server processors (BookS)



  p.version         = 1;

  p.trigger_type    = PPC_BREAKPOINT_TRIGGER_RW;

  p.addr_mode       = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE;

  or

  p.addr_mode       = PPC_BREAKPOINT_MODE_EXACT;



  p.condition_mode  = PPC_BREAKPOINT_CONDITION_NONE;

  p.addr            = (uint64_t) begin_range;

  /* For PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE addr2 needs to be specified, where

   * addr2 - addr <= 8 Bytes.

   */

  p.addr2           = (uint64_t) end_range;

  p.condition_value = 0;



3. PTRACE_DELHWDEBUG



Takes an integer which identifies an existing breakpoint or watchpoint

arch/powerpc/kernel/ptrace.c

+71 −6
Original line number Diff line number Diff line
@@ -1336,6 +1336,12 @@ static int set_dac_range(struct task_struct *child, 
static long ppc_set_hwdebug(struct task_struct *child,

		     struct ppc_hw_breakpoint *bp_info)

{

#ifdef CONFIG_HAVE_HW_BREAKPOINT

	int len = 0;

	struct thread_struct *thread = &(child->thread);

	struct perf_event *bp;

	struct perf_event_attr attr;

#endif /* CONFIG_HAVE_HW_BREAKPOINT */

#ifndef CONFIG_PPC_ADV_DEBUG_REGS

	unsigned long dabr;

#endif
@@ -1379,13 +1385,9 @@ static long ppc_set_hwdebug(struct task_struct *child, 
	 */

	if ((bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_RW) == 0 ||

	    (bp_info->trigger_type & ~PPC_BREAKPOINT_TRIGGER_RW) != 0 ||

	    bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT ||

	    bp_info->condition_mode != PPC_BREAKPOINT_CONDITION_NONE)

		return -EINVAL;



	if (child->thread.dabr)

		return -ENOSPC;



	if ((unsigned long)bp_info->addr >= TASK_SIZE)

		return -EIO;
@@ -1395,15 +1397,63 @@ static long ppc_set_hwdebug(struct task_struct *child, 
		dabr |= DABR_DATA_READ;

	if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)

		dabr |= DABR_DATA_WRITE;

#ifdef CONFIG_HAVE_HW_BREAKPOINT

	if (ptrace_get_breakpoints(child) < 0)

		return -ESRCH;



	child->thread.dabr = dabr;

	/*

	 * Check if the request is for 'range' breakpoints. We can

	 * support it if range < 8 bytes.

	 */

	if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE) {

		len = bp_info->addr2 - bp_info->addr;

	} else if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT) {

		ptrace_put_breakpoints(child);

		return -EINVAL;

	}

	bp = thread->ptrace_bps[0];

	if (bp) {

		ptrace_put_breakpoints(child);

		return -ENOSPC;

	}



	/* Create a new breakpoint request if one doesn't exist already */

	hw_breakpoint_init(&attr);

	attr.bp_addr = (unsigned long)bp_info->addr & ~HW_BREAKPOINT_ALIGN;

	attr.bp_len = len;

	arch_bp_generic_fields(dabr & (DABR_DATA_WRITE | DABR_DATA_READ),

								&attr.bp_type);



	thread->ptrace_bps[0] = bp = register_user_hw_breakpoint(&attr,

					       ptrace_triggered, NULL, child);

	if (IS_ERR(bp)) {

		thread->ptrace_bps[0] = NULL;

		ptrace_put_breakpoints(child);

		return PTR_ERR(bp);

	}



	ptrace_put_breakpoints(child);

	return 1;

#endif /* CONFIG_HAVE_HW_BREAKPOINT */



	if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)

		return -EINVAL;



	if (child->thread.dabr)

		return -ENOSPC;



	child->thread.dabr = dabr;

	return 1;

#endif /* !CONFIG_PPC_ADV_DEBUG_DVCS */

}



static long ppc_del_hwdebug(struct task_struct *child, long addr, long data)

{

#ifdef CONFIG_HAVE_HW_BREAKPOINT

	int ret = 0;

	struct thread_struct *thread = &(child->thread);

	struct perf_event *bp;

#endif /* CONFIG_HAVE_HW_BREAKPOINT */

#ifdef CONFIG_PPC_ADV_DEBUG_REGS

	int rc;
@@ -1423,10 +1473,25 @@ static long ppc_del_hwdebug(struct task_struct *child, long addr, long data) 
#else

	if (data != 1)

		return -EINVAL;



#ifdef CONFIG_HAVE_HW_BREAKPOINT

	if (ptrace_get_breakpoints(child) < 0)

		return -ESRCH;



	bp = thread->ptrace_bps[0];

	if (bp) {

		unregister_hw_breakpoint(bp);

		thread->ptrace_bps[0] = NULL;

	} else

		ret = -ENOENT;

	ptrace_put_breakpoints(child);

	return ret;

#else /* CONFIG_HAVE_HW_BREAKPOINT */

	if (child->thread.dabr == 0)

		return -ENOENT;



	child->thread.dabr = 0;

#endif /* CONFIG_HAVE_HW_BREAKPOINT */



	return 0;

#endif
@@ -1533,7 +1598,7 @@ long arch_ptrace(struct task_struct *child, long request, 
		dbginfo.data_bp_alignment = 4;

#endif

		dbginfo.sizeof_condition = 0;

		dbginfo.features = 0;

		dbginfo.features = PPC_DEBUG_FEATURE_DATA_BP_RANGE;

#endif /* CONFIG_PPC_ADV_DEBUG_REGS */



		if (!access_ok(VERIFY_WRITE, datavp,

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