gdb/nat/aarch64-linux-hw-point.c - binutils-gdb - Git at Google

 /* Copyright (C) 2009-2025 Free Software Foundation, Inc.
    Contributed by ARM Ltd.

    This file is part of GDB.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

 #include "gdbsupport/break-common.h"
 #include "gdbsupport/common-regcache.h"
 #include "nat/linux-nat.h"
 #include "aarch64-linux-hw-point.h"

 #include <sys/uio.h>

 /* The order in which <sys/ptrace.h> and <asm/ptrace.h> are included
    can be important.  <sys/ptrace.h> often declares various PTRACE_*
    enums.  <asm/ptrace.h> often defines preprocessor constants for
    these very same symbols.  When that's the case, build errors will
    result when <asm/ptrace.h> is included before <sys/ptrace.h>.  */
 #include <sys/ptrace.h>
 #include <asm/ptrace.h>

 #include <elf.h>

 /* See aarch64-linux-hw-point.h  */

 bool kernel_supports_any_contiguous_range = true;

 /* Helper for aarch64_notify_debug_reg_change.  Records the
    information about the change of one hardware breakpoint/watchpoint
    setting for the thread LWP.
    N.B.  The actual updating of hardware debug registers is not
    carried out until the moment the thread is resumed.  */

 static int
 debug_reg_change_callback (struct lwp_info *lwp, int is_watchpoint,
 			   unsigned int idx)
 {
   int tid = ptid_of_lwp (lwp).lwp ();
   struct arch_lwp_info *info = lwp_arch_private_info (lwp);
   dr_changed_t *dr_changed_ptr;
   dr_changed_t dr_changed;

   if (info == NULL)
     {
       info = XCNEW (struct arch_lwp_info);
       lwp_set_arch_private_info (lwp, info);
     }

   if (show_debug_regs)
     {
       debug_printf ("debug_reg_change_callback: \n\tOn entry:\n");
       debug_printf ("\ttid%d, dr_changed_bp=0x%s, "
 		    "dr_changed_wp=0x%s\n", tid,
 		    phex (info->dr_changed_bp, 8),
 		    phex (info->dr_changed_wp, 8));
     }

   dr_changed_ptr = is_watchpoint ? &info->dr_changed_wp
     : &info->dr_changed_bp;
   dr_changed = *dr_changed_ptr;

   gdb_assert (idx >= 0
 	      && (idx <= (is_watchpoint ? aarch64_num_wp_regs
 			  : aarch64_num_bp_regs)));

   /* The actual update is done later just before resuming the lwp,
      we just mark that one register pair needs updating.  */
   DR_MARK_N_CHANGED (dr_changed, idx);
   *dr_changed_ptr = dr_changed;

   /* If the lwp isn't stopped, force it to momentarily pause, so
      we can update its debug registers.  */
   if (!lwp_is_stopped (lwp))
     linux_stop_lwp (lwp);

   if (show_debug_regs)
     {
       debug_printf ("\tOn exit:\n\ttid%d, dr_changed_bp=0x%s, "
 		    "dr_changed_wp=0x%s\n", tid,
 		    phex (info->dr_changed_bp, 8),
 		    phex (info->dr_changed_wp, 8));
     }

   return 0;
 }

 /* Notify each thread that their IDXth breakpoint/watchpoint register
    pair needs to be updated.  The message will be recorded in each
    thread's arch-specific data area, the actual updating will be done
    when the thread is resumed.  */

 void
 aarch64_notify_debug_reg_change (ptid_t ptid,
 				 int is_watchpoint, unsigned int idx)
 {
   ptid_t pid_ptid = ptid_t (ptid.pid ());

   iterate_over_lwps (pid_ptid, [=] (struct lwp_info *info)
 			       {
 				 return debug_reg_change_callback (info,
 								   is_watchpoint,
 								   idx);
 			       });
 }

 /* Reconfigure STATE to be compatible with Linux kernels with the PR
    external/20207 bug.  This is called when
    KERNEL_SUPPORTS_ANY_CONTIGUOUS_RANGE transitions to false.  Note we
    don't try to support combining watchpoints with matching (and thus
    shared) masks, as it's too late when we get here.  On buggy
    kernels, GDB will try to first setup the perfect matching ranges,
    which will run out of registers before this function can merge
    them.  It doesn't look like worth the effort to improve that, given
    eventually buggy kernels will be phased out.  */

 static void
 aarch64_downgrade_regs (struct aarch64_debug_reg_state *state)
 {
   for (int i = 0; i < aarch64_num_wp_regs; ++i)
     if ((state->dr_ctrl_wp[i] & 1) != 0)
       {
 	gdb_assert (state->dr_ref_count_wp[i] != 0);
 	uint8_t mask_orig = (state->dr_ctrl_wp[i] >> 5) & 0xff;
 	gdb_assert (mask_orig != 0);
 	static const uint8_t old_valid[] = { 0x01, 0x03, 0x0f, 0xff };
 	uint8_t mask = 0;
 	for (const uint8_t old_mask : old_valid)
 	  if (mask_orig <= old_mask)
 	    {
 	      mask = old_mask;
 	      break;
 	    }
 	gdb_assert (mask != 0);

 	/* No update needed for this watchpoint?  */
 	if (mask == mask_orig)
 	  continue;
 	state->dr_ctrl_wp[i] |= mask << 5;
 	state->dr_addr_wp[i]
 	  = align_down (state->dr_addr_wp[i], AARCH64_HWP_ALIGNMENT);

 	/* Try to match duplicate entries.  */
 	for (int j = 0; j < i; ++j)
 	  if ((state->dr_ctrl_wp[j] & 1) != 0
 	      && state->dr_addr_wp[j] == state->dr_addr_wp[i]
 	      && state->dr_addr_orig_wp[j] == state->dr_addr_orig_wp[i]
 	      && state->dr_ctrl_wp[j] == state->dr_ctrl_wp[i])
 	    {
 	      state->dr_ref_count_wp[j] += state->dr_ref_count_wp[i];
 	      state->dr_ref_count_wp[i] = 0;
 	      state->dr_addr_wp[i] = 0;
 	      state->dr_addr_orig_wp[i] = 0;
 	      state->dr_ctrl_wp[i] &= ~1;
 	      break;
 	    }

 	aarch64_notify_debug_reg_change (current_lwp_ptid (),
 					 1 /* is_watchpoint */, i);
       }
 }

 /* Call ptrace to set the thread TID's hardware breakpoint/watchpoint
    registers with data from *STATE.  */

 void
 aarch64_linux_set_debug_regs (struct aarch64_debug_reg_state *state,
 			      int tid, int watchpoint)
 {
   int i, count;
   struct iovec iov;
   struct user_hwdebug_state regs;
   const CORE_ADDR *addr;
   const unsigned int *ctrl;

   memset (&regs, 0, sizeof (regs));
   iov.iov_base = &regs;
   count = watchpoint ? aarch64_num_wp_regs : aarch64_num_bp_regs;
   addr = watchpoint ? state->dr_addr_wp : state->dr_addr_bp;
   ctrl = watchpoint ? state->dr_ctrl_wp : state->dr_ctrl_bp;
   if (count == 0)
     return;
   iov.iov_len = (offsetof (struct user_hwdebug_state, dbg_regs)
 		 + count * sizeof (regs.dbg_regs[0]));

   for (i = 0; i < count; i++)
     {
       regs.dbg_regs[i].addr = addr[i];
       regs.dbg_regs[i].ctrl = ctrl[i];
     }

   if (ptrace (PTRACE_SETREGSET, tid,
 	      watchpoint ? NT_ARM_HW_WATCH : NT_ARM_HW_BREAK,
 	      (void *) &iov))
     {
       /* Handle Linux kernels with the PR external/20207 bug.  */
       if (watchpoint && errno == EINVAL
 	  && kernel_supports_any_contiguous_range)
 	{
 	  kernel_supports_any_contiguous_range = false;
 	  aarch64_downgrade_regs (state);
 	  aarch64_linux_set_debug_regs (state, tid, watchpoint);
 	  return;
 	}
       error (_("Unexpected error setting hardware debug registers"));
     }
 }

 /* Return true if debug arch level is compatible for hw watchpoints
    and breakpoints.  */

 static bool
 compatible_debug_arch (unsigned int debug_arch)
 {
   if (debug_arch == AARCH64_DEBUG_ARCH_V8)
     return true;
   if (debug_arch == AARCH64_DEBUG_ARCH_V8_1)
     return true;
   if (debug_arch == AARCH64_DEBUG_ARCH_V8_2)
     return true;
   if (debug_arch == AARCH64_DEBUG_ARCH_V8_4)
     return true;
   if (debug_arch == AARCH64_DEBUG_ARCH_V8_8)
     return true;
   if (debug_arch == AARCH64_DEBUG_ARCH_V8_9)
     return true;

   return false;
 }

 /* Get the hardware debug register capacity information from the
    process represented by TID.  */

 void
 aarch64_linux_get_debug_reg_capacity (int tid)
 {
   struct iovec iov;
   struct user_hwdebug_state dreg_state;

   iov.iov_base = &dreg_state;
   iov.iov_len = sizeof (dreg_state);

   /* Get hardware watchpoint register info.  */
   if (ptrace (PTRACE_GETREGSET, tid, NT_ARM_HW_WATCH, &iov) == 0
       && compatible_debug_arch (AARCH64_DEBUG_ARCH (dreg_state.dbg_info)))
     {
       aarch64_num_wp_regs = AARCH64_DEBUG_NUM_SLOTS (dreg_state.dbg_info);
       if (aarch64_num_wp_regs > AARCH64_HWP_MAX_NUM)
 	{
 	  warning (_("Unexpected number of hardware watchpoint registers"
 		     " reported by ptrace, got %d, expected %d."),
 		   aarch64_num_wp_regs, AARCH64_HWP_MAX_NUM);
 	  aarch64_num_wp_regs = AARCH64_HWP_MAX_NUM;
 	}
     }
   else
     {
       warning (_("Unable to determine the number of hardware watchpoints"
 		 " available."));
       aarch64_num_wp_regs = 0;
     }

   /* Get hardware breakpoint register info.  */
   if (ptrace (PTRACE_GETREGSET, tid, NT_ARM_HW_BREAK, &iov) == 0
       && compatible_debug_arch (AARCH64_DEBUG_ARCH (dreg_state.dbg_info)))
     {
       aarch64_num_bp_regs = AARCH64_DEBUG_NUM_SLOTS (dreg_state.dbg_info);
       if (aarch64_num_bp_regs > AARCH64_HBP_MAX_NUM)
 	{
 	  warning (_("Unexpected number of hardware breakpoint registers"
 		     " reported by ptrace, got %d, expected %d."),
 		   aarch64_num_bp_regs, AARCH64_HBP_MAX_NUM);
 	  aarch64_num_bp_regs = AARCH64_HBP_MAX_NUM;
 	}
     }
   else
     {
       warning (_("Unable to determine the number of hardware breakpoints"
 		 " available."));
       aarch64_num_bp_regs = 0;
     }
 }
	/* Copyright (C) 2009-2025 Free Software Foundation, Inc.
	Contributed by ARM Ltd.

	This file is part of GDB.

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program. If not, see <http://www.gnu.org/licenses/>. */

	#include "gdbsupport/break-common.h"
	#include "gdbsupport/common-regcache.h"
	#include "nat/linux-nat.h"
	#include "aarch64-linux-hw-point.h"

	#include <sys/uio.h>

	/* The order in which <sys/ptrace.h> and <asm/ptrace.h> are included
	can be important. <sys/ptrace.h> often declares various PTRACE_*
	enums. <asm/ptrace.h> often defines preprocessor constants for
	these very same symbols. When that's the case, build errors will
	result when <asm/ptrace.h> is included before <sys/ptrace.h>. */
	#include <sys/ptrace.h>
	#include <asm/ptrace.h>

	#include <elf.h>

	/* See aarch64-linux-hw-point.h */

	bool kernel_supports_any_contiguous_range = true;

	/* Helper for aarch64_notify_debug_reg_change. Records the
	information about the change of one hardware breakpoint/watchpoint
	setting for the thread LWP.
	N.B. The actual updating of hardware debug registers is not
	carried out until the moment the thread is resumed. */

	static int
	debug_reg_change_callback (struct lwp_info *lwp, int is_watchpoint,
	unsigned int idx)
	{
	int tid = ptid_of_lwp (lwp).lwp ();
	struct arch_lwp_info *info = lwp_arch_private_info (lwp);
	dr_changed_t *dr_changed_ptr;
	dr_changed_t dr_changed;

	if (info == NULL)
	{
	info = XCNEW (struct arch_lwp_info);
	lwp_set_arch_private_info (lwp, info);
	}

	if (show_debug_regs)
	{
	debug_printf ("debug_reg_change_callback: \n\tOn entry:\n");
	debug_printf ("\ttid%d, dr_changed_bp=0x%s, "
	"dr_changed_wp=0x%s\n", tid,
	phex (info->dr_changed_bp, 8),
	phex (info->dr_changed_wp, 8));
	}

	dr_changed_ptr = is_watchpoint ? &info->dr_changed_wp
	: &info->dr_changed_bp;
	dr_changed = *dr_changed_ptr;

	gdb_assert (idx >= 0
	&& (idx <= (is_watchpoint ? aarch64_num_wp_regs
	: aarch64_num_bp_regs)));

	/* The actual update is done later just before resuming the lwp,
	we just mark that one register pair needs updating. */
	DR_MARK_N_CHANGED (dr_changed, idx);
	*dr_changed_ptr = dr_changed;

	/* If the lwp isn't stopped, force it to momentarily pause, so
	we can update its debug registers. */
	if (!lwp_is_stopped (lwp))
	linux_stop_lwp (lwp);

	if (show_debug_regs)
	{
	debug_printf ("\tOn exit:\n\ttid%d, dr_changed_bp=0x%s, "
	"dr_changed_wp=0x%s\n", tid,
	phex (info->dr_changed_bp, 8),
	phex (info->dr_changed_wp, 8));
	}

	return 0;
	}

	/* Notify each thread that their IDXth breakpoint/watchpoint register
	pair needs to be updated. The message will be recorded in each
	thread's arch-specific data area, the actual updating will be done
	when the thread is resumed. */

	void
	aarch64_notify_debug_reg_change (ptid_t ptid,
	int is_watchpoint, unsigned int idx)
	{
	ptid_t pid_ptid = ptid_t (ptid.pid ());

	iterate_over_lwps (pid_ptid, [=] (struct lwp_info *info)
	{
	return debug_reg_change_callback (info,
	is_watchpoint,
	idx);
	});
	}

	/* Reconfigure STATE to be compatible with Linux kernels with the PR
	external/20207 bug. This is called when
	KERNEL_SUPPORTS_ANY_CONTIGUOUS_RANGE transitions to false. Note we
	don't try to support combining watchpoints with matching (and thus
	shared) masks, as it's too late when we get here. On buggy
	kernels, GDB will try to first setup the perfect matching ranges,
	which will run out of registers before this function can merge
	them. It doesn't look like worth the effort to improve that, given
	eventually buggy kernels will be phased out. */

	static void
	aarch64_downgrade_regs (struct aarch64_debug_reg_state *state)
	{
	for (int i = 0; i < aarch64_num_wp_regs; ++i)
	if ((state->dr_ctrl_wp[i] & 1) != 0)
	{
	gdb_assert (state->dr_ref_count_wp[i] != 0);
	uint8_t mask_orig = (state->dr_ctrl_wp[i] >> 5) & 0xff;
	gdb_assert (mask_orig != 0);
	static const uint8_t old_valid[] = { 0x01, 0x03, 0x0f, 0xff };
	uint8_t mask = 0;
	for (const uint8_t old_mask : old_valid)
	if (mask_orig <= old_mask)
	{
	mask = old_mask;
	break;
	}
	gdb_assert (mask != 0);

	/* No update needed for this watchpoint? */
	if (mask == mask_orig)
	continue;
	state->dr_ctrl_wp[i] \|= mask << 5;
	state->dr_addr_wp[i]
	= align_down (state->dr_addr_wp[i], AARCH64_HWP_ALIGNMENT);

	/* Try to match duplicate entries. */
	for (int j = 0; j < i; ++j)
	if ((state->dr_ctrl_wp[j] & 1) != 0
	&& state->dr_addr_wp[j] == state->dr_addr_wp[i]
	&& state->dr_addr_orig_wp[j] == state->dr_addr_orig_wp[i]
	&& state->dr_ctrl_wp[j] == state->dr_ctrl_wp[i])
	{
	state->dr_ref_count_wp[j] += state->dr_ref_count_wp[i];
	state->dr_ref_count_wp[i] = 0;
	state->dr_addr_wp[i] = 0;
	state->dr_addr_orig_wp[i] = 0;
	state->dr_ctrl_wp[i] &= ~1;
	break;
	}

	aarch64_notify_debug_reg_change (current_lwp_ptid (),
	1 /* is_watchpoint */, i);
	}
	}

	/* Call ptrace to set the thread TID's hardware breakpoint/watchpoint
	registers with data from STATE. /

	void
	aarch64_linux_set_debug_regs (struct aarch64_debug_reg_state *state,
	int tid, int watchpoint)
	{
	int i, count;
	struct iovec iov;
	struct user_hwdebug_state regs;
	const CORE_ADDR *addr;
	const unsigned int *ctrl;

	memset (&regs, 0, sizeof (regs));
	iov.iov_base = &regs;
	count = watchpoint ? aarch64_num_wp_regs : aarch64_num_bp_regs;
	addr = watchpoint ? state->dr_addr_wp : state->dr_addr_bp;
	ctrl = watchpoint ? state->dr_ctrl_wp : state->dr_ctrl_bp;
	if (count == 0)
	return;
	iov.iov_len = (offsetof (struct user_hwdebug_state, dbg_regs)
	+ count * sizeof (regs.dbg_regs[0]));

	for (i = 0; i < count; i++)
	{
	regs.dbg_regs[i].addr = addr[i];
	regs.dbg_regs[i].ctrl = ctrl[i];
	}

	if (ptrace (PTRACE_SETREGSET, tid,
	watchpoint ? NT_ARM_HW_WATCH : NT_ARM_HW_BREAK,
	(void *) &iov))
	{
	/* Handle Linux kernels with the PR external/20207 bug. */
	if (watchpoint && errno == EINVAL
	&& kernel_supports_any_contiguous_range)
	{
	kernel_supports_any_contiguous_range = false;
	aarch64_downgrade_regs (state);
	aarch64_linux_set_debug_regs (state, tid, watchpoint);
	return;
	}
	error (_("Unexpected error setting hardware debug registers"));
	}
	}

	/* Return true if debug arch level is compatible for hw watchpoints
	and breakpoints. */

	static bool
	compatible_debug_arch (unsigned int debug_arch)
	{
	if (debug_arch == AARCH64_DEBUG_ARCH_V8)
	return true;
	if (debug_arch == AARCH64_DEBUG_ARCH_V8_1)
	return true;
	if (debug_arch == AARCH64_DEBUG_ARCH_V8_2)
	return true;
	if (debug_arch == AARCH64_DEBUG_ARCH_V8_4)
	return true;
	if (debug_arch == AARCH64_DEBUG_ARCH_V8_8)
	return true;
	if (debug_arch == AARCH64_DEBUG_ARCH_V8_9)
	return true;

	return false;
	}

	/* Get the hardware debug register capacity information from the
	process represented by TID. */

	void
	aarch64_linux_get_debug_reg_capacity (int tid)
	{
	struct iovec iov;
	struct user_hwdebug_state dreg_state;

	iov.iov_base = &dreg_state;
	iov.iov_len = sizeof (dreg_state);

	/* Get hardware watchpoint register info. */
	if (ptrace (PTRACE_GETREGSET, tid, NT_ARM_HW_WATCH, &iov) == 0
	&& compatible_debug_arch (AARCH64_DEBUG_ARCH (dreg_state.dbg_info)))
	{
	aarch64_num_wp_regs = AARCH64_DEBUG_NUM_SLOTS (dreg_state.dbg_info);
	if (aarch64_num_wp_regs > AARCH64_HWP_MAX_NUM)
	{
	warning (_("Unexpected number of hardware watchpoint registers"
	" reported by ptrace, got %d, expected %d."),
	aarch64_num_wp_regs, AARCH64_HWP_MAX_NUM);
	aarch64_num_wp_regs = AARCH64_HWP_MAX_NUM;
	}
	}
	else
	{
	warning (_("Unable to determine the number of hardware watchpoints"
	" available."));
	aarch64_num_wp_regs = 0;
	}

	/* Get hardware breakpoint register info. */
	if (ptrace (PTRACE_GETREGSET, tid, NT_ARM_HW_BREAK, &iov) == 0
	&& compatible_debug_arch (AARCH64_DEBUG_ARCH (dreg_state.dbg_info)))
	{
	aarch64_num_bp_regs = AARCH64_DEBUG_NUM_SLOTS (dreg_state.dbg_info);
	if (aarch64_num_bp_regs > AARCH64_HBP_MAX_NUM)
	{
	warning (_("Unexpected number of hardware breakpoint registers"
	" reported by ptrace, got %d, expected %d."),
	aarch64_num_bp_regs, AARCH64_HBP_MAX_NUM);
	aarch64_num_bp_regs = AARCH64_HBP_MAX_NUM;
	}
	}
	else
	{
	warning (_("Unable to determine the number of hardware breakpoints"
	" available."));
	aarch64_num_bp_regs = 0;
	}
	}