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Support for HWbreak/watchpoint across fork/vfork on arm-native

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This patch updates arm native support for hwbreak-/watchpoints to enable
support for hwbreak-/watchpoints across fork/vfork. This involves changes to
hwbreak-/watchpoint insertion mechanism to the modern way, by marking debug
registers as needing update, but only really updating them on resume, which is
necessary for supporting watchpoints in non-stop mode. This also updates a
previously maintained per thread hwbreak-/watchpoint cache to a per process
cache which allows target specific code to come in sync with gdb-linux calls to
threads create/destroy and process fork/exit hooks.
This commit is contained in:
Omair Javaid 2014-03-13 01:23:55 +05:00
parent 6d03af93d2
commit 638c5f4962
2 changed files with 304 additions and 124 deletions
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29
gdb/ChangeLog
View File

@ -1,3 +1,32 @@
2014-03-12 Omair Javaid <omair.javaid@linaro.org>
* arm-linux-nat.c (arm_linux_get_hwbp_cap): Updated.
(MAX_BPTS): Define.
(MAX_WPTS): Define.
(struct arm_linux_thread_points): Removed.
(struct arm_linux_process_info): New.
(DEF_VEC_P (arm_linux_thread_points_p)): Removed.
(VEC(arm_linux_thread_points_p) *arm_threads): Removed.
(arm_linux_find_breakpoints_by_tid): Removed.
(struct arch_lwp_info): New.
(arm_linux_find_process_pid): New functions.
(arm_linux_add_process): New functions.
(arm_linux_process_info_get): New functions.
(arm_linux_forget_process): New function.
(arm_linux_get_debug_reg_state): New function.
(struct update_registers_data): New.
(update_registers_callback): New function.
(arm_linux_insert_hw_breakpoint1): Updated.
(arm_linux_remove_hw_breakpoint1): Updated.
(arm_linux_insert_hw_breakpoint): Updated.
(arm_linux_remove_hw_breakpoint): Updated.
(arm_linux_insert_watchpoint): Updated.
(arm_linux_remove_watchpoint): Updated.
(arm_linux_new_thread): Updated.
(arm_linux_prepare_to_resume): New function.
(arm_linux_new_fork): New function.
(_initialize_arm_linux_nat): Updated.
2014-03-12 Pedro Alves <palves@redhat.com>
* Makefile.in (TARGET_FLAGS_TO_PASS): Add TESTS.

399
gdb/arm-linux-nat.c
View File

@ -693,6 +693,11 @@ struct arm_linux_hwbp_cap
gdb_byte bp_count;
};
/* Since we cannot dynamically allocate subfields of arm_linux_process_info,
assume a maximum number of supported break-/watchpoints. */
#define MAX_BPTS 16
#define MAX_WPTS 16
/* Get hold of the Hardware Breakpoint information for the target we are
attached to. Returns NULL if the kernel doesn't support Hardware
breakpoints at all, or a pointer to the information structure. */
@ -721,6 +726,20 @@ arm_linux_get_hwbp_cap (void)
info.max_wp_length = (gdb_byte)((val >> 16) & 0xff);
info.wp_count = (gdb_byte)((val >> 8) & 0xff);
info.bp_count = (gdb_byte)(val & 0xff);
if (info.wp_count > MAX_WPTS)
{
warning (_("arm-linux-gdb supports %d hardware watchpoints but target \
supports %d"), MAX_WPTS, info.wp_count);
info.wp_count = MAX_WPTS;
}
if (info.bp_count > MAX_BPTS)
{
warning (_("arm-linux-gdb supports %d hardware breakpoints but target \
supports %d"), MAX_BPTS, info.bp_count);
info.bp_count = MAX_BPTS;
}
available = (info.arch != 0);
}
}
@ -788,8 +807,8 @@ struct arm_linux_hw_breakpoint
arm_hwbp_control_t control;
};
/* Structure containing arrays of the break and watch points which are have
active in each thread.
/* Structure containing arrays of per process hardware break-/watchpoints
for caching address and control information.
The Linux ptrace interface to hardware break-/watch-points presents the
values in a vector centred around 0 (which is used fo generic information).
@ -809,49 +828,114 @@ struct arm_linux_hw_breakpoint
We treat break-/watch-points with their enable bit clear as being deleted.
*/
typedef struct arm_linux_thread_points
struct arm_linux_debug_reg_state
{
/* Thread ID. */
int tid;
/* Breakpoints for thread. */
struct arm_linux_hw_breakpoint *bpts;
/* Watchpoint for threads. */
struct arm_linux_hw_breakpoint *wpts;
} *arm_linux_thread_points_p;
DEF_VEC_P (arm_linux_thread_points_p);
/* Hardware breakpoints for this process. */
struct arm_linux_hw_breakpoint bpts[MAX_BPTS];
/* Hardware watchpoints for this process. */
struct arm_linux_hw_breakpoint wpts[MAX_WPTS];
};
/* Vector of hardware breakpoints for each thread. */
VEC(arm_linux_thread_points_p) *arm_threads = NULL;
/* Find the list of hardware break-/watch-points for a thread with id TID.
If no list exists for TID we return NULL if ALLOC_NEW is 0, otherwise we
create a new list and return that. */
static struct arm_linux_thread_points *
arm_linux_find_breakpoints_by_tid (int tid, int alloc_new)
/* Per-process arch-specific data we want to keep. */
struct arm_linux_process_info
{
int i;
struct arm_linux_thread_points *t;
/* Linked list. */
struct arm_linux_process_info *next;
/* The process identifier. */
pid_t pid;
/* Hardware break-/watchpoints state information. */
struct arm_linux_debug_reg_state state;
for (i = 0; VEC_iterate (arm_linux_thread_points_p, arm_threads, i, t); ++i)
};
/* Per-thread arch-specific data we want to keep. */
struct arch_lwp_info
{
/* Non-zero if our copy differs from what's recorded in the thread. */
char bpts_changed[MAX_BPTS];
char wpts_changed[MAX_WPTS];
};
static struct arm_linux_process_info *arm_linux_process_list = NULL;
/* Find process data for process PID. */
static struct arm_linux_process_info *
arm_linux_find_process_pid (pid_t pid)
{
struct arm_linux_process_info *proc;
for (proc = arm_linux_process_list; proc; proc = proc->next)
if (proc->pid == pid)
return proc;
return NULL;
}
/* Add process data for process PID. Returns newly allocated info
object. */
static struct arm_linux_process_info *
arm_linux_add_process (pid_t pid)
{
struct arm_linux_process_info *proc;
proc = xcalloc (1, sizeof (*proc));
proc->pid = pid;
proc->next = arm_linux_process_list;
arm_linux_process_list = proc;
return proc;
}
/* Get data specific info for process PID, creating it if necessary.
Never returns NULL. */
static struct arm_linux_process_info *
arm_linux_process_info_get (pid_t pid)
{
struct arm_linux_process_info *proc;
proc = arm_linux_find_process_pid (pid);
if (proc == NULL)
proc = arm_linux_add_process (pid);
return proc;
}
/* Called whenever GDB is no longer debugging process PID. It deletes
data structures that keep track of debug register state. */
static void
arm_linux_forget_process (pid_t pid)
{
struct arm_linux_process_info *proc, **proc_link;
proc = arm_linux_process_list;
proc_link = &arm_linux_process_list;
while (proc != NULL)
{
if (t->tid == tid)
return t;
if (proc->pid == pid)
{
*proc_link = proc->next;
xfree (proc);
return;
}
t = NULL;
if (alloc_new)
{
t = xmalloc (sizeof (struct arm_linux_thread_points));
t->tid = tid;
t->bpts = xzalloc (arm_linux_get_hw_breakpoint_count ()
* sizeof (struct arm_linux_hw_breakpoint));
t->wpts = xzalloc (arm_linux_get_hw_watchpoint_count ()
* sizeof (struct arm_linux_hw_breakpoint));
VEC_safe_push (arm_linux_thread_points_p, arm_threads, t);
proc_link = &proc->next;
proc = *proc_link;
}
}
return t;
/* Get hardware break-/watchpoint state for process PID. */
static struct arm_linux_debug_reg_state *
arm_linux_get_debug_reg_state (pid_t pid)
{
return &arm_linux_process_info_get (pid)->state;
}
/* Initialize an ARM hardware break-/watch-point control register value.
@ -951,45 +1035,72 @@ arm_linux_hw_breakpoint_equal (const struct arm_linux_hw_breakpoint *p1,
return p1->address == p2->address && p1->control == p2->control;
}
/* Callback to mark a watch-/breakpoint to be updated in all threads of
the current process. */
struct update_registers_data
{
int watch;
int index;
};
static int
update_registers_callback (struct lwp_info *lwp, void *arg)
{
struct update_registers_data *data = (struct update_registers_data *) arg;
if (lwp->arch_private == NULL)
lwp->arch_private = XCNEW (struct arch_lwp_info);
/* The actual update is done later just before resuming the lwp,
we just mark that the registers need updating. */
if (data->watch)
lwp->arch_private->wpts_changed[data->index] = 1;
else
lwp->arch_private->bpts_changed[data->index] = 1;
/* If the lwp isn't stopped, force it to momentarily pause, so
we can update its breakpoint registers. */
if (!lwp->stopped)
linux_stop_lwp (lwp);
return 0;
}
/* Insert the hardware breakpoint (WATCHPOINT = 0) or watchpoint (WATCHPOINT
=1) BPT for thread TID. */
static void
arm_linux_insert_hw_breakpoint1 (const struct arm_linux_hw_breakpoint* bpt,
int tid, int watchpoint)
int watchpoint)
{
struct arm_linux_thread_points *t = arm_linux_find_breakpoints_by_tid (tid, 1);
int pid;
ptid_t pid_ptid;
gdb_byte count, i;
struct arm_linux_hw_breakpoint* bpts;
int dir;
struct update_registers_data data;
gdb_assert (t != NULL);
pid = ptid_get_pid (inferior_ptid);
pid_ptid = pid_to_ptid (pid);
if (watchpoint)
{
count = arm_linux_get_hw_watchpoint_count ();
bpts = t->wpts;
dir = -1;
bpts = arm_linux_get_debug_reg_state (pid)->wpts;
}
else
{
count = arm_linux_get_hw_breakpoint_count ();
bpts = t->bpts;
dir = 1;
bpts = arm_linux_get_debug_reg_state (pid)->bpts;
}
for (i = 0; i < count; ++i)
if (!arm_hwbp_control_is_enabled (bpts[i].control))
{
errno = 0;
if (ptrace (PTRACE_SETHBPREGS, tid, dir * ((i << 1) + 1),
&bpt->address) < 0)
perror_with_name (_("Unexpected error setting breakpoint address"));
if (ptrace (PTRACE_SETHBPREGS, tid, dir * ((i << 1) + 2),
&bpt->control) < 0)
perror_with_name (_("Unexpected error setting breakpoint"));
memcpy (bpts + i, bpt, sizeof (struct arm_linux_hw_breakpoint));
break;
data.watch = watchpoint;
data.index = i;
bpts[i] = *bpt;
iterate_over_lwps (pid_ptid, update_registers_callback, &data);
break;
}
gdb_assert (i != count);
@ -999,37 +1110,36 @@ arm_linux_insert_hw_breakpoint1 (const struct arm_linux_hw_breakpoint* bpt,
(WATCHPOINT = 1) BPT for thread TID. */
static void
arm_linux_remove_hw_breakpoint1 (const struct arm_linux_hw_breakpoint *bpt,
int tid, int watchpoint)
int watchpoint)
{
struct arm_linux_thread_points *t = arm_linux_find_breakpoints_by_tid (tid, 0);
int pid;
gdb_byte count, i;
struct arm_linux_hw_breakpoint *bpts;
int dir;
ptid_t pid_ptid;
struct arm_linux_hw_breakpoint* bpts;
struct update_registers_data data;
gdb_assert (t != NULL);
pid = ptid_get_pid (inferior_ptid);
pid_ptid = pid_to_ptid (pid);
if (watchpoint)
{
count = arm_linux_get_hw_watchpoint_count ();
bpts = t->wpts;
dir = -1;
bpts = arm_linux_get_debug_reg_state (pid)->wpts;
}
else
{
count = arm_linux_get_hw_breakpoint_count ();
bpts = t->bpts;
dir = 1;
bpts = arm_linux_get_debug_reg_state (pid)->bpts;
}
for (i = 0; i < count; ++i)
if (arm_linux_hw_breakpoint_equal (bpt, bpts + i))
{
errno = 0;
bpts[i].control = arm_hwbp_control_disable (bpts[i].control);
if (ptrace (PTRACE_SETHBPREGS, tid, dir * ((i << 1) + 2),
&bpts[i].control) < 0)
perror_with_name (_("Unexpected error clearing breakpoint"));
break;
data.watch = watchpoint;
data.index = i;
bpts[i].control = arm_hwbp_control_disable (bpts[i].control);
iterate_over_lwps (pid_ptid, update_registers_callback, &data);
break;
}
gdb_assert (i != count);
@ -1048,8 +1158,8 @@ arm_linux_insert_hw_breakpoint (struct target_ops *self,
return -1;
arm_linux_hw_breakpoint_initialize (gdbarch, bp_tgt, &p);
ALL_LWPS (lp)
arm_linux_insert_hw_breakpoint1 (&p, ptid_get_lwp (lp->ptid), 0);
arm_linux_insert_hw_breakpoint1 (&p, 0);
return 0;
}
@ -1067,8 +1177,8 @@ arm_linux_remove_hw_breakpoint (struct target_ops *self,
return -1;
arm_linux_hw_breakpoint_initialize (gdbarch, bp_tgt, &p);
ALL_LWPS (lp)
arm_linux_remove_hw_breakpoint1 (&p, ptid_get_lwp (lp->ptid), 0);
arm_linux_remove_hw_breakpoint1 (&p, 0);
return 0;
}
@ -1120,8 +1230,8 @@ arm_linux_insert_watchpoint (struct target_ops *self,
return -1;
arm_linux_hw_watchpoint_initialize (addr, len, rw, &p);
ALL_LWPS (lp)
arm_linux_insert_hw_breakpoint1 (&p, ptid_get_lwp (lp->ptid), 1);
arm_linux_insert_hw_breakpoint1 (&p, 1);
return 0;
}
@ -1139,8 +1249,8 @@ arm_linux_remove_watchpoint (struct target_ops *self,
return -1;
arm_linux_hw_watchpoint_initialize (addr, len, rw, &p);
ALL_LWPS (lp)
arm_linux_remove_hw_breakpoint1 (&p, ptid_get_lwp (lp->ptid), 1);
arm_linux_remove_hw_breakpoint1 (&p, 1);
return 0;
}
@ -1196,63 +1306,100 @@ arm_linux_watchpoint_addr_within_range (struct target_ops *target,
static void
arm_linux_new_thread (struct lwp_info *lp)
{
int tid = ptid_get_lwp (lp->ptid);
const struct arm_linux_hwbp_cap *info = arm_linux_get_hwbp_cap ();
int i;
struct arch_lwp_info *info = XCNEW (struct arch_lwp_info);
if (info != NULL)
/* Mark that all the hardware breakpoint/watchpoint register pairs
for this thread need to be initialized. */
for (i = 0; i < MAX_BPTS; i++)
{
int i;
struct arm_linux_thread_points *p;
struct arm_linux_hw_breakpoint *bpts;
if (VEC_empty (arm_linux_thread_points_p, arm_threads))
return;
/* Get a list of breakpoints from any thread. */
p = VEC_last (arm_linux_thread_points_p, arm_threads);
/* Copy that thread's breakpoints and watchpoints to the new thread. */
for (i = 0; i < info->bp_count; i++)
if (arm_hwbp_control_is_enabled (p->bpts[i].control))
arm_linux_insert_hw_breakpoint1 (p->bpts + i, tid, 0);
for (i = 0; i < info->wp_count; i++)
if (arm_hwbp_control_is_enabled (p->wpts[i].control))
arm_linux_insert_hw_breakpoint1 (p->wpts + i, tid, 1);
info->bpts_changed[i] = 1;
info->wpts_changed[i] = 1;
}
lp->arch_private = info;
}
/* Handle thread exit. Tidy up the memory that has been allocated for the
thread. */
/* Called when resuming a thread.
The hardware debug registers are updated when there is any change. */
static void
arm_linux_thread_exit (struct thread_info *tp, int silent)
arm_linux_prepare_to_resume (struct lwp_info *lwp)
{
const struct arm_linux_hwbp_cap *info = arm_linux_get_hwbp_cap ();
int pid, i;
struct arm_linux_hw_breakpoint *bpts, *wpts;
struct arch_lwp_info *arm_lwp_info = lwp->arch_private;
if (info != NULL)
{
int i;
int tid = ptid_get_lwp (tp->ptid);
struct arm_linux_thread_points *t = NULL, *p;
pid = ptid_get_lwp (lwp->ptid);
bpts = arm_linux_get_debug_reg_state (ptid_get_pid (lwp->ptid))->bpts;
wpts = arm_linux_get_debug_reg_state (ptid_get_pid (lwp->ptid))->wpts;
for (i = 0;
VEC_iterate (arm_linux_thread_points_p, arm_threads, i, p); i++)
{
if (p->tid == tid)
{
t = p;
break;
}
}
/* NULL means this is the main thread still going through the shell,
or, no watchpoint has been set yet. In that case, there's
nothing to do. */
if (arm_lwp_info == NULL)
return;
if (t == NULL)
return;
for (i = 0; i < arm_linux_get_hw_breakpoint_count (); i++)
if (arm_lwp_info->bpts_changed[i])
{
errno = 0;
if (arm_hwbp_control_is_enabled (bpts[i].control))
if (ptrace (PTRACE_SETHBPREGS, pid,
(PTRACE_TYPE_ARG3) ((i << 1) + 1), &bpts[i].address) < 0)
perror_with_name (_("Unexpected error setting breakpoint"));
VEC_unordered_remove (arm_linux_thread_points_p, arm_threads, i);
if (bpts[i].control != 0)
if (ptrace (PTRACE_SETHBPREGS, pid,
(PTRACE_TYPE_ARG3) ((i << 1) + 2), &bpts[i].control) < 0)
perror_with_name (_("Unexpected error setting breakpoint"));
xfree (t->bpts);
xfree (t->wpts);
xfree (t);
}
arm_lwp_info->bpts_changed[i] = 0;
}
for (i = 0; i < arm_linux_get_hw_watchpoint_count (); i++)
if (arm_lwp_info->wpts_changed[i])
{
errno = 0;
if (arm_hwbp_control_is_enabled (wpts[i].control))
if (ptrace (PTRACE_SETHBPREGS, pid,
(PTRACE_TYPE_ARG3) -((i << 1) + 1), &wpts[i].address) < 0)
perror_with_name (_("Unexpected error setting watchpoint"));
if (wpts[i].control != 0)
if (ptrace (PTRACE_SETHBPREGS, pid,
(PTRACE_TYPE_ARG3) -((i << 1) + 2), &wpts[i].control) < 0)
perror_with_name (_("Unexpected error setting watchpoint"));
arm_lwp_info->wpts_changed[i] = 0;
}
}
/* linux_nat_new_fork hook. */
static void
arm_linux_new_fork (struct lwp_info *parent, pid_t child_pid)
{
pid_t parent_pid;
struct arm_linux_debug_reg_state *parent_state;
struct arm_linux_debug_reg_state *child_state;
/* NULL means no watchpoint has ever been set in the parent. In
that case, there's nothing to do. */
if (parent->arch_private == NULL)
return;
/* GDB core assumes the child inherits the watchpoints/hw
breakpoints of the parent, and will remove them all from the
forked off process. Copy the debug registers mirrors into the
new process so that all breakpoints and watchpoints can be
removed together. */
parent_pid = ptid_get_pid (parent->ptid);
parent_state = arm_linux_get_debug_reg_state (parent_pid);
child_state = arm_linux_get_debug_reg_state (child_pid);
*child_state = *parent_state;
}
void _initialize_arm_linux_nat (void);
@ -1285,7 +1432,11 @@ _initialize_arm_linux_nat (void)
/* Register the target. */
linux_nat_add_target (t);
/* Handle thread creation and exit */
observer_attach_thread_exit (arm_linux_thread_exit);
/* Handle thread creation and exit. */
linux_nat_set_new_thread (t, arm_linux_new_thread);
linux_nat_set_prepare_to_resume (t, arm_linux_prepare_to_resume);
/* Handle process creation and exit. */
linux_nat_set_new_fork (t, arm_linux_new_fork);
linux_nat_set_forget_process (t, arm_linux_forget_process);
}