[pushed][PATCH 4/7] Arch-specific remote follow fork
Vidya Praveen
vidyapraveen@arm.com
Thu May 14 10:25:00 GMT 2015
Don,
There are several instances of xyz->private->arch_private where xyz
is (struct process_info*). Assume it is a typo (should've been priv
instead of private)?
I atleast see aarch64 build of this fail.
Regards
VP.
On Tue, May 12, 2015 at 06:28:12PM +0100, Don Breazeal wrote:
> This is the version of the patch that I pushed.
> Thanks
> --Don
>
>
> This patch implements the architecture-specific pieces of follow-fork
> for remote and extended-remote Linux targets, which in the current
> implementation copyies the parent's debug register state into the new
> child's data structures. This is required for x86, arm, aarch64, and
> mips.
>
> This follows the native implementation as closely as possible by
> implementing a new linux_target_ops function 'new_fork', which is
> analogous to 'linux_nat_new_fork' in linux-nat.c. In gdbserver, the debug
> registers are stored in the process list, instead of an
> architecture-specific list, so the function arguments are process_info
> pointers instead of an lwp_info and a pid as in the native implementation.
>
> In the MIPS implementation the debug register mirror is stored differently
> from x86, ARM, and aarch64, so instead of doing a simple structure assignment
> I had to clone the list of watchpoint structures.
>
> Tested using gdb.threads/watchpoint-fork.exp on x86, and ran manual tests
> on a MIPS board and an ARM board. Aarch64 hasn't been tested.
>
> gdb/gdbserver/ChangeLog:
>
> * linux-aarch64-low.c (aarch64_linux_new_fork): New function.
> (the_low_target) <new_fork>: Initialize new member.
> * linux-arm-low.c (arm_new_fork): New function.
> (the_low_target) <new_fork>: Initialize new member.
> * linux-low.c (handle_extended_wait): Call new target function
> new_fork.
> * linux-low.h (struct linux_target_ops) <new_fork>: New member.
> * linux-mips-low.c (mips_add_watchpoint): New function
> extracted from mips_insert_point.
> (the_low_target) <new_fork>: Initialize new member.
> (mips_linux_new_fork): New function.
> (mips_insert_point): Call mips_add_watchpoint.
> * linux-x86-low.c (x86_linux_new_fork): New function.
> (the_low_target) <new_fork>: Initialize new member.
> ---
> gdb/gdbserver/ChangeLog | 17 +++++++++
> gdb/gdbserver/linux-aarch64-low.c | 28 +++++++++++++++
> gdb/gdbserver/linux-arm-low.c | 42 ++++++++++++++++++++++
> gdb/gdbserver/linux-low.c | 4 +++
> gdb/gdbserver/linux-low.h | 3 ++
> gdb/gdbserver/linux-mips-low.c | 76 ++++++++++++++++++++++++++++++++-------
> gdb/gdbserver/linux-x86-low.c | 29 +++++++++++++++
> 7 files changed, 187 insertions(+), 12 deletions(-)
>
> diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
> index 0ef695c..0bdcdf3 100644
> --- a/gdb/gdbserver/ChangeLog
> +++ b/gdb/gdbserver/ChangeLog
> @@ -1,5 +1,22 @@
> 2015-05-12 Don Breazeal <donb@codesourcery.com>
>
> + * linux-aarch64-low.c (aarch64_linux_new_fork): New function.
> + (the_low_target) <new_fork>: Initialize new member.
> + * linux-arm-low.c (arm_new_fork): New function.
> + (the_low_target) <new_fork>: Initialize new member.
> + * linux-low.c (handle_extended_wait): Call new target function
> + new_fork.
> + * linux-low.h (struct linux_target_ops) <new_fork>: New member.
> + * linux-mips-low.c (mips_add_watchpoint): New function
> + extracted from mips_insert_point.
> + (the_low_target) <new_fork>: Initialize new member.
> + (mips_linux_new_fork): New function.
> + (mips_insert_point): Call mips_add_watchpoint.
> + * linux-x86-low.c (x86_linux_new_fork): New function.
> + (the_low_target) <new_fork>: Initialize new member.
> +
> +2015-05-12 Don Breazeal <donb@codesourcery.com>
> +
> * linux-low.c (handle_extended_wait): Implement return value,
> rename argument 'event_child' to 'event_lwp', handle
> PTRACE_EVENT_FORK, call internal_error for unrecognized event.
> diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c
> index d44175e..7e6e9ac 100644
> --- a/gdb/gdbserver/linux-aarch64-low.c
> +++ b/gdb/gdbserver/linux-aarch64-low.c
> @@ -1135,6 +1135,33 @@ aarch64_linux_new_thread (struct lwp_info *lwp)
> lwp->arch_private = info;
> }
>
> +static void
> +aarch64_linux_new_fork (struct process_info *parent,
> + struct process_info *child)
> +{
> + /* These are allocated by linux_add_process. */
> + gdb_assert (parent->private != NULL
> + && parent->private->arch_private != NULL);
> + gdb_assert (child->private != NULL
> + && child->private->arch_private != NULL);
> +
> + /* Linux kernel before 2.6.33 commit
> + 72f674d203cd230426437cdcf7dd6f681dad8b0d
> + will inherit hardware debug registers from parent
> + on fork/vfork/clone. Newer Linux kernels create such tasks with
> + zeroed debug registers.
> +
> + 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. The debug registers mirror will become zeroed
> + in the end before detaching the forked off process, thus making
> + this compatible with older Linux kernels too. */
> +
> + *child->private->arch_private = *parent->private->arch_private;
> +}
> +
> /* Called when resuming a thread.
> If the debug regs have changed, update the thread's copies. */
>
> @@ -1299,6 +1326,7 @@ struct linux_target_ops the_low_target =
> NULL,
> aarch64_linux_new_process,
> aarch64_linux_new_thread,
> + aarch64_linux_new_fork,
> aarch64_linux_prepare_to_resume,
> };
>
> diff --git a/gdb/gdbserver/linux-arm-low.c b/gdb/gdbserver/linux-arm-low.c
> index d408dcd..3420dea 100644
> --- a/gdb/gdbserver/linux-arm-low.c
> +++ b/gdb/gdbserver/linux-arm-low.c
> @@ -717,6 +717,47 @@ arm_new_thread (struct lwp_info *lwp)
> lwp->arch_private = info;
> }
>
> +static void
> +arm_new_fork (struct process_info *parent, struct process_info *child)
> +{
> + struct arch_process_info *parent_proc_info = parent->private->arch_private;
> + struct arch_process_info *child_proc_info = child->private->arch_private;
> + struct lwp_info *child_lwp;
> + struct arch_lwp_info *child_lwp_info;
> + int i;
> +
> + /* These are allocated by linux_add_process. */
> + gdb_assert (parent->private != NULL
> + && parent->private->arch_private != NULL);
> + gdb_assert (child->private != NULL
> + && child->private->arch_private != NULL);
> +
> + /* Linux kernel before 2.6.33 commit
> + 72f674d203cd230426437cdcf7dd6f681dad8b0d
> + will inherit hardware debug registers from parent
> + on fork/vfork/clone. Newer Linux kernels create such tasks with
> + zeroed debug registers.
> +
> + 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. The debug registers mirror will become zeroed
> + in the end before detaching the forked off process, thus making
> + this compatible with older Linux kernels too. */
> +
> + *child_proc_info = *parent_proc_info;
> +
> + /* Mark all the hardware breakpoints and watchpoints as changed to
> + make sure that the registers will be updated. */
> + child_lwp = find_lwp_pid (ptid_of (child));
> + child_lwp_info = child_lwp->arch_private;
> + for (i = 0; i < MAX_BPTS; i++)
> + child_lwp_info->bpts_changed[i] = 1;
> + for (i = 0; i < MAX_WPTS; i++)
> + child_lwp_info->wpts_changed[i] = 1;
> +}
> +
> /* Called when resuming a thread.
> If the debug regs have changed, update the thread's copies. */
> static void
> @@ -920,6 +961,7 @@ struct linux_target_ops the_low_target = {
> NULL, /* siginfo_fixup */
> arm_new_process,
> arm_new_thread,
> + arm_new_fork,
> arm_prepare_to_resume,
> };
>
> diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
> index b280c17..d9053ad 100644
> --- a/gdb/gdbserver/linux-low.c
> +++ b/gdb/gdbserver/linux-low.c
> @@ -489,6 +489,10 @@ handle_extended_wait (struct lwp_info *event_lwp, int wstat)
> child_proc->tdesc = tdesc;
> child_lwp->must_set_ptrace_flags = 1;
>
> + /* Clone arch-specific process data. */
> + if (the_low_target.new_fork != NULL)
> + the_low_target.new_fork (parent_proc, child_proc);
> +
> /* Save fork info in the parent thread. */
> event_lwp->waitstatus.kind = TARGET_WAITKIND_FORKED;
> event_lwp->waitstatus.value.related_pid = ptid;
> diff --git a/gdb/gdbserver/linux-low.h b/gdb/gdbserver/linux-low.h
> index 41067d6..3300da9 100644
> --- a/gdb/gdbserver/linux-low.h
> +++ b/gdb/gdbserver/linux-low.h
> @@ -187,6 +187,9 @@ struct linux_target_ops
> allocate it here. */
> void (*new_thread) (struct lwp_info *);
>
> + /* Hook to call, if any, when a new fork is attached. */
> + void (*new_fork) (struct process_info *parent, struct process_info *child);
> +
> /* Hook to call prior to resuming a thread. */
> void (*prepare_to_resume) (struct lwp_info *);
>
> diff --git a/gdb/gdbserver/linux-mips-low.c b/gdb/gdbserver/linux-mips-low.c
> index 7988d07..4601ad0 100644
> --- a/gdb/gdbserver/linux-mips-low.c
> +++ b/gdb/gdbserver/linux-mips-low.c
> @@ -344,6 +344,68 @@ mips_linux_new_thread (struct lwp_info *lwp)
> lwp->arch_private = info;
> }
>
> +/* Create a new mips_watchpoint and add it to the list. */
> +
> +static void
> +mips_add_watchpoint (struct arch_process_info *private, CORE_ADDR addr,
> + int len, int watch_type)
> +{
> + struct mips_watchpoint *new_watch;
> + struct mips_watchpoint **pw;
> +
> + new_watch = xmalloc (sizeof (struct mips_watchpoint));
> + new_watch->addr = addr;
> + new_watch->len = len;
> + new_watch->type = watch_type;
> + new_watch->next = NULL;
> +
> + pw = &private->current_watches;
> + while (*pw != NULL)
> + pw = &(*pw)->next;
> + *pw = new_watch;
> +}
> +
> +/* Hook to call when a new fork is attached. */
> +
> +static void
> +mips_linux_new_fork (struct process_info *parent,
> + struct process_info *child)
> +{
> + struct arch_process_info *parent_private;
> + struct arch_process_info *child_private;
> + struct mips_watchpoint *wp;
> +
> + /* These are allocated by linux_add_process. */
> + gdb_assert (parent->private != NULL
> + && parent->private->arch_private != NULL);
> + gdb_assert (child->private != NULL
> + && child->private->arch_private != NULL);
> +
> + /* Linux kernel before 2.6.33 commit
> + 72f674d203cd230426437cdcf7dd6f681dad8b0d
> + will inherit hardware debug registers from parent
> + on fork/vfork/clone. Newer Linux kernels create such tasks with
> + zeroed debug registers.
> +
> + 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. The debug registers mirror will become zeroed
> + in the end before detaching the forked off process, thus making
> + this compatible with older Linux kernels too. */
> +
> + parent_private = parent->private->arch_private;
> + child_private = child->private->arch_private;
> +
> + child_private->watch_readback_valid = parent_private->watch_readback_valid;
> + child_private->watch_readback = parent_private->watch_readback;
> +
> + for (wp = parent_private->current_watches; wp != NULL; wp = wp->next)
> + mips_add_watchpoint (child_private, wp->addr, wp->len, wp->type);
> +
> + child_private->watch_mirror = parent_private->watch_mirror;
> +}
> /* This is the implementation of linux_target_ops method
> prepare_to_resume. If the watch regs have changed, update the
> thread's copies. */
> @@ -397,8 +459,6 @@ mips_insert_point (enum raw_bkpt_type type, CORE_ADDR addr,
> struct process_info *proc = current_process ();
> struct arch_process_info *priv = proc->priv->arch_private;
> struct pt_watch_regs regs;
> - struct mips_watchpoint *new_watch;
> - struct mips_watchpoint **pw;
> int pid;
> long lwpid;
> enum target_hw_bp_type watch_type;
> @@ -425,16 +485,7 @@ mips_insert_point (enum raw_bkpt_type type, CORE_ADDR addr,
> return -1;
>
> /* It fit. Stick it on the end of the list. */
> - new_watch = xmalloc (sizeof (struct mips_watchpoint));
> - new_watch->addr = addr;
> - new_watch->len = len;
> - new_watch->type = watch_type;
> - new_watch->next = NULL;
> -
> - pw = &priv->current_watches;
> - while (*pw != NULL)
> - pw = &(*pw)->next;
> - *pw = new_watch;
> + mips_add_watchpoint (priv, addr, len, watch_type);
>
> priv->watch_mirror = regs;
>
> @@ -845,6 +896,7 @@ struct linux_target_ops the_low_target = {
> NULL, /* siginfo_fixup */
> mips_linux_new_process,
> mips_linux_new_thread,
> + mips_linux_new_fork,
> mips_linux_prepare_to_resume
> };
>
> diff --git a/gdb/gdbserver/linux-x86-low.c b/gdb/gdbserver/linux-x86-low.c
> index 763df08..4aef7b7 100644
> --- a/gdb/gdbserver/linux-x86-low.c
> +++ b/gdb/gdbserver/linux-x86-low.c
> @@ -634,6 +634,34 @@ x86_linux_new_process (void)
> return info;
> }
>
> +/* Target routine for linux_new_fork. */
> +
> +static void
> +x86_linux_new_fork (struct process_info *parent, struct process_info *child)
> +{
> + /* These are allocated by linux_add_process. */
> + gdb_assert (parent->priv != NULL
> + && parent->priv->arch_private != NULL);
> + gdb_assert (child->priv != NULL
> + && child->priv->arch_private != NULL);
> +
> + /* Linux kernel before 2.6.33 commit
> + 72f674d203cd230426437cdcf7dd6f681dad8b0d
> + will inherit hardware debug registers from parent
> + on fork/vfork/clone. Newer Linux kernels create such tasks with
> + zeroed debug registers.
> +
> + 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. The debug registers mirror will become zeroed
> + in the end before detaching the forked off process, thus making
> + this compatible with older Linux kernels too. */
> +
> + *child->priv->arch_private = *parent->priv->arch_private;
> +}
> +
> /* See nat/x86-dregs.h. */
>
> struct x86_debug_reg_state *
> @@ -3263,6 +3291,7 @@ struct linux_target_ops the_low_target =
> x86_siginfo_fixup,
> x86_linux_new_process,
> x86_linux_new_thread,
> + x86_linux_new_fork,
> x86_linux_prepare_to_resume,
> x86_linux_process_qsupported,
> x86_supports_tracepoints,
> --
> 1.8.1.1
>
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