This patch adds a new ptrace request PTRACE_PEEKSIGINFO.
This request is used to retrieve information about signals starting with
the specified sequence number. Siginfo_t structures are copied from the
child into the buffer starting at "data".
The argument "addr" is a pointer to struct ptrace_peeksiginfo_args.
struct ptrace_peeksiginfo_args {
u64 off; /* from which siginfo to start */
u32 nr; /* how may siginfos to take */
u32 flags;
};
Currently here is only one flag PTRACE_PEEKSIGINFO_SHARED for dumping
signals from process-wide shared queue. If this flag is not set, a
signal is read from a per-thread queue. A result siginfo contains a
kernel part of si_code which usually striped, but it's required for
queuing the same siginfo back during restore of pending signals.
The request PTRACE_PEEKSIGINFO returns a number of dumped signals.
If a signal with the specified sequence number doesn't exist, ptrace
returns 0.
This functionality is required for checkpointing pending signals.
The prototype of this code was developed by Oleg Nesterov.
v2: * don't wrapped on CONFIG_CHECKPOINT_RESTORE. This functionality is
going to be used in gdb.
* use ptrace_peeksiginfo_args, because addr is too small for
encoding a signal number and flags.
Cc: Roland McGrath <rol...@redhat.com>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
Cc: David Howells <dhowe...@redhat.com>
Cc: Dave Jones <da...@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpa...@gmail.com>
Cc: Pavel Emelyanov <xe...@parallels.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Pedro Alves <pal...@redhat.com>
Signed-off-by: Andrey Vagin <ava...@openvz.org>
---
include/uapi/linux/ptrace.h | 12 +++++++
kernel/ptrace.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+)
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index 022ab18..01b4bd8 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -5,6 +5,7 @@
/* has the defines to get at the registers. */
+#include <linux/types.h>
#define PTRACE_TRACEME 0
#define PTRACE_PEEKTEXT 1
@@ -52,6 +53,17 @@
#define PTRACE_INTERRUPT 0x4207
#define PTRACE_LISTEN 0x4208
+#define PTRACE_PEEKSIGINFO 0x4209
+
+struct ptrace_peeksiginfo_args {
+ __u64 off; /* from which siginfo to start */
+ __u32 nr; /* how may siginfos to take */
+ __u32 flags;
+};
+
+/* Read signals from a shared (process wide) queue */
+#define PTRACE_PEEKSIGINFO_SHARED (1 << 0)
+
/* Wait extended result codes for the above trace options. */
#define PTRACE_EVENT_FORK 1
#define PTRACE_EVENT_VFORK 2
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 6cbeaae..ceecdcd 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -24,6 +24,7 @@
#include <linux/regset.h>
#include <linux/hw_breakpoint.h>
#include <linux/cn_proc.h>
+#include <linux/compat.h>
static int ptrace_trapping_sleep_fn(void *flags)
@@ -618,6 +619,77 @@ static int ptrace_setsiginfo(struct task_struct *child,
const siginfo_t *info)
return error;
}
+static int ptrace_peek_siginfo(struct task_struct *child,
+ unsigned long addr,
+ unsigned long data)
+{
+ struct ptrace_peeksiginfo_args arg;
+ struct sigpending *pending;
+ struct sigqueue *q;
+ siginfo_t info;
+ long long off;
+ int ret, i;
+
+ ret = copy_from_user(&arg, (void __user *) addr,
+ sizeof(struct ptrace_peeksiginfo_args));
+ if (ret)
+ return ret;
+
+ if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
+ pending = &child->signal->shared_pending;
+ else
+ pending = &child->pending;
+
+ if (arg.flags & ~PTRACE_PEEKSIGINFO_SHARED)
+ return -EINVAL; /* unknown flags */
+
+ for (i = 0; i < arg.nr; i++) {
+ off = arg.off + i;
+
+ spin_lock_irq(&child->sighand->siglock);
+ list_for_each_entry(q, &pending->list, list) {
+ if (!off--) {
+ copy_siginfo(&info, &q->info);
+ break;
+ }
+ }
+ spin_unlock_irq(&child->sighand->siglock);
+
+ if (off >= 0)
+ break;
+
+#ifdef CONFIG_COMPAT
+ if (unlikely(is_compat_task())) {
+ compat_siginfo_t __user *uinfo = compat_ptr(data);
+
+ ret = copy_siginfo_to_user32(uinfo, &info);
+ if (!ret)
+ ret = __put_user(info.si_code, &uinfo->si_code);
+ } else
+#endif
+ {
+ siginfo_t __user *uinfo = (siginfo_t __user *) data;
+
+ ret = copy_siginfo_to_user(uinfo, &info);
+ if (!ret)
+ ret = __put_user(info.si_code, &uinfo->si_code);
+ }
+
+ if (ret)
+ break;
+
+ data += sizeof(siginfo_t);
+
+ if (signal_pending(current)) {
+ i++;
+ break;
+ }
+
+ cond_resched();
+ }
+
+ return i ? : ret;
+}
#ifdef PTRACE_SINGLESTEP
#define is_singlestep(request) ((request) == PTRACE_SINGLESTEP)
@@ -742,6 +814,10 @@ int ptrace_request(struct task_struct *child, long request,
ret = put_user(child->ptrace_message, datalp);
break;
+ case PTRACE_PEEKSIGINFO:
+ ret = ptrace_peek_siginfo(child, addr, data);
+ break;
+
case PTRACE_GETSIGINFO:
ret = ptrace_getsiginfo(child, &siginfo);
if (!ret)
--
1.7.11.7
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