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-rw-r--r--gdb/linux-nat.c144
1 files changed, 136 insertions, 8 deletions
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 1308844..98f6347 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -67,6 +67,10 @@
# endif
#endif /* HAVE_PERSONALITY */
+/* To be used when one needs to know wether a
+ WSTOPSIG (status) is a syscall */
+#define TRAP_IS_SYSCALL (SIGTRAP | 0x80)
+
/* This comment documents high-level logic of this file.
Waiting for events in sync mode
@@ -279,6 +283,11 @@ struct simple_pid_list *stopped_pids;
static int linux_supports_tracefork_flag = -1;
+/* This variable is a tri-state flag: -1 for unknown, 0 if PTRACE_O_TRACESYSGOOD
+ can not be used, 1 if it can. */
+
+static int linux_supports_tracesysgood_flag = -1;
+
/* If we have PTRACE_O_TRACEFORK, this flag indicates whether we also have
PTRACE_O_TRACEVFORKDONE. */
@@ -290,6 +299,9 @@ static int linux_supports_tracevforkdone_flag = -1;
linux_nat_wait should behave as if async mode was off. */
static int linux_nat_async_mask_value = 1;
+/* Stores the current used ptrace() options. */
+static int current_ptrace_options = 0;
+
/* The read/write ends of the pipe registered as waitable file in the
event loop. */
static int linux_nat_event_pipe[2] = { -1, -1 };
@@ -525,6 +537,43 @@ linux_test_for_tracefork (int original_pid)
restore_child_signals_mask (&prev_mask);
}
+/* Determine if PTRACE_O_TRACESYSGOOD can be used to follow syscalls.
+
+ We try to enable syscall tracing on ORIGINAL_PID. If this fails,
+ we know that the feature is not available. This may change the tracing
+ options for ORIGINAL_PID, but we'll be setting them shortly anyway. */
+
+static void
+linux_test_for_tracesysgood (int original_pid)
+{
+ int ret;
+ sigset_t prev_mask;
+
+ /* We don't want those ptrace calls to be interrupted. */
+ block_child_signals (&prev_mask);
+
+ linux_supports_tracesysgood_flag = 0;
+
+ ret = ptrace (PTRACE_SETOPTIONS, original_pid, 0, PTRACE_O_TRACESYSGOOD);
+ if (ret != 0)
+ goto out;
+
+ linux_supports_tracesysgood_flag = 1;
+out:
+ restore_child_signals_mask (&prev_mask);
+}
+
+/* Determine wether we support PTRACE_O_TRACESYSGOOD option available.
+ This function also sets linux_supports_tracesysgood_flag. */
+
+static int
+linux_supports_tracesysgood (int pid)
+{
+ if (linux_supports_tracesysgood_flag == -1)
+ linux_test_for_tracesysgood (pid);
+ return linux_supports_tracesysgood_flag;
+}
+
/* Return non-zero iff we have tracefork functionality available.
This function also sets linux_supports_tracefork_flag. */
@@ -544,12 +593,27 @@ linux_supports_tracevforkdone (int pid)
return linux_supports_tracevforkdone_flag;
}
+static void
+linux_enable_tracesysgood (ptid_t ptid)
+{
+ int pid = ptid_get_lwp (ptid);
+
+ if (pid == 0)
+ pid = ptid_get_pid (ptid);
+
+ if (linux_supports_tracesysgood (pid) == 0)
+ return;
+
+ current_ptrace_options |= PTRACE_O_TRACESYSGOOD;
+
+ ptrace (PTRACE_SETOPTIONS, pid, 0, current_ptrace_options);
+}
+
void
linux_enable_event_reporting (ptid_t ptid)
{
int pid = ptid_get_lwp (ptid);
- int options;
if (pid == 0)
pid = ptid_get_pid (ptid);
@@ -557,15 +621,16 @@ linux_enable_event_reporting (ptid_t ptid)
if (! linux_supports_tracefork (pid))
return;
- options = PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACEEXEC
- | PTRACE_O_TRACECLONE;
+ current_ptrace_options |= PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK
+ | PTRACE_O_TRACEEXEC | PTRACE_O_TRACECLONE;
+
if (linux_supports_tracevforkdone (pid))
- options |= PTRACE_O_TRACEVFORKDONE;
+ current_ptrace_options |= PTRACE_O_TRACEVFORKDONE;
/* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to support
read-only process state. */
- ptrace (PTRACE_SETOPTIONS, pid, 0, options);
+ ptrace (PTRACE_SETOPTIONS, pid, 0, current_ptrace_options);
}
static void
@@ -573,6 +638,7 @@ linux_child_post_attach (int pid)
{
linux_enable_event_reporting (pid_to_ptid (pid));
check_for_thread_db ();
+ linux_enable_tracesysgood (pid_to_ptid (pid));
}
static void
@@ -580,6 +646,7 @@ linux_child_post_startup_inferior (ptid_t ptid)
{
linux_enable_event_reporting (ptid);
check_for_thread_db ();
+ linux_enable_tracesysgood (ptid);
}
static int
@@ -810,6 +877,20 @@ linux_child_insert_exec_catchpoint (int pid)
error (_("Your system does not support exec catchpoints."));
}
+static int
+linux_child_set_syscall_catchpoint (int pid, int needed, int any_count,
+ int table_size, int *table)
+{
+ if (! linux_supports_tracesysgood (pid))
+ error (_("Your system does not support syscall catchpoints."));
+ /* On GNU/Linux, we ignore the arguments. It means that we only
+ enable the syscall catchpoints, but do not disable them.
+
+ Also, we do not use the `table' information because we do not
+ filter system calls here. We let GDB do the logic for us. */
+ return 0;
+}
+
/* On GNU/Linux there are no real LWP's. The closest thing to LWP's
are processes sharing the same VM space. A multi-threaded process
is basically a group of such processes. However, such a grouping
@@ -1982,6 +2063,47 @@ linux_handle_extended_wait (struct lwp_info *lp, int status,
return 0;
}
+ /* Used for 'catch syscall' feature. */
+ if (WSTOPSIG (status) == TRAP_IS_SYSCALL)
+ {
+ if (catch_syscall_enabled () == 0)
+ ourstatus->kind = TARGET_WAITKIND_IGNORE;
+ else
+ {
+ struct regcache *regcache = get_thread_regcache (lp->ptid);
+ struct gdbarch *gdbarch = get_regcache_arch (regcache);
+
+ ourstatus->value.syscall_number =
+ (int) gdbarch_get_syscall_number (gdbarch, lp->ptid);
+
+ /* If we are catching this specific syscall number, then we
+ should update the target_status to reflect which event
+ has occurred. But if this syscall is not to be caught,
+ then we can safely mark the event as a SYSCALL_RETURN.
+
+ This is particularly needed if:
+
+ - We are catching any syscalls, or
+ - We are catching the syscall "exit"
+
+ In this case, as the syscall "exit" *doesn't* return,
+ then GDB would be confused because it would mark the last
+ syscall event as a SYSCALL_ENTRY. After that, if we re-ran the
+ inferior GDB will think that the first syscall event is
+ the opposite of a SYSCALL_ENTRY, which is the SYSCALL_RETURN.
+ Therefore, GDB would report inverted syscall events. */
+ if (catching_syscall_number (ourstatus->value.syscall_number))
+ ourstatus->kind =
+ (lp->syscall_state == TARGET_WAITKIND_SYSCALL_ENTRY) ?
+ TARGET_WAITKIND_SYSCALL_RETURN : TARGET_WAITKIND_SYSCALL_ENTRY;
+ else
+ ourstatus->kind = TARGET_WAITKIND_SYSCALL_RETURN;
+
+ lp->syscall_state = ourstatus->kind;
+ }
+ return 0;
+ }
+
internal_error (__FILE__, __LINE__,
_("unknown ptrace event %d"), event);
}
@@ -2580,11 +2702,16 @@ linux_nat_filter_event (int lwpid, int status, int options)
}
/* Save the trap's siginfo in case we need it later. */
- if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP)
+ if (WIFSTOPPED (status)
+ && (WSTOPSIG (status) == SIGTRAP || WSTOPSIG (status) == TRAP_IS_SYSCALL))
save_siginfo (lp);
- /* Handle GNU/Linux's extended waitstatus for trace events. */
- if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP && status >> 16 != 0)
+ /* Handle GNU/Linux's extended waitstatus for trace events.
+ It is necessary to check if WSTOPSIG is signaling that
+ the inferior is entering/exiting a system call. */
+ if (WIFSTOPPED (status)
+ && ((WSTOPSIG (status) == TRAP_IS_SYSCALL)
+ || (WSTOPSIG (status) == SIGTRAP && status >> 16 != 0)))
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
@@ -4510,6 +4637,7 @@ linux_target_install_ops (struct target_ops *t)
t->to_insert_fork_catchpoint = linux_child_insert_fork_catchpoint;
t->to_insert_vfork_catchpoint = linux_child_insert_vfork_catchpoint;
t->to_insert_exec_catchpoint = linux_child_insert_exec_catchpoint;
+ t->to_set_syscall_catchpoint = linux_child_set_syscall_catchpoint;
t->to_pid_to_exec_file = linux_child_pid_to_exec_file;
t->to_post_startup_inferior = linux_child_post_startup_inferior;
t->to_post_attach = linux_child_post_attach;
generated by cgit v1.1 at 2024-12-01 20:50:55 +0000