From a911d87ad714cbfbbc5c5752cb8b445a7e70196c Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Wed, 13 Jan 2016 10:40:33 +0000 Subject: Fix PR19388: Can't access $_siginfo in breakpoint (catch signal) condition This commit merges both the registers and $_siginfo "thread running/executing" checks into a single function. Accessing $_siginfo from a "catch signal" breakpoint condition doesn't work. The condition always fails with "Selected thread is running": (gdb) catch signal Catchpoint 3 (standard signals) (gdb) condition $bpnum $_siginfo.si_signo == 5 (gdb) continue Continuing. Error in testing breakpoint condition: Selected thread is running. Catchpoint 3 (signal SIGUSR1), 0x0000003615e35877 in __GI_raise (sig=10) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56 56 return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig); (gdb) When accessing the $_siginfo object, we check whether the thread is marked running (external/public) state and refuse the access if so. This is so "print $_siginfo" at the prompt fails nicelly when the current thread is running. While evaluating breakpoint conditionals, we haven't decided yet whether the thread is going to stop, so is_running still returns true, and we thus always error out. Evaluating an expression that requires registers access is really conceptually the same -- we could think of $_siginfo as a pseudo register. However, in that case we check whether the thread is marked executing (internal/private state), not running (external/public state). Changing the $_siginfo validation to check is_executing as well fixes the bug in question. Note that checking is_executing is not fully correct, not even for registers. See PR 19389. However, I think this is the lesser of two evils and ends up as an improvement. We at least now have a single place to fix. Tested on x86_64 GNU/Linux. gdb/ChangeLog: 2016-01-13 Pedro Alves PR breakpoints/19388 * frame.c (get_current_frame): Use validate_registers_access. * gdbthread.h (validate_registers_access): Declare. * infrun.c (validate_siginfo_access): Delete. (siginfo_value_read, siginfo_value_write): Use validate_registers_access. * thread.c (validate_registers_access): New function. gdb/testsuite/ChangeLog: 2016-01-13 Pedro Alves PR breakpoints/19388 * gdb.base/catch-signal-siginfo-cond.c: New file. * gdb.base/catch-signal-siginfo-cond.exp: New file. --- gdb/thread.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'gdb/thread.c') diff --git a/gdb/thread.c b/gdb/thread.c index 4c2259f..56526e4 100644 --- a/gdb/thread.c +++ b/gdb/thread.c @@ -1098,6 +1098,28 @@ finish_thread_state_cleanup (void *arg) finish_thread_state (*ptid_p); } +/* See gdbthread.h. */ + +void +validate_registers_access (void) +{ + /* No selected thread, no registers. */ + if (ptid_equal (inferior_ptid, null_ptid)) + error (_("No thread selected.")); + + /* Don't try to read from a dead thread. */ + if (is_exited (inferior_ptid)) + error (_("The current thread has terminated")); + + /* ... or from a spinning thread. FIXME: This isn't actually fully + correct. It'll allow an user-requested access (e.g., "print $pc" + at the prompt) when a thread is not executing for some internal + reason, but is marked running from the user's perspective. E.g., + the thread is waiting for its turn in the step-over queue. */ + if (is_executing (inferior_ptid)) + error (_("Selected thread is running.")); +} + int pc_in_thread_step_range (CORE_ADDR pc, struct thread_info *thread) { -- cgit v1.1