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 <palves@redhat.com> 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 <palves@redhat.com> PR breakpoints/19388 * gdb.base/catch-signal-siginfo-cond.c: New file. * gdb.base/catch-signal-siginfo-cond.exp: New file.
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8 changed files with 144 additions and 29 deletions
27
gdb/infrun.c
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gdb/infrun.c
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@ -8684,25 +8684,6 @@ signals_info (char *signum_exp, int from_tty)
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"to change these tables.\n"));
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}
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/* Check if it makes sense to read $_siginfo from the current thread
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at this point. If not, throw an error. */
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static void
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validate_siginfo_access (void)
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{
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/* No current inferior, no siginfo. */
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if (ptid_equal (inferior_ptid, null_ptid))
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error (_("No thread selected."));
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/* Don't try to read from a dead thread. */
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if (is_exited (inferior_ptid))
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error (_("The current thread has terminated"));
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/* ... or from a spinning thread. */
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if (is_running (inferior_ptid))
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error (_("Selected thread is running."));
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}
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/* The $_siginfo convenience variable is a bit special. We don't know
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for sure the type of the value until we actually have a chance to
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fetch the data. The type can change depending on gdbarch, so it is
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@ -8721,7 +8702,9 @@ siginfo_value_read (struct value *v)
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{
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LONGEST transferred;
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validate_siginfo_access ();
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/* If we can access registers, so can we access $_siginfo. Likewise
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vice versa. */
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validate_registers_access ();
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transferred =
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target_read (¤t_target, TARGET_OBJECT_SIGNAL_INFO,
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@ -8742,7 +8725,9 @@ siginfo_value_write (struct value *v, struct value *fromval)
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{
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LONGEST transferred;
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validate_siginfo_access ();
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/* If we can access registers, so can we access $_siginfo. Likewise
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vice versa. */
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validate_registers_access ();
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transferred = target_write (¤t_target,
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TARGET_OBJECT_SIGNAL_INFO,
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