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Fix Solaris regression (PR tdep/30252)

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PR tdep/30252 reports that using GDB on Solaris fails an assertion in
target_resume:

 target.c:2648: internal-error: target_resume: Assertion `inferior_ptid != null_ptid' failed.
 A problem internal to GDB has been detected,
 further debugging may prove unreliable.
 Quit this debugging session? (y or n)

The backtrace, after running it through c++filt, looks like:

 ----- Backtrace -----
 0xa18914 gdb_internal_backtrace_1
	 /root/binutils-gdb/gdb/bt-utils.c:122
 0xa18914 gdb_internal_backtrace()
	 /root/binutils-gdb/gdb/bt-utils.c:168
 0xdec834 internal_vproblem
	 /root/binutils-gdb/gdb/utils.c:401
 0xdecad8 internal_verror(char const*, int, char const*, __va_list_tag*)
	 /root/binutils-gdb/gdb/utils.c:481
 0xf3638c internal_error_loc(char const*, int, char const*, ...)
	 /root/binutils-gdb/gdbsupport/errors.cc:58
 0xd70580 target_resume(ptid_t, int, gdb_signal)
	 /root/binutils-gdb/gdb/target.c:2648
 0xc59e85 procfs_target::wait(ptid_t, target_waitstatus*, enum_flags<target_wait_flag>)
	 /root/binutils-gdb/gdb/procfs.c:2187
 0xcf6da7 sol_thread_target::wait(ptid_t, target_waitstatus*, enum_flags<target_wait_flag>)
	 /root/binutils-gdb/gdb/sol-thread.c:442
 0xd73711 target_wait(ptid_t, target_waitstatus*, enum_flags<target_wait_flag>)
	 /root/binutils-gdb/gdb/target.c:2586
 ...

The problem is that the procfs backend, while inside target_wait,
called target_resume without switching to the leader thread of that
resumption.

The target_resume interface is:

 /* Resume execution (or prepare for execution) of the current thread
    (INFERIOR_PTID), while optionally letting other threads of the
    current process or all processes run free.
    ...

Thus calling target_resume with inferior_ptid == null_ptid is bogus.

target_wait (which leads to procfs_target::wait on Solaris) is called
with inferior_ptid == null_ptid on entry exactly to help catch such
bogus uses.

From the backtrace, it seems that the relevant line in question is
procfs.c:2187:

2186  /* How to keep going without returning to wfi: */
2187  target_continue_no_signal (ptid);
2188  goto wait_again;

target_continue_no_signal is a small wrapper around target_resume,
which would make sense.

The fix is to not call target_resume or go via the target stack at
all.  Instead, factor out a new proc_resume function out of
procfs_target::resume, and call that.  The new function does not rely
on inferior_ptid.

I've not been able to test it myself, but Petr confirmed it fixes the
assertion failure with his test case, and Marcel Telka also confirmed
it solves the problem.

Tested-By: Petr Šumbera <petr.sumbera@oracle.com>
Tested-By: Marcel Telka <marcel@telka.sk>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30252
Change-Id: I6213c59b081d400a22e799ee621c2eff6dcafbf3
This commit is contained in:
Pedro Alves
2023-07-06 15:05:11 +01:00
parent 3ee1593a53
commit dfe07f10de
1 changed files with 25 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

46
gdb/procfs.c
View File

@@ -589,6 +589,8 @@ static int proc_iterate_over_threads
(procinfo *pi,
int (*func) (procinfo *, procinfo *, void *),
void *ptr);
static void proc_resume (procinfo *pi, ptid_t scope_ptid,
int step, enum gdb_signal signo);
static void
proc_warn (procinfo *pi, const char *func, int line)
@@ -2119,7 +2121,7 @@ wait_again:
gdb_printf (_("[%s exited]\n"),
target_pid_to_str (retval).c_str ());
delete_thread (find_thread_ptid (this, retval));
target_continue_no_signal (ptid);
proc_resume (pi, ptid, 0, GDB_SIGNAL_0);
goto wait_again;
}
else if (what == SYS_exit)
@@ -2183,8 +2185,7 @@ wait_again:
i, sysargs[i]);
}
/* How to keep going without returning to wfi: */
target_continue_no_signal (ptid);
proc_resume (pi, ptid, 0, GDB_SIGNAL_0);
goto wait_again;
}
break;
@@ -2217,7 +2218,7 @@ wait_again:
if (!in_thread_list (this, temp_ptid))
add_thread (this, temp_ptid);
target_continue_no_signal (ptid);
proc_resume (pi, ptid, 0, GDB_SIGNAL_0);
goto wait_again;
}
else if (what == SYS_lwp_exit)
@@ -2249,7 +2250,7 @@ wait_again:
i, sysargs[i]);
}
target_continue_no_signal (ptid);
proc_resume (pi, ptid, 0, GDB_SIGNAL_0);
goto wait_again;
}
break;
@@ -2428,20 +2429,16 @@ invalidate_cache (procinfo *parent, procinfo *pi, void *ptr)
return 0;
}
/* Make the child process runnable. Normally we will then call
procfs_wait and wait for it to stop again (unless gdb is async).
/* Make child process PI runnable.
If STEP is true, then arrange for the child to stop again after
executing a single instruction. If SIGNO is zero, then cancel any
pending signal; if non-zero, then arrange for the indicated signal
to be delivered to the child when it runs. If PID is -1, then
allow any child thread to run; if non-zero, then allow only the
indicated thread to run. (not implemented yet). */
executing a single instruction. SCOPE_PTID, STEP and SIGNO are
like in the target_resume interface. */
void
procfs_target::resume (ptid_t ptid, int step, enum gdb_signal signo)
static void
proc_resume (procinfo *pi, ptid_t scope_ptid, int step, enum gdb_signal signo)
{
procinfo *pi, *thread;
procinfo *thread;
int native_signo;
/* FIXME: Check/reword. */
@@ -2453,10 +2450,6 @@ procfs_target::resume (ptid_t ptid, int step, enum gdb_signal signo)
So basically PR_STEP is the sole argument that must be passed
to proc_run_process. */
/* Find procinfo for main process. */
pi = find_procinfo_or_die (inferior_ptid.pid (), 0);
/* First cut: ignore pid argument. */
errno = 0;
/* Convert signal to host numbering. */
@@ -2473,11 +2466,11 @@ procfs_target::resume (ptid_t ptid, int step, enum gdb_signal signo)
/* Void the process procinfo's caches. */
invalidate_cache (NULL, pi, NULL);
if (ptid.pid () != -1)
if (scope_ptid.pid () != -1)
{
/* Resume a specific thread, presumably suppressing the
others. */
thread = find_procinfo (ptid.pid (), ptid.lwp ());
thread = find_procinfo (scope_ptid.pid (), scope_ptid.lwp ());
if (thread != NULL)
{
if (thread->tid != 0)
@@ -2502,6 +2495,17 @@ procfs_target::resume (ptid_t ptid, int step, enum gdb_signal signo)
}
}
/* Implementation of target_ops::resume. */
void
procfs_target::resume (ptid_t scope_ptid, int step, enum gdb_signal signo)
{
/* Find procinfo for main process. */
procinfo *pi = find_procinfo_or_die (inferior_ptid.pid (), 0);
proc_resume (pi, scope_ptid, step, signo);
}
/* Set up to trace signals in the child process. */
void