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Add basic event handling in the NetBSD target

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Implement the following events:
 - single step (TRAP_TRACE)
 - software breakpoint (TRAP_DBREG)
 - exec() (TRAP_EXEC)
 - syscall entry/exit (TRAP_SCE / TRAP_SCX)

Add support for NetBSD specific ::wait () and ::resume ().

Instruct the generic code that exec and syscall events are supported.

Define an empty nbsd_get_syscall_number as it is prerequisite for
catching syscall entry and exit events, even if it is unused.
This function is used to detect whether the gdbarch supports the
'catch syscall' feature.

gdb/ChangeLog:

       * nbsd-nat.c: Include "sys/wait.h".
       (nbsd_resume, nbsd_nat_target::resume, nbsd_wait)
       (nbsd_nat_target::wait, nbsd_nat_target::insert_exec_catchpoint)
       (nbsd_nat_target::remove_exec_catchpoint)
       (nbsd_nat_target::set_syscall_catchpoint): Add.
       * nbsd-nat.h (nbsd_nat_target::resume, nbsd_nat_target::wait)
       (nbsd_nat_target::insert_exec_catchpoint)
       (nbsd_nat_target::remove_exec_catchpoint)
       (nbsd_nat_target::set_syscall_catchpoint): Add.
       * nbsd-tdep.c (nbsd_get_syscall_number): Add.
       (nbsd_init_abi): Call `set_gdbarch_get_syscall_number' and pass
       `nbsd_get_syscall_number'.
This commit is contained in:
Kamil Rytarowski 2020-04-29 01:57:38 +02:00
parent cb4c35cfbe
commit f94b2e0387
4 changed files with 264 additions and 0 deletions
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15
gdb/ChangeLog
View File

@ -1,3 +1,18 @@
2020-04-29 Kamil Rytarowski <n54@gmx.com>
* nbsd-nat.c: Include "sys/wait.h".
(nbsd_resume, nbsd_nat_target::resume, nbsd_wait)
(nbsd_nat_target::wait, nbsd_nat_target::insert_exec_catchpoint)
(nbsd_nat_target::remove_exec_catchpoint)
(nbsd_nat_target::set_syscall_catchpoint): Add.
* nbsd-nat.h (nbsd_nat_target::resume, nbsd_nat_target::wait)
(nbsd_nat_target::insert_exec_catchpoint)
(nbsd_nat_target::remove_exec_catchpoint)
(nbsd_nat_target::set_syscall_catchpoint): Add.
* nbsd-tdep.c (nbsd_get_syscall_number): Add.
(nbsd_init_abi): Call `set_gdbarch_get_syscall_number' and pass
`nbsd_get_syscall_number'.
2020-04-29 Tom Tromey <tom@tromey.com>
* stack.c (print_block_frame_labels): Remove.

222
gdb/nbsd-nat.c
View File

@ -28,6 +28,7 @@
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/sysctl.h>
#include <sys/wait.h>
/* Return the name of a file that can be opened to get the symbols for
the child process identified by PID. */
@ -539,3 +540,224 @@ nbsd_nat_target::info_proc (const char *args, enum info_proc_what what)
return true;
}
/* Resume execution of a specified PTID, that points to a process or a thread
within a process. If one thread is specified, all other threads are
suspended. If STEP is nonzero, single-step it. If SIGNAL is nonzero,
give it that signal. */
static void
nbsd_resume(nbsd_nat_target *target, ptid_t ptid, int step,
enum gdb_signal signal)
{
int request;
gdb_assert (minus_one_ptid != ptid);
if (ptid.lwp_p ())
{
/* If ptid is a specific LWP, suspend all other LWPs in the process. */
inferior *inf = find_inferior_ptid (target, ptid);
for (thread_info *tp : inf->non_exited_threads ())
{
if (tp->ptid.lwp () == ptid.lwp ())
request = PT_RESUME;
else
request = PT_SUSPEND;
if (ptrace (request, tp->ptid.pid (), NULL, tp->ptid.lwp ()) == -1)
perror_with_name (("ptrace"));
}
}
else
{
/* If ptid is a wildcard, resume all matching threads (they won't run
until the process is continued however). */
for (thread_info *tp : all_non_exited_threads (target, ptid))
if (ptrace (PT_RESUME, tp->ptid.pid (), NULL, tp->ptid.lwp ()) == -1)
perror_with_name (("ptrace"));
}
if (step)
{
for (thread_info *tp : all_non_exited_threads (target, ptid))
if (ptrace (PT_SETSTEP, tp->ptid.pid (), NULL, tp->ptid.lwp ()) == -1)
perror_with_name (("ptrace"));
}
else
{
for (thread_info *tp : all_non_exited_threads (target, ptid))
if (ptrace (PT_CLEARSTEP, tp->ptid.pid (), NULL, tp->ptid.lwp ()) == -1)
perror_with_name (("ptrace"));
}
if (catch_syscall_enabled () > 0)
request = PT_SYSCALL;
else
request = PT_CONTINUE;
/* An address of (void *)1 tells ptrace to continue from
where it was. If GDB wanted it to start some other way, we have
already written a new program counter value to the child. */
if (ptrace (request, ptid.pid (), (void *)1, gdb_signal_to_host (signal)) == -1)
perror_with_name (("ptrace"));
}
/* Resume execution of thread PTID, or all threads of all inferiors
if PTID is -1. If STEP is nonzero, single-step it. If SIGNAL is nonzero,
give it that signal. */
void
nbsd_nat_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
{
if (minus_one_ptid != ptid)
nbsd_resume (this, ptid, step, signal);
else
{
for (inferior *inf : all_non_exited_inferiors (this))
nbsd_resume (this, ptid_t (inf->pid, 0, 0), step, signal);
}
}
/* Implement a safe wrapper around waitpid(). */
static pid_t
nbsd_wait (ptid_t ptid, struct target_waitstatus *ourstatus, int options)
{
pid_t pid;
int status;
set_sigint_trap ();
do
{
/* The common code passes WNOHANG that leads to crashes, overwrite it. */
pid = waitpid (ptid.pid (), &status, 0);
}
while (pid == -1 && errno == EINTR);
clear_sigint_trap ();
if (pid == -1)
perror_with_name (_("Child process unexpectedly missing"));
store_waitstatus (ourstatus, status);
return pid;
}
/* Wait for the child specified by PTID to do something. Return the
process ID of the child, or MINUS_ONE_PTID in case of error; store
the status in *OURSTATUS. */
ptid_t
nbsd_nat_target::wait (ptid_t ptid, struct target_waitstatus *ourstatus,
int target_options)
{
pid_t pid = nbsd_wait (ptid, ourstatus, target_options);
ptid_t wptid = ptid_t (pid);
/* If the child stopped, keep investigating its status. */
if (ourstatus->kind != TARGET_WAITKIND_STOPPED)
return wptid;
/* Extract the event and thread that received a signal. */
ptrace_siginfo_t psi;
if (ptrace (PT_GET_SIGINFO, pid, &psi, sizeof (psi)) == -1)
perror_with_name (("ptrace"));
/* Pick child's siginfo_t. */
siginfo_t *si = &psi.psi_siginfo;
int lwp = psi.psi_lwpid;
int signo = si->si_signo;
const int code = si->si_code;
/* Construct PTID with a specified thread that received the event.
If a signal was targeted to the whole process, lwp is 0. */
wptid = ptid_t (pid, lwp, 0);
/* Bail out on non-debugger oriented signals.. */
if (signo != SIGTRAP)
return wptid;
/* Stop examining non-debugger oriented SIGTRAP codes. */
if (code <= SI_USER || code == SI_NOINFO)
return wptid;
if (in_thread_list (this, ptid_t (pid)))
thread_change_ptid (this, ptid_t (pid), wptid);
if (code == TRAP_EXEC)
{
ourstatus->kind = TARGET_WAITKIND_EXECD;
ourstatus->value.execd_pathname = xstrdup (pid_to_exec_file (pid));
return wptid;
}
if (code == TRAP_TRACE)
{
/* Unhandled at this level. */
return wptid;
}
if (code == TRAP_SCE || code == TRAP_SCX)
{
int sysnum = si->si_sysnum;
if (!catch_syscall_enabled () || !catching_syscall_number (sysnum))
{
/* If the core isn't interested in this event, ignore it. */
ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
return wptid;
}
ourstatus->kind =
(code == TRAP_SCE) ? TARGET_WAITKIND_SYSCALL_ENTRY :
TARGET_WAITKIND_SYSCALL_RETURN;
ourstatus->value.syscall_number = sysnum;
return wptid;
}
if (code == TRAP_BRKPT)
{
/* Unhandled at this level. */
return wptid;
}
/* Unclassified SIGTRAP event. */
ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
return wptid;
}
/* Implement the "insert_exec_catchpoint" target_ops method. */
int
nbsd_nat_target::insert_exec_catchpoint (int pid)
{
/* Nothing to do. */
return 0;
}
/* Implement the "remove_exec_catchpoint" target_ops method. */
int
nbsd_nat_target::remove_exec_catchpoint (int pid)
{
/* Nothing to do. */
return 0;
}
/* Implement the "set_syscall_catchpoint" target_ops method. */
int
nbsd_nat_target::set_syscall_catchpoint (int pid, bool needed,
int any_count,
gdb::array_view<const int> syscall_counts)
{
/* Ignore the arguments. inf-ptrace.c will use PT_SYSCALL which
will catch all system call entries and exits. The system calls
are filtered by GDB rather than the kernel. */
return 0;
}

9
gdb/nbsd-nat.h
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@ -38,6 +38,15 @@ struct nbsd_nat_target : public inf_ptrace_target
int find_memory_regions (find_memory_region_ftype func, void *data) override;
bool info_proc (const char *, enum info_proc_what) override;
void resume (ptid_t, int, enum gdb_signal) override;
ptid_t wait (ptid_t, struct target_waitstatus *, int) override;
int insert_exec_catchpoint (int pid) override;
int remove_exec_catchpoint (int pid) override;
int set_syscall_catchpoint (int pid, bool needed, int any_count,
gdb::array_view<const int> syscall_counts)
override;
};
#endif /* nbsd-nat.h */

18
gdb/nbsd-tdep.c
View File

@ -444,6 +444,21 @@ nbsd_info_proc_mappings_entry (int addr_bit, ULONGEST kve_start,
}
}
/* Implement the "get_syscall_number" gdbarch method. */
static LONGEST
nbsd_get_syscall_number (struct gdbarch *gdbarch, thread_info *thread)
{
/* NetBSD doesn't use gdbarch_get_syscall_number since NetBSD
native targets fetch the system call number from the
'si_sysnum' member of siginfo_t in nbsd_nat_target::wait.
However, system call catching requires this function to be
set. */
internal_error (__FILE__, __LINE__, _("nbsd_get_sycall_number called"));
}
/* See nbsd-tdep.h. */
void
@ -453,4 +468,7 @@ nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
set_gdbarch_gdb_signal_to_target (gdbarch, nbsd_gdb_signal_to_target);
set_gdbarch_skip_solib_resolver (gdbarch, nbsd_skip_solib_resolver);
set_gdbarch_auxv_parse (gdbarch, svr4_auxv_parse);
/* `catch syscall' */
set_gdbarch_get_syscall_number (gdbarch, nbsd_get_syscall_number);
}