From 21987b9c060033d367abc50c29f786df4c21b10c Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Sun, 29 Sep 2019 08:50:15 -0600 Subject: Add RAII class for blocking gdb signals This adds configury support and an RAII class that can be used to temporarily block signals that are used by gdb. (This class is not used in this patch, but it split out for easier review.) The idea of this patch is that these signals should only be delivered to the main thread. So, when creating a background thread, they are temporarily blocked; the blocked state is inherited by the new thread. The sigprocmask man page says: The use of sigprocmask() is unspecified in a multithreaded process; see pthread_sigmask(3). This patch changes gdb to use pthread_sigmask when appropriate, by introducing a convenience define. I've updated gdbserver as well, because I had to touch gdbsupport, and because the threading patches will make it link against the thread library. I chose not to touch the NTO code, because I don't know anything about that platform and because I cannot test it. Finally, this modifies an existing spot in the Guile layer to use the new facility. gdb/ChangeLog 2019-11-26 Tom Tromey * gdbsupport/signals-state-save-restore.c (original_signal_mask): Remove comment. (save_original_signals_state, restore_original_signals_state): Use gdb_sigmask. * linux-nat.c (block_child_signals, restore_child_signals_mask) (_initialize_linux_nat): Use gdb_sigmask. * guile/guile.c (_initialize_guile): Use block_signals. * Makefile.in (HFILES_NO_SRCDIR): Add gdb-sigmask.h. * gdbsupport/gdb-sigmask.h: New file. * event-top.c (async_sigtstp_handler): Use gdb_sigmask. * cp-support.c (gdb_demangle): Use gdb_sigmask. * gdbsupport/common.m4 (GDB_AC_COMMON): Check for pthread_sigmask. * configure, config.in: Rebuild. * gdbsupport/block-signals.h: New file. gdb/gdbserver/ChangeLog 2019-11-26 Tom Tromey * remote-utils.c (block_unblock_async_io): Use gdb_sigmask. * linux-low.c (linux_wait_for_event_filtered, linux_async): Use gdb_sigmask. * configure, config.in: Rebuild. Change-Id: If3f37dc57dd859c226e9e4d79458a0514746e8c6 --- gdb/gdbserver/ChangeLog | 7 +++ gdb/gdbserver/config.in | 3 + gdb/gdbserver/configure | 128 +++++++++++++++++++++++++++++++++++++++++++ gdb/gdbserver/linux-low.c | 17 +++--- gdb/gdbserver/remote-utils.c | 3 +- 5 files changed, 149 insertions(+), 9 deletions(-) (limited to 'gdb/gdbserver') diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index eee4b81..00b0a0d 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,5 +1,12 @@ 2019-11-26 Tom Tromey + * remote-utils.c (block_unblock_async_io): Use gdb_sigmask. + * linux-low.c (linux_wait_for_event_filtered, linux_async): Use + gdb_sigmask. + * configure, config.in: Rebuild. + +2019-11-26 Tom Tromey + * Makefile.in (PTHREAD_CFLAGS, PTHREAD_LIBS): New variables. (INTERNAL_CFLAGS_BASE): Use PTHREAD_CFLAGS. (GDBSERVER_LIBS): Use PTHREAD_LIBS. diff --git a/gdb/gdbserver/config.in b/gdb/gdbserver/config.in index 4276bce..3027ffa 100644 --- a/gdb/gdbserver/config.in +++ b/gdb/gdbserver/config.in @@ -195,6 +195,9 @@ /* Have PTHREAD_PRIO_INHERIT. */ #undef HAVE_PTHREAD_PRIO_INHERIT +/* Define to 1 if you have the `pthread_sigmask' function. */ +#undef HAVE_PTHREAD_SIGMASK + /* Define if the target supports PTRACE_GETFPXREGS for extended register access. */ #undef HAVE_PTRACE_GETFPXREGS diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure index 882c192..8d34a6c 100755 --- a/gdb/gdbserver/configure +++ b/gdb/gdbserver/configure @@ -1972,6 +1972,119 @@ $as_echo "$ac_res" >&6; } } # ac_fn_c_check_decl +# ac_fn_cxx_try_link LINENO +# ------------------------- +# Try to link conftest.$ac_ext, and return whether this succeeded. +ac_fn_cxx_try_link () +{ + as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack + rm -f conftest.$ac_objext conftest$ac_exeext + if { { ac_try="$ac_link" +case "(($ac_try" in + *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;; + *) ac_try_echo=$ac_try;; +esac +eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\"" +$as_echo "$ac_try_echo"; } >&5 + (eval "$ac_link") 2>conftest.err + ac_status=$? + if test -s conftest.err; then + grep -v '^ *+' conftest.err >conftest.er1 + cat conftest.er1 >&5 + mv -f conftest.er1 conftest.err + fi + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; } && { + test -z "$ac_cxx_werror_flag" || + test ! -s conftest.err + } && test -s conftest$ac_exeext && { + test "$cross_compiling" = yes || + test -x conftest$ac_exeext + }; then : + ac_retval=0 +else + $as_echo "$as_me: failed program was:" >&5 +sed 's/^/| /' conftest.$ac_ext >&5 + + ac_retval=1 +fi + # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information + # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would + # interfere with the next link command; also delete a directory that is + # left behind by Apple's compiler. We do this before executing the actions. + rm -rf conftest.dSYM conftest_ipa8_conftest.oo + eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno + as_fn_set_status $ac_retval + +} # ac_fn_cxx_try_link + +# ac_fn_cxx_check_func LINENO FUNC VAR +# ------------------------------------ +# Tests whether FUNC exists, setting the cache variable VAR accordingly +ac_fn_cxx_check_func () +{ + as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2" >&5 +$as_echo_n "checking for $2... " >&6; } +if eval \${$3+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +/* Define $2 to an innocuous variant, in case declares $2. + For example, HP-UX 11i declares gettimeofday. */ +#define $2 innocuous_$2 + +/* System header to define __stub macros and hopefully few prototypes, + which can conflict with char $2 (); below. + Prefer to if __STDC__ is defined, since + exists even on freestanding compilers. */ + +#ifdef __STDC__ +# include +#else +# include +#endif + +#undef $2 + +/* Override any GCC internal prototype to avoid an error. + Use char because int might match the return type of a GCC + builtin and then its argument prototype would still apply. */ +#ifdef __cplusplus +extern "C" +#endif +char $2 (); +/* The GNU C library defines this for functions which it implements + to always fail with ENOSYS. Some functions are actually named + something starting with __ and the normal name is an alias. */ +#if defined __stub_$2 || defined __stub___$2 +choke me +#endif + +int +main () +{ +return $2 (); + ; + return 0; +} +_ACEOF +if ac_fn_cxx_try_link "$LINENO"; then : + eval "$3=yes" +else + eval "$3=no" +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext +fi +eval ac_res=\$$3 + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5 +$as_echo "$ac_res" >&6; } + eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno + +} # ac_fn_cxx_check_func + # ac_fn_c_compute_int LINENO EXPR VAR INCLUDES # -------------------------------------------- # Tries to find the compile-time value of EXPR in a program that includes @@ -7609,6 +7722,21 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext fi { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gdb_cv_cxx_std_thread" >&5 $as_echo "$gdb_cv_cxx_std_thread" >&6; } + + # This check must be here, while LIBS includes any necessary + # threading library. + for ac_func in pthread_sigmask +do : + ac_fn_cxx_check_func "$LINENO" "pthread_sigmask" "ac_cv_func_pthread_sigmask" +if test "x$ac_cv_func_pthread_sigmask" = xyes; then : + cat >>confdefs.h <<_ACEOF +#define HAVE_PTHREAD_SIGMASK 1 +_ACEOF + +fi +done + + LIBS="$save_LIBS" CXXFLAGS="$save_CXXFLAGS" fi diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index f34811c..688a395 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -50,6 +50,7 @@ #include "gdbsupport/common-inferior.h" #include "nat/fork-inferior.h" #include "gdbsupport/environ.h" +#include "gdbsupport/gdb-sigmask.h" #include "gdbsupport/scoped_restore.h" #ifndef ELFMAG0 /* Don't include here. If it got included by gdb_proc_service.h @@ -2689,7 +2690,7 @@ linux_wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid, /* Make sure SIGCHLD is blocked until the sigsuspend below. Block all signals while here. */ sigfillset (&block_mask); - sigprocmask (SIG_BLOCK, &block_mask, &prev_mask); + gdb_sigmask (SIG_BLOCK, &block_mask, &prev_mask); /* Always pull all events out of the kernel. We'll randomly select an event LWP out of all that have events, to prevent @@ -2775,7 +2776,7 @@ linux_wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid, { if (debug_threads) debug_printf ("LLW: exit (no unwaited-for LWP)\n"); - sigprocmask (SIG_SETMASK, &prev_mask, NULL); + gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); return -1; } @@ -2785,7 +2786,7 @@ linux_wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid, if (debug_threads) debug_printf ("WNOHANG set, no event found\n"); - sigprocmask (SIG_SETMASK, &prev_mask, NULL); + gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); return 0; } @@ -2794,11 +2795,11 @@ linux_wait_for_event_filtered (ptid_t wait_ptid, ptid_t filter_ptid, debug_printf ("sigsuspend'ing\n"); sigsuspend (&prev_mask); - sigprocmask (SIG_SETMASK, &prev_mask, NULL); + gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); goto retry; } - sigprocmask (SIG_SETMASK, &prev_mask, NULL); + gdb_sigmask (SIG_SETMASK, &prev_mask, NULL); current_thread = event_thread; @@ -6215,7 +6216,7 @@ linux_async (int enable) sigemptyset (&mask); sigaddset (&mask, SIGCHLD); - sigprocmask (SIG_BLOCK, &mask, NULL); + gdb_sigmask (SIG_BLOCK, &mask, NULL); if (enable) { @@ -6223,7 +6224,7 @@ linux_async (int enable) { linux_event_pipe[0] = -1; linux_event_pipe[1] = -1; - sigprocmask (SIG_UNBLOCK, &mask, NULL); + gdb_sigmask (SIG_UNBLOCK, &mask, NULL); warning ("creating event pipe failed."); return previous; @@ -6249,7 +6250,7 @@ linux_async (int enable) linux_event_pipe[1] = -1; } - sigprocmask (SIG_UNBLOCK, &mask, NULL); + gdb_sigmask (SIG_UNBLOCK, &mask, NULL); } return previous; diff --git a/gdb/gdbserver/remote-utils.c b/gdb/gdbserver/remote-utils.c index d7da4b7..c7f97f3 100644 --- a/gdb/gdbserver/remote-utils.c +++ b/gdb/gdbserver/remote-utils.c @@ -28,6 +28,7 @@ #include "gdbsupport/rsp-low.h" #include "gdbsupport/netstuff.h" #include "gdbsupport/filestuff.h" +#include "gdbsupport/gdb-sigmask.h" #include #if HAVE_SYS_IOCTL_H #include @@ -807,7 +808,7 @@ block_unblock_async_io (int block) sigemptyset (&sigio_set); sigaddset (&sigio_set, SIGIO); - sigprocmask (block ? SIG_BLOCK : SIG_UNBLOCK, &sigio_set, NULL); + gdb_sigmask (block ? SIG_BLOCK : SIG_UNBLOCK, &sigio_set, NULL); #endif } -- cgit v1.1