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Hi, Some tests in gdb.threads/multiple-step-overs.exp fail on arm target when the displaced stepping on, but they pass when displaced stepping is off. FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: step: step FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: next: next FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: continue: continue FAIL: gdb.threads/multiple-step-overs.exp: displaced=on: signal thr1: continue to sigusr1_handler when displaced stepping is on, Sending packet: $vCont;c#a8...infrun: infrun_async(1)^M <--- [1] infrun: prepare_to_wait^M infrun: target_wait (-1.0.0, status) =^M infrun: -1.0.0 [Thread 0],^M infrun: status->kind = ignore^M infrun: TARGET_WAITKIND_IGNORE^M infrun: prepare_to_wait^M Packet received: T05swbreak:;0b:f8faffbe;0d:409ee7b6;0f:d0880000;thread:p635.636;core:0;^M infrun: target_wait (-1.0.0, status) =^M infrun: 1589.1590.0 [Thread 1590],^M infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP^M infrun: TARGET_WAITKIND_STOPPED^M infrun: stop_pc = 0x88d0^M infrun: context switch^M infrun: Switching context from Thread 1591 to Thread 1590^ GDB resumes the whole process (all threads) rather than the specific thread for which GDB wants to step over the breakpoint (as shown in [1]). That is wrong because we resume a single thread and leave others stopped when doing a normal step over where we temporarily remove the breakpoint, single-step, reinsert the breakpoint, is that if we let other threads run in the period while the breakpoint is removed, then these other threads could miss the breakpoint. Since with displaced stepping, we don't ever remove the breakpoint, it should be fine to let other threads run. However, there's another reason that we should not let other threads run: that is the case where some of those threads are also stopped for a breakpoint that itself needs to be stepped over. If we just let those threads run, then they immediately re-trap their breakpoint again. when displaced stepping is off, GDB behaves correctly, only resumes the specific thread (as shown in [2]). Sending packet: $vCont;c:p611.613#b2...infrun: infrun_async(1)^M <-- [2] infrun: prepare_to_wait^M infrun: target_wait (-1.0.0, status) =^M infrun: -1.0.0 [Thread 0],^M infrun: status->kind = ignore^M infrun: TARGET_WAITKIND_IGNORE^M infrun: prepare_to_wait^M Packet received: T05swbreak:;0b:f8faffbe;0d:409e67b6;0f:48880000;thread:p611.613;core:1;^M infrun: target_wait (-1.0.0, status) =^M infrun: 1553.1555.0 [Thread 1555],^M infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP^M infrun: TARGET_WAITKIND_STOPPED^M infrun: clear_step_over_info^M infrun: stop_pc = 0x8848 The current logic in GDB on deciding the set of threads to resume is: /* Decide the set of threads to ask the target to resume. */ if ((step || thread_has_single_step_breakpoints_set (tp)) && tp->control.trap_expected) { /* We're allowing a thread to run past a breakpoint it has hit, by single-stepping the thread with the breakpoint removed. In which case, we need to single-step only this thread, and keep others stopped, as they can miss this breakpoint if allowed to run. */ resume_ptid = inferior_ptid; } else resume_ptid = internal_resume_ptid (user_step); it doesn't handle the case correctly that GDB continue (instead of single step) the thread for displaced stepping. I also update the comment below to reflect the code. I remove the "with the breakpoint removed" comment, because GDB doesn't remove breakpoints in displaced stepping, so we don't have to worry that other threads may miss the breakpoint. Patch is regression tested on both x86_64-linux and arm-linux. gdb: 2015-11-17 Yao Qi <yao.qi@linaro.org> * infrun.c (resume): Check control.trap_expected only when deciding the set of threads to resume. |
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binutils | ||
config | ||
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elfcpp | ||
etc | ||
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gprof | ||
include | ||
intl | ||
ld | ||
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compile | ||
config-ml.in | ||
config.guess | ||
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config.sub | ||
configure | ||
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COPYING3 | ||
COPYING3.LIB | ||
COPYING.LIB | ||
COPYING.LIBGLOSS | ||
COPYING.NEWLIB | ||
depcomp | ||
djunpack.bat | ||
install-sh | ||
libtool.m4 | ||
lt~obsolete.m4 | ||
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README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.