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When I exercise GDBserver software single step, I see the following error, which has been already handled by GDB properly. In GDBserver log, we can see, GDBserver tries to single step instruction on 0xb6e0a6e4, and destination address is 0xffff0fe0, stop pc is 0xb6e0a6e4 Writing f001f0e7 to 0xffff0fe0 in process 7132 Failed to insert breakpoint at 0xffff0fe0 (Input/output error). Failed to insert breakpoint at 0xffff0fe0 (-1). (gdb) disassemble __aeabi_read_tp,+8 Dump of assembler code from 0xb6e0a6e0 to 0xb6e0a6e8: 0xb6e0a6e0 <__aeabi_read_tp+0>: mvn r0, #61440 ; 0xf000 0xb6e0a6e4 <__aeabi_read_tp+4>: sub pc, r0, #31 however, it fails inserting breakpoint there. This problem has already fixed by GDB, see comments in arm-linux-tdep.c:arm_linux_software_single_step /* The Linux kernel offers some user-mode helpers in a high page. We can not read this page (as of 2.6.23), and even if we could then we couldn't set breakpoints in it, and even if we could then the atomic operations would fail when interrupted. They are all called as functions and return to the address in LR, so step to there instead. */ so we need to do the same thing in GDB side as well. This patch adds a new field fixup in arm_get_next_pcs_ops, so that we can fix up PC for arm-linux target. In this way, both GDB and GDBserver can single step instructions going to kernel helpers. gdb: 2016-02-12 Yao Qi <yao.qi@linaro.org> * arch/arm-get-next-pcs.c (arm_get_next_pcs): Call self->ops->fixup if it isn't NULL. * arch/arm-get-next-pcs.h: Include gdb_vecs.h. (struct arm_get_next_pcs_ops) <fixup>: New field. * arch/arm-linux.c: Include common-regcache.h and arch/arm-get-next-pcs.h. (arm_linux_get_next_pcs_fixup): New function. * arch/arm-linux.h (arm_linux_get_next_pcs_fixup): Declare. * arm-linux-tdep.c (arm_linux_get_next_pcs_ops): Initialize it with arm_linux_get_next_pcs_fixup. (arm_linux_software_single_step): Move code to arm_linux_get_next_pcs_fixup. * arm-tdep.c (arm_get_next_pcs_ops): Initialize it. gdb/gdbserver: 2016-02-12 Yao Qi <yao.qi@linaro.org> * linux-arm-low.c (get_next_pcs_ops): Initialize it with arm_linux_get_next_pcs_fixup.
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.