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[binutils-gdb] [ARM] Make thumb2_breakpoint static again
- From: sergiodj+buildbot at redhat dot com
- To: gdb-testers at sourceware dot org
- Date: Thu, 14 Jan 2016 04:39:48 -0500
- Subject: [binutils-gdb] [ARM] Make thumb2_breakpoint static again
- Authentication-results: sourceware.org; auth=none
*** TEST RESULTS FOR COMMIT 1b451dda5f8905b26bafafe00423335d4fffe8dd ***
Author: Yao Qi <yao.qi@linaro.org>
Branch: master
Commit: 1b451dda5f8905b26bafafe00423335d4fffe8dd
[ARM] Make thumb2_breakpoint static again
This patch makes thumb2_breakpoint static. When writing this patch,
I find the only reason we keep thumb2_breakpoint extern is that it
is used as an argument passed to arm_gdbserver_get_next_pcs. However,
field arm_thumb2_breakpoint is only used in a null check in
thumb_get_next_pcs_raw, so I wonder why do need to pass thumb2_breakpoint
to arm_gdbserver_get_next_pcs.
thumb2_breakpoint was added by Daniel Jacobowitz in order to support
single-step IT block
https://sourceware.org/ml/gdb-patches/2010-01/msg00624.html the logic
there was if we have 32-bit thumb-2 breakpoint defined, we can safely
single-step IT block, otherwise, we can't. Daniel didn't want to use
16-bit thumb BKPT instruction, because it triggers even on instruction
which should be executed. Secondly, using 16-bit thumb illegal
instruction on top of 32-bit thumb instruction may break the meaning of
original IT blocks, because the other 16-bit can be regarded as an
instruction. See more explanations from Daniel's kernel patch
http://www.spinics.net/lists/arm-kernel/msg80476.html
Let us back to this patch, GDB/GDBserver can safely single step
IT block if thumb2_breakpoint is defined, but the single step logic
doesn't have to know the thumb-2 breakpoint instruction. Only
breakpoint insertion mechanism decides to use which breakpoint
instruction. In the software single step code, instead of pass
thumb2_breakpoint, we can pass a boolean variable
has_thumb2_breakpoint indicate whether the target has thumb-2
breakpoint defined, which is equivalent to the original code.
Regression tested on arm-linux. No regression.
gdb:
2016-01-14 Yao Qi <yao.qi@linaro.org>
* arch/arm-get-next-pcs.c (arm_get_next_pcs_ctor): Change
argument arm_thumb2_breakpoint to has_thumb2_breakpoint.
(thumb_get_next_pcs_raw): Check has_thumb2_breakpoint
instead.
* arch/arm-get-next-pcs.h (struct arm_get_next_pcs)
<arm_thumb2_breakpoint>: Remove.
<has_thumb2_breakpoint>: New field.
(arm_get_next_pcs_ctor): Update declaration.
* arm-linux-tdep.c (arm_linux_software_single_step): Pass
1 to arm_get_next_pcs_ctor.
* arm-tdep.c (arm_software_single_step): Pass 0 to
arm_get_next_pcs_ctor.
gdb/gdbserver:
2016-01-14 Yao Qi <yao.qi@linaro.org>
* linux-aarch32-low.c (thumb2_breakpoint): Make it static.
* linux-aarch32-low.h (thumb2_breakpoint): Remove declaration.
* linux-arm-low.c (arm_gdbserver_get_next_pcs): Pass 1 to
arm_get_next_pcs_ctor.
- Follow-Ups:
- Failures on Debian-s390x-native-gdbserver-m64, branch master
- Failures on Debian-s390x-m64, branch master
- Failures on Debian-s390x-native-extended-gdbserver-m64, branch master
- Failures on RHEL-s390x-m64, branch master
- Failures on Fedora-i686, branch master
- Failures on Fedora-x86_64-cxx-build-m64, branch master
- Failures on Debian-i686, branch master
- Failures on Fedora-ppc64be-cc-with-index, branch master
- Failures on Fedora-x86_64-native-extended-gdbserver-m64, branch master
- Failures on Fedora-x86_64-native-gdbserver-m64, branch master
- Failures on Fedora-x86_64-native-gdbserver-m32, branch master
- Failures on Fedora-s390x-m64, branch master
- Failures on AIX-POWER7-plain, branch master
- Failures on Fedora-ppc64be-m64, branch master
- Failures on Fedora-ppc64le-native-extended-gdbserver-m64, branch master
- Failures on Fedora-ppc64be-native-gdbserver-m64, branch master
- Failures on Fedora-ppc64le-cc-with-index, branch master
- Failures on Fedora-ppc64be-native-extended-gdbserver-m64, branch master
- Failures on Fedora-ppc64le-native-gdbserver-m64, branch master
- Failures on Fedora-ppc64le-m64, branch master