[PATCH v2 0/7] Software breakpoints support for ARM linux in GDBServer.

[Antoine Tremblay <antoine dot tremblay at ericsson dot com>]

In this v2 :

The main change is that the functions breakpoint_from_pc and
breakpoint_from_kind are now called upstream in the call flow.
As suggested in : https://sourceware.org/ml/gdb-patches/2015-09/msg00597.html

Thus the patchset is restructured for that, patches have been renamed and
reordered.

Patches that have changed have their own v2 comment.

Original comment is also updated :

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This patch series adds software breakpoint support for ARM on linux in
GDBServer.

This is a subset of a previous patchset :
https://sourceware.org/ml/gdb-patches/2015-09/msg00221.html

Other patches in that previous patchset will be sent after.

The problematic with ARM software breakpoints is that it can have 3 different
breakpoints one for each instruction set : arm, thumb, thumb2.

So we need to be able to set different kinds of breakpoints when GDBServer sets
it's own breakpoints or when a breakpoint is set using GDB's Z0 packet.

In order to allow that the patches :

[PATCH v2 1/7] Add breakpoint_from_pc target_ops for software breakpoints in
GDBServer.

Adds a new target operation to replace the static breakpoint and breakpoint_len
operation so that the target can return the proper GDBServer breakpoint.

[PATCH v2 2/7] Add breakpoint_from_kind target_ops for software breakpoints in
GDBServer.

Software breakpoints set by GDB can have a arch specific encoded length called
the breakpoint kind like it is the case for ARM.

This patch adds a target operation such that the correct breakpoint can be
returned based on that kind.

[PATCH v2 3/7] Implement breakpoint_from_kind for supported architectures in
GDBServer.

x86 and aarch64 support software breakpoints from GDB and need to implement
breakpoint_from_kind.

[PATCH v2 4/7] Support breakpoint kinds for software breakpoints in GDBServer.

This is the main patch of the set, it handles the GDBServer's software
breakpoints by calling the breakpoint_from_pc operation and GDB's software
breakpoints by calling breakpoint_from_kind.

[PATCH v2 5/7] Implement breakpoint_from_pc for ARM in GDBServer.

This patch adds the ARM implementation of that target operation, selecting the
thumb, thumb2, or arm breakpoint based on the PC addresss and the flags encoded
in it.

[PATCH v2 6/7] Refactor the breakpoint definitions in linux-arm-low.c.

This patch refactors the breakpoint definitions a bit to be more clear.

[PATCH v2 7/7] Support software breakpoints for ARM linux in GDBServer.

And finally software breakpoints via Z0 packets are enabled for ARM.

This patchset has no regressions, tested on ubuntu 14.04 ARMv7 and x86.
With gdbserver-{native,extended} / { -marm -mthumb }

Note also that while I could not test directly thumbv1 instructions with gcc
-marmv4t , manual testing of the software breakpoints was done for thumv1
instructions.