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AArch64 Watchpoints: Make sure we are only setting supported no of debug registers.
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Authored by omjavaid on Sep 1 2015, 2:52 AM.

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Summary

This patch makes sure that we are setting the correct number of hardware breakpoint or watchpoint registers while setting/clearing hardware watchpoints/breakpoints.

In current implementation of AArch64 Watchpoints we try to set all debug registers present in user_hwdebug_state structure.

There are more debug registers declared by user_hwdebug_state than the one exported to ptrace for hardware watchpoints and hardware breakpoints.

We only should be setting the N number of registers supported by the target in response to read debug registers calls.

Failure to do so results in unexpected watchpoint behavior.

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omjavaid updated this revision to Diff 33671.Sep 1 2015, 2:52 AM
omjavaid retitled this revision from to AArch64 Watchpoints: Make sure we are only setting supported no of debug registers..
omjavaid updated this object.
omjavaid added a reviewer: tberghammer.
omjavaid added a subscriber: lldb-commits.
tberghammer requested changes to this revision.Sep 1 2015, 5:23 AM
tberghammer edited edge metadata.
tberghammer added inline comments.
source/Plugins/Process/Linux/NativeRegisterContextLinux_arm64.cpp
820–821 ↗(On Diff #33671)

You are using offsetof with a value determined in runtime (m_max_hwp_supported) what won't be work in all case (it isn't standard compliance AFAIK). I suggest to sue the following version instead:

ioVec.iov_len = (offsetof (struct user_hwdebug_state, dbg_regs) + sizeof (dreg_state.dbg_regs [0]) * m_max_hwp_supported);
This revision now requires changes to proceed.Sep 1 2015, 5:23 AM
omjavaid updated this revision to Diff 37748.Oct 19 2015, 6:21 AM
omjavaid edited edge metadata.

This patch fixes unexpected behaviour of watchpoint code on Nexus 9 (AArch64).

tberghammer accepted this revision.Oct 19 2015, 6:37 AM
tberghammer edited edge metadata.

LGTM

This revision is now accepted and ready to land.Oct 19 2015, 6:37 AM
This revision was automatically updated to reflect the committed changes.