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author | Will Deacon <will.deacon@arm.com> | 2013-12-17 17:09:08 +0000 |
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committer | Catalin Marinas <catalin.marinas@arm.com> | 2013-12-19 17:41:25 +0000 |
commit | cdc27c27843248ae7eb0df5fc261dd004eaa5670 (patch) | |
tree | 202d38bcf449e2a9edb9e2e8da9384078b1af660 /arch/arm64/include/asm/io.h | |
parent | 319e2e3f63c348a9b66db4667efa73178e18b17d (diff) | |
download | blackbird-op-linux-cdc27c27843248ae7eb0df5fc261dd004eaa5670.tar.gz blackbird-op-linux-cdc27c27843248ae7eb0df5fc261dd004eaa5670.zip |
arm64: ptrace: avoid using HW_BREAKPOINT_EMPTY for disabled events
Commit 8f34a1da35ae ("arm64: ptrace: use HW_BREAKPOINT_EMPTY type for
disabled breakpoints") fixed an issue with GDB trying to zero breakpoint
control registers. The problem there is that the arch hw_breakpoint code
will attempt to create a (disabled), execute breakpoint of length 0.
This will fail validation and report unexpected failure to GDB. To avoid
this, we treated disabled breakpoints as HW_BREAKPOINT_EMPTY, but that
seems to have broken with recent kernels, causing watchpoints to be
treated as TYPE_INST in the core code and returning ENOSPC for any
further breakpoints.
This patch fixes the problem by prioritising the `enable' field of the
breakpoint: if it is cleared, we simply update the perf_event_attr to
indicate that the thing is disabled and don't bother changing either the
type or the length. This reinforces the behaviour that the breakpoint
control register is essentially read-only apart from the enable bit
when disabling a breakpoint.
Cc: <stable@vger.kernel.org>
Reported-by: Aaron Liu <liucy214@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/io.h')
0 files changed, 0 insertions, 0 deletions