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| author | Will Deacon <will.deacon@arm.com> | 2015-10-07 11:37:36 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2015-10-07 14:19:10 +0100 |
| commit | 8f48c0629049fdebb6e783803325bff19176d3fd (patch) | |
| tree | 9a4db87caafbcecc4bd96fce953b6a884a081774 | |
| parent | 120798d2e7d1ac87365fe5ea91b074bb42ca1eff (diff) | |
| download | linux-8f48c0629049fdebb6e783803325bff19176d3fd.tar.gz linux-8f48c0629049fdebb6e783803325bff19176d3fd.tar.bz2 linux-8f48c0629049fdebb6e783803325bff19176d3fd.zip | |
arm64: hw_breakpoint: use target state to determine ABI behaviour
The arm64 hw_breakpoint interface is slightly less flexible than its
32-bit counterpart, thanks to some changes in the architecture rendering
unaligned watchpoint addresses obselete for AArch64.
However, in a multi-arch environment (i.e. debugging a 32-bit target
with a 64-bit GDB under a 64-bit kernel), we need to provide a feature
compatible interface to GDB in order for debugging to function correctly.
This patch adds a new helper, is_compat_bp, to our hw_breakpoint
implementation which changes the interface behaviour based on the
architecture of the debug target as opposed to the debugger itself.
This allows debugged to function as expected for multi-arch
configurations without relying on deprecated architectural behaviours
when debugging native applications.
Cc: Yao Qi <yao.qi@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | arch/arm64/kernel/hw_breakpoint.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index bba85c8f8037..46465d9fbc4d 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -163,6 +163,20 @@ enum hw_breakpoint_ops { HW_BREAKPOINT_RESTORE }; +static int is_compat_bp(struct perf_event *bp) +{ + struct task_struct *tsk = bp->hw.target; + + /* + * tsk can be NULL for per-cpu (non-ptrace) breakpoints. + * In this case, use the native interface, since we don't have + * the notion of a "compat CPU" and could end up relying on + * deprecated behaviour if we use unaligned watchpoints in + * AArch64 state. + */ + return tsk && is_compat_thread(task_thread_info(tsk)); +} + /** * hw_breakpoint_slot_setup - Find and setup a perf slot according to * operations @@ -420,7 +434,7 @@ static int arch_build_bp_info(struct perf_event *bp) * Watchpoints can be of length 1, 2, 4 or 8 bytes. */ if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { - if (is_compat_task()) { + if (is_compat_bp(bp)) { if (info->ctrl.len != ARM_BREAKPOINT_LEN_2 && info->ctrl.len != ARM_BREAKPOINT_LEN_4) return -EINVAL; @@ -477,7 +491,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp) * AArch32 tasks expect some simple alignment fixups, so emulate * that here. */ - if (is_compat_task()) { + if (is_compat_bp(bp)) { if (info->ctrl.len == ARM_BREAKPOINT_LEN_8) alignment_mask = 0x7; else |