From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 15 Sep 2015 17:16:13 +0100 Subject: [PATCH] arm64: hw_breakpoint: use target state to determine ABI behaviour Message-ID: <1442333773-16446-1-git-send-email-will.deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 Cc: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm64/kernel/hw_breakpoint.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index bba85c8f8037..2926c3dd6479 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -163,6 +163,12 @@ enum hw_breakpoint_ops { HW_BREAKPOINT_RESTORE }; +static int is_compat_bp(struct perf_event *bp) +{ + struct task_struct *tsk = bp->hw.target; + return tsk && is_compat_thread(task_thread_info(tsk)); +} + /** * hw_breakpoint_slot_setup - Find and setup a perf slot according to * operations @@ -420,7 +426,7 @@ 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 +483,7 @@ 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 -- 2.1.4