From: "Rob Herring (Arm)" <robh@kernel•org>
To: Will Deacon <will@kernel•org>,
Mark Rutland <mark.rutland@arm•com>,
Catalin Marinas <catalin.marinas@arm•com>,
Jonathan Corbet <corbet@lwn•net>,
Shuah Khan <skhan@linuxfoundation•org>
Cc: Anshuman Khandual <anshuman.khandual@arm•com>,
linux-arm-kernel@lists•infradead.org,
linux-perf-users@vger•kernel.org, linux-kernel@vger•kernel.org,
linux-doc@vger•kernel.org
Subject: [PATCH v4 1/6] arm64: hw_breakpoint: Disallow breakpoints in no kprobe code
Date: Tue, 07 Apr 2026 09:29:43 -0500 [thread overview]
Message-ID: <20260407-arm-debug-8-9-v4-1-a4864e69b0ea@kernel.org> (raw)
In-Reply-To: <20260407-arm-debug-8-9-v4-0-a4864e69b0ea@kernel.org>
Taking debug exceptions while manipulating the breakpoints is likely to
be unsafe. The setting kprobes in the breakpoint code is already
forbidden, but the setting of h/w breakpoints is not. Copy what x86 does
and exclude breakpoints that fall within the kprobe section.
Signed-off-by: Rob Herring (Arm) <robh@kernel•org>
---
arch/arm64/kernel/hw_breakpoint.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
index ab76b36dce82..38fbd67b2a6e 100644
--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -418,6 +418,16 @@ static int arch_build_bp_info(struct perf_event *bp,
/* Type */
switch (attr->bp_type) {
case HW_BREAKPOINT_X:
+ /*
+ * We don't allow kernel breakpoints in places that are not
+ * acceptable for kprobes. On non-kprobes kernels, we don't
+ * allow kernel breakpoints at all.
+ */
+ if (attr->bp_addr >= TASK_SIZE_MAX) {
+ if (within_kprobe_blacklist(attr->bp_addr))
+ return -EINVAL;
+ }
+
hw->ctrl.type = ARM_BREAKPOINT_EXECUTE;
break;
case HW_BREAKPOINT_R:
--
2.53.0
next prev parent reply other threads:[~2026-04-07 14:30 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-07 14:29 [PATCH v4 0/6] arm64: Add support for FEAT_Debugv8p9 Rob Herring (Arm)
2026-04-07 14:29 ` Rob Herring (Arm) [this message]
2026-05-28 10:57 ` [PATCH v4 1/6] arm64: hw_breakpoint: Disallow breakpoints in no kprobe code Will Deacon
2026-04-07 14:29 ` [PATCH v4 2/6] arm64: hw_breakpoint: Add additional kprobe excluded functions Rob Herring (Arm)
2026-04-07 14:29 ` [PATCH v4 3/6] arm64: hw_breakpoint: Add lockdep_assert_irqs_disabled() on install/uninstall Rob Herring (Arm)
2026-05-28 10:57 ` Will Deacon
2026-04-07 14:29 ` [PATCH v4 4/6] arm64/cpufeature: Add field details for ID_AA64DFR1_EL1 register Rob Herring (Arm)
2026-05-28 10:57 ` Will Deacon
2026-04-07 14:29 ` [PATCH v4 5/6] arm64/boot: Enable EL2 requirements for FEAT_Debugv8p9 Rob Herring (Arm)
2026-05-28 10:58 ` Will Deacon
2026-04-07 14:29 ` [PATCH v4 6/6] arm64: hw_breakpoint: Enable FEAT_Debugv8p9 Rob Herring (Arm)
2026-05-28 11:05 ` Will Deacon
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