From: Will Deacon <will@kernel•org>
To: "Rob Herring (Arm)" <robh@kernel•org>
Cc: Mark Rutland <mark.rutland@arm•com>,
Catalin Marinas <catalin.marinas@arm•com>,
Jonathan Corbet <corbet@lwn•net>,
Shuah Khan <skhan@linuxfoundation•org>,
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: Re: [PATCH v4 1/6] arm64: hw_breakpoint: Disallow breakpoints in no kprobe code
Date: Thu, 28 May 2026 11:57:12 +0100 [thread overview]
Message-ID: <ahgfiNTct7d4dLPL@willie-the-truck> (raw)
In-Reply-To: <20260407-arm-debug-8-9-v4-1-a4864e69b0ea@kernel.org>
On Tue, Apr 07, 2026 at 09:29:43AM -0500, Rob Herring (Arm) wrote:
> 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.
It would be good to spell this out a little more clearly, as "likely to
be unsafe" is very vague. There's also plenty of breakpoint handling
code outside of the arch backend (e.g. in kernel/events/) which doesn't
seem to be in the no-kprobes section, so it's not clear why that's ok.
Will
next prev parent reply other threads:[~2026-05-28 10:57 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 ` [PATCH v4 1/6] arm64: hw_breakpoint: Disallow breakpoints in no kprobe code Rob Herring (Arm)
2026-05-28 10:57 ` Will Deacon [this message]
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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