From: "Jose Fernandez (Anthropic)" <jose.fernandez@linux.dev>
To: Bill Wendling <morbo@google.com>
Cc: "Steven Rostedt" <rostedt@goodmis.org>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
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"Yonghong Song" <yonghong.song@linux.dev>,
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live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
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llvm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
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rust-for-linux@vger.kernel.org, "Ben Cressey" <ben@cressey.dev>,
"Florent Revest (Anthropic)" <florent.revest@linux.dev>
Subject: Re: [PATCH v2 6/9] arm64: cfi: Use CONFIG_ARM64_FUNCTION_PREFIX_NOPS for the type hash offset
Date: Sun, 27 Sep 2026 14:05:38 +0000 [thread overview]
Message-ID: <arkimpxRmauCfcn8@linux.dev> (raw)
In-Reply-To: <CAGG=3QVs=e5JtAs-D98vDsj2ax9H0gH-_rPc0oKhx-vNpq_RyQ@mail.gmail.com>
On Fri, Sep 25, 2026 at 12:17 PM Bill Wendling wrote:
> > + return 4 + 4 * CONFIG_ARM64_FUNCTION_PREFIX_NOPS;
>
> *drive by review* Could you explain the two fours in this equation
> with a comment? (Feel free to ignore this if it's obvious to
> developers.)
The first is the type hash and the second is the size of a NOP. For v3
I'll spell the second one out and add a comment for the first.
/* The 4-byte type hash sits before the prefix NOPs. */
return 4 + CONFIG_ARM64_FUNCTION_PREFIX_NOPS * AARCH64_INSN_SIZE;
- Jose
next prev parent reply other threads:[~2026-09-27 14:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 22:35 [PATCH v2 0/9] arm64: ftrace: support CALL_OPS on kernels built with kCFI Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 1/9] ftrace: Do not leak a module's empty page group Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 2/9] ftrace: Let ftrace_call_adjust() reject a patch site Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 3/9] scripts/sorttable: Make the arm64 before_func offset configurable Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 4/9] compiler_types: Let notrace keep the function prefix NOPs Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 5/9] arm64: ftrace: Make the CALL_OPS prefix layout configurable Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 6/9] arm64: cfi: Use CONFIG_ARM64_FUNCTION_PREFIX_NOPS for the type hash offset Jose Fernandez (Anthropic)
2026-09-24 23:40 ` Alexei Starovoitov
2026-09-25 19:17 ` Bill Wendling
2026-09-27 14:05 ` Jose Fernandez (Anthropic) [this message]
2026-09-24 22:35 ` [PATCH v2 7/9] arm64: ftrace: Support CALL_OPS on kernels built with kCFI Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 8/9] arm64: ftrace: Use five prefix NOPs on ThinLTO kernels with BTI Jose Fernandez (Anthropic)
2026-09-24 22:35 ` [PATCH v2 9/9] arm64: ftrace: Allow CALL_OPS on kCFI kernels built with Rust Jose Fernandez (Anthropic)
2026-09-24 23:25 ` bot+bpf-ci
-- strict thread matches above, loose matches on Subject: below --
2026-09-26 9:33 [PATCH v2 6/9] arm64: cfi: Use CONFIG_ARM64_FUNCTION_PREFIX_NOPS for the type hash offset MaeeFilho FL
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