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Message-ID: <20241028152512.GB2484@willie-the-truck>
Date: Mon, 28 Oct 2024 15:25:13 +0000
From: Will Deacon <will@...nel.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
Florent Revest <revest@...omium.org>,
linux-trace-kernel@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>, bpf <bpf@...r.kernel.org>,
Alexei Starovoitov <ast@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
Alan Maguire <alan.maguire@...cle.com>,
Mark Rutland <mark.rutland@....com>, linux-arch@...r.kernel.org,
Catalin Marinas <catalin.marinas@....com>,
Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>,
Michael Ellerman <mpe@...erman.id.au>,
Nicholas Piggin <npiggin@...il.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Naveen N Rao <naveen@...nel.org>,
Madhavan Srinivasan <maddy@...ux.ibm.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH v18 01/17] fgraph: Pass ftrace_regs to entryfunc
On Sat, Oct 26, 2024 at 01:35:30PM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
>
> Pass ftrace_regs to the fgraph_ops::entryfunc(). If ftrace_regs is not
> available, it passes a NULL instead. User callback function can access
> some registers (including return address) via this ftrace_regs.
>
> Note that the ftrace_regs can be NULL when the arch does NOT define:
> HAVE_DYNAMIC_FTRACE_WITH_ARGS or HAVE_DYNAMIC_FTRACE_WITH_REGS.
> More specifically, if HAVE_DYNAMIC_FTRACE_WITH_REGS is defined but
> not the HAVE_DYNAMIC_FTRACE_WITH_ARGS, and the ftrace ops used to
> register the function callback does not set FTRACE_OPS_FL_SAVE_REGS.
> In this case, ftrace_regs can be NULL in user callback.
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Huacai Chen <chenhuacai@...nel.org>
> Cc: WANG Xuerui <kernel@...0n.name>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Nicholas Piggin <npiggin@...il.com>
> Cc: Christophe Leroy <christophe.leroy@...roup.eu>
> Cc: Naveen N Rao <naveen@...nel.org>
> Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>
> Cc: Paul Walmsley <paul.walmsley@...ive.com>
> Cc: Palmer Dabbelt <palmer@...belt.com>
> Cc: Albert Ou <aou@...s.berkeley.edu>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: x86@...nel.org
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
>
> ---
> Changes in v18:
> - Remove unclear comment about `regs->fp` access on arm64.
> Changes in v16:
> - Add a note when the ftrace_regs can be NULL.
> - Update against for the latest kernel.
> Changes in v11:
> - Update for the latest for-next branch.
> Changes in v8:
> - Just pass ftrace_regs to the handler instead of adding a new
> entryregfunc.
> - Update riscv ftrace_graph_func().
> Changes in v3:
> - Update for new multiple fgraph.
> ---
> arch/arm64/kernel/ftrace.c | 15 ++++++++-
For the arm64 bits:
Acked-by: Will Deacon <will@...nel.org>
Will
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