From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F7C112883D; Fri, 16 Feb 2024 12:49:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708087789; cv=none; b=T6ZSYqqVQqb8p342TLW5jWqD6xHxpM9WvDQcqxqZsQTSQCurwjYH+/JGxY/4bv8zk9GWe3Uv1h11E1m4ALNEzTEa7RUdl/yRcN4GckgUx21r/V5AvJU/aCETR1jy2mq3XcRFBk9VprcfUQhWEVCIGab88RZ+2kgaH6VyrimhSZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708087789; c=relaxed/simple; bh=pqG7w2RnbS8BjbrhNK5arbiLuDG9/PkGucdIlBTC7jQ=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=VzUerZfRrZuvm1RpE2WVmVJwH5JSghCIz08ypAGr+Gx1uXInjc1sAmXaVtoFgU09bvH305tan7gjhLEbY8EvlQWrJMko0DZG+SSxW4Rf0hNSs410Wnm9FII+/HpCEs66HbW8070ryi8pvnuc/pDuXTajdQxTKgOAiFKncZPKvlk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lYsvJKr6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lYsvJKr6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A3A0C433F1; Fri, 16 Feb 2024 12:49:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708087789; bh=pqG7w2RnbS8BjbrhNK5arbiLuDG9/PkGucdIlBTC7jQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=lYsvJKr6f1cDQxULIAqOHGUjAPWhOUnOdn1C+TbA8lA3hxsduzPKxdBLGgwMBWB7M kiXdCnYEOkDVenej53oTYpjgJAbNbJMslgDuo74yB6I0Z09mVh1Hy3KIGvELHcNg5P PIoj+BzPZJWi0VNasRgsWJcxOHw0hP/SiKKfr7w/SCOZVtCkXYmWw3TQANXo4MvF9L QNCSQJQ8Xt8/QPm3ts66EB6M+k9HvH42s3MzbnbXOPE6LEhtYvY6ZGvEOsH+quo7XJ c9FCslRDZWKZesYSbUiKnMwQsS6/+c9d1LIdCL14Z8sM4lBx3V7aixtpy5NZI7WeDA El3dXqDQ7QqrQ== Date: Fri, 16 Feb 2024 21:49:27 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Alexei Starovoitov , Florent Revest , linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Mark Rutland , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: Re: [PATCH v7 25/36] arm64: ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS Message-Id: <20240216214927.9f25ba478d24883c72bdec81@kernel.org> In-Reply-To: <20240215111021.05163ba1@gandalf.local.home> References: <170723204881.502590.11906735097521170661.stgit@devnote2> <170723232647.502590.10808588686838195094.stgit@devnote2> <20240215111021.05163ba1@gandalf.local.home> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 15 Feb 2024 11:10:21 -0500 Steven Rostedt wrote: > On Wed, 7 Feb 2024 00:12:06 +0900 > "Masami Hiramatsu (Google)" wrote: > > > From: Masami Hiramatsu (Google) > > > > Enable CONFIG_HAVE_FUNCTION_GRAPH_FREGS on arm64. Note that this > > depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS which is enabled if the > > compiler supports "-fpatchable-function-entry=2". If not, it > > continue to use ftrace_ret_regs. > > > > Signed-off-by: Masami Hiramatsu (Google) > > --- > > Changes in v3: > > - Newly added. > > --- > > arch/arm64/Kconfig | 2 ++ > > arch/arm64/include/asm/ftrace.h | 6 ++++++ > > arch/arm64/kernel/entry-ftrace.S | 28 ++++++++++++++++++++++++++++ > > 3 files changed, 36 insertions(+) > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index aa7c1d435139..34becd41ae66 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -194,6 +194,8 @@ config ARM64 > > select HAVE_DYNAMIC_FTRACE > > select HAVE_DYNAMIC_FTRACE_WITH_ARGS \ > > if $(cc-option,-fpatchable-function-entry=2) > > + select HAVE_FUNCTION_GRAPH_FREGS \ > > + if HAVE_DYNAMIC_FTRACE_WITH_ARGS > > select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS \ > > if DYNAMIC_FTRACE_WITH_ARGS && DYNAMIC_FTRACE_WITH_CALL_OPS > > select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS \ > > diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h > > index ab158196480c..efd5dbf74dd6 100644 > > --- a/arch/arm64/include/asm/ftrace.h > > +++ b/arch/arm64/include/asm/ftrace.h > > @@ -131,6 +131,12 @@ ftrace_regs_set_return_value(struct ftrace_regs *fregs, > > fregs->regs[0] = ret; > > } > > > > +static __always_inline unsigned long > > +ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs) > > +{ > > + return fregs->fp; > > +} > > + > > static __always_inline void > > ftrace_override_function_with_return(struct ftrace_regs *fregs) > > { > > diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S > > index f0c16640ef21..d87ccdb9e678 100644 > > --- a/arch/arm64/kernel/entry-ftrace.S > > +++ b/arch/arm64/kernel/entry-ftrace.S > > @@ -328,6 +328,33 @@ SYM_FUNC_END(ftrace_stub_graph) > > * Run ftrace_return_to_handler() before going back to parent. > > * @fp is checked against the value passed by ftrace_graph_caller(). > > */ > > +#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS > > +SYM_CODE_START(return_to_handler) > > + /* save ftrace_regs except for PC */ > > + sub sp, sp, #FREGS_SIZE > > + stp x0, x1, [sp, #FREGS_X0] > > + stp x2, x3, [sp, #FREGS_X2] > > + stp x4, x5, [sp, #FREGS_X4] > > + stp x6, x7, [sp, #FREGS_X6] > > + str x8, [sp, #FREGS_X8] > > + str x29, [sp, #FREGS_FP] > > + str x9, [sp, #FREGS_LR] > > + str x10, [sp, #FREGS_SP] > > Here too. The above is just garbage. > > Let's not fill in garbarge registers. The above is useless on return of a > function. Heck, adding zeros is better than this. But really, we need to > have ftrace regs to have some kind of flag that can state what it holds. > Right now I see three states: > > 1 - holds all regs and pt_regs can be retrieved > 2 - only holds function entry regs (parameters and stack) > 3 - only holds function exit regs (return value and stack) > > Don't save anything else unless needed. OK, it is reasonable to save the registers depending on the context. Thanks, > > -- Steve > > > + > > + mov x0, sp > > + bl ftrace_return_to_handler // addr = ftrace_return_to_hander(fregs); > > + mov x30, x0 // restore the original return address > > + > > + /* restore return value regs */ > > + ldp x0, x1, [sp, #FREGS_X0] > > + ldp x2, x3, [sp, #FREGS_X2] > > + ldp x4, x5, [sp, #FREGS_X4] > > + ldp x6, x7, [sp, #FREGS_X6] > > + add sp, sp, #FREGS_SIZE > > + > > + ret > > +SYM_CODE_END(return_to_handler) > > +#else /* !CONFIG_HAVE_FUNCTION_GRAPH_FREGS */ > > SYM_CODE_START(return_to_handler) > > /* save return value regs */ > > sub sp, sp, #FGRET_REGS_SIZE > > @@ -350,4 +377,5 @@ SYM_CODE_START(return_to_handler) > > > > ret > > SYM_CODE_END(return_to_handler) > > +#endif /* CONFIG_HAVE_FUNCTION_GRAPH_FREGS */ > > #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ > -- Masami Hiramatsu (Google)