From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 205F0C38A2D for ; Tue, 25 Oct 2022 10:31:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=H8ckDe1vo7z8/FVw+Nb/eeVVclq8FabNQ8l1dzFZ90k=; b=GG4MP7GDdPbA9Q Kf0qsJkJW0Of7nNgXv8o+qe22gHd8tY6OpF0znHGMvENqQHUP71D2v2rHBYupYUAD6YaepiGJLMjE fIb7c8BdekbKvJH6NuuZspsuCvAVC9+/5zZ/2bSA/vLDj5RCQ8aZAjnUTjH8GfUV4F2p3oet4AKhn WE1RJ8d41j1y0p8ZHQDqeWQJwjMjd+bSFFMSTGUO2Rxw9+SPap5G2ac1Nel8H0fb4PtJl7t/xAyBH oVAziPMR1ayqlSGhVWwgEFzWVOci9gdkAvaMQ6bz1egcKq8/OcCQXf8eMNpou+Yvmp6PNtSqNbndo E5t6MiqFiWVifvKxfoxg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1onHCq-004nWR-06; Tue, 25 Oct 2022 10:30:48 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1onHCm-004nVN-IC for linux-arm-kernel@lists.infradead.org; Tue, 25 Oct 2022 10:30:46 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C9A02D6E; Tue, 25 Oct 2022 03:30:48 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.7.133]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4EC7B3F7B4; Tue, 25 Oct 2022 03:30:41 -0700 (PDT) Date: Tue, 25 Oct 2022 11:30:38 +0100 From: Mark Rutland To: Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, revest@chromium.org, rostedt@goodmis.org, will@kernel.org Subject: Re: [PATCH 3/4] ftrace: abstract DYNAMIC_FTRACE_WITH_ARGS accesses Message-ID: References: <20221024140846.3555435-1-mark.rutland@arm.com> <20221024140846.3555435-4-mark.rutland@arm.com> <20221025174001.cf5a189a23aaeadc2c8887a2@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20221025174001.cf5a189a23aaeadc2c8887a2@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221025_033044_724352_F16532F3 X-CRM114-Status: GOOD ( 42.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 25, 2022 at 05:40:01PM +0900, Masami Hiramatsu wrote: > Hi Mark, > > On Mon, 24 Oct 2022 15:08:45 +0100 > Mark Rutland wrote: > > > In subsequent patches we'll arrange for architectures to have an > > ftrace_regs which is entirely distinct from pt_regs. In preparation for > > this, we need to minimize the use of pt_regs to where strictly necessary > > in the core ftrace code. > > > > This patch adds new ftrace_regs_{get,set}_*() helpers which can be used > > to manipulate ftrace_regs. When CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS=y, > > these can always be used on any ftrace_regs, and when > > CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS=n these can be used when regs are > > available. A new ftrace_regs_has_args(fregs) helper is added which code > > can use to check when these are usable. > > Can you also add the ftrace_regs_query_register_offset() as a wrapper of > regs_query_register_offset()? I would like to use it for fprobe_events. Sure! Just to check, with FTRACE_WITH_REGS, does fprobe always sample the full pt_regs, or do callers also need to check ftrace_regs_has_args(fregs)? I ask because if neither of those are the case, with FTRACE_WITH_REGS, ftrace_regs_query_register_offset() would accept names of registers which might not have been sampled, and could give offsets to uninitialized memory. Atop that, I'm not exactly sure what to implement for powerpc/s390/x86 here. If those might be used without a full pt_regs, I think ftrace_regs_query_register_offset() should also take the fregs as a parameter and use that to check which registers are available. ... does that make sense to you? Thanks, Mark. > > Thank you, > > > > > Co-developed-by: Florent Revest > > Signed-off-by: Florent Revest > > Signed-off-by: Mark Rutland > > Cc: Masami Hiramatsu > > Cc: Steven Rostedt > > --- > > arch/powerpc/include/asm/ftrace.h | 17 +++++++++++++++++ > > arch/s390/include/asm/ftrace.h | 17 +++++++++++++++++ > > arch/x86/include/asm/ftrace.h | 14 ++++++++++++++ > > include/linux/ftrace.h | 27 +++++++++++++++++++++++++++ > > kernel/trace/Kconfig | 6 +++--- > > 5 files changed, 78 insertions(+), 3 deletions(-) > > > > diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h > > index c3eb48f67566..faecb20d78bf 100644 > > --- a/arch/powerpc/include/asm/ftrace.h > > +++ b/arch/powerpc/include/asm/ftrace.h > > @@ -44,6 +44,23 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, > > regs_set_return_ip(&fregs->regs, ip); > > } > > > > +static __always_inline unsigned long > > +ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs) > > +{ > > + return instruction_pointer(&fregs->regs) > > +} > > + > > +#define ftrace_regs_get_argument(fregs, n) \ > > + regs_get_kernel_argument(&(fregs)->regs, n) > > +#define ftrace_regs_get_stack_pointer(fregs) \ > > + kernel_stack_pointer(&(fregs)->regs) > > +#define ftrace_regs_return_value(fregs) \ > > + regs_return_value(&(fregs)->regs) > > +#define ftrace_regs_set_return_value(fregs, ret) \ > > + regs_set_return_value(&(fregs)->regs, ret) > > +#define ftrace_override_function_with_return(fregs) \ > > + override_function_with_return(&(fregs)->regs) > > + > > struct ftrace_ops; > > > > #define ftrace_graph_func ftrace_graph_func > > diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h > > index b8957882404f..5fdc806458aa 100644 > > --- a/arch/s390/include/asm/ftrace.h > > +++ b/arch/s390/include/asm/ftrace.h > > @@ -54,6 +54,12 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs * > > return NULL; > > } > > > > +static __always_inline unsigned long > > +ftrace_regs_get_instruction_pointer(const struct ftrace_regs *fregs) > > +{ > > + return fregs->regs.psw.addr; > > +} > > + > > static __always_inline void > > ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, > > unsigned long ip) > > @@ -61,6 +67,17 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, > > fregs->regs.psw.addr = ip; > > } > > > > +#define ftrace_regs_get_argument(fregs, n) \ > > + regs_get_kernel_argument(&(fregs)->regs, n) > > +#define ftrace_regs_get_stack_pointer(fregs) \ > > + kernel_stack_pointer(&(fregs)->regs) > > +#define ftrace_regs_return_value(fregs) \ > > + regs_return_value(&(fregs)->regs) > > +#define ftrace_regs_set_return_value(fregs, ret) \ > > + regs_set_return_value(&(fregs)->regs, ret) > > +#define ftrace_override_function_with_return(fregs) \ > > + override_function_with_return(&(fregs)->regs) > > + > > /* > > * When an ftrace registered caller is tracing a function that is > > * also set by a register_ftrace_direct() call, it needs to be > > diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h > > index b73e858bd96f..b3737b42e8a1 100644 > > --- a/arch/x86/include/asm/ftrace.h > > +++ b/arch/x86/include/asm/ftrace.h > > @@ -51,6 +51,20 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs) > > #define ftrace_regs_set_instruction_pointer(fregs, _ip) \ > > do { (fregs)->regs.ip = (_ip); } while (0) > > > > +#define ftrace_regs_get_instruction_pointer(fregs) \ > > + ((fregs)->regs.ip) > > + > > +#define ftrace_regs_get_argument(fregs, n) \ > > + regs_get_kernel_argument(&(fregs)->regs, n) > > +#define ftrace_regs_get_stack_pointer(fregs) \ > > + kernel_stack_pointer(&(fregs)->regs) > > +#define ftrace_regs_return_value(fregs) \ > > + regs_return_value(&(fregs)->regs) > > +#define ftrace_regs_set_return_value(fregs, ret) \ > > + regs_set_return_value(&(fregs)->regs, ret) > > +#define ftrace_override_function_with_return(fregs) \ > > + override_function_with_return(&(fregs)->regs) > > + > > struct ftrace_ops; > > #define ftrace_graph_func ftrace_graph_func > > void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > > index e9905f741916..3b13e3c21438 100644 > > --- a/include/linux/ftrace.h > > +++ b/include/linux/ftrace.h > > @@ -125,6 +125,33 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs > > return arch_ftrace_get_regs(fregs); > > } > > > > +/* > > + * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs. > > + * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs. > > + */ > > +static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs) > > +{ > > + if (IS_ENABLED(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS)) > > + return true; > > + > > + return ftrace_get_regs(fregs) != NULL; > > +} > > + > > +#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS > > +#define ftrace_regs_get_instruction_pointer(fregs) \ > > + instruction_pointer(ftrace_get_regs(fregs)) > > +#define ftrace_regs_get_argument(fregs, n) \ > > + regs_get_kernel_argument(ftrace_get_regs(fregs), n) > > +#define ftrace_regs_get_stack_pointer(fregs) \ > > + kernel_stack_pointer(ftrace_get_regs(fregs)) > > +#define ftrace_regs_return_value(fregs) \ > > + regs_return_value(ftrace_get_regs(fregs)) > > +#define ftrace_regs_set_return_value(fregs, ret) \ > > + regs_set_return_value(ftrace_get_regs(fregs), ret) > > +#define ftrace_override_function_with_return(fregs) \ > > + override_function_with_return(ftrace_get_regs(fregs)) > > +#endif > > + > > typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip, > > struct ftrace_ops *op, struct ftrace_regs *fregs); > > > > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > > index e9e95c790b8e..2c6611c13f99 100644 > > --- a/kernel/trace/Kconfig > > +++ b/kernel/trace/Kconfig > > @@ -46,10 +46,10 @@ config HAVE_DYNAMIC_FTRACE_WITH_ARGS > > bool > > help > > If this is set, then arguments and stack can be found from > > - the pt_regs passed into the function callback regs parameter > > + the ftrace_regs passed into the function callback regs parameter > > by default, even without setting the REGS flag in the ftrace_ops. > > - This allows for use of regs_get_kernel_argument() and > > - kernel_stack_pointer(). > > + This allows for use of ftrace_regs_get_argument() and > > + ftrace_regs_get_stack_pointer(). > > > > config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE > > bool > > -- > > 2.30.2 > > > > > -- > Masami Hiramatsu (Google) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel