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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pk9gdjSI; 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="pk9gdjSI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A665EC4CECF; Tue, 3 Dec 2024 09:08:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733216938; bh=MhgX52Eeuu6R9TGkJAO3G2bq54KKg9pdjOsDcDxCj5Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pk9gdjSIyiJyObIFwMRTmLwxuFq7gozJzR2VHw3ptBbwCH7t/gjIxSeBls7YJWFoq O0+CYPz8vnNzEZUj9AmrFFKoD+SYNHOO6XMbwCQUPcKzGWQ0wA2PbWT85ahxAxjxd1 NQZgKPhpBdYvkmhvDwyGfZNKoJ5FBAL57tqHPzeSQ4gPzlyNB3VVjbOH/TjVJOIr4K iZvy76yfjGNeH6jP1nQZ/K0SVgSnXFoKLY5Vs1flTwe+95UuBOH4MYtEGEkxus6Ifw hmSaNL8Q8KuGTvA8ZJeYvlRdZQqUwBV/s3fxE0ioRs+qcEtrEDI1eim+gboV8Ou0cz LnwikBV1gAg+w== Date: Tue, 3 Dec 2024 11:08:44 +0200 From: Mike Rapoport To: Andrew Morton Cc: Borislav Petkov , Dave Hansen , Ingo Molnar , Masami Hiramatsu , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH] x86/ftrace: fix boot time slowdown Message-ID: References: <20241124140705.2883-1-rppt@kernel.org> 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-Disposition: inline In-Reply-To: <20241124140705.2883-1-rppt@kernel.org> Gentle ping On Sun, Nov 24, 2024 at 04:07:05PM +0200, Mike Rapoport wrote: > From: "Mike Rapoport (Microsoft)" > > Steven Rostedt reported slowdown by over 30ms caused by commit 9bfc4824fd48 > ("x86/module: prepare module loading for ROX allocations of text") > > Before: > > # cat /sys/kernel/tracing/dyn_ftrace_total_info > 57695 pages:231 groups: 9 > ftrace boot update time = 14733459 (ns) > ftrace module total update time = 449016 (ns) > > After: > > # cat /sys/kernel/tracing/dyn_ftrace_total_info > 57708 pages:231 groups: 9 > ftrace boot update time = 47195374 (ns) > ftrace module total update time = 592080 (ns) > > The slowdown happened because initial patching of kernel code for ftrace > was switched from text_poke_early() to text_poke() to accommodate ftrace > updates of module text allocated as ROX. > > Restore the use of text_poke_early() for boot time patching of the kernel > code. > > Reported-by: Steven Rostedt > Closes: https://lore.kernel.org/all/20241118132501.4eddb46c@gandalf.local.home > Fixes: 9bfc4824fd48 ("x86/module: prepare module loading for ROX allocations of text") > Signed-off-by: Mike Rapoport (Microsoft) > --- > arch/x86/kernel/ftrace.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c > index 4dd0ad6c94d6..9e50288abbaa 100644 > --- a/arch/x86/kernel/ftrace.c > +++ b/arch/x86/kernel/ftrace.c > @@ -111,7 +111,7 @@ static int ftrace_verify_code(unsigned long ip, const char *old_code) > */ > static int __ref > ftrace_modify_code_direct(unsigned long ip, const char *old_code, > - const char *new_code) > + const char *new_code, struct module *mod) > { > int ret = ftrace_verify_code(ip, old_code); > if (ret) > @@ -120,6 +120,8 @@ ftrace_modify_code_direct(unsigned long ip, const char *old_code, > /* replace the text with the new text */ > if (ftrace_poke_late) { > text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL); > + } else if (!mod) { > + text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE); > } else { > mutex_lock(&text_mutex); > text_poke((void *)ip, new_code, MCOUNT_INSN_SIZE); > @@ -145,7 +147,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long ad > * just modify the code directly. > */ > if (addr == MCOUNT_ADDR) > - return ftrace_modify_code_direct(ip, old, new); > + return ftrace_modify_code_direct(ip, old, new, mod); > > /* > * x86 overrides ftrace_replace_code -- this function will never be used > @@ -164,7 +166,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > new = ftrace_call_replace(ip, addr); > > /* Should only be called when module is loaded */ > - return ftrace_modify_code_direct(rec->ip, old, new); > + return ftrace_modify_code_direct(rec->ip, old, new, NULL); > } > > /* > > base-commit: 9f16d5e6f220661f73b36a4be1b21575651d8833 > -- > 2.45.2 > -- Sincerely yours, Mike.