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 DDBFF13B7BC; Wed, 25 Dec 2024 13:16:05 +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=1735132566; cv=none; b=K6Hs7keYYgxiuY0TThoOCpLm6hWaZex5CvMBr1mDIPg1P/rOcmz7d+BnSfYy5XAC/wgobby1VZb6J2RvHl2hDTA4KhW0/HfLUQQMwcG+u/2PWy2/GvQzkgEIVw7Z/qB5AR/w9p4vKy9euNjc9CNv9dJJeqfoTXVDHSbc/eaZA8Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735132566; c=relaxed/simple; bh=q5BNQGeW9LCi3HafFO4y8fWKetca2MbVVSIzF7LA34k=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=Ch0MycjI9jwB9SWG8UvvgfeZncKtnslTKMIdtSClQ2f2mssPHKaDlzfNgq2p9Ts2gL+OttymG3PDdbpj2esF7ma1YgpFSAr2h7TFdfzGThiL5O8I6H2o/UTzBpKlv6FPqk+yGf55WcKUv5McBv+ZmjYN4lkCxy9HfTfsjm1fyTE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jR947iTL; 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="jR947iTL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6EAC3C4CECD; Wed, 25 Dec 2024 13:16:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1735132565; bh=q5BNQGeW9LCi3HafFO4y8fWKetca2MbVVSIzF7LA34k=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=jR947iTL60tY2z5dzqd/kOXIeuu/raDz6BuYK2r3v1qD0DCeb9DF6w9YvjZS+ot+C oaRoxq4oiuVJgiQlTCG4GHvte3I8ePXdxvsbHOnqJ1ZZLERiu9V1hWyrwDabt6bnWL XERe4K9oJPMlhwT8CWqHM3yFOX2v/xaV/j9PXfa36VDlSJL4f4ukwe1B+hW6g92Pve z0msuytLuJJ6+63M0/h2t+OIKrYnHUXRrSVO6BK8gGDkAuF2zTdb8YB51yQpc/hlxJ FKzB8Lu9fjUQzjIJCU8gVBrvINH7N+iBWasiwlqzovCR6yn5oUoyjUbuiaciJlsBBG oatYHzx+xSdFg== Date: Wed, 25 Dec 2024 22:15:55 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Sven Schnelle , Paul Walmsley , Palmer Dabbelt , Albert Ou , Guo Ren , Donglin Peng , Zheng Yejian , bpf@vger.kernel.org Subject: Re: [PATCH v2 1/4] ftrace: Add print_function_args() Message-Id: <20241225221555.092d66edb15d7693646c7945@kernel.org> In-Reply-To: <20241223201541.898496620@goodmis.org> References: <20241223201347.609298489@goodmis.org> <20241223201541.898496620@goodmis.org> X-Mailer: Sylpheed 3.8.0beta1 (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 Mon, 23 Dec 2024 15:13:48 -0500 Steven Rostedt wrote: > From: Sven Schnelle > > Add a function to decode argument types with the help of BTF. Will > be used to display arguments in the function and function graph > tracer. > > It can only handle simply arguments and up to FTRACE_REGS_MAX_ARGS number > of arguments. When it hits a max, it will print ", ...": > > page_to_skb(vi=0xffff8d53842dc980, rq=0xffff8d53843a0800, page=0xfffffc2e04337c00, offset=6160, len=64, truesize=1536, ...) > > And if it hits an argument that is not recognized, it will print the raw > value and the type of argument it is: > > make_vfsuid(idmap=0xffffffff87f99db8, fs_userns=0xffffffff87e543c0, kuid=0x0 (STRUCT)) > __pti_set_user_pgtbl(pgdp=0xffff8d5384ab47f8, pgd=0x110e74067 (STRUCT)) > > Co-developed-by: Steven Rostedt (Google) > Signed-off-by: Sven Schnelle > Signed-off-by: Steven Rostedt (Google) > --- > Changes since v1: https://lore.kernel.org/20240904065908.1009086-5-svens@linux.ibm.com > > - Added Config option FUNCTION_TRACE_ARGS to this patch > (unconditional if dependencies are met) > > - Changed the print_function_args() function to take an array of > unsigned long args and not the ftrace_regs pointer. The ftrace_regs > should be opaque from generic code. > > - Have the function print the name of an BTF type that is not supported. > > - Added FTRACE_REGS_MAX_ARGS as the number of arguments saved in > the event and printed out. > > - Print "...," if the number of arguments goes past FTRACE_REGS_MAX_ARGS. > > include/linux/ftrace_regs.h | 5 +++ > kernel/trace/Kconfig | 6 +++ > kernel/trace/trace_output.c | 78 +++++++++++++++++++++++++++++++++++++ > kernel/trace/trace_output.h | 9 +++++ > 4 files changed, 98 insertions(+) > > diff --git a/include/linux/ftrace_regs.h b/include/linux/ftrace_regs.h > index bbc1873ca6b8..15627ceea9bc 100644 > --- a/include/linux/ftrace_regs.h > +++ b/include/linux/ftrace_regs.h > @@ -35,4 +35,9 @@ struct ftrace_regs; > > #endif /* HAVE_ARCH_FTRACE_REGS */ > > +/* This can be overridden by the architectures */ > +#ifndef FTRACE_REGS_MAX_ARGS > +# define FTRACE_REGS_MAX_ARGS 6 > +#endif > + > #endif /* _LINUX_FTRACE_REGS_H */ > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index d570b8b9c0a9..60412c1012ef 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -263,6 +263,12 @@ config FUNCTION_GRAPH_RETADDR > the function is called. This feature is off by default, and you can > enable it via the trace option funcgraph-retaddr. > > +config FUNCTION_TRACE_ARGS > + bool > + depends on HAVE_FUNCTION_ARG_ACCESS_API > + depends on DEBUG_INFO_BTF For using the BTF APIs, we also needs BPF_SYSCALL (DEBUG_INFO_BTF just compiles the BTF info into the kernel binary.) Others looks good to me. Revewied-by: Masami Hiramatsu (Google) Thanks! > + default y > + > config DYNAMIC_FTRACE > bool "enable/disable function tracing dynamically" > depends on FUNCTION_TRACER > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index da748b7cbc4d..40d6c7a9e0c4 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -12,8 +12,11 @@ > #include > #include > #include > +#include > +#include > > #include "trace_output.h" > +#include "trace_btf.h" > > /* must be a power of 2 */ > #define EVENT_HASHSIZE 128 > @@ -680,6 +683,81 @@ int trace_print_lat_context(struct trace_iterator *iter) > return !trace_seq_has_overflowed(s); > } > > +#ifdef CONFIG_FUNCTION_TRACE_ARGS > +void print_function_args(struct trace_seq *s, unsigned long *args, > + unsigned long func) > +{ > + const struct btf_param *param; > + const struct btf_type *t; > + const char *param_name; > + char name[KSYM_NAME_LEN]; > + unsigned long arg; > + struct btf *btf; > + s32 tid, nr = 0; > + int i; > + > + trace_seq_printf(s, "("); > + > + if (!args) > + goto out; > + if (lookup_symbol_name(func, name)) > + goto out; > + > + btf = bpf_get_btf_vmlinux(); > + if (IS_ERR_OR_NULL(btf)) > + goto out; > + > + t = btf_find_func_proto(name, &btf); > + if (IS_ERR_OR_NULL(t)) > + goto out; > + > + param = btf_get_func_param(t, &nr); > + if (!param) > + goto out_put; > + > + for (i = 0; i < nr; i++) { > + /* This only prints what the arch allows (6 args by default) */ > + if (i == FTRACE_REGS_MAX_ARGS) { > + trace_seq_puts(s, "..."); > + break; > + } > + > + arg = args[i]; > + > + param_name = btf_name_by_offset(btf, param[i].name_off); > + if (param_name) > + trace_seq_printf(s, "%s=", param_name); > + t = btf_type_skip_modifiers(btf, param[i].type, &tid); > + > + switch (t ? BTF_INFO_KIND(t->info) : BTF_KIND_UNKN) { > + case BTF_KIND_UNKN: > + trace_seq_putc(s, '?'); > + /* Still print unknown type values */ > + fallthrough; > + case BTF_KIND_PTR: > + trace_seq_printf(s, "0x%lx", arg); > + break; > + case BTF_KIND_INT: > + trace_seq_printf(s, "%ld", arg); > + break; > + case BTF_KIND_ENUM: > + trace_seq_printf(s, "%ld", arg); > + break; > + default: > + /* This does not handle complex arguments */ > + trace_seq_printf(s, "0x%lx (%s)", arg, btf_type_str(t)); > + break; > + } > + if (i < nr - 1) > + trace_seq_printf(s, ", "); > + } > +out_put: > + btf_put(btf); > +out: > + trace_seq_printf(s, ")"); > +} > +#endif > + > /** > * ftrace_find_event - find a registered event > * @type: the type of event to look for > diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h > index dca40f1f1da4..2e305364f2a9 100644 > --- a/kernel/trace/trace_output.h > +++ b/kernel/trace/trace_output.h > @@ -41,5 +41,14 @@ extern struct rw_semaphore trace_event_sem; > #define SEQ_PUT_HEX_FIELD(s, x) \ > trace_seq_putmem_hex(s, &(x), sizeof(x)) > > +#ifdef CONFIG_FUNCTION_TRACE_ARGS > +void print_function_args(struct trace_seq *s, unsigned long *args, > + unsigned long func); > +#else > +static inline void print_function_args(struct trace_seq *s, unsigned long *args, > + unsigned long func) { > + trace_seq_puts(s, "()"); > +} > +#endif > #endif > > -- > 2.45.2 > > -- Masami Hiramatsu (Google)