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 7318979D8; Fri, 21 Jun 2024 13:40:25 +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=1718977225; cv=none; b=Aanopwt6SxZ1z6JHrieGaILol3a63bmNVxLD3yCvq0suIYGr+AV6pZgyNyp7ZDZi1V+jzbDkeHCDi2PCx+TzhoAiYRsYfxijnmW10p5yycAdGVDOObEJ9KdtjCJdIJ9h57MTxtkhp9Uk178jT/nL/JwTCAhXuQsiC1k7IBDR4Xo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718977225; c=relaxed/simple; bh=fOM9ylRhcgz7ECY4ZWBxL26DxUUgMk2Ed4FUd7Ji+6U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UZeB6yVDZ5KJ9vBTomCxx/qWbkvCDv7TJ7SJNCm7X6Esz6tTzABML7hEdW/PJQUUEtzMo8JmtwpNY8P1sswRh1eajednpn5BBrv/D0R6+1P8qSZdh8Ft+woa1Ab06Xigz8Yw1A0MaDybP3C8J84dbqbEdt+ylNhcGUY4DTt9HPA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mFWEwid5; 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="mFWEwid5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D28AC2BBFC; Fri, 21 Jun 2024 13:40:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718977225; bh=fOM9ylRhcgz7ECY4ZWBxL26DxUUgMk2Ed4FUd7Ji+6U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mFWEwid5hPzLHOOsv6GRlXK77oTJTmYrJ+9RYGaGj27q9SUUEFK91cNe1FmlNF/KO yTeYnA+VyXkvNXqHiB8InaMF+8NeszlOKHFEoTe8ujJvPy7BjGjJLnsoV2J34aLyPa Wp0+6yYfpSaPwd//HeQfFSkNYseTHKUznZIklu+u+wFJJQzLjNpfadlpOcAtqp7nnE mo4+YER6IPhNNnX1iQJzdlaugqSjihe0G+JMyRZxKrc1RYSKex+JE9X5aHJ5Qhp0VQ nqwnoyMoCbVX5T6cI/Y2OfD2ZQ+0MvgW4nNvIb81kWJ7zMrVrldbU81mqdr7Mu6JD+ HwWVht1Xsm9zQ== Date: Fri, 21 Jun 2024 10:40:22 -0300 From: Arnaldo Carvalho de Melo To: Howard Chu Cc: Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Kan Liang , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH v2 2/5] perf trace: Augment enum syscall arguments with BTF Message-ID: References: <20240619082042.4173621-1-howardchu95@gmail.com> <20240619082042.4173621-3-howardchu95@gmail.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Jun 21, 2024 at 03:16:26AM +0800, Howard Chu wrote: > Hello, > > The fixes are on the perf-tools-next branch at: > https://github.com/Sberm/linux.git > > please use > ``` > git pull https://github.com/Sberm/linux.git perf-tools-next > ``` > > I'm no git expert so please tell me if something is wrong. So, you combined everything into just one patch and there is no commit log message, I'll see if I can redo it from the last broken out patch series you submitted. - Arnaldo > P.S. not my proudest patch, changed too many things, might be buggy. > If there're bugs please let me know. > > On Fri, Jun 21, 2024 at 12:34 AM Howard Chu wrote: > > > > Hello Arnaldo, > > > > Thanks for the review, the code is refined based on your comments. > > There is just a little thing: > > > > On Thu, Jun 20, 2024 at 1:59 AM Howard Chu wrote: > > > > > > Hello, > > > > > > Thanks for the in-depth review. > > > > > > On Wed, Jun 19, 2024 at 9:44 PM Arnaldo Carvalho de Melo > > > wrote: > > > > > > > > On Wed, Jun 19, 2024 at 04:20:39PM +0800, Howard Chu wrote: > > > > > This is a feature implemented on the basis of the previous bug fix > > > > > https://lore.kernel.org/linux-perf-users/d18a9606-ac9f-4ca7-afaf-fcf4c951cb90@web.de/T/#t > > > > > > > > > > In this patch, BTF is used to turn enum value to the corresponding > > > > > enum variable name. There is only one system call that uses enum value > > > > > as its argument, that is `landlock_add_rule()`. > > > > > > > > > > The vmlinux btf is loaded lazily, when user decided to trace the > > > > > `landlock_add_rule` syscall. But if one decides to run `perf trace` > > > > > without any arguments, the behaviour is to trace `landlock_add_rule`, > > > > > so vmlinux btf will be loaded by default. > > > > > > > > > > before: > > > > > > > > > > ``` > > > > > perf $ ./perf trace -e landlock_add_rule > > > > > 0.000 ( 0.008 ms): ldlck-test/438194 landlock_add_rule(rule_type: 2) = -1 EBADFD (File descriptor in bad state) > > > > > 0.010 ( 0.001 ms): ldlck-test/438194 landlock_add_rule(rule_type: 1) = -1 EBADFD (File descriptor in bad state) > > > > > ``` > > > > > > > > > > after: > > > > > > > > > > ``` > > > > > perf $ ./perf trace -e landlock_add_rule > > > > > 0.000 ( 0.029 ms): ldlck-test/438194 landlock_add_rule(rule_type: LANDLOCK_RULE_NET_PORT) = -1 EBADFD (File descriptor in bad state) > > > > > 0.036 ( 0.004 ms): ldlck-test/438194 landlock_add_rule(rule_type: LANDLOCK_RULE_PATH_BENEATH) = -1 EBADFD (File descriptor in bad state) > > > > > ``` > > > > > Tested-by: Arnaldo Carvalho de Melo > > > > > Suggested-by: Arnaldo Carvalho de Melo > > > > > Reviewed-by: Arnaldo Carvalho de Melo > > > > > Signed-off-by: Howard Chu > > > > > --- > > > > > tools/perf/builtin-trace.c | 96 ++++++++++++++++++++++++++++++++++++-- > > > > > 1 file changed, 91 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c > > > > > index c4fa8191253d..d93f34e9af74 100644 > > > > > --- a/tools/perf/builtin-trace.c > > > > > +++ b/tools/perf/builtin-trace.c > > > > > @@ -19,6 +19,7 @@ > > > > > #ifdef HAVE_LIBBPF_SUPPORT > > > > > #include > > > > > #include > > > > > +#include > > > > > #ifdef HAVE_BPF_SKEL > > > > > #include "bpf_skel/augmented_raw_syscalls.skel.h" > > > > > #endif > > > > > @@ -110,6 +111,11 @@ struct syscall_arg_fmt { > > > > > const char *name; > > > > > u16 nr_entries; // for arrays > > > > > bool show_zero; > > > > > + bool is_enum; > > > > > + struct { > > > > > + void *entries; > > > > > + u16 nr_entries; > > > > > + } btf_entry; > > > > > }; > > > > > > > > > > struct syscall_fmt { > > > > > @@ -140,6 +146,7 @@ struct trace { > > > > > #ifdef HAVE_BPF_SKEL > > > > > struct augmented_raw_syscalls_bpf *skel; > > > > > #endif > > > > > + struct btf *btf; > > > > > struct record_opts opts; > > > > > struct evlist *evlist; > > > > > struct machine *host; > > > > > @@ -897,6 +904,56 @@ static size_t syscall_arg__scnprintf_getrandom_flags(char *bf, size_t size, > > > > > .strtoul = STUL_STRARRAY_FLAGS, \ > > > > > .parm = &strarray__##array, } > > > > > > > > > > +static int btf_enum_find_entry(struct btf *btf, char *type, struct syscall_arg_fmt *arg_fmt) > > > > > +{ > > > > > + const struct btf_type *bt; > > > > > + char enum_prefix[][16] = { "enum", "const enum" }, *ep; > > > > > + int id; > > > > > + size_t i; > > > > > + > > > > > + for (i = 0; i < ARRAY_SIZE(enum_prefix); i++) { > > > > > + ep = enum_prefix[i]; > > > > > + if (strlen(type) > strlen(ep) + 1 && strstarts(type, ep)) > > > > > > > > No need for the strlen test? I.e. plain using strstarts() should be > > > > enough? > > > > > > Agree. Thanks for pointing that out. Although if string 'type' is > > > 'enum' and prefix is 'enum', strstarts() will be true, but to do 'type > > > += strlen(ep) + 1', and then access 'type', might give us an > > > out-of-range access, but I don't think 'type' will ever be just 'enum' > > > or 'const enum', so I'll delete it then. > > > > > > > > > > > > + type += strlen(ep) + 1; > > > > > + } > > > > > + > > > > > + id = btf__find_by_name(btf, type); > > > > > + if (id < 0) > > > > > + return -1; > > > > > + > > > > > + bt = btf__type_by_id(btf, id); > > > > > + if (bt == NULL) > > > > > > > > a pr_debug() stating that something that tracefs says should be in BTF > > > > and isn't found there seems to be of value here. > > > > > > Sure. > > > > > > > > > > > > + return -1; > > > > > + > > > > > + arg_fmt->btf_entry.entries = btf_enum(bt); > > > > > + arg_fmt->btf_entry.nr_entries = btf_vlen(bt); > > > > > + > > > > > + return 0; > > > > > +} > > > > > + > > > > > +static size_t btf_enum_scnprintf(char *bf, size_t size, int val, struct btf *btf, char *type, > > > > > + struct syscall_arg_fmt *arg_fmt) > > > > > +{ > > > > > + struct btf_enum *be; > > > > > + int i; > > > > > + > > > > > + /* if btf_entry is NULL, find and save it to arg_fmt */ > > > > > + if (arg_fmt->btf_entry.entries == NULL) > > > > > + if (btf_enum_find_entry(btf, type, arg_fmt)) > > > > > + return 0; > > > > > + > > > > > + be = (struct btf_enum *)arg_fmt->btf_entry.entries; > > > > > > > > struct btf_enum *be = (struct btf_enum *)arg_fmt->btf_entry.entries; > > > > > > > > arg_fmt->btf_entry.entries is (void *), so we don't need the (struct > > > > btf_enum *) cast here, removing it makes the code more compact. And > > > > since we move the declaration to the same line, the info about its type > > > > is there as well. > > > > > > Sure, thanks. > > > > > > > > > > > > + > > > > > + for (i = 0; i < arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > > > > > > > > > > > for (int i = 0; i < arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > > > I did this, it's all good. But here: > > > > for (i = 0, be = arg_fmt->btf_entry.entries; i < > > arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > > > I can't do > > > > for (int i = 0, struct btf_enum *be = arg_fmt->btf_entry.entries; i < > > arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > > > The compiler will show errors: > > > > builtin-trace.c: In function ‘btf_enum_scnprintf’: > > builtin-trace.c:996:25: error: expected identifier or ‘(’ before ‘struct’ > > 996 | for (int i = 0, struct btf_enum *be = > > arg_fmt->btf_entry.entries; i < arg_fmt->btf_entry.nr_entries; ++i, > > ++be) { > > | ^~~~~~ > > builtin-trace.c:996:117: error: ‘be’ undeclared (first use in this > > function); did you mean ‘bf’? > > 996 | for (int i = 0, struct btf_enum *be = > > arg_fmt->btf_entry.entries; i < arg_fmt->btf_entry.nr_entries; ++i, > > ++be) { > > | > > ^~ > > | > > bf > > builtin-trace.c:996:117: note: each undeclared identifier is reported > > only once for each function it appears in > > > > This is not good either: > > > > for (int i = 0, be = arg_fmt->btf_entry.entries; i < > > arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > > > builtin-trace.c: In function ‘btf_enum_scnprintf’: > > builtin-trace.c:998:25: error: declaration of ‘be’ shadows a previous > > local [-Werror=shadow] > > 998 | for (int i = 0, be = arg_fmt->btf_entry.entries; i < > > arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > | ^~ > > builtin-trace.c:991:26: note: shadowed declaration is here > > 991 | struct btf_enum *be; > > | ^~ > > builtin-trace.c:998:30: error: initialization of ‘int’ from ‘void *’ > > makes integer from pointer without a cast [-Wint-conversion] > > 998 | for (int i = 0, be = arg_fmt->btf_entry.entries; i < > > arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > | ^~~~~~~ > > > > But I can do: > > > > ``` > > be = arg_fmt->btf_entry.entries; > > > > for (int i = 0; i < arg_fmt->btf_entry.nr_entries; ++i, ++be) { > > ``` > > > > Thanks, > > Howard > > > > > > > > > > > > ⬢[acme@toolbox perf-tools-next]$ git grep 'for (int ' tools/perf/ | wc -l > > > > 99 > > > > ⬢[acme@toolbox perf-tools-next]$ > > > > > > > > Doing it this way makes the code more compact and is allowed even in > > > > kernel code since some time ago: > > > > > > Sure. > > > > > > > > > > > ⬢[acme@toolbox perf-tools-next]$ git grep 'for (int ' drivers/ | wc -l > > > > 294 > > > > ⬢[acme@toolbox perf-tools-next]$ git grep 'for (int ' kernel/ | wc -l > > > > 12 > > > > ⬢[acme@toolbox perf-tools-next]$ git grep 'for (int ' net/ | wc -l > > > > 3 > > > > ⬢[acme@toolbox perf-tools-next]$ git grep 'for (int ' mm/ | wc -l > > > > 21 > > > > ⬢[acme@toolbox perf-tools-next]$ > > > > > > > > > + if (be->val == val) { > > > > > + return scnprintf(bf, size, "%s", > > > > > + btf__name_by_offset(btf, be->name_off)); > > > > > + } > > > > > + } > > > > > + > > > > > + return 0; > > > > > +} > > > > > + > > > > > #include "trace/beauty/arch_errno_names.c" > > > > > #include "trace/beauty/eventfd.c" > > > > > #include "trace/beauty/futex_op.c" > > > > > @@ -1699,6 +1756,15 @@ static void trace__symbols__exit(struct trace *trace) > > > > > symbol__exit(); > > > > > } > > > > > > > > > > +static void trace__load_vmlinux_btf(struct trace *trace) > > > > > +{ > > > > > + trace->btf = btf__load_vmlinux_btf(); > > > > > + if (verbose > 0) { > > > > > + fprintf(trace->output, trace->btf ? "vmlinux BTF loaded\n" : > > > > > + "Failed to load vmlinux BTF\n"); > > > > > + } > > > > > +} > > > > > + > > > > > static int syscall__alloc_arg_fmts(struct syscall *sc, int nr_args) > > > > > { > > > > > int idx; > > > > > @@ -1744,7 +1810,7 @@ static const struct syscall_arg_fmt *syscall_arg_fmt__find_by_name(const char *n > > > > > } > > > > > > > > > > static struct tep_format_field * > > > > > -syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field *field) > > > > > +syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field *field, bool *use_btf) > > > > > { > > > > > struct tep_format_field *last_field = NULL; > > > > > int len; > > > > > @@ -1782,6 +1848,8 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field > > > > > * 7 unsigned long > > > > > */ > > > > > arg->scnprintf = SCA_FD; > > > > > + } else if (strstr(field->type, "enum") && use_btf != NULL) { > > > > > + *use_btf = arg->is_enum = true; > > > > > > > > Here you have to check if use_btf is NULL, as you, in this patch, later > > > > call syscall_arg_fmt__init_array(arg, field, NULL) in > > > > evsel__init_tp_arg_scnprintf(), probably you tested it all at the end of > > > > the patch series, we have to make sure that it works after each patch, > > > > so that we keep the codebase bisectable. > > > > > > I'm sorry, could you enlighten me on this? I thought: > > > ``` > > > else if (strstr(field->type, "enum") && use_btf != NULL) { > > > ``` > > > is doing the NULL checking. If you mean making sure the NULL checking > > > appears in all patches, I thought this is where we should introduce > > > the checking. Tiny reminder, the [1/5] patch is your syscalltbl > > > traversal bug fix. > > > > > > > > > > > > } else { > > > > > const struct syscall_arg_fmt *fmt = > > > > > syscall_arg_fmt__find_by_name(field->name); > > > > > @@ -1796,9 +1864,10 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field > > > > > return last_field; > > > > > } > > > > > > > > > > -static int syscall__set_arg_fmts(struct syscall *sc) > > > > > +static int syscall__set_arg_fmts(struct syscall *sc, bool *use_btf) > > > > > { > > > > > - struct tep_format_field *last_field = syscall_arg_fmt__init_array(sc->arg_fmt, sc->args); > > > > > + struct tep_format_field *last_field = syscall_arg_fmt__init_array(sc->arg_fmt, sc->args, > > > > > + use_btf); > > > > > > > > > > if (last_field) > > > > > sc->args_size = last_field->offset + last_field->size; > > > > > @@ -1810,7 +1879,9 @@ static int trace__read_syscall_info(struct trace *trace, int id) > > > > > { > > > > > char tp_name[128]; > > > > > struct syscall *sc; > > > > > + int err; > > > > > const char *name = syscalltbl__name(trace->sctbl, id); > > > > > + bool use_btf = false; > > > > > > > > > > #ifdef HAVE_SYSCALL_TABLE_SUPPORT > > > > > if (trace->syscalls.table == NULL) { > > > > > @@ -1883,7 +1954,12 @@ static int trace__read_syscall_info(struct trace *trace, int id) > > > > > sc->is_exit = !strcmp(name, "exit_group") || !strcmp(name, "exit"); > > > > > sc->is_open = !strcmp(name, "open") || !strcmp(name, "openat"); > > > > > > > > > > - return syscall__set_arg_fmts(sc); > > > > > + err = syscall__set_arg_fmts(sc, &use_btf); > > > > > + > > > > > + if (use_btf && trace->btf == NULL) > > > > > + trace__load_vmlinux_btf(trace); > > > > > + > > > > > + return err; > > > > > } > > > > > > > > > > static int evsel__init_tp_arg_scnprintf(struct evsel *evsel) > > > > > @@ -1891,7 +1967,7 @@ static int evsel__init_tp_arg_scnprintf(struct evsel *evsel) > > > > > struct syscall_arg_fmt *fmt = evsel__syscall_arg_fmt(evsel); > > > > > > > > > > if (fmt != NULL) { > > > > > - syscall_arg_fmt__init_array(fmt, evsel->tp_format->format.fields); > > > > > + syscall_arg_fmt__init_array(fmt, evsel->tp_format->format.fields, NULL); > > > > > return 0; > > > > > } > > > > > > > > > > @@ -2103,6 +2179,16 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size, > > > > > if (trace->show_arg_names) > > > > > printed += scnprintf(bf + printed, size - printed, "%s: ", field->name); > > > > > > > > > > + if (sc->arg_fmt[arg.idx].is_enum && trace->btf) { > > > > > + size_t p = btf_enum_scnprintf(bf + printed, size - printed, val, > > > > > + trace->btf, field->type, > > > > > + &sc->arg_fmt[arg.idx]); > > > > > + if (p) { > > > > > + printed += p; > > > > > + continue; > > > > > + } > > > > > + } > > > > > + > > > > > printed += syscall_arg_fmt__scnprintf_val(&sc->arg_fmt[arg.idx], > > > > > bf + printed, size - printed, &arg, val); > > > > > } > > > > > -- > > > > > 2.45.2 > > > > > > > > > > > Thanks, > > > Howard