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Tue, 11 Jun 2019 19:49:19 -0700 (PDT) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id D21EA41149; Tue, 11 Jun 2019 23:49:17 -0300 (-03) Date: Tue, 11 Jun 2019 23:49:17 -0300 To: Leo Yan Cc: Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Adrian Hunter , Mathieu Poirier , Mike Leach , Suzuki K Poulose , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH v2 3/4] perf augmented_raw_syscalls: Support arm64 raw syscalls Message-ID: <20190612024917.GG28689@kernel.org> References: <20190606094845.4800-1-leo.yan@linaro.org> <20190606094845.4800-4-leo.yan@linaro.org> <20190606133838.GC30166@kernel.org> <20190606141231.GC5970@leoy-ThinkPad-X240s> <20190606144412.GC21245@kernel.org> <20190607095831.GG5970@leoy-ThinkPad-X240s> <20190609131849.GB6357@leoy-ThinkPad-X240s> <20190610184754.GU21245@kernel.org> <20190611041831.GA3959@leoy-ThinkPad-X240s> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190611041831.GA3959@leoy-ThinkPad-X240s> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Tue, Jun 11, 2019 at 12:18:31PM +0800, Leo Yan escreveu: > On Mon, Jun 10, 2019 at 03:47:54PM -0300, Arnaldo Carvalho de Melo wrote: > > [...] > > > > > I tested with the lastest perf/core branch which contains the patch: > > > > 'perf augmented_raw_syscalls: Tell which args are filenames and how > > > > many bytes to copy' and got the error as below: > > > > > > > > # perf trace -e string -e /mnt/linux-kernel/linux-cs-dev/tools/perf/examples/bpf/augmented_raw_syscalls.c > > > > Error: Invalid syscall access, chmod, chown, creat, futimesat, lchown, link, lstat, mkdir, mknod, newfstatat, open, readlink, rename, > > > > rmdir, stat, statfs, symlink, truncate, unlink > > > > Humm, I think that we can just make the code that parses the > > tools/perf/trace/strace/groups/string file to ignore syscalls it can't > > find in the syscall_tbl, i.e. trace those if they exist in the arch. > > Agree. > > > > > Hint: try 'perf list syscalls:sys_enter_*' > > > > Hint: and: 'man syscalls' > > > > > > > > So seems mksyscalltbl has not included completely for syscalls, I > > > > use below command to generate syscalltbl_arm64[] array and it don't > > > > include related entries for access, chmod, chown, etc ... > > > > So, we need to investigate why is that these are missing, good thing we > > have this 'strings' group :-) > > > > > > You could refer the generated syscalltbl_arm64 in: > > > > http://paste.ubuntu.com/p/8Bj7Jkm2mP/ > > > > > > After digging into this issue on Arm64, below is summary info: > > > > > > - arm64 uses the header include/uapi/linux/unistd.h to define system > > > call numbers, in this header some system calls are not defined (I > > > think the reason is these system calls are obsolete at the end) so the > > > corresponding strings are missed in the array syscalltbl_native, > > > for arm64 the array is defined in the file: > > > tools/perf/arch/arm64/include/generated/asm/syscalls.c. > > > > Yeah, I looked at the 'access' case and indeed it is not present in > > include/uapi/asm-generic/unistd.h, which is the place > > include/uapi/linux/unistd.h ends up. > > > > Ok please take a look at the patch at the end of this message, should be ok? > > > > I tested it by changing the strace/gorups/string file to have a few > > unknown syscalls, running it with -v we see: > > > > [root@quaco perf]# perf trace -v -e string ls > > Skipping unknown syscalls: access99, acct99, add_key99 > > > > normal operation not considering those unknown syscalls. > > I did testing with the patch, but it failed after I added eBPF event > with below command, I even saw segmentation fault; please see below > inline comments. > > perf --debug verbose=10 trace -e string -e \ > /mnt/linux-kernel/linux-cs-dev/tools/perf/examples/bpf/augmented_raw_syscalls.c > > [...] > > > commit e0b34a78c4ed0a6422f5b2dafa0c8936e537ee41 > > Author: Arnaldo Carvalho de Melo > > Date: Mon Jun 10 15:37:45 2019 -0300 > > > > perf trace: Skip unknown syscalls when expanding strace like syscall groups > > > > We have $INSTALL_DIR/share/perf-core/strace/groups/string files with > > syscalls that should be selected when 'string' is used, meaning, in this > > case, syscalls that receive as one of its arguments a string, like a > > pathname. > > > > But those were first selected and tested on x86_64, and end up failing > > in architectures where some of those syscalls are not available, like > > the 'access' syscall on arm64, which makes using 'perf trace -e string' > > in such archs to fail. > > > > Since this the routine doing the validation is used only when reading > > such files, do not fail when some syscall is not found in the > > syscalltbl, instead just use pr_debug() to register that in case people > > are suspicious of problems. > > > > Now using 'perf trace -e string' should work on arm64, selecting only > > the syscalls that have a string and are available on that architecture. > > > > Reported-by: Leo Yan > > Cc: Adrian Hunter > > Cc: Alexander Shishkin > > Cc: Alexei Starovoitov > > Cc: Daniel Borkmann > > Cc: Jiri Olsa > > Cc: Martin KaFai Lau > > Cc: Mathieu Poirier > > Cc: Mike Leach > > Cc: Namhyung Kim > > Cc: Song Liu > > Cc: Suzuki K Poulose > > Cc: Yonghong Song > > Link: https://lkml.kernel.org/n/tip-oa4c2x8p3587jme0g89fyg18@git.kernel.org > > Signed-off-by: Arnaldo Carvalho de Melo > > > > diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c > > index 1a2a605cf068..eb70a4b71755 100644 > > --- a/tools/perf/builtin-trace.c > > +++ b/tools/perf/builtin-trace.c > > @@ -1529,6 +1529,7 @@ static int trace__read_syscall_info(struct trace *trace, int id) > > static int trace__validate_ev_qualifier(struct trace *trace) > > { > > int err = 0, i; > > + bool printed_invalid_prefix = false; > > size_t nr_allocated; > > struct str_node *pos; > > > > @@ -1555,14 +1556,15 @@ static int trace__validate_ev_qualifier(struct trace *trace) > > if (id >= 0) > > goto matches; > > > > - if (err == 0) { > > - fputs("Error:\tInvalid syscall ", trace->output); > > - err = -EINVAL; > > + if (!printed_invalid_prefix) { > > + pr_debug("Skipping unknown syscalls: "); > > + printed_invalid_prefix = true; > > } else { > > - fputs(", ", trace->output); > > + pr_debug(", "); > > } > > > > - fputs(sc, trace->output); > > + pr_debug("%s", sc); > > + continue; > > Here adds 'continue' so that we want to let ev_qualifier_ids.entries > to only store valid system call ids. But this is not sufficient, > because we have initialized ev_qualifier_ids.nr at the beginning of > the function: > > trace->ev_qualifier_ids.nr = strlist__nr_entries(trace->ev_qualifier); > This sentence will set ids number to the string table's length; but > actually some strings are not really supported; this leads to some > items in trace->ev_qualifier_ids.entries[] will be not initialized > properly. > > If we want to get neat entries and entry number, I suggest at the > beginning of the function we use variable 'nr_allocated' to store > string table length and use it to allocate entries: > > nr_allocated = strlist__nr_entries(trace->ev_qualifier); > trace->ev_qualifier_ids.entries = malloc(nr_allocated * > sizeof(trace->ev_qualifier_ids.entries[0])); > > If we find any matched string, then increment the nr field under > 'matches' tag: > > matches: > trace->ev_qualifier_ids.nr++; > trace->ev_qualifier_ids.entries[i++] = id; > > This can ensure the entries[0..nr-1] has valid id and we can use > ev_qualifier_ids.nr to maintain the valid system call numbers. yeah, you're right, I'll address these issues in a followup patch, tomorrow. - Arnaldo > > > } > > matches: > > trace->ev_qualifier_ids.entries[i++] = id; > > @@ -1591,15 +1593,14 @@ static int trace__validate_ev_qualifier(struct trace *trace) > > } > > } > > > > - if (err < 0) { > > - fputs("\nHint:\ttry 'perf list syscalls:sys_enter_*'" > > - "\nHint:\tand: 'man syscalls'\n", trace->output); > > -out_free: > > - zfree(&trace->ev_qualifier_ids.entries); > > - trace->ev_qualifier_ids.nr = 0; > > - } > > out: > > + if (printed_invalid_prefix) > > + pr_debug("\n"); > > return err; > > +out_free: > > + zfree(&trace->ev_qualifier_ids.entries); > > + trace->ev_qualifier_ids.nr = 0; > > + goto out; > > Nitpick: directly return err and 'goto out' is not necessary. > > Thanks, > Leo Yan > > > } > > > > /* -- - Arnaldo