Em Tue, Jun 11, 2019 at 11:49:17PM -0300, Arnaldo Carvalho de Melo escreveu: > 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 > > > <SNIP other verbose messages> > > > 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 <acme@xxxxxxxxxx> > > > 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 <leo.yan@xxxxxxxxxx> > > > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx> > > > Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> > > > Cc: Alexei Starovoitov <ast@xxxxxxxxxx> > > > Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx> > > > Cc: Jiri Olsa <jolsa@xxxxxxxxxx> > > > Cc: Martin KaFai Lau <kafai@xxxxxx> > > > Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> > > > Cc: Mike Leach <mike.leach@xxxxxxxxxx> > > > Cc: Namhyung Kim <namhyung@xxxxxxxxxx> > > > Cc: Song Liu <songliubraving@xxxxxx> > > > Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx> > > > Cc: Yonghong Song <yhs@xxxxxx> > > > Link: https://lkml.kernel.org/n/tip-oa4c2x8p3587jme0g89fyg18@xxxxxxxxxxxxxx > > > Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> > > > > > > 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. This is equivalent and I think the smallest patch, I'll add one on top doing what you suggested about nr_allocated getting the strlist__nr_entries() and also will rename i to nr_used to contrast with nr_allocated, and then at the end set ev_qualifier_ids.nr to nr_used. - Arnaldo diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index eb70a4b71755..bd1f00e7a2eb 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1528,9 +1528,9 @@ static int trace__read_syscall_info(struct trace *trace, int id) static int trace__validate_ev_qualifier(struct trace *trace) { - int err = 0, i; + int err = 0; bool printed_invalid_prefix = false; - size_t nr_allocated; + size_t nr_allocated, i; struct str_node *pos; trace->ev_qualifier_ids.nr = strlist__nr_entries(trace->ev_qualifier); @@ -1575,7 +1575,7 @@ static int trace__validate_ev_qualifier(struct trace *trace) id = syscalltbl__strglobmatch_next(trace->sctbl, sc, &match_next); if (id < 0) break; - if (nr_allocated == trace->ev_qualifier_ids.nr) { + if (nr_allocated == i) { void *entries; nr_allocated += 8; @@ -1588,11 +1588,11 @@ static int trace__validate_ev_qualifier(struct trace *trace) } trace->ev_qualifier_ids.entries = entries; } - trace->ev_qualifier_ids.nr++; trace->ev_qualifier_ids.entries[i++] = id; } } + trace->ev_qualifier_ids.nr = i; out: if (printed_invalid_prefix) pr_debug("\n");
