Arm64 ELF section '.note.stapsdt' uses string format "-4@[sp, NUM]" if
the probe is to access data in stack, e.g. below is an example for
dumping Arm64 ELF file and shows the argument format:
Arguments: -4@[sp, 12] -4@[sp, 8] -4@[sp, 4]
Comparing against other archs' argument format, Arm64's argument
introduces an extra space character in the middle of square brackets,
due to argv_split() uses space as splitter, the argument is wrongly
divided into two items.
To support Arm64 SDT, this patch fixes up for this case, if any item
contains sub string "[sp", concatenates the two continuous items. And
adds the detailed explaination in comment.
Signed-off-by: Leo Yan <[email protected]>
---
tools/perf/util/probe-file.c | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 064b63a6a3f3..60878c859e60 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -794,6 +794,8 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
char *ret = NULL, **args;
int i, args_count, err;
unsigned long long ref_ctr_offset;
+ char *arg;
+ int arg_idx = 0;
if (strbuf_init(&buf, 32) < 0)
return NULL;
@@ -815,8 +817,34 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
if (note->args) {
args = argv_split(note->args, &args_count);
- for (i = 0; i < args_count; ++i) {
- if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0)
+ for (i = 0; i < args_count; ) {
+ /*
+ * FIXUP: Arm64 ELF section '.note.stapsdt' uses string
+ * format "-4@[sp, NUM]" if a probe is to access data in
+ * the stack, e.g. below is an example for the SDT
+ * Arguments:
+ *
+ * Arguments: -4@[sp, 12] -4@[sp, 8] -4@[sp, 4]
+ *
+ * Since the string introduces an extra space character
+ * in the middle of square brackets, the argument is
+ * divided into two items. Fixup for this case, if an
+ * item contains sub string "[sp,", need to concatenate
+ * the two items.
+ */
+ if (strstr(args[i], "[sp,") && (i+1) < args_count) {
+ arg = strcat(args[i], args[i+1]);
+ i += 2;
+ } else {
+ arg = strdup(args[i]);
+ i += 1;
+ }
+
+ err = synthesize_sdt_probe_arg(&buf, arg_idx, arg);
+ free(arg);
+ arg_idx++;
+
+ if (err < 0)
goto error;
}
}
--
2.17.1
Em Wed, Dec 23, 2020 at 02:39:04PM +0800, Leo Yan escreveu:
> Arm64 ELF section '.note.stapsdt' uses string format "-4@[sp, NUM]" if
> the probe is to access data in stack, e.g. below is an example for
> dumping Arm64 ELF file and shows the argument format:
>
> Arguments: -4@[sp, 12] -4@[sp, 8] -4@[sp, 4]
>
> Comparing against other archs' argument format, Arm64's argument
> introduces an extra space character in the middle of square brackets,
> due to argv_split() uses space as splitter, the argument is wrongly
> divided into two items.
>
> To support Arm64 SDT, this patch fixes up for this case, if any item
> contains sub string "[sp", concatenates the two continuous items. And
> adds the detailed explaination in comment.
>
> Signed-off-by: Leo Yan <[email protected]>
> ---
> tools/perf/util/probe-file.c | 32 ++++++++++++++++++++++++++++++--
> 1 file changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 064b63a6a3f3..60878c859e60 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -794,6 +794,8 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
> char *ret = NULL, **args;
> int i, args_count, err;
> unsigned long long ref_ctr_offset;
> + char *arg;
> + int arg_idx = 0;
>
> if (strbuf_init(&buf, 32) < 0)
> return NULL;
> @@ -815,8 +817,34 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
> if (note->args) {
> args = argv_split(note->args, &args_count);
>
> - for (i = 0; i < args_count; ++i) {
> - if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0)
> + for (i = 0; i < args_count; ) {
> + /*
> + * FIXUP: Arm64 ELF section '.note.stapsdt' uses string
> + * format "-4@[sp, NUM]" if a probe is to access data in
> + * the stack, e.g. below is an example for the SDT
> + * Arguments:
> + *
> + * Arguments: -4@[sp, 12] -4@[sp, 8] -4@[sp, 4]
> + *
> + * Since the string introduces an extra space character
> + * in the middle of square brackets, the argument is
> + * divided into two items. Fixup for this case, if an
> + * item contains sub string "[sp,", need to concatenate
> + * the two items.
> + */
> + if (strstr(args[i], "[sp,") && (i+1) < args_count) {
> + arg = strcat(args[i], args[i+1]);
> + i += 2;
> + } else {
> + arg = strdup(args[i]);
> + i += 1;
> + }
> +
> + err = synthesize_sdt_probe_arg(&buf, arg_idx, arg);
> + free(arg);
So you free here unconditionally because either you used something you
got from argv_split() that strdup'ed all the entries in the array it
returns, or that you strdup'ed in the else branch.
But then you may not free all the things argv_split() returned, right?
Also, that strcat(args[i], args[i+1]), are you sure that is safe? strcat
expects dest to have enough space for the concatenation, I don't see
argv_split[] adding extra bytes, just a strdup().
So probably you need asprintf() where you use strcat() and then, at the
end of the loop, you need to free what argv_split() returned, using
argv_free(), no?
Also please check strdup() (and then asprintf) managed to allocate, else
synthesize_sdt_probe_arg() will receive its 'desc' argument as NULL, do
_another_ strdup on it and boom.
Or am I missing something? :)
I just looked ant synthesize_sdt_probe_command() is leaking the args it
gets from argv_split()
So this patch is needed, ack?
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 064b63a6a3f311cd..bbecb449ea944395 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -791,7 +791,7 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
const char *sdtgrp)
{
struct strbuf buf;
- char *ret = NULL, **args;
+ char *ret = NULL;
int i, args_count, err;
unsigned long long ref_ctr_offset;
@@ -813,12 +813,19 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
goto out;
if (note->args) {
- args = argv_split(note->args, &args_count);
+ char **args = argv_split(note->args, &args_count);
+
+ if (args == NULL)
+ goto error;
for (i = 0; i < args_count; ++i) {
- if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0)
+ if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0) {
+ argv_free(args);
goto error;
+ }
}
+
+ argv_free(args);
}
out:
On Thu, Dec 24, 2020 at 10:51:39AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Dec 23, 2020 at 02:39:04PM +0800, Leo Yan escreveu:
> > Arm64 ELF section '.note.stapsdt' uses string format "-4@[sp, NUM]" if
> > the probe is to access data in stack, e.g. below is an example for
> > dumping Arm64 ELF file and shows the argument format:
> >
> > Arguments: -4@[sp, 12] -4@[sp, 8] -4@[sp, 4]
> >
> > Comparing against other archs' argument format, Arm64's argument
> > introduces an extra space character in the middle of square brackets,
> > due to argv_split() uses space as splitter, the argument is wrongly
> > divided into two items.
> >
> > To support Arm64 SDT, this patch fixes up for this case, if any item
> > contains sub string "[sp", concatenates the two continuous items. And
> > adds the detailed explaination in comment.
> >
> > Signed-off-by: Leo Yan <[email protected]>
> > ---
> > tools/perf/util/probe-file.c | 32 ++++++++++++++++++++++++++++++--
> > 1 file changed, 30 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> > index 064b63a6a3f3..60878c859e60 100644
> > --- a/tools/perf/util/probe-file.c
> > +++ b/tools/perf/util/probe-file.c
> > @@ -794,6 +794,8 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
> > char *ret = NULL, **args;
> > int i, args_count, err;
> > unsigned long long ref_ctr_offset;
> > + char *arg;
> > + int arg_idx = 0;
> >
> > if (strbuf_init(&buf, 32) < 0)
> > return NULL;
> > @@ -815,8 +817,34 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
> > if (note->args) {
> > args = argv_split(note->args, &args_count);
> >
> > - for (i = 0; i < args_count; ++i) {
> > - if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0)
> > + for (i = 0; i < args_count; ) {
> > + /*
> > + * FIXUP: Arm64 ELF section '.note.stapsdt' uses string
> > + * format "-4@[sp, NUM]" if a probe is to access data in
> > + * the stack, e.g. below is an example for the SDT
> > + * Arguments:
> > + *
> > + * Arguments: -4@[sp, 12] -4@[sp, 8] -4@[sp, 4]
> > + *
> > + * Since the string introduces an extra space character
> > + * in the middle of square brackets, the argument is
> > + * divided into two items. Fixup for this case, if an
> > + * item contains sub string "[sp,", need to concatenate
> > + * the two items.
> > + */
> > + if (strstr(args[i], "[sp,") && (i+1) < args_count) {
> > + arg = strcat(args[i], args[i+1]);
> > + i += 2;
> > + } else {
> > + arg = strdup(args[i]);
> > + i += 1;
> > + }
> > +
> > + err = synthesize_sdt_probe_arg(&buf, arg_idx, arg);
> > + free(arg);
>
> So you free here unconditionally because either you used something you
> got from argv_split() that strdup'ed all the entries in the array it
> returns, or that you strdup'ed in the else branch.
> But then you may not free all the things argv_split() returned, right?
Yes.
> Also, that strcat(args[i], args[i+1]), are you sure that is safe? strcat
> expects dest to have enough space for the concatenation, I don't see
> argv_split[] adding extra bytes, just a strdup().
Correct, will change to use asprintf().
> So probably you need asprintf() where you use strcat() and then, at the
> end of the loop, you need to free what argv_split() returned, using
> argv_free(), no?
>
> Also please check strdup() (and then asprintf) managed to allocate, else
> synthesize_sdt_probe_arg() will receive its 'desc' argument as NULL, do
> _another_ strdup on it and boom.
Will add checking for the pointer from strdup()/asprintf().
> Or am I missing something? :)
>
> I just looked ant synthesize_sdt_probe_command() is leaking the args it
> gets from argv_split()
>
> So this patch is needed, ack?
Below change is good for me. In the next respin, I will add this new
patch with your author name and send out.
Thanks a lot for the review, Masami & Arnaldo!
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 064b63a6a3f311cd..bbecb449ea944395 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -791,7 +791,7 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
> const char *sdtgrp)
> {
> struct strbuf buf;
> - char *ret = NULL, **args;
> + char *ret = NULL;
> int i, args_count, err;
> unsigned long long ref_ctr_offset;
>
> @@ -813,12 +813,19 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
> goto out;
>
> if (note->args) {
> - args = argv_split(note->args, &args_count);
> + char **args = argv_split(note->args, &args_count);
> +
> + if (args == NULL)
> + goto error;
>
> for (i = 0; i < args_count; ++i) {
> - if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0)
> + if (synthesize_sdt_probe_arg(&buf, i, args[i]) < 0) {
> + argv_free(args);
> goto error;
> + }
> }
> +
> + argv_free(args);
> }
>
> out: