Done. Sorry, I actually pushed the change to my yhs_dev branch last
night, but forgot to generate a pull request ...
On Tue, Jun 6, 2017 at 8:59 PM, Brenden Blanco <bbla...@gmail.com> wrote:
> Yonghong, can you send a PR for your branch?
>
> On Tue, Jun 6, 2017 at 12:20 AM, Y Song via iovisor-dev
> <iovisor-dev@lists.iovisor.org> wrote:
>>
>> Hi, Tetsuo,
>>
>> You are right. The bug is actually introduced by my last patch. I just
>> focused one aspect of issue and inadvertently introduced another
>> *blocker* bug.
>>
>> I just pushed a patch. Thanks a lot for reporting the issue and
>> testing out the fix.
>>
>> Yonghong
>>
>> On Mon, Jun 5, 2017 at 5:25 PM, Tetsuo Handa
>> <penguin-ker...@i-love.sakura.ne.jp> wrote:
>> > Hello.
>> >
>> > I changed the hook as below and confirmed that cp == NULL at
>> > bpf_probe_read().
>> > That is, it is bpf_usdt_readarg() which got broken.
>> >
>> > ----------
>> > int do_start(struct pt_regs *ctx) {
>> > char *cp = NULL;
>> > bpf_usdt_readarg(1, ctx, &cp);
>> > struct { char query[QUERY_MAX]; } data = { };
>> > if (cp != NULL)
>> > bpf_probe_read(&data.query, sizeof(data.query), (void *) cp);
>> > else
>> > data.query[0] = '!';
>> > events.perf_submit(ctx, &data, sizeof(data));
>> > return 0;
>> > };
>> > ----------
>> >
>> > If I do
>> >
>> > - std::string cptr = tfm::format("*((volatile %s *)dest)", ctype);
>> > + std::string cptr = tfm::format("*((%s *)dest)", ctype);
>> >
>> > (i.e. drop only "volatile " part) in that commit like below
>> >
>> > ----------
>> > diff --git a/src/cc/usdt.cc b/src/cc/usdt.cc
>> > --- a/src/cc/usdt.cc
>> > +++ b/src/cc/usdt.cc
>> > @@ -152,7 +152,7 @@ bool Probe::usdt_getarg(std::ostream &stream) {
>> >
>> > for (size_t arg_n = 0; arg_n < arg_count; ++arg_n) {
>> > std::string ctype = largest_arg_type(arg_n);
>> > - std::string cptr("dest");
>> > + std::string cptr = tfm::format("*((%s *)dest)", ctype);
>> >
>> > tfm::format(stream,
>> > "static __always_inline int _bpf_readarg_%s_%d("
>> > ----------
>> >
>> > USDT probe works again as well as build warning shown below goes away.
>> >
>> > ----------
>> > /virtual/main.c:4:8: warning: incompatible integer to pointer conversion
>> > assigning to 'void *' from 'volatile uint64_t' (aka 'volatile unsigned long
>> > long') [-Wint-conversion]
>> > dest = *(volatile uint64_t *)&ctx->bx;
>> > ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > ----------
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>
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