Fixing issue #1515.

Currently, each usdt probe (provider, probe_name) can only
have locations from the single binary. It is possible that
USDT probes are defined in a header file which eventually causes
the same usdt probe having locations in several different
binary/shared_objects. In such cases, we are not able to attach
the same bpf program to all these locations.

This patch addresses this issue by defining each location to
be `bin_path + addr_offset` vs. previous `addr_offset` only.
This way, each internal Probe class can represent all locations
for the same (provider, probe_name) pair.

The `tplist.py` output is re-organized with the (provider, probe_name)
in the top level like below:
```
...
rtld:lll_futex_wake [sema 0x0]
  location #1 /usr/lib64/ld-2.17.so 0xaac8
    argument #1 8 unsigned bytes @ di
    argument #2 4 signed   bytes @ 1
    argument #3 4 signed   bytes @ 0
  location #2 /usr/lib64/ld-2.17.so 0xe9b9
    argument #1 8 unsigned bytes @ di
    argument #2 4 signed   bytes @ 1
    argument #3 4 signed   bytes @ 0
  location #3 /usr/lib64/ld-2.17.so 0xef3b
    argument #1 8 unsigned bytes @ di
    argument #2 4 signed   bytes @ 1
    argument #3 4 signed   bytes @ 0
...
```

Tested with the following commands
```
  tplist.py
  trace.py -p <pid> 'u::probe "arg1 = %d", arg1'
  trace.py u:<binary_path>:probe "arg1 = %d", arg1'
  argdist.py -p <pid> 'u::probe():s64:arg1'
  argdist.py -C 'u:<binary_path>:probe():s64:arg1'
  funccount.py -p <pid> 'u:<binary_path>:probe'
  funccount.py 'u:<binary_path>:probe'
```
Signed-off-by: Yonghong Song <yhs@fb.com>

Add new bpf_xdp_adjust_meta to docs/kernel-versions.md

Try use new API to create [k,u]probe with perf_event_open

Also adjust the order of helper functions.

New kernel API allows creating [k,u]probe with perf_event_open.
This patch tries to use the new API. If the new API doesn't work,
we fall back to old API.

bpf_detach_probe() looks up the event being removed. If the event
is not found, we skip the clean up procedure.
Signed-off-by: Song Liu <songliubraving@fb.com>

The new [k,u]probe API allows creating [k,u]probe together with
perf_event_open. This patch adds functions to use the new API.

Note: these new functions are not used until next patch, so this patch
doesn't change the behavior. The change is splitted into two patches
for cleaner review.
Signed-off-by: Song Liu <songliubraving@fb.com>

Increase bpf_attach_tracing_event buffer size

tcptracer: initialize skc_net variable

fix a verifier failure

when running with latest linus tree and net-next, the python test
tests/python/test_tracepoint.py failed with the following
symptoms:
```
......
 R0=map_value(id=0,off=0,ks=4,vs=64,imm=0) R6=map_value(id=0,off=0,ks=4,vs=64,imm=0) R7=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
34: (69) r1 = *(u16 *)(r7 +8)
35: (67) r1 <<= 48
36: (c7) r1 s>>= 48
37: (0f) r7 += r1
math between ctx pointer and register with unbounded min value is not allowed
......
```

The reason of failure is due to added tightening in verifier introduced by
the following commit:
```
commit f4be569a429987343e3f424d3854b3622ffae436
Author: Alexei Starovoitov <ast@kernel.org>
Date: Mon Dec 18 20:12:00 2017 -0800

bpf: fix integer overflows
......

```

The patch changes `offset` type in `ctx + offset` from signed to
unsigned so that we do not have `unbounded min value` so the
test trace_tracepoint.py can pass.
Signed-off-by: Yonghong Song <yhs@fb.com>

sync bpf compat headers with latest net-next

Signed-off-by: Yonghong Song <yhs@fb.com>

fix runqlen.py with 4.15 kernel

The following kernel commit changes linux_src:kernel/sched/sched.h
struct cfs_rq structure:

```
commit 1ea6c46a23f1213d1972bfae220db5c165e27bba
Author: Peter Zijlstra <peterz@infradead.org>
Date:   Sat May 6 15:59:54 2017 +0200

    sched/fair: Propagate an effective runnable_load_avg

    The load balancer uses runnable_load_avg as load indicator. For
    !cgroup this is:

      runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq

    That is, a direct sum of all runnable tasks on that runqueue. As
    opposed to load_avg, which is a sum of all tasks on the runqueue,
    which includes a blocked component.
...
```

The commit is in kernel 4.15 release and will make current
runqlen.py internal cfs_rq_partial structure not syncing with the kernel one.
As a result, runqlen.py will produce incorrect results on 4.15.

This patch attempts to solve this issue by compiling a bpf program,
which accesses one of fields introduced by the above commit.
The successful compilation will indicate that we should amend
the cfs_rq_partial structure.
Signed-off-by: Yonghong Song <yhs@fb.com>

tcplife: add tcp:tcp_set_state tracepoint support

fix a compilation error with latest llvm/clang trunk

bcc build with latest llvm/clang trunk failed with the
below error:
......
[ 35%] Built target api-static
/home/yhs/work/bcc/src/cc/frontends/clang/tp_frontend_action.cc: In member function ‘bool ebpf::TracepointTypeVisitor::Visit
FunctionDecl(clang::FunctionDecl*)’:
/home/yhs/work/bcc/src/cc/frontends/clang/tp_frontend_action.cc:163:60: error: no matching function for call to ‘clang::Qual
Type::getAsString(clang::SplitQualType)’
         auto type_name = QualType::getAsString(type.split());
                                                            ^
......

The error is caused by the below clang commit:
commit fcc28fd8cc8139cf1e4763459447880768579d8e
Author: Aaron Ballman <aaron@aaronballman.com>
Date:   Thu Dec 21 21:42:42 2017 +0000

    Re-commit r321223, which adds a printing policy to the ASTDumper.
......
-  std::string getAsString() const {
-    return getAsString(split());
+  static std::string getAsString(SplitQualType split,
+                                 const PrintingPolicy &Policy) {
+    return getAsString(split.Ty, split.Quals, Policy);
   }
+  static std::string getAsString(const Type *ty, Qualifiers qs,
+                                 const PrintingPolicy &Policy);

-  static std::string getAsString(SplitQualType split) {
-    return getAsString(split.Ty, split.Quals);
-  }
-
-  static std::string getAsString(const Type *ty, Qualifiers qs);
-
+  std::string getAsString() const;
   std::string getAsString(const PrintingPolicy &Policy) const;
......

The signature of static function getAsString(), which is used
in src/cc/frontends/clang/tp_frontend_action.cc, got changed,
and this caused the compilation error.

The patch chooses a different way to get type_name which works
for llvm 4.0 to 6.0 (tested).
Signed-off-by: Yonghong Song <yhs@fb.com>

CentOS 6 support

fix build issue for llvm 5.0.1

Fix issue #1502.
A few cmake version checking greater than 5 includes 5.0.1
which results in compilation failure. Change version checking
to explicitly equal to or greater than version 6.
Signed-off-by: Yonghong Song <yhs@fb.com>

ucalls: convert bytes to str

Fix incorrect lost_cb type in Python

Fix and improvement for perf_reader's lost_cb

Handle unknown user in cachetop

tcpretrans: extend for sum up

histogram: support sorting bucket before dumping table

Improve trace.py formatting and printing options

add a test case for bucket_sort_fn and show its
use scenario as well

add examples for including additional header files

Update for new bpf_perf_{event|prog}_read_value helpers