linux-toradex.git/samples/bpf, branch v5.10-rc2

bpf, libbpf: Guard bpf inline asm from bpf_tail_call_static

2020-10-21T23:46:52+00:00

Yaniv reported a compilation error after pulling latest libbpf:

  [...]
  ../libbpf/src/root/usr/include/bpf/bpf_helpers.h:99:10: error:
  unknown register name 'r0' in asm
                     : "r0", "r1", "r2", "r3", "r4", "r5");
  [...]

The issue got triggered given Yaniv was compiling tracing programs with native
target (e.g. x86) instead of BPF target, hence no BTF generated vmlinux.h nor
CO-RE used, and later llc with -march=bpf was invoked to compile from LLVM IR
to BPF object file. Given that clang was expecting x86 inline asm and not BPF
one the error complained that these regs don't exist on the former.

Guard bpf_tail_call_static() with defined(__bpf__) where BPF inline asm is valid
to use. BPF tracing programs on more modern kernels use BPF target anyway and
thus the bpf_tail_call_static() function will be available for them. BPF inline
asm is supported since clang 7 (clang <= 6 otherwise throws same above error),
and __bpf_unreachable() since clang 8, therefore include the latter condition
in order to prevent compilation errors for older clang versions. Given even an
old Ubuntu 18.04 LTS has official LLVM packages all the way up to llvm-10, I did
not bother to special case the __bpf_unreachable() inside bpf_tail_call_static()
further.

Also, undo the sockex3_kern's use of bpf_tail_call_static() sample given they
still have the old hacky way to even compile networking progs with native instead
of BPF target so bpf_tail_call_static() won't be defined there anymore.

Fixes: 0e9f6841f664 ("bpf, libbpf: Add bpf_tail_call_static helper for bpf programs")
Reported-by: Yaniv Agman 
Signed-off-by: Daniel Borkmann 
Acked-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Tested-by: Yaniv Agman 
Link: https://lore.kernel.org/bpf/CAMy7=ZUk08w5Gc2Z-EKi4JFtuUCaZYmE4yzhJjrExXpYKR4L8w@mail.gmail.com
Link: https://lore.kernel.org/bpf/20201021203257.26223-1-daniel@iogearbox.net

samples: bpf: Refactor XDP kern program maps with BTF-defined map

2020-10-11T19:14:36+00:00

Most of the samples were converted to use the new BTF-defined MAP as
they moved to libbpf, but some of the samples were missing.

Instead of using the previous BPF MAP definition, this commit refactors
xdp_monitor and xdp_sample_pkts_kern MAP definition with the new
BTF-defined MAP format.

Also, this commit removes the max_entries attribute at PERF_EVENT_ARRAY
map type. The libbpf's bpf_object__create_map() will automatically
set max_entries to the maximum configured number of CPUs on the host.

Signed-off-by: Daniel T. Lee 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20201010181734.1109-4-danieltimlee@gmail.com

samples: bpf: Replace attach_tracepoint() to attach() in xdp_redirect_cpu

2020-10-11T19:14:36+00:00

>From commit d7a18ea7e8b6 ("libbpf: Add generic bpf_program__attach()"),
for some BPF programs, it is now possible to attach BPF programs
with __attach() instead of explicitly calling __attach_().

This commit refactors the __attach_tracepoint() with libbpf's generic
__attach() method. In addition, this refactors the logic of setting
the map FD to simplify the code. Also, the missing removal of
bpf_load.o in Makefile has been fixed.

Signed-off-by: Daniel T. Lee 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20201010181734.1109-3-danieltimlee@gmail.com

samples: bpf: Refactor xdp_monitor with libbpf

2020-10-11T19:14:36+00:00

To avoid confusion caused by the increasing fragmentation of the BPF
Loader program, this commit would like to change to the libbpf loader
instead of using the bpf_load.

Thanks to libbpf's bpf_link interface, managing the tracepoint BPF
program is much easier. bpf_program__attach_tracepoint manages the
enable of tracepoint event and attach of BPF programs to it with a
single interface bpf_link, so there is no need to manage event_fd and
prog_fd separately.

This commit refactors xdp_monitor with using this libbpf API, and the
bpf_load is removed and migrated to libbpf.

Signed-off-by: Daniel T. Lee 
Signed-off-by: Alexei Starovoitov 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20201010181734.1109-2-danieltimlee@gmail.com

samples: bpf: Driver interrupt statistics in xdpsock

2020-10-06T18:46:50+00:00

Add an option to count the number of interrupts generated per second and
total number of interrupts during the lifetime of the application for a
given interface. This information is extracted from /proc/interrupts. Since
there is no naming convention across drivers, the user must provide the
string which is specific to their interface in the /proc/interrupts file on
the command line.

Usage:

./xdpsock ... -I 

eg. for queue 0 of i40e device eth0:

./xdpsock ... -I i40e-eth0-TxRx-0

Signed-off-by: Ciara Loftus 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20201002133612.31536-3-ciara.loftus@intel.com

samples: bpf: Count syscalls in xdpsock

2020-10-06T18:46:50+00:00

Categorise and record syscalls issued in the xdpsock sample app. The
categories recorded are:

  rx_empty_polls:    polls when the rx ring is empty
  fill_fail_polls:   polls when failed to get addr from fill ring
  copy_tx_sendtos:   sendtos issued for tx when copy mode enabled
  tx_wakeup_sendtos: sendtos issued when tx ring needs waking up
  opt_polls:         polls issued since the '-p' flag is set

Print the stats using '-a' on the xdpsock command line.

Signed-off-by: Ciara Loftus 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20201002133612.31536-2-ciara.loftus@intel.com

samples: bpf: Split xdpsock stats into new struct

2020-10-06T18:46:50+00:00

New statistics will be added in future commits. In preparation for this,
let's split out the existing statistics into their own struct.

Signed-off-by: Ciara Loftus 
Signed-off-by: Alexei Starovoitov 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20201002133612.31536-1-ciara.loftus@intel.com

samples/bpf: Fix a compilation error with fallthrough marking

2020-10-06T18:45:03+00:00

Compiling samples/bpf hits an error related to fallthrough marking.
    ...
    CC  samples/bpf/hbm.o
  samples/bpf/hbm.c: In function ‘main’:
  samples/bpf/hbm.c:486:4: error: ‘fallthrough’ undeclared (first use in this function)
      fallthrough;
      ^~~~~~~~~~~

The "fallthrough" is not defined under tools/include directory.
Rather, it is "__fallthrough" is defined in linux/compiler.h.
Including "linux/compiler.h" and using "__fallthrough" fixed the issue.

Signed-off-by: Yonghong Song 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20201006043427.1891805-1-yhs@fb.com

samples/bpf: Change Makefile to cope with latest llvm

2020-10-06T18:45:03+00:00

With latest llvm trunk, bpf programs under samples/bpf
directory, if using CORE, may experience the following
errors:

LLVM ERROR: Cannot select: intrinsic %llvm.preserve.struct.access.index
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace.
Stack dump:
0. Program arguments: llc -march=bpf -filetype=obj -o samples/bpf/test_probe_write_user_kern.o
1. Running pass 'Function Pass Manager' on module ''.
2. Running pass 'BPF DAG->DAG Pattern Instruction Selection' on function '@bpf_prog1'
#0 0x000000000183c26c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int)
(/data/users/yhs/work/llvm-project/llvm/build.cur/install/bin/llc+0x183c26c)
...
#7 0x00000000017c375e (/data/users/yhs/work/llvm-project/llvm/build.cur/install/bin/llc+0x17c375e)
#8 0x00000000016a75c5 llvm::SelectionDAGISel::CannotYetSelect(llvm::SDNode*)
(/data/users/yhs/work/llvm-project/llvm/build.cur/install/bin/llc+0x16a75c5)
#9 0x00000000016ab4f8 llvm::SelectionDAGISel::SelectCodeCommon(llvm::SDNode*, unsigned char const*,
unsigned int) (/data/users/yhs/work/llvm-project/llvm/build.cur/install/bin/llc+0x16ab4f8)
...
Aborted (core dumped) | llc -march=bpf -filetype=obj -o samples/bpf/test_probe_write_user_kern.o

The reason is due to llvm change https://reviews.llvm.org/D87153
where the CORE relocation global generation is moved from the beginning
of target dependent optimization (llc) to the beginning
of target independent optimization (opt).

Since samples/bpf programs did not use vmlinux.h and its clang compilation
uses native architecture, we need to adjust arch triple at opt level
to do CORE relocation global generation properly. Otherwise, the above
error will appear.

This patch fixed the issue by introduce opt and llvm-dis to compilation chain,
which will do proper CORE relocation global generation as well as O2 level
optimization. Tested with llvm10, llvm11 and trunk/llvm12.

Signed-off-by: Yonghong Song
Signed-off-by: Alexei Starovoitov
Acked-by: Andrii Nakryiko
Link: https://lore.kernel.org/bpf/20201006043427.1891742-1-yhs@fb.com

bpf, selftests: Use bpf_tail_call_static where appropriate

2020-09-30T18:50:35+00:00

For those locations where we use an immediate tail call map index use the
newly added bpf_tail_call_static() helper.

Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Acked-by: Martin KaFai Lau 
Link: https://lore.kernel.org/bpf/3cfb2b799a62d22c6e7ae5897c23940bdcc24cbc.1601477936.git.daniel@iogearbox.net