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Yonghong Song d69bafe6ee selftests/bpf: Fix usdt multispec failure with arm64/clang20 selftest build 
When building the selftest with arm64/clang20, the following test failed:
  ...
  ubtest_multispec_usdt:PASS:usdt_100_called 0 nsec
  subtest_multispec_usdt:PASS:usdt_100_sum 0 nsec
  subtest_multispec_usdt:FAIL:usdt_300_bad_attach unexpected pointer: 0xaaaad82a2a80
  #471/2   usdt/multispec:FAIL
  #471     usdt:FAIL

But arm64/gcc11 built kernel selftests succeeded. Further debug found arm64/clang
generated code has much less argument pattern after dedup, but gcc generated
code has a lot more.

Check usdt probes with usdt.test.o on arm64 platform:

with gcc11 build binary:
  stapsdt              0x0000002e       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x00000000000054f8, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[sp]
  stapsdt              0x00000031       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x0000000000005510, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[sp, 4]
  ...
  stapsdt              0x00000032       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x0000000000005660, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[sp, 60]
  ...
  stapsdt              0x00000034       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x00000000000070e8, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[sp, 1192]
  stapsdt              0x00000034       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x0000000000007100, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[sp, 1196]
  ...
  stapsdt              0x00000032       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x0000000000009ec4, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[sp, 60]

with clang20 build binary:
  stapsdt              0x0000002e       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x00000000000009a0, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[x9]
  stapsdt              0x0000002e       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x00000000000009b8, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[x9]
  ...
  stapsdt              0x0000002e       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x0000000000002590, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[x9]
  stapsdt              0x0000002e       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x00000000000025a8, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[x8]
  ...
  stapsdt              0x0000002f       NT_STAPSDT (SystemTap probe descriptors)
    Provider: test
    Name: usdt_300
    Location: 0x0000000000007fdc, Base: 0x0000000000000000, Semaphore: 0x0000000000000008
    Arguments: -4@[x10]

There are total 300 locations for usdt_300. For gcc11 built binary, there are
300 spec's. But for clang20 built binary, there are 3 spec's. The default
BPF_USDT_MAX_SPEC_CNT is 256, so bpf_program__attach_usdt() will fail for gcc
but it will succeed with clang.

To fix the problem, do not do bpf_program__attach_usdt() for usdt_300
with arm64/clang setup.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250624211802.2198821-1-yonghong.song@linux.dev
2025-06-25 12:52:54 -07:00
..
accounting
arch perf tools improvements and fixes for Linux v6.16: 2025-06-03 15:11:44 -07:00
bootconfig tools/bootconfig: specify LDFLAGS as an argument to CC 2025-05-16 11:22:54 +09:00
bpf bpftool: Fix memory leak in dump_xx_nlmsg on realloc failure 2025-06-20 11:32:36 -07:00
build tools build: Don't show libbfd build status as it is opt-in 2025-04-10 10:45:30 -03:00
certs
cgroup
counter
crypto
debugging
firewire
firmware
gpio
hv tools: hv: Enable debug logs for hv_kvp_daemon 2025-05-23 16:30:55 +00:00
iio
include bpf: adjust path to trace_output sample eBPF program 2025-06-10 08:10:21 -07:00
kvm/kvm_stat
laptop
leds
lib libbpf: Support link-based cgroup attach with options 2025-06-09 16:28:30 -07:00
memory-model tools/memory-model/Documentation: Fix SRCU section in explanation.txt 2025-04-23 12:17:04 -07:00
mm
net Networking changes for 6.16. 2025-05-28 15:24:36 -07:00
objtool Rust changes for v6.16 2025-06-04 21:18:37 -07:00
pcmcia
perf perf tools improvements and fixes for Linux v6.16: 2025-06-03 15:11:44 -07:00
power platform-drivers-x86 for v6.16-1 2025-05-29 10:19:22 -07:00
rcu
sched_ext sched_ext: change the variable name for slice refill event 2025-04-18 17:25:39 -10:00
scripts tools headers: Update the syscall table with the kernel sources 2025-04-10 09:28:24 -07:00
sound
spi
testing selftests/bpf: Fix usdt multispec failure with arm64/clang20 selftest build 2025-06-25 12:52:54 -07:00
thermal
time
tracing tracing tools updates for v6.16: 2025-05-29 20:59:52 -07:00
usb
verification
virtio
wmi
workqueue
writeback
Makefile tools/Makefile: Add ynl target 2025-04-28 17:18:48 -07:00