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Filename Latest commit message Latest commit date
Yonghong Song cbd0b6268a selftests/bpf: Fix pyperf180 compilation failure with clang18
[ Upstream commit 100888fb6d8a185866b1520031ee7e3182b173de ]

With latest clang18 (main branch of llvm-project repo), when building bpf selftests,
    [~/work/bpf-next (master)]$ make -C tools/testing/selftests/bpf LLVM=1 -j

The following compilation error happens:
    fatal error: error in backend: Branch target out of insn range
    ...
    Stack dump:
    0.      Program arguments: clang -g -Wall -Werror -D__TARGET_ARCH_x86 -mlittle-endian
      -I/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/include
      -I/home/yhs/work/bpf-next/tools/testing/selftests/bpf -I/home/yhs/work/bpf-next/tools/include/uapi
      -I/home/yhs/work/bpf-next/tools/testing/selftests/usr/include -idirafter
      /home/yhs/work/llvm-project/llvm/build.18/install/lib/clang/18/include -idirafter /usr/local/include
      -idirafter /usr/include -Wno-compare-distinct-pointer-types -DENABLE_ATOMICS_TESTS -O2 --target=bpf
      -c progs/pyperf180.c -mcpu=v3 -o /home/yhs/work/bpf-next/tools/testing/selftests/bpf/pyperf180.bpf.o
    1.      <eof> parser at end of file
    2.      Code generation
    ...

The compilation failure only happens to cpu=v2 and cpu=v3. cpu=v4 is okay
since cpu=v4 supports 32-bit branch target offset.

The above failure is due to upstream llvm patch [1] where some inlining behavior
are changed in clang18.

To workaround the issue, previously all 180 loop iterations are fully unrolled.
The bpf macro __BPF_CPU_VERSION__ (implemented in clang18 recently) is used to avoid
unrolling changes if cpu=v4. If __BPF_CPU_VERSION__ is not available and the
compiler is clang18, the unrollng amount is unconditionally reduced.

  [1] 1a2e77cf9e

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-02-23 08:24:57 +01:00
arch KVM: s390: fix setting of fpc register 2024-02-23 08:24:56 +01:00
block block: Remove special-casing of compound pages 2024-02-23 08:24:49 +01:00
certs
crypto crypto: api - Disallow identical driver names 2024-02-23 08:24:48 +01:00
Documentation rename(): fix the locking of subdirectories 2024-02-23 08:24:49 +01:00
drivers wifi: rt2x00: restart beacon queue when hardware reset 2024-02-23 08:24:56 +01:00
fs ext4: avoid online resizing failures due to oversized flex bg 2024-02-23 08:24:56 +01:00
include x86/entry/ia32: Ensure s32 is sign extended to s64 2024-02-23 08:24:53 +01:00
init rootfs: Fix support for rootfstype= when root= is given 2024-01-25 14:34:30 -08:00
ipc
kernel audit: Send netlink ACK before setting connection in auditd_set 2024-02-23 08:24:54 +01:00
lib ida: Fix crash in ida_free when the bitmap is empty 2024-01-25 14:34:21 -08:00
LICENSES
mm mm: fix unmap_mapping_range high bits shift bug 2024-01-15 18:25:28 +01:00
net SUNRPC: Fix a suspicious RCU usage warning 2024-02-23 08:24:56 +01:00
samples samples/bpf: Fix buffer overflow in tcp_basertt 2023-07-27 08:37:07 +02:00
scripts sign-file: Fix incorrect return values check 2023-12-20 15:41:17 +01:00
security apparmor: avoid crash when parsed profile name is empty 2024-01-25 14:34:31 -08:00
sound ALSA: oxygen: Fix right channel of capture volume mixer 2024-01-25 14:34:30 -08:00
tools selftests/bpf: Fix pyperf180 compilation failure with clang18 2024-02-23 08:24:57 +01:00
usr
virt KVM: Destroy target device if coalesced MMIO unregistration fails 2023-03-11 16:44:01 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS iio: stx104: Move to addac subdirectory 2023-08-30 16:27:12 +02:00
Makefile Linux 5.4.268 2024-01-25 14:34:33 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.