https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123502
Bug ID: 123502
Summary: xdp-tools fails tests for bpf (bitwise operator &= on
pointer prohibited)
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: sjames at gcc dot gnu.org
Blocks: 121462
Target Milestone: ---
Building xdp-tools w/ gcc's bpf target (*) run into a verifier failure :
```
$ cd xdp-monitor
$ make test
...
0: R1=ctx() R10=fp0
0: (79) r0 = *(u64 *)(r1 +8)
func 'xdp_devmap_xmit' arg1 has btf_id 3027 type STRUCT 'net_device'
1: R0=trusted_ptr_net_device() R1=ctx()
1: (bf) r5 = r1 ; R1=ctx() R5=ctx()
2: (79) r2 = *(u64 *)(r5 +0)
func 'xdp_devmap_xmit' arg0 has btf_id 3027 type STRUCT 'net_device'
3: R2=trusted_ptr_net_device() R5=ctx()
3: (79) r7 = *(u64 *)(r5 +32) ; R5=ctx() R7=scalar()
4: (81) r1 = *(s32 *)(r0 +0) ; R0=trusted_ptr_net_device()
R1=scalar(smin=0xffffffff80000000,smax=0x7fffffff)
5: (81) r6 = *(s32 *)(r2 +0) ; R2=trusted_ptr_net_device()
R6=scalar(smin=0xffffffff80000000,smax=0x7fffffff)
6: (b7) r0 = 0 ; R0=0
7: (79) r2 = *(u64 *)(r5 +24) ; R2=scalar() R5=ctx()
8: (bf) r3 = r10 ; R3=fp0 R10=fp0
9: (79) r5 = *(u64 *)(r5 +16) ; R5=scalar()
10: (07) r3 += -57 ; R3=fp-57
11: (18) r9 = 0xffff9f57ea870080 ;
R9=map_value(map=xdp_moni.rodata,ks=4,vs=260,off=128)
13: (57) r3 &= -64
R3 bitwise operator &= on pointer prohibited
processed 13 insns (limit 1000000) max_states_per_insn 0 total_states
0 peak_states 0 mark_read 0
-- END PROG LOAD LOG --
libbpf: prog 'tp_xdp_devmap_xmit_multi': failed to load: -EACCES
libbpf: failed to load object 'xdp_monitor'
libbpf: failed to load BPF skeleton 'xdp_monitor': -EACCES
Failed to xdp_monitor__load: Permission denied
Duration : 578638.3s
Command './xdp-monitor -vv' exited with status 4
Test test_monitor exited with return code: 4
make: *** [../lib/common.mk:132: test] Error 1
```
```
$ bpf-unknown-none-gcc -v
Using built-in specs.
COLLECT_GCC=bpf-unknown-none-gcc
COLLECT_LTO_WRAPPER=/usr/lib/bpf-toolchain/libexec/gcc/bpf-unknown-none/15/lto-wrapper
Target: bpf-unknown-none
Configured with:
/var/tmp/portage/sys-devel/bpf-toolchain-15.2.0_p2/work/gcc/configure
--build=x86_64-pc-linux-gnu --target=bpf-unknown-none --docdir=/.skip
--infodir=/.skip --mandir=/.skip MAKEINFO=: --prefix=/usr/lib/bpf-toolchain
--host=x86_64-pc-linux-gnu --disable-bootstrap --disable-cc1 --disable-cet
--disable-gcov --disable-gomp --disable-nls --disable-libcc1
--disable-libquadmath --disable-libsanitizer --disable-libssp --disable-libvtv
--disable-shared --disable-werror --enable-languages=c
--with-gcc-major-version-only --with-system-zlib --without-isl --without-zstd
--disable-multilib CXX='x86_64-pc-linux-gnu-g++ -std=c++14'
Thread model: single
Supported LTO compression algorithms: zlib
gcc version 15.2.0 (GCC)
```
```
$ uname -a
Linux mop 6.18.3 #1 SMP PREEMPT_DYNAMIC Fri Jan 2 17:31:07 GMT 2026 x86_64 AMD
Ryzen 9 3950X 16-Core Processor AuthenticAMD GNU/Linux
```
(*) I'll include how to build this separately.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121462
[Bug 121462] [meta-bug] BPF verifier issues
