[BPF] LLVM ERROR: Branch target out of insn range

[yzewei]

Guys, I encountered a problem during compilation. How can I fix it?

• development：
• llvm 16
• clang 16
• kernel 6.8.0-rc5
• os fedora/anolis
• platform loongarch64

LLVM ERROR: Branch target out of insn range
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: llc -march=bpf -filetype=obj -o /build/rd/libs/driver/bpf/probe.o /build/rd/libs/driver/bpf/probe.ll
 #0 0x00007fffe9fe4538 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/lib64/libLLVM-16.so+0xcb8538)
 #1 0x00007fffe9fe1ff8 llvm::sys::RunSignalHandlers() (/lib64/libLLVM-16.so+0xcb5ff8)
 #2 0x00007fffe9fe52e0 (/lib64/libLLVM-16.so+0xcb92e0)
 #3 0x00007ffffe87489c (linux-vdso.so.1+0x89c)
 #4 0x00007fffe8fb8464 __pthread_kill_implementation.constprop.0 (/lib64/libc.so.6+0x88464)
 #5 0x00007fffe8f6b87c raise (/lib64/libc.so.6+0x3b87c)
 #6 0x00007fffe8f54218 abort (/lib64/libc.so.6+0x24218)
 #7 0x00007fffe9f0e710 llvm::report_fatal_error(llvm::Twine const&, bool) (/lib64/libLLVM-16.so+0xbe2710)
 #8 0x00007fffe9f0e558 llvm::report_fatal_error(llvm::Twine const&, bool) (/lib64/libLLVM-16.so+0xbe2558)
 #9 0x00007fffec669f70 (/lib64/libLLVM-16.so+0x333df70)
#10 0x00007fffeb70a31c llvm::MCAssembler::layout(llvm::MCAsmLayout&) (/lib64/libLLVM-16.so+0x23de31c)
#11 0x00007fffeb70a5a8 llvm::MCAssembler::Finish() (/lib64/libLLVM-16.so+0x23de5a8)
#12 0x00007fffeb72e008 llvm::MCELFStreamer::finishImpl() (/lib64/libLLVM-16.so+0x2402008)
#13 0x00007fffea8ec080 llvm::AsmPrinter::doFinalization(llvm::Module&) (/lib64/libLLVM-16.so+0x15c0080)
#14 0x00007fffea15f4ec llvm::FPPassManager::doFinalization(llvm::Module&) (/lib64/libLLVM-16.so+0xe334ec)
#15 0x00007fffea157d20 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/lib64/libLLVM-16.so+0xe2bd20)
#16 0x000000012000db88 main (/usr/bin/llc+0x12000db88)
#17 0x00007fffe8f544a8 __libc_start_call_main (/lib64/libc.so.6+0x244a8)
#18 0x00007fffe8f545ac __libc_start_main@@GLIBC_2.36 (/lib64/libc.so.6+0x245ac)
#19 0x000000012000b0a8 _start (/usr/bin/llc+0x12000b0a8)
make[7]: *** [/build/rd/libs/driver/bpf/Makefile:56: /build/rd/libs/driver/bpf/probe.o] Aborted (core dumped)
make[6]: *** [/home/yzw/workspace/linux-chenhuacai/Makefile:1921: /build/rd/libs/driver/bpf] Error 2
make[5]: *** [Makefile:240: __sub-make] Error 2
make[4]: *** [Makefile:39: all] Error 2
make[3]: *** [driver/bpf/CMakeFiles/bpf.dir/build.make:70: driver/bpf/CMakeFiles/bpf] Error 2
make[2]: *** [CMakeFiles/Makefile2:859: driver/bpf/CMakeFiles/bpf.dir/all] Error 2
make[1]: *** [CMakeFiles/Makefile2:866: driver/bpf/CMakeFiles/bpf.dir/rule] Error 2
make: *** [Makefile:312: bpf] Error 2

[dtcxzyw]

/build/rd/libs/driver/bpf/probe.ll

Could you please provide the LLVM IR? Can you reproduce it with llvm-18 or later?

[yzewei]

@dtcxzyw The same error occurs under llvm-18, which occurs in https://github.com/falcosecurity/libs/blob/master/driver/bpf/probe.c

[yzewei]

@dtcxzyw Is there any latest progress?

[dtcxzyw]

cc @inclyc @eddyz87

[eddyz87]

Hi @yzewei,

The probe.c source file has a lot of include files, so I can't try it locally.
Is it possible to minimize it, or produce a C file w/o includes, or produce an LLVM IR file (using -S -emit-llvm)?
Basing on the error message alone, it looks like some branch instruction needs to encode an offset bigger than 2^16 instructions, which exceeds limits for branching instructions of cpuv3. So, on a surface, it looks like -mcpuv4 option should help, but I need to have a reproducible example to say for sure.

[yzewei]

Hi @yzewei,

The probe.c source file has a lot of include files, so I can't try it locally. Is it possible to minimize it, or produce a C file w/o includes, or produce an LLVM IR file (using -S -emit-llvm)? Basing on the error message alone, it looks like some branch instruction needs to encode an offset bigger than 2^16 instructions, which exceeds limits for branching instructions of cpuv3. So, on a surface, it looks like -mcpuv4 option should help, but I need to have a reproducible example to say for sure.

Of course, I will upload the file (probe.ll) https://github.com/yzewei/libs/releases/download/probe.ll/probe_IR.tar.gz
Thanks for your reply! @eddyz87

[eddyz87]

@yzewei,

Of course, I will upload the file (probe.ll) https://github.com/yzewei/libs/releases/download/probe.ll/probe_IR.tar.gz Thanks for your reply! @eddyz87

Hm, I tried the following command: llc --mtriple=bpfel -mcpu=v3 probe.ll -o /dev/null using both LLVM version 18.1.2 and 19.0.0git (current main), and command does not fail.

Could you please double check if such llc command fails on your side?

[yzewei]

There is no problem compiling the IR file with this command.
Is this because of the compile option --mtriple=bpfel, Can you tell me why?
llc -march=bpf -mcpu=v3 -filetype=obj -o /home/yzw/rd/libs/driver/bpf/probe.o /home/yzw/rd/libs/driver/bpf/probe.ll
An error will still be reported when this instruction is executed correctly：

[root@fedora build]# llc -march=bpf -mcpu=v3 -filetype=obj -o /home/yzw/rd/libs/driver/bpf/probe.o /home/yzw/rd/libs/driver/bpf/probe.ll
LLVM ERROR: Branch target out of insn range
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: llc -march=bpf -mcpu=v3 -filetype=obj -o /home/yzw/rd/libs/driver/bpf/probe.o /home/yzw/rd/libs/driver/bpf/probe.ll
 #0 0x00007fffe8a61acc llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/lib64/libLLVM-18.so+0xa61acc)
 #1 0x00007fffe8a5f9a0 llvm::sys::RunSignalHandlers() (/lib64/libLLVM-18.so+0xa5f9a0)
 #2 0x00007fffe8a5fd88 (/lib64/libLLVM-18.so+0xa5fd88)
 #3 0x00007ffffd7b889c (linux-vdso.so.1+0x89c)
 #4 0x00007ffff009ef58 __pthread_kill_implementation.constprop.0 (/lib64/libc.so.6+0x82f58)
 #5 0x00007ffff00591e0 raise (/lib64/libc.so.6+0x3d1e0)
 #6 0x00007ffff00442f4 abort (/lib64/libc.so.6+0x282f4)
 #7 0x00007fffe89a4d74 llvm::report_fatal_error(llvm::StringRef, bool) (/lib64/libLLVM-18.so+0x9a4d74)
 #8 0x00007fffe89a4dec llvm::install_bad_alloc_error_handler(void (*)(void*, char const*, bool), void*) (/lib64/libLLVM-18.so+0x9a4dec)
 #9 0x00007fffeb34d19c (/lib64/libLLVM-18.so+0x334d19c)
#10 0x00007fffea214eec llvm::MCAssembler::layout(llvm::MCAsmLayout&) (/lib64/libLLVM-18.so+0x2214eec)
#11 0x00007fffea215060 llvm::MCAssembler::Finish() (/lib64/libLLVM-18.so+0x2215060)
#12 0x00007fffe93ba8c4 llvm::AsmPrinter::doFinalization(llvm::Module&) (/lib64/libLLVM-18.so+0x13ba8c4)
#13 0x00007fffe8baa138 llvm::FPPassManager::doFinalization(llvm::Module&) (/lib64/libLLVM-18.so+0xbaa138)
#14 0x00007fffe8bb53e4 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/lib64/libLLVM-18.so+0xbb53e4)
#15 0x0000555557f87f38 (/usr/bin/llc+0x17f38)
#16 0x0000555557f7fbb4 main (/usr/bin/llc+0xfbb4)
#17 0x00007ffff004482c __libc_start_call_main (/lib64/libc.so.6+0x2882c)
#18 0x00007ffff0044918 __libc_start_main@@GLIBC_2.36 (/lib64/libc.so.6+0x28918)
#19 0x0000555557f80140 _start (/usr/bin/llc+0x10140)
已放弃

[inclyc]

Duplicated to #55669 ?

Refer: #55669 (comment)

[inclyc]

Is this because of the compile option --mtriple=bpfel, Can you tell me why?

How about --mtriple=bpfeb ?