Song Liu 2995f9a8d4 selftests/bpf: Keep the loop in bpf_testmod_loop_test ... Some compilers (for example clang-15) optimize bpf_testmod_loop_test and remove the loop: gcc version (gdb) disassemble bpf_testmod_loop_test Dump of assembler code for function bpf_testmod_loop_test: 0x0000000000000570 <+0>: callq 0x575 <bpf_testmod_loop_test+5> 0x0000000000000575 <+5>: xor %eax,%eax 0x0000000000000577 <+7>: test %edi,%edi 0x0000000000000579 <+9>: jle 0x587 <bpf_testmod_loop_test+23> 0x000000000000057b <+11>: xor %edx,%edx 0x000000000000057d <+13>: add %edx,%eax 0x000000000000057f <+15>: add $0x1,%edx 0x0000000000000582 <+18>: cmp %edx,%edi 0x0000000000000584 <+20>: jne 0x57d <bpf_testmod_loop_test+13> 0x0000000000000586 <+22>: retq 0x0000000000000587 <+23>: retq clang-15 version (gdb) disassemble bpf_testmod_loop_test Dump of assembler code for function bpf_testmod_loop_test: 0x0000000000000450 <+0>: nopl 0x0(%rax,%rax,1) 0x0000000000000455 <+5>: test %edi,%edi 0x0000000000000457 <+7>: jle 0x46b <bpf_testmod_loop_test+27> 0x0000000000000459 <+9>: lea -0x1(%rdi),%eax 0x000000000000045c <+12>: lea -0x2(%rdi),%ecx 0x000000000000045f <+15>: imul %rax,%rcx 0x0000000000000463 <+19>: shr %rcx 0x0000000000000466 <+22>: lea -0x1(%rdi,%rcx,1),%eax 0x000000000000046a <+26>: retq 0x000000000000046b <+27>: xor %eax,%eax 0x000000000000046d <+29>: retq Note: The jne instruction is removed in clang-15 version. Force the compile to keep the loop by making sum volatile. Signed-off-by: Song Liu <song@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20230412210423.900851-4-song@kernel.org		2023-04-13 14:32:05 +02:00
..
.gitignore	selftests/bpf: Add bpf_testmod kernel module for testing	2020-12-03 17:38:20 -08:00
bpf_testmod-events.h	bpf/selftests: Add test for writable bare tracepoint	2021-10-08 13:22:57 -07:00
bpf_testmod.c	selftests/bpf: Keep the loop in bpf_testmod_loop_test	2023-04-13 14:32:05 +02:00
bpf_testmod.h	selftests/bpf: implement and test custom testmod_seq iterator	2023-03-08 16:19:51 -08:00
Makefile	selftests/bpf: Add bpf_testmod kernel module for testing	2020-12-03 17:38:20 -08:00