Add a test that checks R0-R5 are preserved across arch_bpf_timed_may_goto() calls.
Use bpf_get_prandom_u32() to avoid the verifier removing the checks via DCE. Suggested-by: Björn Töpel <[email protected]> Signed-off-by: Feng Jiang <[email protected]> --- .../selftests/bpf/progs/verifier_may_goto_1.c | 57 ++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c b/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c index 4bdf4256a41e..98d59108d097 100644 --- a/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c +++ b/tools/testing/selftests/bpf/progs/verifier_may_goto_1.c @@ -106,4 +106,61 @@ __naked void may_goto_batch_2(void) : __clobber_all); } +/* + * Use bpf_get_prandom_u32() to prevent DCE from removing the checks. + * retval: 0=all ok, 1-6=R0-R5 clobbered. + */ +SEC("raw_tp") +__description("timed may_goto preserves R0-R5") +__arch_x86_64 +__arch_arm64 +__arch_riscv64 +__success +__retval(0) +__naked void timed_may_goto_preserves_regs(void) +{ + asm volatile ( + "call %[bpf_get_prandom_u32];" + "r6 = r0;" + "r0 = 0x1111;" + "r0 += r6;" + "r1 = 0x2222;" + "r1 += r6;" + "r2 = 0x3333;" + "r2 += r6;" + "r3 = 0x4444;" + "r3 += r6;" + "r4 = 0x5555;" + "r4 += r6;" + "r5 = 0x6666;" + "r5 += r6;" + ".8byte %[may_goto];" + ".8byte %[loop];" + "r0 -= r6;" + "r1 -= r6;" + "r2 -= r6;" + "r3 -= r6;" + "r4 -= r6;" + "r5 -= r6;" + "if r0 != 0x1111 goto 1f;" + "if r1 != 0x2222 goto 2f;" + "if r2 != 0x3333 goto 3f;" + "if r3 != 0x4444 goto 4f;" + "if r4 != 0x5555 goto 5f;" + "if r5 != 0x6666 goto 6f;" + "r0 = 0;" + "exit;" + "1: r0 = 1; exit;" + "2: r0 = 2; exit;" + "3: r0 = 3; exit;" + "4: r0 = 4; exit;" + "5: r0 = 5; exit;" + "6: r0 = 6; exit;" + : + : __imm(bpf_get_prandom_u32), + __imm_insn(may_goto, BPF_RAW_INSN(BPF_JMP | BPF_JCOND, 0, 0, 1, 0)), + __imm_insn(loop, BPF_RAW_INSN(BPF_JMP | BPF_JA, 0, 0, -2, 0)) + : __clobber_all); +} + char _license[] SEC("license") = "GPL"; -- 2.53.0
