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bpf/tests: Add exhaustive test of LD_IMM64 immediate magnitudes
This patch adds a test for the 64-bit immediate load, a two-instruction operation, to verify correctness for all possible magnitudes of the immediate operand. Mainly intended for JIT testing. Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20210914091842.4186267-8-johan.almbladh@anyfinetworks.com
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@ -1104,6 +1104,60 @@ static int bpf_fill_alu32_mod_reg(struct bpf_test *self)
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return __bpf_fill_alu32_reg(self, BPF_MOD);
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}
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/*
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* Test the two-instruction 64-bit immediate load operation for all
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* power-of-two magnitudes of the immediate operand. For each MSB, a block
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* of immediate values centered around the power-of-two MSB are tested,
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* both for positive and negative values. The test is designed to verify
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* the operation for JITs that emit different code depending on the magnitude
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* of the immediate value. This is often the case if the native instruction
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* immediate field width is narrower than 32 bits.
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*/
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static int bpf_fill_ld_imm64(struct bpf_test *self)
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{
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int block = 64; /* Increase for more tests per MSB position */
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int len = 3 + 8 * 63 * block * 2;
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struct bpf_insn *insn;
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int bit, adj, sign;
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int i = 0;
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insn = kmalloc_array(len, sizeof(*insn), GFP_KERNEL);
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if (!insn)
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return -ENOMEM;
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insn[i++] = BPF_ALU64_IMM(BPF_MOV, R0, 0);
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for (bit = 0; bit <= 62; bit++) {
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for (adj = -block / 2; adj < block / 2; adj++) {
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for (sign = -1; sign <= 1; sign += 2) {
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s64 imm = sign * ((1LL << bit) + adj);
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/* Perform operation */
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i += __bpf_ld_imm64(&insn[i], R1, imm);
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/* Load reference */
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insn[i++] = BPF_ALU32_IMM(BPF_MOV, R2, imm);
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insn[i++] = BPF_ALU32_IMM(BPF_MOV, R3,
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(u32)(imm >> 32));
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insn[i++] = BPF_ALU64_IMM(BPF_LSH, R3, 32);
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insn[i++] = BPF_ALU64_REG(BPF_OR, R2, R3);
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/* Check result */
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insn[i++] = BPF_JMP_REG(BPF_JEQ, R1, R2, 1);
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insn[i++] = BPF_EXIT_INSN();
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}
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}
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}
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insn[i++] = BPF_ALU64_IMM(BPF_MOV, R0, 1);
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insn[i++] = BPF_EXIT_INSN();
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self->u.ptr.insns = insn;
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self->u.ptr.len = len;
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BUG_ON(i != len);
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return 0;
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}
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/*
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* Exhaustive tests of JMP operations for all combinations of power-of-two
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@ -10245,6 +10299,15 @@ static struct bpf_test tests[] = {
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.fill_helper = bpf_fill_alu32_mod_reg,
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.nr_testruns = NR_PATTERN_RUNS,
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},
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/* LD_IMM64 immediate magnitudes */
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{
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"LD_IMM64: all immediate value magnitudes",
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{ },
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INTERNAL | FLAG_NO_DATA,
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{ },
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{ { 0, 1 } },
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.fill_helper = bpf_fill_ld_imm64,
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},
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/* JMP immediate magnitudes */
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{
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"JMP_JSET_K: all immediate value magnitudes",
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