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bpf/tests: Add exhaustive test of LD_IMM64 immediate magnitudes

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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
This commit is contained in:
Johan Almbladh 2021-09-14 11:18:35 +02:00 committed by Daniel Borkmann
parent a7d2e752e5
commit 2e80761194
1 changed files with 63 additions and 0 deletions
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63
lib/test_bpf.c
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@ -1104,6 +1104,60 @@ static int bpf_fill_alu32_mod_reg(struct bpf_test *self)
return __bpf_fill_alu32_reg(self, BPF_MOD);
}
/*
* Test the two-instruction 64-bit immediate load operation for all
* power-of-two magnitudes of the immediate operand. For each MSB, a block
* of immediate values centered around the power-of-two MSB are tested,
* both for positive and negative values. The test is designed to verify
* the operation for JITs that emit different code depending on the magnitude
* of the immediate value. This is often the case if the native instruction
* immediate field width is narrower than 32 bits.
*/
static int bpf_fill_ld_imm64(struct bpf_test *self)
{
int block = 64; /* Increase for more tests per MSB position */
int len = 3 + 8 * 63 * block * 2;
struct bpf_insn *insn;
int bit, adj, sign;
int i = 0;
insn = kmalloc_array(len, sizeof(*insn), GFP_KERNEL);
if (!insn)
return -ENOMEM;
insn[i++] = BPF_ALU64_IMM(BPF_MOV, R0, 0);
for (bit = 0; bit <= 62; bit++) {
for (adj = -block / 2; adj < block / 2; adj++) {
for (sign = -1; sign <= 1; sign += 2) {
s64 imm = sign * ((1LL << bit) + adj);
/* Perform operation */
i += __bpf_ld_imm64(&insn[i], R1, imm);
/* Load reference */
insn[i++] = BPF_ALU32_IMM(BPF_MOV, R2, imm);
insn[i++] = BPF_ALU32_IMM(BPF_MOV, R3,
(u32)(imm >> 32));
insn[i++] = BPF_ALU64_IMM(BPF_LSH, R3, 32);
insn[i++] = BPF_ALU64_REG(BPF_OR, R2, R3);
/* Check result */
insn[i++] = BPF_JMP_REG(BPF_JEQ, R1, R2, 1);
insn[i++] = BPF_EXIT_INSN();
}
}
}
insn[i++] = BPF_ALU64_IMM(BPF_MOV, R0, 1);
insn[i++] = BPF_EXIT_INSN();
self->u.ptr.insns = insn;
self->u.ptr.len = len;
BUG_ON(i != len);
return 0;
}
/*
* Exhaustive tests of JMP operations for all combinations of power-of-two
@ -10245,6 +10299,15 @@ static struct bpf_test tests[] = {
.fill_helper = bpf_fill_alu32_mod_reg,
.nr_testruns = NR_PATTERN_RUNS,
},
/* LD_IMM64 immediate magnitudes */
{
"LD_IMM64: all immediate value magnitudes",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_ld_imm64,
},
/* JMP immediate magnitudes */
{
"JMP_JSET_K: all immediate value magnitudes",