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bpf/tests: Add test of ALU shifts with operand register aliasing
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This patch adds a tests of ALU32 and ALU64 LSH/RSH/ARSH operations for the
case when the two operands are the same register. Mainly intended to test
JITs that implement ALU64 shifts with 32-bit CPU instructions.

Also renamed related helper functions for consistency with the new tests.

Signed-off-by: Johan Almbladh <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]
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@borkmann
Johan Almbladh authored and borkmann committed Oct 1, 2021
1 parent 6fae2e8 commit 6881360
Showing 1 changed file with 149 additions and 13 deletions.
162 changes: 149 additions & 13 deletions lib/test_bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -660,37 +660,37 @@ static int __bpf_fill_alu_shift(struct bpf_test *self, u8 op,

self->u.ptr.insns = insn;
self->u.ptr.len = len;
BUG_ON(i > len);
BUG_ON(i != len);

return 0;
}

static int bpf_fill_alu_lsh_imm(struct bpf_test *self)
static int bpf_fill_alu64_lsh_imm(struct bpf_test *self)
{
return __bpf_fill_alu_shift(self, BPF_LSH, BPF_K, false);
}

static int bpf_fill_alu_rsh_imm(struct bpf_test *self)
static int bpf_fill_alu64_rsh_imm(struct bpf_test *self)
{
return __bpf_fill_alu_shift(self, BPF_RSH, BPF_K, false);
}

static int bpf_fill_alu_arsh_imm(struct bpf_test *self)
static int bpf_fill_alu64_arsh_imm(struct bpf_test *self)
{
return __bpf_fill_alu_shift(self, BPF_ARSH, BPF_K, false);
}

static int bpf_fill_alu_lsh_reg(struct bpf_test *self)
static int bpf_fill_alu64_lsh_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift(self, BPF_LSH, BPF_X, false);
}

static int bpf_fill_alu_rsh_reg(struct bpf_test *self)
static int bpf_fill_alu64_rsh_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift(self, BPF_RSH, BPF_X, false);
}

static int bpf_fill_alu_arsh_reg(struct bpf_test *self)
static int bpf_fill_alu64_arsh_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift(self, BPF_ARSH, BPF_X, false);
}
Expand Down Expand Up @@ -725,6 +725,86 @@ static int bpf_fill_alu32_arsh_reg(struct bpf_test *self)
return __bpf_fill_alu_shift(self, BPF_ARSH, BPF_X, true);
}

/*
* Test an ALU register shift operation for all valid shift values
* for the case when the source and destination are the same.
*/
static int __bpf_fill_alu_shift_same_reg(struct bpf_test *self, u8 op,
bool alu32)
{
int bits = alu32 ? 32 : 64;
int len = 3 + 6 * bits;
struct bpf_insn *insn;
int i = 0;
u64 val;

insn = kmalloc_array(len, sizeof(*insn), GFP_KERNEL);
if (!insn)
return -ENOMEM;

insn[i++] = BPF_ALU64_IMM(BPF_MOV, R0, 0);

for (val = 0; val < bits; val++) {
u64 res;

/* Perform operation */
insn[i++] = BPF_ALU64_IMM(BPF_MOV, R1, val);
if (alu32)
insn[i++] = BPF_ALU32_REG(op, R1, R1);
else
insn[i++] = BPF_ALU64_REG(op, R1, R1);

/* Compute the reference result */
__bpf_alu_result(&res, val, val, op);
if (alu32)
res = (u32)res;
i += __bpf_ld_imm64(&insn[i], R2, res);

/* Check the actual 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;
}

static int bpf_fill_alu64_lsh_same_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift_same_reg(self, BPF_LSH, false);
}

static int bpf_fill_alu64_rsh_same_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift_same_reg(self, BPF_RSH, false);
}

static int bpf_fill_alu64_arsh_same_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift_same_reg(self, BPF_ARSH, false);
}

static int bpf_fill_alu32_lsh_same_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift_same_reg(self, BPF_LSH, true);
}

static int bpf_fill_alu32_rsh_same_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift_same_reg(self, BPF_RSH, true);
}

static int bpf_fill_alu32_arsh_same_reg(struct bpf_test *self)
{
return __bpf_fill_alu_shift_same_reg(self, BPF_ARSH, true);
}

/*
* Common operand pattern generator for exhaustive power-of-two magnitudes
* tests. The block size parameters can be adjusted to increase/reduce the
Expand Down Expand Up @@ -11788,47 +11868,47 @@ static struct bpf_test tests[] = {
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu_lsh_imm,
.fill_helper = bpf_fill_alu64_lsh_imm,
},
{
"ALU64_RSH_K: all shift values",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu_rsh_imm,
.fill_helper = bpf_fill_alu64_rsh_imm,
},
{
"ALU64_ARSH_K: all shift values",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu_arsh_imm,
.fill_helper = bpf_fill_alu64_arsh_imm,
},
{
"ALU64_LSH_X: all shift values",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu_lsh_reg,
.fill_helper = bpf_fill_alu64_lsh_reg,
},
{
"ALU64_RSH_X: all shift values",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu_rsh_reg,
.fill_helper = bpf_fill_alu64_rsh_reg,
},
{
"ALU64_ARSH_X: all shift values",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu_arsh_reg,
.fill_helper = bpf_fill_alu64_arsh_reg,
},
/* Exhaustive test of ALU32 shift operations */
{
Expand Down Expand Up @@ -11879,6 +11959,62 @@ static struct bpf_test tests[] = {
{ { 0, 1 } },
.fill_helper = bpf_fill_alu32_arsh_reg,
},
/*
* Exhaustive test of ALU64 shift operations when
* source and destination register are the same.
*/
{
"ALU64_LSH_X: all shift values with the same register",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu64_lsh_same_reg,
},
{
"ALU64_RSH_X: all shift values with the same register",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu64_rsh_same_reg,
},
{
"ALU64_ARSH_X: all shift values with the same register",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu64_arsh_same_reg,
},
/*
* Exhaustive test of ALU32 shift operations when
* source and destination register are the same.
*/
{
"ALU32_LSH_X: all shift values with the same register",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu32_lsh_same_reg,
},
{
"ALU32_RSH_X: all shift values with the same register",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu32_rsh_same_reg,
},
{
"ALU32_ARSH_X: all shift values with the same register",
{ },
INTERNAL | FLAG_NO_DATA,
{ },
{ { 0, 1 } },
.fill_helper = bpf_fill_alu32_arsh_same_reg,
},
/* ALU64 immediate magnitudes */
{
"ALU64_MOV_K: all immediate value magnitudes",
Expand Down

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