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bpf: Add the get_reg_width function

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Put calculation of the register value width into a dedicated function.
This function will also be used in a following commit.

Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Link: https://lore.kernel.org/r/20240108205209.838365-8-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Maxim Mikityanskiy 2024-01-08 22:52:01 +02:00 committed by Alexei Starovoitov
parent 8e0e074aaf
commit 87e51ac6cb
1 changed files with 7 additions and 2 deletions
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9
kernel/bpf/verifier.c
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@ -4450,6 +4450,11 @@ static bool is_bpf_st_mem(struct bpf_insn *insn)
return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM;
}
static int get_reg_width(struct bpf_reg_state *reg)
{
return fls64(reg->umax_value);
}
/* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
* stack boundary and alignment are checked in check_mem_access()
*/
@ -4502,7 +4507,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
if (reg && !(off % BPF_REG_SIZE) && register_is_bounded(reg) && env->bpf_capable) {
save_register_state(env, state, spi, reg, size);
/* Break the relation on a narrowing spill. */
if (fls64(reg->umax_value) > BITS_PER_BYTE * size)
if (get_reg_width(reg) > BITS_PER_BYTE * size)
state->stack[spi].spilled_ptr.id = 0;
} else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) &&
insn->imm != 0 && env->bpf_capable) {
@ -13959,7 +13964,7 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
return -EACCES;
} else if (src_reg->type == SCALAR_VALUE) {
if (insn->off == 0) {
bool is_src_reg_u32 = src_reg->umax_value <= U32_MAX;
bool is_src_reg_u32 = get_reg_width(src_reg) <= 32;
if (is_src_reg_u32)
assign_scalar_id_before_mov(env, src_reg);