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bpf: replace register_is_const() with is_reg_const()

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The addition of is_reg_const() in commit 171de12646d2 ("bpf: generalize
is_branch_taken to handle all conditional jumps in one place") has made the
register_is_const() redundant. Give the former has more feature, plus the
fact the latter is only used in one place, replace register_is_const() with
is_reg_const(), and remove the definition of register_is_const.

This requires moving the definition of is_reg_const() further up. And since
the comment of reg_const_value() reference is_reg_const(), move it up as
well.

Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231108140043.12282-1-shung-hsi.yu@suse.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Shung-Hsi Yu 2023-11-08 22:00:41 +08:00 committed by Alexei Starovoitov
parent 27007fae70
commit 82ce364c60
1 changed files with 11 additions and 16 deletions
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27
kernel/bpf/verifier.c
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@ -4690,9 +4690,17 @@ static bool register_is_null(struct bpf_reg_state *reg)
return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
}
static bool register_is_const(struct bpf_reg_state *reg)
/* check if register is a constant scalar value */
static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32)
{
return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off);
return reg->type == SCALAR_VALUE &&
tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off);
}
/* assuming is_reg_const() is true, return constant value of a register */
static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
{
return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value;
}
static bool __is_scalar_unbounded(struct bpf_reg_state *reg)
@ -10050,7 +10058,7 @@ record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
val = reg->var_off.value;
max = map->max_entries;
if (!(register_is_const(reg) && val < max)) {
if (!(is_reg_const(reg, false) && val < max)) {
bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
return 0;
}
@ -14220,19 +14228,6 @@ static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
}));
}
/* check if register is a constant scalar value */
static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32)
{
return reg->type == SCALAR_VALUE &&
tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off);
}
/* assuming is_reg_const() is true, return constant value of a register */
static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
{
return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value;
}
/*
* <reg1> <op> <reg2>, currently assuming reg2 is a constant
*/