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bpf: Add the assign_scalar_id_before_mov function

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Extract the common code that generates a register ID for src_reg before
MOV if needed into a new function. This function will also be used in
a following commit.

Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240108205209.838365-7-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Maxim Mikityanskiy
2024-01-08 22:52:00 +02:00
committed by Alexei Starovoitov
parent b827eee4c4
commit 8e0e074aaf
1 changed files with 19 additions and 14 deletions
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kernel/bpf/verifier.c
+19 -14
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@@ -4403,6 +4403,18 @@ static bool __is_pointer_value(bool allow_ptr_leaks,
return reg->type != SCALAR_VALUE;
}
static void assign_scalar_id_before_mov(struct bpf_verifier_env *env,
struct bpf_reg_state *src_reg)
{
if (src_reg->type == SCALAR_VALUE && !src_reg->id &&
!tnum_is_const(src_reg->var_off))
/* Ensure that src_reg has a valid ID that will be copied to
* dst_reg and then will be used by find_equal_scalars() to
* propagate min/max range.
*/
src_reg->id = ++env->id_gen;
}
/* Copy src state preserving dst->parent and dst->live fields */
static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_state *src)
{
@@ -13905,20 +13917,13 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
if (BPF_SRC(insn->code) == BPF_X) {
struct bpf_reg_state *src_reg = regs + insn->src_reg;
struct bpf_reg_state *dst_reg = regs + insn->dst_reg;
bool need_id = src_reg->type == SCALAR_VALUE && !src_reg->id &&
!tnum_is_const(src_reg->var_off);
if (BPF_CLASS(insn->code) == BPF_ALU64) {
if (insn->off == 0) {
/* case: R1 = R2
* copy register state to dest reg
*/
if (need_id)
/* Assign src and dst registers the same ID
* that will be used by find_equal_scalars()
* to propagate min/max range.
*/
src_reg->id = ++env->id_gen;
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
dst_reg->live |= REG_LIVE_WRITTEN;
dst_reg->subreg_def = DEF_NOT_SUBREG;
@@ -13933,8 +13938,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
bool no_sext;
no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
if (no_sext && need_id)
src_reg->id = ++env->id_gen;
if (no_sext)
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
if (!no_sext)
dst_reg->id = 0;
@@ -13956,8 +13961,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
if (insn->off == 0) {
bool is_src_reg_u32 = src_reg->umax_value <= U32_MAX;
if (is_src_reg_u32 && need_id)
src_reg->id = ++env->id_gen;
if (is_src_reg_u32)
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
/* Make sure ID is cleared if src_reg is not in u32
* range otherwise dst_reg min/max could be incorrectly
@@ -13971,8 +13976,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
/* case: W1 = (s8, s16)W2 */
bool no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
if (no_sext && need_id)
src_reg->id = ++env->id_gen;
if (no_sext)
assign_scalar_id_before_mov(env, src_reg);
copy_register_state(dst_reg, src_reg);
if (!no_sext)
dst_reg->id = 0;