On Tue, Mar 26, 2019 at 7:06 PM Jiong Wang <jiong.wang@xxxxxxxxxxxxx> wrote:
>
> In previous patch, we have split register arg type for sub-register read,
> but haven't touch read liveness.
>
> This patch further split read liveness into REG_LIVE_READ64 and
> REG_LIVE_READ32. Liveness propagation code are updated accordingly.
>
> After this split, customized actions could be defined when propagating full
> register read (REG_LIVE_READ64) or sub-register read (REG_LIVE_READ32).
>
> Signed-off-by: Jiong Wang <jiong.wang@xxxxxxxxxxxxx>
[...]
> @@ -1374,7 +1374,8 @@ static int check_stack_read(struct bpf_verifier_env *env,
> return -EACCES;
> }
> mark_reg_read(env, ®_state->stack[spi].spilled_ptr,
> - reg_state->stack[spi].spilled_ptr.parent);
> + reg_state->stack[spi].spilled_ptr.parent,
> + size == BPF_REG_SIZE);
Isn't it possible to use a 4-byte read on the upper half of an 8-byte
stack slot?
> if (value_regno >= 0) {
> if (zeros == size) {
> /* any size read into register is zero extended,
> @@ -2220,7 +2221,8 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
> * the whole slot to be marked as 'read'
> */
> mark_reg_read(env, &state->stack[spi].spilled_ptr,
> - state->stack[spi].spilled_ptr.parent);
> + state->stack[spi].spilled_ptr.parent,
> + access_size == BPF_REG_SIZE);
Same thing as above.
> }
> return update_stack_depth(env, state, off);
> }
[...]
