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.w...@netronome.com>
---
include/linux/bpf_verifier.h | 9 ++++++---
kernel/bpf/verifier.c | 30 +++++++++++++++++++++---------
2 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index f03c86a..27761ab 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -37,11 +37,14 @@
/* Reg hasn't been read or written this branch. */
#define REG_LIVE_NONE 0x0
/* Reg was read, so we're sensitive to initial value. */
-#define REG_LIVE_READ 0x1
+#define REG_LIVE_READ32 0x1
+/* Likewise, but full 64-bit content matters. */
+#define REG_LIVE_READ64 0x2
+#define REG_LIVE_READ (REG_LIVE_READ32 | REG_LIVE_READ64)
/* Reg was written first, screening off later reads. */
-#define REG_LIVE_WRITTEN 0x2
+#define REG_LIVE_WRITTEN 0x4
/* Liveness won't be updating this register anymore. */
-#define REG_LIVE_DONE 0x4
+#define REG_LIVE_DONE 0x8
struct bpf_reg_state {
/* Ordering of fields matters. See states_equal() */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 245bb3c..b95c438 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1126,7 +1126,7 @@ static int check_subprogs(struct bpf_verifier_env *env)
*/
static int mark_reg_read(struct bpf_verifier_env *env,
const struct bpf_reg_state *state,
- struct bpf_reg_state *parent)
+ struct bpf_reg_state *parent, bool dw_read)
{
bool writes = parent == state->parent; /* Observe write marks */
@@ -1141,7 +1141,7 @@ static int mark_reg_read(struct bpf_verifier_env *env,
return -EFAULT;
}
/* ... then we depend on parent's value */
- parent->live |= REG_LIVE_READ;
+ parent->live |= dw_read ? REG_LIVE_READ64 : REG_LIVE_READ32;
state = parent;
parent = state->parent;
writes = true;
@@ -1170,7 +1170,7 @@ static int check_reg_arg(struct bpf_verifier_env *env,
u32 regno,
/* We don't need to worry about FP liveness because it's
read-only */
if (regno != BPF_REG_FP)
return mark_reg_read(env, ®s[regno],
- regs[regno].parent);
+ regs[regno].parent, true);
} else {
/* check whether register used as dest operand can be written
to */
if (regno == BPF_REG_FP) {
@@ -1357,7 +1357,7 @@ static int check_stack_read(struct bpf_verifier_env *env,
state->regs[value_regno].live |= REG_LIVE_WRITTEN;
}
mark_reg_read(env, ®_state->stack[spi].spilled_ptr,
- reg_state->stack[spi].spilled_ptr.parent);
+ reg_state->stack[spi].spilled_ptr.parent, true);
return 0;
} else {
int zeros = 0;
@@ -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);
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);
}
return update_stack_depth(env, state, off);
}
@@ -6059,7 +6061,7 @@ static int propagate_liveness_reg(struct bpf_verifier_env
*env,
if (parent_reg->live & flag || !(reg->live & flag))
return 0;
- err = mark_reg_read(env, reg, parent_reg);
+ err = mark_reg_read(env, reg, parent_reg, flag == REG_LIVE_READ64);
if (err)
return err;
@@ -6092,7 +6094,12 @@ static int propagate_liveness(struct bpf_verifier_env
*env,
regs = vstate->frame[vstate->curframe]->regs;
/* We don't need to worry about FP liveness because it's read-only */
for (i = 0; i < BPF_REG_FP; i++) {
- err = propagate_liveness_reg(env, ®s[i], &parent_regs[i]);
+ err = propagate_liveness_reg(env, ®s[i], &parent_regs[i],
+ REG_LIVE_READ64);
+ if (err < 0)
+ return err;
+ err = propagate_liveness_reg(env, ®s[i], &parent_regs[i],
+ REG_LIVE_READ32);
if (err < 0)
return err;
}
@@ -6107,7 +6114,12 @@ static int propagate_liveness(struct bpf_verifier_env
*env,
parent_reg = &parent->stack[i].spilled_ptr;
reg = &state->stack[i].spilled_ptr;
- err = propagate_liveness_reg(env, reg, parent_reg);
+ err = propagate_liveness_reg(env, reg, parent_reg,
+ REG_LIVE_READ64);
+ if (err < 0)
+ return err;
+ err = propagate_liveness_reg(env, reg, parent_reg,
+ REG_LIVE_READ32);
if (err < 0)
return err;
}
--
2.7.4
