bpf: introduce function calls (verification)

[linux-2.6-microblaze.git] / include / linux / bpf_verifier.h

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 91a583b..1f23408 100644 (file)
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -76,6 +76,14 @@ struct bpf_reg_state {
        s64 smax_value; /* maximum possible (s64)value */
        u64 umin_value; /* minimum possible (u64)value */
        u64 umax_value; /* maximum possible (u64)value */
+       /* Inside the callee two registers can be both PTR_TO_STACK like
+        * R1=fp-8 and R2=fp-8, but one of them points to this function stack
+        * while another to the caller's stack. To differentiate them 'frameno'
+        * is used which is an index in bpf_verifier_state->frame[] array
+        * pointing to bpf_func_state.
+        * This field must be second to last, for states_equal() reasons.
+        */
+       u32 frameno;
        /* This field must be last, for states_equal() reasons. */
        enum bpf_reg_liveness live;
 };
@@ -96,13 +104,34 @@ struct bpf_stack_state {
 /* state of the program:
  * type of all registers and stack info
  */
-struct bpf_verifier_state {
+struct bpf_func_state {
        struct bpf_reg_state regs[MAX_BPF_REG];
        struct bpf_verifier_state *parent;
+       /* index of call instruction that called into this func */
+       int callsite;
+       /* stack frame number of this function state from pov of
+        * enclosing bpf_verifier_state.
+        * 0 = main function, 1 = first callee.
+        */
+       u32 frameno;
+       /* subprog number == index within subprog_stack_depth
+        * zero == main subprog
+        */
+       u32 subprogno;
+
+       /* should be second to last. See copy_func_state() */
        int allocated_stack;
        struct bpf_stack_state *stack;
 };
 
+#define MAX_CALL_FRAMES 8
+struct bpf_verifier_state {
+       /* call stack tracking */
+       struct bpf_func_state *frame[MAX_CALL_FRAMES];
+       struct bpf_verifier_state *parent;
+       u32 curframe;
+};
+
 /* linked list of verifier states used to prune search */
 struct bpf_verifier_state_list {
        struct bpf_verifier_state state;
@@ -163,12 +192,15 @@ struct bpf_verifier_env {
        struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
        struct bpf_verifer_log log;
        u32 subprog_starts[BPF_MAX_SUBPROGS];
+       u16 subprog_stack_depth[BPF_MAX_SUBPROGS + 1];
        u32 subprog_cnt;
 };
 
 static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
 {
-       return env->cur_state->regs;
+       struct bpf_verifier_state *cur = env->cur_state;
+
+       return cur->frame[cur->curframe]->regs;
 }
 
 #if defined(CONFIG_NET) && defined(CONFIG_BPF_SYSCALL)