bpf: unify 32-bit and 64-bit is_branch_taken logic

Combine 32-bit and 64-bit is_branch_taken logic for SCALAR_VALUE
registers. It makes it easier to see parallels between two domains
(32-bit and 64-bit), and makes subsequent refactoring more
straightforward.

No functional changes.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231102033759.2541186-16-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 17bbff33e0e8a06c5865bfcda0ed6a76b93e23a6..c77cca5c44611f17d705a423eb173b406c66283b 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -14204,166 +14204,86 @@ static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
 /*
  * <reg1> <op> <reg2>, currently assuming reg2 is a constant
  */
-static int is_branch32_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode)
+static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
+                                 u8 opcode, bool is_jmp32)
 {
-       struct tnum subreg = tnum_subreg(reg1->var_off);
-       u32 val = (u32)tnum_subreg(reg2->var_off).value;
-       s32 sval = (s32)val;
+       struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off;
+       u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value;
+       u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value;
+       s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value;
+       s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value;
+       u64 uval = is_jmp32 ? (u32)tnum_subreg(reg2->var_off).value : reg2->var_off.value;
+       s64 sval = is_jmp32 ? (s32)uval : (s64)uval;
 
        switch (opcode) {
        case BPF_JEQ:
-               if (tnum_is_const(subreg))
-                       return !!tnum_equals_const(subreg, val);
-               else if (val < reg1->u32_min_value || val > reg1->u32_max_value)
+               if (tnum_is_const(t1))
+                       return !!tnum_equals_const(t1, uval);
+               else if (uval < umin1 || uval > umax1)
                        return 0;
-               else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value)
+               else if (sval < smin1 || sval > smax1)
                        return 0;
                break;
        case BPF_JNE:
-               if (tnum_is_const(subreg))
-                       return !tnum_equals_const(subreg, val);
-               else if (val < reg1->u32_min_value || val > reg1->u32_max_value)
+               if (tnum_is_const(t1))
+                       return !tnum_equals_const(t1, uval);
+               else if (uval < umin1 || uval > umax1)
                        return 1;
-               else if (sval < reg1->s32_min_value || sval > reg1->s32_max_value)
+               else if (sval < smin1 || sval > smax1)
                        return 1;
                break;
        case BPF_JSET:
-               if ((~subreg.mask & subreg.value) & val)
+               if ((~t1.mask & t1.value) & uval)
                        return 1;
-               if (!((subreg.mask | subreg.value) & val))
+               if (!((t1.mask | t1.value) & uval))
                        return 0;
                break;
        case BPF_JGT:
-               if (reg1->u32_min_value > val)
+               if (umin1 > uval )
                        return 1;
-               else if (reg1->u32_max_value <= val)
+               else if (umax1 <= uval)
                        return 0;
                break;
        case BPF_JSGT:
-               if (reg1->s32_min_value > sval)
+               if (smin1 > sval)
                        return 1;
-               else if (reg1->s32_max_value <= sval)
+               else if (smax1 <= sval)
                        return 0;
                break;
        case BPF_JLT:
-               if (reg1->u32_max_value < val)
+               if (umax1 < uval)
                        return 1;
-               else if (reg1->u32_min_value >= val)
+               else if (umin1 >= uval)
                        return 0;
                break;
        case BPF_JSLT:
-               if (reg1->s32_max_value < sval)
+               if (smax1 < sval)
                        return 1;
-               else if (reg1->s32_min_value >= sval)
+               else if (smin1 >= sval)
                        return 0;
                break;
        case BPF_JGE:
-               if (reg1->u32_min_value >= val)
+               if (umin1 >= uval)
                        return 1;
-               else if (reg1->u32_max_value < val)
+               else if (umax1 < uval)
                        return 0;
                break;
        case BPF_JSGE:
-               if (reg1->s32_min_value >= sval)
+               if (smin1 >= sval)
                        return 1;
-               else if (reg1->s32_max_value < sval)
+               else if (smax1 < sval)
                        return 0;
                break;
        case BPF_JLE:
-               if (reg1->u32_max_value <= val)
+               if (umax1 <= uval)
                        return 1;
-               else if (reg1->u32_min_value > val)
+               else if (umin1 > uval)
                        return 0;
                break;
        case BPF_JSLE:
-               if (reg1->s32_max_value <= sval)
+               if (smax1 <= sval)
                        return 1;
-               else if (reg1->s32_min_value > sval)
-                       return 0;
-               break;
-       }
-
-       return -1;
-}
-
-
-/*
- * <reg1> <op> <reg2>, currently assuming reg2 is a constant
- */
-static int is_branch64_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2, u8 opcode)
-{
-       u64 val = reg2->var_off.value;
-       s64 sval = (s64)val;
-
-       switch (opcode) {
-       case BPF_JEQ:
-               if (tnum_is_const(reg1->var_off))
-                       return !!tnum_equals_const(reg1->var_off, val);
-               else if (val < reg1->umin_value || val > reg1->umax_value)
-                       return 0;
-               else if (sval < reg1->smin_value || sval > reg1->smax_value)
-                       return 0;
-               break;
-       case BPF_JNE:
-               if (tnum_is_const(reg1->var_off))
-                       return !tnum_equals_const(reg1->var_off, val);
-               else if (val < reg1->umin_value || val > reg1->umax_value)
-                       return 1;
-               else if (sval < reg1->smin_value || sval > reg1->smax_value)
-                       return 1;
-               break;
-       case BPF_JSET:
-               if ((~reg1->var_off.mask & reg1->var_off.value) & val)
-                       return 1;
-               if (!((reg1->var_off.mask | reg1->var_off.value) & val))
-                       return 0;
-               break;
-       case BPF_JGT:
-               if (reg1->umin_value > val)
-                       return 1;
-               else if (reg1->umax_value <= val)
-                       return 0;
-               break;
-       case BPF_JSGT:
-               if (reg1->smin_value > sval)
-                       return 1;
-               else if (reg1->smax_value <= sval)
-                       return 0;
-               break;
-       case BPF_JLT:
-               if (reg1->umax_value < val)
-                       return 1;
-               else if (reg1->umin_value >= val)
-                       return 0;
-               break;
-       case BPF_JSLT:
-               if (reg1->smax_value < sval)
-                       return 1;
-               else if (reg1->smin_value >= sval)
-                       return 0;
-               break;
-       case BPF_JGE:
-               if (reg1->umin_value >= val)
-                       return 1;
-               else if (reg1->umax_value < val)
-                       return 0;
-               break;
-       case BPF_JSGE:
-               if (reg1->smin_value >= sval)
-                       return 1;
-               else if (reg1->smax_value < sval)
-                       return 0;
-               break;
-       case BPF_JLE:
-               if (reg1->umax_value <= val)
-                       return 1;
-               else if (reg1->umin_value > val)
-                       return 0;
-               break;
-       case BPF_JSLE:
-               if (reg1->smax_value <= sval)
-                       return 1;
-               else if (reg1->smin_value > sval)
+               else if (smin1 > sval)
                        return 0;
                break;
        }
@@ -14477,9 +14397,7 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg
                }
        }
 
-       if (is_jmp32)
-               return is_branch32_taken(reg1, reg2, opcode);
-       return is_branch64_taken(reg1, reg2, opcode);
+       return is_scalar_branch_taken(reg1, reg2, opcode, is_jmp32);
 }
 
 /* Adjusts the register min/max values in the case that the dst_reg is the
@@ -14489,15 +14407,15 @@ static int is_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg
  */
 static void reg_set_min_max(struct bpf_reg_state *true_reg,
                            struct bpf_reg_state *false_reg,
-                           u64 val, u32 val32,
+                           u64 uval, u32 uval32,
                            u8 opcode, bool is_jmp32)
 {
        struct tnum false_32off = tnum_subreg(false_reg->var_off);
        struct tnum false_64off = false_reg->var_off;
        struct tnum true_32off = tnum_subreg(true_reg->var_off);
        struct tnum true_64off = true_reg->var_off;
-       s64 sval = (s64)val;
-       s32 sval32 = (s32)val32;
+       s64 sval = (s64)uval;
+       s32 sval32 = (s32)uval32;
 
        /* If the dst_reg is a pointer, we can't learn anything about its
         * variable offset from the compare (unless src_reg were a pointer into
@@ -14520,49 +14438,49 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg,
         */
        case BPF_JEQ:
                if (is_jmp32) {
-                       __mark_reg32_known(true_reg, val32);
+                       __mark_reg32_known(true_reg, uval32);
                        true_32off = tnum_subreg(true_reg->var_off);
                } else {
-                       ___mark_reg_known(true_reg, val);
+                       ___mark_reg_known(true_reg, uval);
                        true_64off = true_reg->var_off;
                }
                break;
        case BPF_JNE:
                if (is_jmp32) {
-                       __mark_reg32_known(false_reg, val32);
+                       __mark_reg32_known(false_reg, uval32);
                        false_32off = tnum_subreg(false_reg->var_off);
                } else {
-                       ___mark_reg_known(false_reg, val);
+                       ___mark_reg_known(false_reg, uval);
                        false_64off = false_reg->var_off;
                }
                break;
        case BPF_JSET:
                if (is_jmp32) {
-                       false_32off = tnum_and(false_32off, tnum_const(~val32));
-                       if (is_power_of_2(val32))
+                       false_32off = tnum_and(false_32off, tnum_const(~uval32));
+                       if (is_power_of_2(uval32))
                                true_32off = tnum_or(true_32off,
-                                                    tnum_const(val32));
+                                                    tnum_const(uval32));
                } else {
-                       false_64off = tnum_and(false_64off, tnum_const(~val));
-                       if (is_power_of_2(val))
+                       false_64off = tnum_and(false_64off, tnum_const(~uval));
+                       if (is_power_of_2(uval))
                                true_64off = tnum_or(true_64off,
-                                                    tnum_const(val));
+                                                    tnum_const(uval));
                }
                break;
        case BPF_JGE:
        case BPF_JGT:
        {
                if (is_jmp32) {
-                       u32 false_umax = opcode == BPF_JGT ? val32  : val32 - 1;
-                       u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32;
+                       u32 false_umax = opcode == BPF_JGT ? uval32  : uval32 - 1;
+                       u32 true_umin = opcode == BPF_JGT ? uval32 + 1 : uval32;
 
                        false_reg->u32_max_value = min(false_reg->u32_max_value,
                                                       false_umax);
                        true_reg->u32_min_value = max(true_reg->u32_min_value,
                                                      true_umin);
                } else {
-                       u64 false_umax = opcode == BPF_JGT ? val    : val - 1;
-                       u64 true_umin = opcode == BPF_JGT ? val + 1 : val;
+                       u64 false_umax = opcode == BPF_JGT ? uval    : uval - 1;
+                       u64 true_umin = opcode == BPF_JGT ? uval + 1 : uval;
 
                        false_reg->umax_value = min(false_reg->umax_value, false_umax);
                        true_reg->umin_value = max(true_reg->umin_value, true_umin);
@@ -14591,16 +14509,16 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg,
        case BPF_JLT:
        {
                if (is_jmp32) {
-                       u32 false_umin = opcode == BPF_JLT ? val32  : val32 + 1;
-                       u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32;
+                       u32 false_umin = opcode == BPF_JLT ? uval32  : uval32 + 1;
+                       u32 true_umax = opcode == BPF_JLT ? uval32 - 1 : uval32;
 
                        false_reg->u32_min_value = max(false_reg->u32_min_value,
                                                       false_umin);
                        true_reg->u32_max_value = min(true_reg->u32_max_value,
                                                      true_umax);
                } else {
-                       u64 false_umin = opcode == BPF_JLT ? val    : val + 1;
-                       u64 true_umax = opcode == BPF_JLT ? val - 1 : val;
+                       u64 false_umin = opcode == BPF_JLT ? uval    : uval + 1;
+                       u64 true_umax = opcode == BPF_JLT ? uval - 1 : uval;
 
                        false_reg->umin_value = max(false_reg->umin_value, false_umin);
                        true_reg->umax_value = min(true_reg->umax_value, true_umax);
@@ -14649,7 +14567,7 @@ static void reg_set_min_max(struct bpf_reg_state *true_reg,
  */
 static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
                                struct bpf_reg_state *false_reg,
-                               u64 val, u32 val32,
+                               u64 uval, u32 uval32,
                                u8 opcode, bool is_jmp32)
 {
        opcode = flip_opcode(opcode);
@@ -14657,7 +14575,7 @@ static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
         * BPF_JA, can't get here.
         */
        if (opcode)
-               reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32);
+               reg_set_min_max(true_reg, false_reg, uval, uval32, opcode, is_jmp32);
 }
 
 /* Regs are known to be equal, so intersect their min/max/var_off */