Fix behavior around jumps with immediate values > 0x7fffffff in the i…

…nterpreter (#447) * Add test for sign extension in unsigned jump Signed-off-by: Alan Jowett <alan.jowett@microsoft.com> * Fix interpreter to match jit behavior Signed-off-by: Alan Jowett <alan.jowett@microsoft.com> * Make sign extension explicit Signed-off-by: Alan Jowett <alan.jowett@microsoft.com> * PR feedback Signed-off-by: Alan Jowett <alan.jowett@microsoft.com> --------- Signed-off-by: Alan Jowett <alan.jowett@microsoft.com> Co-authored-by: Alan Jowett <alan.jowett@microsoft.com>
iovisor · May 8, 2024 · e8de891 · e8de891
1 parent db3e2d3
commit e8de891
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Showing 2 changed files with 23 additions and 12 deletions.
diff --git a/external/bpf_conformance b/external/bpf_conformance
diff --git a/vm/ubpf_vm.c b/vm/ubpf_vm.c
@@ -293,6 +293,17 @@ i32(uint64_t x)
     return x;
 }
 
+/**
+ * @brief Sign extend immediate value to a signed 64-bit value.
+ *
+ * @param[in] immediate The signed 32-bit immediate value to sign extend.
+ * @return The sign extended 64-bit value.
+ */
+static int64_t i64(int32_t immediate) {
+    return (int64_t)immediate;
+
+}
+
 #define IS_ALIGNED(x, a) (((uintptr_t)(x) & ((a)-1)) == 0)
 
 inline static uint64_t
@@ -685,7 +696,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             pc += inst.offset;
             break;
         case EBPF_OP_JEQ_IMM:
-            if (reg[inst.dst] == inst.imm) {
+            if (reg[inst.dst] == (uint64_t)i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -705,7 +716,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JGT_IMM:
-            if (reg[inst.dst] > u32(inst.imm)) {
+            if (reg[inst.dst] > (uint64_t)i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -725,7 +736,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JGE_IMM:
-            if (reg[inst.dst] >= u32(inst.imm)) {
+            if (reg[inst.dst] >= (uint64_t)i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -745,7 +756,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JLT_IMM:
-            if (reg[inst.dst] < u32(inst.imm)) {
+            if (reg[inst.dst] < (uint64_t)i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -765,7 +776,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JLE_IMM:
-            if (reg[inst.dst] <= u32(inst.imm)) {
+            if (reg[inst.dst] <= (uint64_t)i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -785,7 +796,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JSET_IMM:
-            if (reg[inst.dst] & inst.imm) {
+            if (reg[inst.dst] & (uint64_t)i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -805,7 +816,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JNE_IMM:
-            if (reg[inst.dst] != inst.imm) {
+            if (reg[inst.dst] != (uint64_t)i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -825,7 +836,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JSGT_IMM:
-            if ((int64_t)reg[inst.dst] > inst.imm) {
+            if ((int64_t)reg[inst.dst] > i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -845,7 +856,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JSGE_IMM:
-            if ((int64_t)reg[inst.dst] >= inst.imm) {
+            if ((int64_t)reg[inst.dst] >= i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -865,7 +876,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JSLT_IMM:
-            if ((int64_t)reg[inst.dst] < inst.imm) {
+            if ((int64_t)reg[inst.dst] < i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;
@@ -885,7 +896,7 @@ ubpf_exec(const struct ubpf_vm* vm, void* mem, size_t mem_len, uint64_t* bpf_ret
             }
             break;
         case EBPF_OP_JSLE_IMM:
-            if ((int64_t)reg[inst.dst] <= inst.imm) {
+            if ((int64_t)reg[inst.dst] <= i64(inst.imm)) {
                 pc += inst.offset;
             }
             break;