MAISTRA-2648: WASM fix for s390x

Fixes WASM on s390x https://issues.redhat.com/browse/MAISTRA-2648
The permanent fixes are:
proxy-wasm/proxy-wasm-cpp-host#198
proxy-wasm/proxy-wasm-cpp-host#282

Author: knm3000

include/proxy-wasm/exports.h

@@ -44,12 +44,13 @@ template <typename Pairs> size_t pairsSize(const Pairs &result) {
 
 template <typename Pairs> void marshalPairs(const Pairs &result, char *buffer) {
   char *b = buffer;
-  *reinterpret_cast<uint32_t *>(b) = result.size();
+  bool reverse = "null" != contextOrEffectiveContext()->wasmVm()->runtime();
+  *reinterpret_cast<uint32_t *>(b) = reverse ? htowasm(result.size()) : result.size();
   b += sizeof(uint32_t);
   for (auto &p : result) {
-    *reinterpret_cast<uint32_t *>(b) = p.first.size();
+    *reinterpret_cast<uint32_t *>(b) = reverse ? htowasm(p.first.size()) : p.first.size();
     b += sizeof(uint32_t);
-    *reinterpret_cast<uint32_t *>(b) = p.second.size();
+    *reinterpret_cast<uint32_t *>(b) = reverse ? htowasm(p.second.size()) : p.second.size();
     b += sizeof(uint32_t);
   }
   for (auto &p : result) {

include/proxy-wasm/word.h

@@ -21,6 +21,16 @@ namespace proxy_wasm {
 
 #include "proxy_wasm_common.h"
 
+// Use byteswap functions only when compiling for big-endian platforms.
+#if defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) &&                                    \
+    __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define htowasm(x) __builtin_bswap32(x)
+#define wasmtoh(x) __builtin_bswap32(x)
+#else
+#define htowasm(x) (x)
+#define wasmtoh(x) (x)
+#endif
+
 // Represents a Wasm-native word-sized datum. On 32-bit VMs, the high bits are always zero.
 // The Wasm/VM API treats all bits as significant.
 struct Word {

src/exports.cc

@@ -46,16 +46,22 @@ Pairs toPairs(std::string_view buffer) {
   if (buffer.size() < sizeof(uint32_t)) {
     return {};
   }
-  auto size = *reinterpret_cast<const uint32_t *>(b);
+  bool reverse = "null" != contextOrEffectiveContext()->wasmVm()->runtime();
+  auto size = reverse ? wasmtoh(*reinterpret_cast<const uint32_t *>(b))
+                      : *reinterpret_cast<const uint32_t *>(b);
   b += sizeof(uint32_t);
   if (sizeof(uint32_t) + size * 2 * sizeof(uint32_t) > buffer.size()) {
     return {};
   }
   result.resize(size);
   for (uint32_t i = 0; i < size; i++) {
-    result[i].first = std::string_view(nullptr, *reinterpret_cast<const uint32_t *>(b));
+    result[i].first =
+        std::string_view(nullptr, reverse ? wasmtoh(*reinterpret_cast<const uint32_t *>(b))
+                                          : *reinterpret_cast<const uint32_t *>(b));
     b += sizeof(uint32_t);
-    result[i].second = std::string_view(nullptr, *reinterpret_cast<const uint32_t *>(b));
+    result[i].second =
+        std::string_view(nullptr, reverse ? wasmtoh(*reinterpret_cast<const uint32_t *>(b))
+                                          : *reinterpret_cast<const uint32_t *>(b));
     b += sizeof(uint32_t);
   }
   for (auto &p : result) {
@@ -652,6 +658,7 @@ Word grpc_send(Word token, Word message_ptr, Word message_size, Word end_stream)
 // logs.
 Word writevImpl(Word fd, Word iovs, Word iovs_len, Word *nwritten_ptr) {
   auto context = contextOrEffectiveContext();
+  bool reverse = "null" != context->wasmVm()->runtime();
 
   // Read syscall args.
   uint64_t log_level;
@@ -675,7 +682,9 @@ Word writevImpl(Word fd, Word iovs, Word iovs_len, Word *nwritten_ptr) {
     }
     const uint32_t *iovec = reinterpret_cast<const uint32_t *>(memslice.value().data());
     if (iovec[1] /* buf_len */) {
-      memslice = context->wasmVm()->getMemory(iovec[0] /* buf */, iovec[1] /* buf_len */);
+      auto iovec0 = reverse ? wasmtoh(iovec[0]) : iovec[0];
+      auto iovec1 = reverse ? wasmtoh(iovec[1]) : iovec[1];
+      memslice = context->wasmVm()->getMemory(iovec0 /* buf */, iovec1 /* buf_len */);
       if (!memslice) {
         return 21; // __WASI_EFAULT
       }

src/signature_util.cc

@@ -83,6 +83,7 @@ bool SignatureUtil::verifySignature(std::string_view bytecode, std::string &mess
 
   uint32_t alg_id;
   std::memcpy(&alg_id, payload.data(), sizeof(uint32_t));
+  alg_id = wasmtoh(alg_id);
 
   if (alg_id != 2) {
     message = "Signature has a wrong alg_id (want: 2, is: " + std::to_string(alg_id) + ")";

src/v8/v8.cc

@@ -432,7 +432,7 @@ bool V8::getWord(uint64_t pointer, Word *word) {
   }
   uint32_t word32;
   ::memcpy(&word32, memory_->data() + pointer, size);
-  word->u64_ = word32;
+  word->u64_ = wasmtoh(word32);
   return true;
 }
 
@@ -441,7 +441,7 @@ bool V8::setWord(uint64_t pointer, Word word) {
   if (pointer + size > memory_->data_size()) {
     return false;
   }
-  uint32_t word32 = word.u32();
+  uint32_t word32 = htowasm(word.u32());
   ::memcpy(memory_->data() + pointer, &word32, size);
   return true;
 }

src/wamr/wamr.cc

@@ -339,7 +339,7 @@ bool Wamr::getWord(uint64_t pointer, Word *word) {
 
   uint32_t word32;
   ::memcpy(&word32, wasm_memory_data(memory_.get()) + pointer, size);
-  word->u64_ = word32;
+  word->u64_ = wasmtoh(word32);
   return true;
 }
 
@@ -348,7 +348,7 @@ bool Wamr::setWord(uint64_t pointer, Word word) {
   if (pointer + size > wasm_memory_data_size(memory_.get())) {
     return false;
   }
-  uint32_t word32 = word.u32();
+  uint32_t word32 = htowasm(word.u32());
   ::memcpy(wasm_memory_data(memory_.get()) + pointer, &word32, size);
   return true;
 }

src/wasmtime/wasmtime.cc

@@ -354,7 +354,7 @@ bool Wasmtime::getWord(uint64_t pointer, Word *word) {
 
   uint32_t word32;
   ::memcpy(&word32, wasm_memory_data(memory_.get()) + pointer, size);
-  word->u64_ = word32;
+  word->u64_ = wasmtoh(word32);
   return true;
 }
 
@@ -363,7 +363,7 @@ bool Wasmtime::setWord(uint64_t pointer, Word word) {
   if (pointer + size > wasm_memory_data_size(memory_.get())) {
     return false;
   }
-  uint32_t word32 = word.u32();
+  uint32_t word32 = htowasm(word.u32());
   ::memcpy(wasm_memory_data(memory_.get()) + pointer, &word32, size);
   return true;
 }

src/wavm/wavm.cc

@@ -344,12 +344,12 @@ bool Wavm::getWord(uint64_t pointer, Word *data) {
   auto p = reinterpret_cast<char *>(memory_base_ + pointer);
   uint32_t data32;
   memcpy(&data32, p, sizeof(uint32_t));
-  data->u64_ = data32;
+  data->u64_ = wasmtoh(data32);
   return true;
 }
 
 bool Wavm::setWord(uint64_t pointer, Word data) {
-  uint32_t data32 = data.u32();
+  uint32_t data32 = htowasm(data.u32());
   return setMemory(pointer, sizeof(uint32_t), &data32);
 }
 

test/runtime_test.cc

@@ -56,7 +56,7 @@ TEST_P(TestVM, Memory) {
   ASSERT_TRUE(vm_->getWord(0x2000, &word));
   ASSERT_EQ(100, word.u64_);
 
-  int32_t data[2] = {-1, 200};
+  uint32_t data[2] = {htowasm(static_cast<uint32_t>(-1)), htowasm(200)};
   ASSERT_TRUE(vm_->setMemory(0x200, sizeof(int32_t) * 2, static_cast<void *>(data)));
   ASSERT_TRUE(vm_->getWord(0x200, &word));
   ASSERT_EQ(-1, static_cast<int32_t>(word.u64_));