[z/OS] Implement shared memory handling for JIT (#89933)

Fix 'use of undeclared identifier' build errors for shm_ functions on
z/OS by implementing the functionality using shmget(), shmat(), and
shmdt(). Use the BLAKE3 hash to map the name of the shared memory to a
key.

---------

Co-authored-by: Kai Nacke <[email protected]>

Author: fanbo-meng

llvm/lib/ExecutionEngine/Orc/MemoryMapper.cpp

@@ -16,6 +16,10 @@
 #if defined(LLVM_ON_UNIX) && !defined(__ANDROID__)
 #include <fcntl.h>
 #include <sys/mman.h>
+#if defined(__MVS__)
+#include "llvm/Support/BLAKE3.h"
+#include <sys/shm.h>
+#endif
 #include <unistd.h>
 #elif defined(_WIN32)
 #include <windows.h>
@@ -239,6 +243,24 @@ void SharedMemoryMapper::reserve(size_t NumBytes,
 
 #if defined(LLVM_ON_UNIX)
 
+#if defined(__MVS__)
+        ArrayRef<uint8_t> Data(
+            reinterpret_cast<const uint8_t *>(SharedMemoryName.c_str()),
+            SharedMemoryName.size());
+        auto HashedName = BLAKE3::hash<sizeof(key_t)>(Data);
+        key_t Key = *reinterpret_cast<key_t *>(HashedName.data());
+        int SharedMemoryId =
+            shmget(Key, NumBytes, IPC_CREAT | __IPC_SHAREAS | 0700);
+        if (SharedMemoryId < 0) {
+          return OnReserved(errorCodeToError(
+              std::error_code(errno, std::generic_category())));
+        }
+        LocalAddr = shmat(SharedMemoryId, nullptr, 0);
+        if (LocalAddr == reinterpret_cast<void *>(-1)) {
+          return OnReserved(errorCodeToError(
+              std::error_code(errno, std::generic_category())));
+        }
+#else
         int SharedMemoryFile = shm_open(SharedMemoryName.c_str(), O_RDWR, 0700);
         if (SharedMemoryFile < 0) {
           return OnReserved(errorCodeToError(errnoAsErrorCode()));
@@ -254,6 +276,7 @@ void SharedMemoryMapper::reserve(size_t NumBytes,
         }
 
         close(SharedMemoryFile);
+#endif
 
 #elif defined(_WIN32)
 
@@ -373,8 +396,13 @@ void SharedMemoryMapper::release(ArrayRef<ExecutorAddr> Bases,
 
 #if defined(LLVM_ON_UNIX)
 
+#if defined(__MVS__)
+      if (shmdt(Reservations[Base].LocalAddr) < 0)
+        Err = joinErrors(std::move(Err), errorCodeToError(errnoAsErrorCode()));
+#else
       if (munmap(Reservations[Base].LocalAddr, Reservations[Base].Size) != 0)
         Err = joinErrors(std::move(Err), errorCodeToError(errnoAsErrorCode()));
+#endif
 
 #elif defined(_WIN32)
 
@@ -415,7 +443,11 @@ SharedMemoryMapper::~SharedMemoryMapper() {
 
 #if defined(LLVM_ON_UNIX) && !defined(__ANDROID__)
 
+#if defined(__MVS__)
+    shmdt(R.second.LocalAddr);
+#else
     munmap(R.second.LocalAddr, R.second.Size);
+#endif
 
 #elif defined(_WIN32)
 

llvm/lib/ExecutionEngine/Orc/TargetProcess/ExecutorSharedMemoryMapperService.cpp

@@ -18,6 +18,10 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/mman.h>
+#if defined(__MVS__)
+#include "llvm/Support/BLAKE3.h"
+#include <sys/shm.h>
+#endif
 #include <unistd.h>
 #endif
 
@@ -59,6 +63,21 @@ ExecutorSharedMemoryMapperService::reserve(uint64_t Size) {
     SharedMemoryName = SharedMemoryNameStream.str();
   }
 
+#if defined(__MVS__)
+  ArrayRef<uint8_t> Data(
+      reinterpret_cast<const uint8_t *>(SharedMemoryName.c_str()),
+      SharedMemoryName.size());
+  auto HashedName = BLAKE3::hash<sizeof(key_t)>(Data);
+  key_t Key = *reinterpret_cast<key_t *>(HashedName.data());
+  int SharedMemoryId =
+      shmget(Key, Size, IPC_CREAT | IPC_EXCL | __IPC_SHAREAS | 0700);
+  if (SharedMemoryId < 0)
+    return errorCodeToError(errnoAsErrorCode());
+
+  void *Addr = shmat(SharedMemoryId, nullptr, 0);
+  if (Addr == reinterpret_cast<void *>(-1))
+    return errorCodeToError(errnoAsErrorCode());
+#else
   int SharedMemoryFile =
       shm_open(SharedMemoryName.c_str(), O_RDWR | O_CREAT | O_EXCL, 0700);
   if (SharedMemoryFile < 0)
@@ -73,6 +92,7 @@ ExecutorSharedMemoryMapperService::reserve(uint64_t Size) {
     return errorCodeToError(errnoAsErrorCode());
 
   close(SharedMemoryFile);
+#endif
 
 #elif defined(_WIN32)
 
@@ -131,6 +151,9 @@ Expected<ExecutorAddr> ExecutorSharedMemoryMapperService::initialize(
 
 #if defined(LLVM_ON_UNIX)
 
+#if defined(__MVS__)
+      // TODO Is it possible to change the protection level?
+#else
     int NativeProt = 0;
     if ((Segment.RAG.Prot & MemProt::Read) == MemProt::Read)
       NativeProt |= PROT_READ;
@@ -141,6 +164,7 @@ Expected<ExecutorAddr> ExecutorSharedMemoryMapperService::initialize(
 
     if (mprotect(Segment.Addr.toPtr<void *>(), Segment.Size, NativeProt))
       return errorCodeToError(errnoAsErrorCode());
+#endif
 
 #elif defined(_WIN32)
 
@@ -239,8 +263,15 @@ Error ExecutorSharedMemoryMapperService::release(
 
 #if defined(LLVM_ON_UNIX)
 
+#if defined(__MVS__)
+    (void)Size;
+
+    if (shmdt(Base.toPtr<void *>()) < 0)
+      Err = joinErrors(std::move(Err), errorCodeToError(errnoAsErrorCode()));
+#else
     if (munmap(Base.toPtr<void *>(), Size) != 0)
       Err = joinErrors(std::move(Err), errorCodeToError(errnoAsErrorCode()));
+#endif
 
 #elif defined(_WIN32)
     (void)Size;