8284949: riscv: Add Zero support for the 32-bit RISC-V architecture

Co-authored-by: Junfeng Xie <xiejunfeng3@huawei.com>
Reviewed-by: erikj, stuefe, ihse, yadongwang

make/autoconf/libraries.m4

@@ -144,7 +144,8 @@ AC_DEFUN_ONCE([LIB_SETUP_LIBRARIES],
          test "x$OPENJDK_TARGET_CPU" = xmips ||
          test "x$OPENJDK_TARGET_CPU" = xmipsel ||
          test "x$OPENJDK_TARGET_CPU" = xppc ||
-         test "x$OPENJDK_TARGET_CPU" = xsh); then
+         test "x$OPENJDK_TARGET_CPU" = xsh ||
+         test "x$OPENJDK_TARGET_CPU" = xriscv32); then
       BASIC_JVM_LIBS="$BASIC_JVM_LIBS -latomic"
     fi
   fi

make/autoconf/platform.m4

@@ -126,6 +126,12 @@ AC_DEFUN([PLATFORM_EXTRACT_VARS_FROM_CPU],
       VAR_CPU_BITS=64
       VAR_CPU_ENDIAN=little
       ;;
+    riscv32)
+      VAR_CPU=riscv32
+      VAR_CPU_ARCH=riscv
+      VAR_CPU_BITS=32
+      VAR_CPU_ENDIAN=little
+      ;;
     riscv64)
       VAR_CPU=riscv64
       VAR_CPU_ARCH=riscv
@@ -561,6 +567,8 @@ AC_DEFUN([PLATFORM_SETUP_LEGACY_VARS_HELPER],
     HOTSPOT_$1_CPU_DEFINE=PPC64
   elif test "x$OPENJDK_$1_CPU" = xppc64le; then
     HOTSPOT_$1_CPU_DEFINE=PPC64
+  elif test "x$OPENJDK_$1_CPU" = xriscv32; then
+    HOTSPOT_$1_CPU_DEFINE=RISCV32
   elif test "x$OPENJDK_$1_CPU" = xriscv64; then
     HOTSPOT_$1_CPU_DEFINE=RISCV64
 

src/hotspot/os/linux/os_linux.cpp

@@ -1628,7 +1628,11 @@ void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
     {EM_PARISC,      EM_PARISC,  ELFCLASS32, ELFDATA2MSB, (char*)"PARISC"},
     {EM_68K,         EM_68K,     ELFCLASS32, ELFDATA2MSB, (char*)"M68k"},
     {EM_AARCH64,     EM_AARCH64, ELFCLASS64, ELFDATA2LSB, (char*)"AARCH64"},
-    {EM_RISCV,       EM_RISCV,   ELFCLASS64, ELFDATA2LSB, (char*)"RISC-V"},
+#ifdef _LP64
+    {EM_RISCV,       EM_RISCV,   ELFCLASS64, ELFDATA2LSB, (char*)"RISCV64"},
+#else
+    {EM_RISCV,       EM_RISCV,   ELFCLASS32, ELFDATA2LSB, (char*)"RISCV32"},
+#endif
     {EM_LOONGARCH,   EM_LOONGARCH, ELFCLASS64, ELFDATA2LSB, (char*)"LoongArch"},
   };
 
@@ -2476,7 +2480,7 @@ void os::get_summary_cpu_info(char* cpuinfo, size_t length) {
 #elif defined(PPC)
   strncpy(cpuinfo, "PPC64", length);
 #elif defined(RISCV)
-  strncpy(cpuinfo, "RISCV64", length);
+  strncpy(cpuinfo, LP64_ONLY("RISCV64") NOT_LP64("RISCV32"), length);
 #elif defined(S390)
   strncpy(cpuinfo, "S390", length);
 #elif defined(SPARC)

src/hotspot/os/linux/waitBarrier_linux.cpp

@@ -38,6 +38,13 @@
 
 #define guarantee_with_errno(cond, msg) check_with_errno(guarantee, cond, msg)
 
+// 32-bit RISC-V has no SYS_futex syscall.
+#ifdef RISCV32
+  #if !defined(SYS_futex) && defined(SYS_futex_time64)
+    #define SYS_futex SYS_futex_time64
+  #endif
+#endif
+
 static int futex(volatile int *addr, int futex_op, int op_arg) {
   return syscall(SYS_futex, addr, futex_op, op_arg, NULL, NULL, 0);
 }