8199138: Add RISC-V support to Zero

Reviewed-by: erikj, stuefe

make/autoconf/platform.m4

@@ -120,6 +120,12 @@ AC_DEFUN([PLATFORM_EXTRACT_VARS_FROM_CPU],
       VAR_CPU_BITS=64
       VAR_CPU_ENDIAN=little
       ;;
+    riscv64)
+      VAR_CPU=riscv64
+      VAR_CPU_ARCH=riscv
+      VAR_CPU_BITS=64
+      VAR_CPU_ENDIAN=little
+      ;;
     s390)
       VAR_CPU=s390
       VAR_CPU_ARCH=s390
@@ -485,6 +491,8 @@ AC_DEFUN([PLATFORM_SETUP_LEGACY_VARS_HELPER],
     HOTSPOT_$1_CPU_DEFINE=S390
   elif test "x$OPENJDK_$1_CPU" = xs390x; then
     HOTSPOT_$1_CPU_DEFINE=S390
+  elif test "x$OPENJDK_$1_CPU" = xriscv64; then
+    HOTSPOT_$1_CPU_DEFINE=RISCV
   elif test "x$OPENJDK_$1_CPU" != x; then
     HOTSPOT_$1_CPU_DEFINE=$(echo $OPENJDK_$1_CPU | tr a-z A-Z)
   fi

src/hotspot/os/linux/os_linux.cpp

@@ -1851,6 +1851,9 @@ void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
 #ifndef EM_AARCH64
   #define EM_AARCH64    183               /* ARM AARCH64 */
 #endif
+#ifndef EM_RISCV
+  #define EM_RISCV      243               /* RISC-V */
+#endif
 
   static const arch_t arch_array[]={
     {EM_386,         EM_386,     ELFCLASS32, ELFDATA2LSB, (char*)"IA 32"},
@@ -1877,6 +1880,7 @@ 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"},
   };
 
 #if  (defined IA32)
@@ -1911,9 +1915,11 @@ void * os::dll_load(const char *filename, char *ebuf, int ebuflen) {
   static  Elf32_Half running_arch_code=EM_68K;
 #elif  (defined SH)
   static  Elf32_Half running_arch_code=EM_SH;
+#elif  (defined RISCV)
+  static  Elf32_Half running_arch_code=EM_RISCV;
 #else
     #error Method os::dll_load requires that one of following is defined:\
-        AARCH64, ALPHA, ARM, AMD64, IA32, IA64, M68K, MIPS, MIPSEL, PARISC, __powerpc__, __powerpc64__, S390, SH, __sparc
+        AARCH64, ALPHA, ARM, AMD64, IA32, IA64, M68K, MIPS, MIPSEL, PARISC, __powerpc__, __powerpc64__, RISCV, S390, SH, __sparc
 #endif
 
   // Identify compatibility class for VM's architecture and library's architecture