linux-user, x86_64, i386: cleanup TARGET_NR_arch_prctl

Define do_arch_prctl() for i386 and x86_64, but return -TARGET_ENOSYS
for i386.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20200310103403.3284090-14-laurent@vivier.eu>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/linux-user/i386/target_cpu.h b/linux-user/i386/target_cpu.h
index 0b44530..2207d24 100644
--- a/linux-user/i386/target_cpu.h
+++ b/linux-user/i386/target_cpu.h
@@ -33,6 +33,8 @@
 {
 }
 
+abi_long do_arch_prctl(CPUX86State *env, int code, abi_ulong addr);
+
 #if defined(TARGET_ABI32)
 abi_long do_set_thread_area(CPUX86State *env, abi_ulong ptr);
 
@@ -42,8 +44,6 @@
     cpu_x86_load_seg(env, R_GS, env->segs[R_GS].selector);
 }
 #else
-abi_long do_arch_prctl(CPUX86State *env, int code, abi_ulong addr);
-
 static inline void cpu_set_tls(CPUX86State *env, target_ulong newtls)
 {
     do_arch_prctl(env, TARGET_ARCH_SET_FS, newtls);
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 6107834..35f4146 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5545,6 +5545,10 @@
     { 0, 0, 0, 0 }
 };
 
+/*
+ * NOTE: TARGET_ABI32 is defined for TARGET_I386 (but not for TARGET_X86_64)
+ *       TARGET_I386 is defined if TARGET_X86_64 is defined
+ */
 #if defined(TARGET_I386)
 
 /* NOTE: there is really one LDT for all the threads */
@@ -5684,7 +5688,7 @@
     return ret;
 }
 
-#if defined(TARGET_I386) && defined(TARGET_ABI32)
+#if defined(TARGET_ABI32)
 abi_long do_set_thread_area(CPUX86State *env, abi_ulong ptr)
 {
     uint64_t *gdt_table = g2h(env->gdt.base);
@@ -5816,9 +5820,12 @@
     unlock_user_struct(target_ldt_info, ptr, 1);
     return 0;
 }
-#endif /* TARGET_I386 && TARGET_ABI32 */
 
-#ifndef TARGET_ABI32
+abi_long do_arch_prctl(CPUX86State *env, int code, abi_ulong addr)
+{
+    return -ENOSYS;
+}
+#else
 abi_long do_arch_prctl(CPUX86State *env, int code, abi_ulong addr)
 {
     abi_long ret = 0;
@@ -5851,7 +5858,7 @@
     }
     return ret;
 }
-#endif
+#endif /* defined(TARGET_ABI32 */
 
 #endif /* defined(TARGET_I386) */
 
@@ -10321,11 +10328,7 @@
         break;
 #ifdef TARGET_NR_arch_prctl
     case TARGET_NR_arch_prctl:
-#if defined(TARGET_I386) && !defined(TARGET_ABI32)
         return do_arch_prctl(cpu_env, arg1, arg2);
-#else
-#error unreachable
-#endif
 #endif
 #ifdef TARGET_NR_pread64
     case TARGET_NR_pread64: