hurd: Implement prefer_map_32bit_exec tunable

This makes the prefer_map_32bit_exec tunable no longer Linux-specific.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230423215526.346009-4-bugaevc@gmail.com>

sysdeps/mach/hurd/dl-sysdep.c

@@ -462,6 +462,11 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset)
   if (prot & PROT_EXEC)
     vmprot |= VM_PROT_EXECUTE;
 
+#ifdef __LP64__
+  if ((addr == NULL) && (prot & PROT_EXEC)
+      && HAS_ARCH_FEATURE (Prefer_MAP_32BIT_EXEC))
+    flags |= MAP_32BIT;
+#endif
   mask = (flags & MAP_32BIT) ? ~(vm_address_t) 0x7FFFFFFF : 0;
 
   if (flags & MAP_ANON)

sysdeps/mach/hurd/mmap.c

@@ -18,6 +18,7 @@
 #include <sys/types.h>
 #include <sys/mman.h>
 #include <errno.h>
+#include <ldsodefs.h>
 #include <hurd.h>
 #include <hurd/fd.h>
 
@@ -55,6 +56,11 @@ __mmap (void *addr, size_t len, int prot, int flags, int fd, off_t offset)
 
   copy = ! (flags & MAP_SHARED);
 
+#ifdef __LP64__
+  if ((addr == NULL) && (prot & PROT_EXEC)
+      && HAS_ARCH_FEATURE (Prefer_MAP_32BIT_EXEC))
+    flags |= MAP_32BIT;
+#endif
   mask = (flags & MAP_32BIT) ? ~(vm_address_t) 0x7FFFFFFF : 0;
 
   switch (flags & MAP_TYPE)

sysdeps/unix/sysv/linux/x86_64/64/Makefile

@@ -1,25 +1,2 @@
 # The default ABI is 64.
 default-abi := 64
-
-ifeq ($(subdir),elf)
-
-tests-map-32bit = \
-  tst-map-32bit-1a \
-  tst-map-32bit-1b \
-# tests-map-32bit
-tst-map-32bit-1a-no-pie = yes
-tst-map-32bit-1b-no-pie = yes
-tests += $(tests-map-32bit)
-
-modules-map-32bit = \
-  tst-map-32bit-mod \
-# modules-map-32bit
-modules-names += $(modules-map-32bit)
-
-$(objpfx)tst-map-32bit-mod.so: $(libsupport)
-tst-map-32bit-1a-ENV = LD_PREFER_MAP_32BIT_EXEC=1
-$(objpfx)tst-map-32bit-1a: $(objpfx)tst-map-32bit-mod.so
-tst-map-32bit-1b-ENV = GLIBC_TUNABLES=glibc.cpu.prefer_map_32bit_exec=1
-$(objpfx)tst-map-32bit-1b: $(objpfx)tst-map-32bit-mod.so
-
-endif

sysdeps/x86_64/64/Makefile

@@ -0,0 +1,22 @@
+ifeq ($(subdir),elf)
+
+tests-map-32bit = \
+  tst-map-32bit-1a \
+  tst-map-32bit-1b \
+# tests-map-32bit
+tst-map-32bit-1a-no-pie = yes
+tst-map-32bit-1b-no-pie = yes
+tests += $(tests-map-32bit)
+
+modules-map-32bit = \
+  tst-map-32bit-mod \
+# modules-map-32bit
+modules-names += $(modules-map-32bit)
+
+$(objpfx)tst-map-32bit-mod.so: $(libsupport)
+tst-map-32bit-1a-ENV = LD_PREFER_MAP_32BIT_EXEC=1
+$(objpfx)tst-map-32bit-1a: $(objpfx)tst-map-32bit-mod.so
+tst-map-32bit-1b-ENV = GLIBC_TUNABLES=glibc.cpu.prefer_map_32bit_exec=1
+$(objpfx)tst-map-32bit-1b: $(objpfx)tst-map-32bit-mod.so
+
+endif