user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/tests/rtld/ifunc/lib.c

@@ -0,0 +1,35 @@
+#include <stdint.h>
+
+static uint64_t foo_impl(void) {
+    return 420;
+}
+
+#if defined(__riscv) && !defined(USE_HOST_LIBC)
+#include <sys/hwprobe.h>
+#elif defined(__riscv)
+int __riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count, size_t cpusetsize, cpu_set_t *cpus,
+	unsigned int flags) __attribute__((access(read_write, 1, 2)));
+
+typedef int (*__riscv_hwprobe_t)(struct riscv_hwprobe *pairs, size_t pair_count,
+	size_t cpusetsize, cpu_set_t *cpus, unsigned int flags) __attribute__((access(read_write, 1, 2)));
+#endif
+
+#if defined(__riscv)
+#include <stdlib.h>
+
+static uint64_t (*foo_resolver(long long, __riscv_hwprobe_t hwprobe, void *))(void) {
+	if (!hwprobe)
+		return NULL;
+	struct riscv_hwprobe pairs[1] = {
+		{ .key = 4, .value = 0 }
+	};
+	hwprobe(pairs, 1, 0, 0, 0);
+	return foo_impl;
+}
+#else
+static uint64_t (*foo_resolver(void))(void) {
+    return foo_impl;
+}
+#endif
+
+uint64_t foo(void) __attribute__((ifunc("foo_resolver")));

user/include/mlibc/tests/rtld/ifunc/meson.build

@@ -0,0 +1,5 @@
+libifunc_test = shared_library('ifunc-test', 'lib.c', dependencies: libc_dep)
+test_link_with = [libifunc_test]
+
+libifunc_test_native = shared_library('native-ifunc-test', 'lib.c', native: true)
+test_native_link_with = [libifunc_test_native]

user/include/mlibc/tests/rtld/ifunc/test.c

@@ -0,0 +1,10 @@
+#include <assert.h>
+
+int foo(void);
+
+int main(void) {
+	int res = foo();
+	assert(res == 420);
+
+	return 0;
+}