w+x not working

#define _BSD_SOURCE  // MAP_ANONYMOUS
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <sys/mman.h>

#define PAGE_SIZE 4096

struct asmbuf {
    uint8_t code[PAGE_SIZE - sizeof(uint64_t)];
    uint64_t count;
};
struct asmbuf *
asmbuf_create(void)
{
    int prot = PROT_READ | PROT_WRITE | PROT_EXEC;
    int flags = MAP_ANONYMOUS | MAP_PRIVATE;
    return mmap(NULL, PAGE_SIZE, prot, flags, -1, 0);
}

void
asmbuf_free(struct asmbuf *buf)
{
    munmap(buf, PAGE_SIZE);
}

void
asmbuf_finalize(struct asmbuf *buf)
{
	int i=0;
    mprotect(buf, PAGE_SIZE, PROT_READ|PROT_EXEC);
}

void
asm_insbuf(struct asmbuf *buf, int size, uint64_t ins)
{
  for (int i = 0;i<size; i++) {
        buf->code[buf->count++] = (ins>> (i * 8)) & 0xff;
}
}

void
asmbuf_immediate(struct asmbuf *buf, int size, const void *value)
{
    memcpy(buf->code + buf->count, value, size);
    buf->count += size;
}

int main()
{
    /* Compile input program */
    struct asmbuf *buf = asmbuf_create();

asm_insbuf(buf,4,0xd10043ff);
asm_insbuf(buf,4,0x2a1f03e0);
asm_insbuf(buf,4,0xb80ff3ff);
asm_insbuf(buf,4,0x910043ff);
//asm_insbuf(buf,4,0xd2800040); 
asm_insbuf(buf,4,0xd2800088);
asm_insbuf(buf,4,0xd4000001);
asm_insbuf(buf,4,0xd65f03c0); 
/*

       0: d10043ff     	sub	sp, sp, #0x10
       4: 2a1f03e0     	mov	w0, wzr
       8: b9000fff     	str	wzr, [sp, #0xc]
       c: 910043ff     	add	sp, sp, #0x10
*/
 int(*test)(int,char*,int) = (void *)buf->code;
//asmbuf_finalize(buf);
	test(11,"helloworld\n",11);


    asmbuf_free(buf);
    return 0;
}

working w^x

#define _BSD_SOURCE  // MAP_ANONYMOUS
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <sys/mman.h>

#define PAGE_SIZE 4096

struct asmbuf {
    uint8_t code[PAGE_SIZE - sizeof(uint64_t)];
    uint64_t count;
};

struct asmbuf *
asmbuf_create(void)
{
    int prot = PROT_READ | PROT_WRITE;
    int flags = MAP_ANONYMOUS | MAP_PRIVATE;
    return mmap(NULL, PAGE_SIZE, prot, flags, -1, 0);
}

void
asmbuf_free(struct asmbuf *buf)
{
    munmap(buf, PAGE_SIZE);
}

void
asmbuf_finalize(struct asmbuf *buf)
{
	int i=0;
    mprotect(buf, PAGE_SIZE, PROT_READ|PROT_EXEC);
}

void
asm_insbuf(struct asmbuf *buf, int size, uint64_t ins)
{
  for (int i = 0;i<size; i++) {
        buf->code[buf->count++] = (ins>> (i * 8)) & 0xff;
}
}

void
asmbuf_immediate(struct asmbuf *buf, int size, const void *value)
{
    memcpy(buf->code + buf->count, value, size);
    buf->count += size;
}

int main()
{
    /* Compile input program */
    struct asmbuf *buf = asmbuf_create();

asm_insbuf(buf,4,0xd10043ff);
asm_insbuf(buf,4,0x2a1f03e0);
asm_insbuf(buf,4,0xb80ff3ff);
asm_insbuf(buf,4,0x910043ff);
//asm_insbuf(buf,4,0xd2800040); 
asm_insbuf(buf,4,0xd2800088);
asm_insbuf(buf,4,0xd4000001);
asm_insbuf(buf,4,0xd65f03c0); 
/*

       0: d10043ff     	sub	sp, sp, #0x10
       4: 2a1f03e0     	mov	w0, wzr
       8: b9000fff     	str	wzr, [sp, #0xc]
       c: 910043ff     	add	sp, sp, #0x10
*/
 int(*test)(int,char*,int) = (void *)buf->code;
asmbuf_finalize(buf);
	test(11,"helloworld\n",11);


    asmbuf_free(buf);
    return 0;
}