SMAP Checker

check_smap.c

#include <linux/module.h>
#include <linux/kernel.h>

static int __init smap_check_init(void) {
    unsigned int eax, ebx, ecx, edx;

    eax = 7;
    ecx = 0;
    asm volatile(
        "cpuid"
        : "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
        : "a"(eax), "c"(ecx)
    );

    if (ebx & (1 << 20))
        pr_info("✅ This CPU supports SMAP!\n");
    else
        pr_info("❌ This CPU does NOT support SMAP.\n");

    return 0;
}

static void __exit smap_check_exit(void) {
    pr_info("SMAP check module unloaded.\n");
}

module_init(smap_check_init);
module_exit(smap_check_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Minimal SMAP check kernel module");

Makefile

obj-m += check_smap.o

all:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean