native features!

kernel/src/kmain.c

@@ -30,6 +30,9 @@ __noreturn void _start(void) {
 	cpuid(&eax, (void*)&s[0], (void*)&s[8], (void*)&s[4]);
 	pr_info("[kernel] CPUID_GETVENDORID: %s\n", s);
 
+	// enable processor extensions
+	detect_processor_features();
+
 	// System init
 	if ((err = gdt_init()) < 0)
 		panic(NULL, "Failed to initalize GDT. (%d)", err);
@@ -43,8 +46,7 @@ __noreturn void _start(void) {
 	if ((err = pag_init()) < 0)
 		panic(NULL, "Failed to initalize Paging. (%d)", err);
 
-	// random number generation
-	rand_init();
+
 	// test random number generation
 	printk("Random number generation test:\n");
 	for (uint8_t i = 0; i <= 16; i++) {

kernel/src/random.c

@@ -25,18 +25,16 @@ uint64_t rand_software() {
 	return LFSR;
 }
 
-void rand_init() {
-	uint32_t eax = 1, ebx = 0, ecx = 0, edx = 0;
-	cpuid(&eax, &ebx, &ecx, &edx);
+void rand_init(bool rdrand, bool rdseed) {
 
 	// check for RDRAND
-	if ((ecx >> 30) & 1) {
+	if (rdrand) {
 		get_random_number = rand_rdrand;
 	} else {
 		printk("[\e[33mWARNING\e[0m] RDRAND not available falling back "
 		       "to software\n");
 		// check for RDSEED
-		if ((ebx >> 18) & 1) {
+		if (rdseed) {
 			asm(".intel_syntax noprefix\n"
 			    "rdseed %0\n"
 			    ".att_syntax prefix\n"

kernel/src/system.c

@@ -1,52 +1,93 @@
+#include "types.h"
 #include <kernel.h>
+#include <random.h>
 #include <system.h>
-
 void cpuid(uint32_t* eax, uint32_t* ebx, uint32_t* ecx, uint32_t* edx) {
-	__asm__ volatile ("cpuid"
-		: "=a"(*eax), "=b"(*ebx), "=c"(*ecx), "=d"(*edx)
-		: "a"(*eax)
-		: "memory");
+	__asm__ volatile("cpuid"
+			 : "=a"(*eax), "=b"(*ebx), "=c"(*ecx), "=d"(*edx)
+			 : "a"(*eax)
+			 : "memory");
 }
 
-void iowait(void) {
-	outb(0x80, 0);
-}
+void iowait(void) { outb(0x80, 0); }
 
 uint8_t inb(uint16_t port) {
 	uint8_t r;
-	__asm__ volatile ("inb %1, %0" : "=a"(r) : "dN"(port));
+	__asm__ volatile("inb %1, %0" : "=a"(r) : "dN"(port));
 	return r;
 }
 
 void outb(uint16_t port, uint8_t data) {
-	__asm__ volatile ("outb %1, %0" :: "dN"(port), "a"(data));
+	__asm__ volatile("outb %1, %0" ::"dN"(port), "a"(data));
 }
 
 uint16_t inw(uint16_t port) {
 	uint16_t r;
-	__asm__ volatile ("inw %1, %0" : "=a"(r) : "dN"(port));
+	__asm__ volatile("inw %1, %0" : "=a"(r) : "dN"(port));
 	return r;
 }
 
 void outw(uint16_t port, uint16_t data) {
-	__asm__ volatile ("outw %1, %0" :: "dN"(port), "a"(data));
+	__asm__ volatile("outw %1, %0" ::"dN"(port), "a"(data));
 }
 
 uint32_t inl(uint16_t port) {
 	uint32_t r;
-	__asm__ volatile ("inl %1, %0" : "=a"(r) : "dN"(port));
+	__asm__ volatile("inl %1, %0" : "=a"(r) : "dN"(port));
 	return r;
 }
 
 void outl(uint16_t port, uint32_t data) {
-	__asm__ volatile ("outl %1, %0" :: "dN"(port), "a"(data));
+	__asm__ volatile("outl %1, %0" ::"dN"(port), "a"(data));
 }
 
-void cli(void) {
-	__asm__ volatile ("cli");
+void cli(void) { __asm__ volatile("cli"); }
+
+void sti(void) { __asm__ volatile("sti"); }
+
+uint8_t (*popcountll)(uint64_t num);
+
+extern uint8_t popcountll_native(uint64_t num);
+asm(".intel_syntax noprefix\n"
+    ".global popcountll_native\n"
+    "popcountll_native:"
+    "   popcnt rax, rdi\n"
+    "   ret\n"
+    ".att_syntax prefix\n");
+
+// I have no idea how this works but it is apperently called SWAR
+uint8_t popcountll_software(uint64_t num) {
+	num = num - ((num >> 1) & 0x5555555555555555ULL);
+	num = (num & 0x3333333333333333ULL) +
+	      ((num >> 2) & 0x3333333333333333ULL);
+	num = (num + (num >> 4)) & 0x0f0f0f0f0f0f0f0fULL;
+	return (int)((num * 0x0101010101010101ULL) >> 56);
 }
 
-void sti(void) {
-	__asm__ volatile ("sti");
-}
+void detect_processor_features() {
+	// leaf 1
+	uint32_t eax = 1, ebx = 0, ecx = 0, edx = 0;
+	cpuid(&eax, &ebx, &ecx, &edx);
 
+	bool rdrand = false;
+	if (ecx & CPUID_FEAT_ECX_RDRAND) {
+		rdrand = true;
+	}
+
+	if (ecx & CPUID_FEAT_ECX_POPCNT) {
+		popcountll = popcountll_native;
+	} else {
+		popcountll = popcountll_software;
+	}
+
+	// leaf 7
+	eax = 7, ebx = 0, ecx = 0, edx = 0;
+	cpuid(&eax, &ebx, &ecx, &edx);
+	bool rdseed = false;
+	if (ebx & CPUID_FEAT_EBX_RDSEED) {
+		rdseed = true;
+	}
+
+	// init rng
+	rand_init(rdrand, rdseed);
+}