smp: processor wakeup

kernel-src/arch/x86-64/main.c

@@ -58,6 +58,7 @@ void kernel_entry() {
 	timekeeper_init(arch_hpet_ticks, u);
 	arch_apic_timerinit();
 	sched_init();
+	arch_smp_wakeup();
 	vfs_init();
 	tmpfs_init();
 	devfs_init();

kernel-src/arch/x86-64/mmu.c

@@ -177,7 +177,7 @@ void arch_mmu_switch(pagetableptr_t table) {
 	asm volatile("mov %%rax, %%cr3" : : "a"(table));
 }
 
-// hhdm pointer to template to be used for new mappings
+// hhdm pointer to template to be used for new mappings and smp bootup
 static pagetableptr_t template;
 
 pagetableptr_t arch_mmu_newtable() {
@@ -276,6 +276,10 @@ void arch_mmu_init() {
 		}
 	}
 
+	arch_mmu_apswitch();
+}
+
+void arch_mmu_apswitch() {
 	arch_mmu_switch(FROM_HHDM(template));
 	interrupt_register(14, pfisr, NULL, IPL_IGNORE);
 }

kernel-src/arch/x86-64/smp.c

@@ -0,0 +1,70 @@
+#include <limine.h>
+#include <logging.h>
+#include <kernel/pmm.h>
+#include <arch/cpu.h>
+#include <arch/gdt.h>
+#include <arch/idt.h>
+#include <kernel/cmdline.h>
+
+static volatile struct limine_smp_request smprequest = {
+	.id = LIMINE_SMP_REQUEST
+};
+
+// set to 1 because of the bsp
+size_t cpusawake = 1;
+
+static void cpuwakeup(struct limine_smp_info *info) {
+	cpu_set((cpu_t *)info->extra_argument);
+
+	arch_gdt_reload();
+	arch_idt_reload();
+	dpc_init();
+	arch_mmu_apswitch();
+
+	cpu_initstate();
+	arch_apic_timerinit();
+
+	__atomic_add_fetch(&cpusawake, 1, __ATOMIC_SEQ_CST);
+	// TODO let other processors run threads and applications
+	for (;;) CPU_HALT();
+}
+
+// if the nosmp argument is given to the kernel, this is what the APs will jump to
+static void cpuwakeuphalt(struct limine_smp_info *info) {
+	for (;;) CPU_HALT();
+}
+
+void arch_smp_wakeup() {
+	struct limine_smp_response *response = smprequest.response;
+	if (response == NULL) {
+		// TODO try to detect the other processors manually
+		printf("smp: limine smp request response not present\n");
+		return;
+	}
+
+	printf("smp: %d processor%s\n", response->cpu_count, response->cpu_count > 1 ? "s" : "");
+
+	// use physical pages so the other cpus have it on the hhdm
+	cpu_t *apcpu = pmm_alloc(ROUND_UP(sizeof(cpu_t) * response->cpu_count, PAGE_SIZE) / PAGE_SIZE, PMM_SECTION_DEFAULT);
+	__assert(apcpu);
+	apcpu = MAKE_HHDM(apcpu);
+
+	void (*wakeupfn)(struct limine_smp_info *) = cmdline_get("nosmp") ? cpuwakeuphalt : cpuwakeup;
+
+	// make the other processors jump to cpuwakeup()
+	for (int i = 0; i < response->cpu_count; ++i) {
+		// skip the bootstrap processor
+		if (response->cpus[i]->lapic_id == response->bsp_lapic_id)
+			continue;
+
+		response->cpus[i]->extra_argument = (uint64_t)&apcpu[i];
+
+		__atomic_store_n(&response->cpus[i]->goto_address, wakeupfn, __ATOMIC_SEQ_CST);
+	}
+
+	// wait for other cpus to boot up
+	if (wakeupfn == cpuwakeup)
+		while (__atomic_load_n(&cpusawake, __ATOMIC_SEQ_CST) != response->cpu_count) asm("pause");
+
+	printf("smp: awoke other processors\n");
+}

kernel-src/include/x86-64/arch/mmu.h

@@ -34,5 +34,6 @@ bool arch_mmu_ispresent(pagetableptr_t table, void *vaddr);
 bool arch_mmu_iswritable(pagetableptr_t table, void *vaddr);
 pagetableptr_t arch_mmu_newtable();
 void arch_mmu_init();
+void arch_mmu_apswitch();
 
 #endif

kernel-src/include/x86-64/arch/smp.h

@@ -0,0 +1,6 @@
+#ifndef _SMP_H
+#define _SMP_H
+
+void arch_smp_wakeup();
+
+#endif