mango/kernel/percpu.c

#include <socks/percpu.h>
#include <socks/cpu.h>
#include <socks/vm.h>
#include <stdint.h>
#include <stddef.h>

extern char __percpu_start[];
extern char __percpu_end[];

static void *percpu_buffer = NULL;
static size_t percpu_stride = 0;

extern kern_status_t init_per_cpu_areas(void)
{
	unsigned int last_cpu = cpu_get_highest_available() + 1;

	percpu_stride = (uintptr_t)__percpu_end - (uintptr_t)__percpu_start;
	if (percpu_stride & 0x7) {
		percpu_stride &= ~0x7;
		percpu_stride += 0x8;
	}

	percpu_buffer = kmalloc(last_cpu * percpu_stride, 0);
	return KERN_OK;
}

extern void *__percpu_get(unsigned int cpu, void *var)
{
	uintptr_t pvar = (uintptr_t)var;
	uintptr_t percpu_start = (uintptr_t)__percpu_start;
	uintptr_t percpu_end = (uintptr_t)__percpu_end;

	if (pvar < percpu_start || pvar >= percpu_end) {
		return NULL;
	}

	size_t var_offset = pvar - percpu_start;

	return (char *)percpu_buffer + (cpu * percpu_stride) + var_offset;
}