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#include "proc/context.h"
#include "proc/kthread.h"
#include <main/cpuid.h>
#include "main/apic.h"
#include "main/gdt.h"
typedef struct context_initial_func_args
{
context_func_t func;
long arg1;
void *arg2;
} packed context_initial_func_args_t;
static void __context_thread_initial_func(context_initial_func_args_t args)
{
preemption_reset();
apic_setipl(IPL_LOW);
intr_enable();
void *result = (args.func)(args.arg1, args.arg2);
kthread_exit(result);
panic("\nReturned from kthread_exit.\n");
}
void context_setup_raw(context_t *c, void (*func)(), void *kstack,
size_t kstacksz, pml4_t *pml4)
{
KASSERT(NULL != pml4);
KASSERT(PAGE_ALIGNED(kstack));
c->c_kstack = (uintptr_t)kstack;
c->c_kstacksz = kstacksz;
c->c_pml4 = pml4;
c->c_rsp = (uintptr_t)kstack + kstacksz;
c->c_rsp -= sizeof(uintptr_t);
*((uintptr_t *)c->c_rsp) = 0;
c->c_rbp = c->c_rsp;
c->c_rip = (uintptr_t)func;
}
/*
* Initializes a context_t struct with the given parameters. arg1 and arg2 will
* appear as arguments to the function passed in when this context is first
* used.
*/
void context_setup(context_t *c, context_func_t func, long arg1, void *arg2,
void *kstack, size_t kstacksz, pml4_t *pml4)
{
KASSERT(NULL != pml4);
KASSERT(PAGE_ALIGNED(kstack));
c->c_kstack = (uintptr_t)kstack;
c->c_kstacksz = kstacksz;
c->c_pml4 = pml4;
/* put the arguments for __context_thread_initial_func onto the
* stack */
c->c_rsp = (uintptr_t)kstack + kstacksz;
c->c_rsp -= sizeof(arg2);
*(void **)c->c_rsp = arg2;
c->c_rsp -= sizeof(arg1);
*(long *)c->c_rsp = arg1;
c->c_rsp -= sizeof(context_func_t);
*(context_func_t *)c->c_rsp = func;
// Take space for the function return address (unused)
c->c_rsp -= sizeof(uintptr_t);
c->c_rbp = c->c_rsp;
c->c_rip = (uintptr_t)__context_thread_initial_func;
}
/*
* WARNING!! POTENTIAL EDITOR BEWARE!!
* IF YOU REMOVE THE PT_SET CALLS BELOW,
* YOU ***MUST*** DEAL WITH SMP TLB SHOOTDOWN
*
* IN OTHER WORDS, THINK *VERY* CAREFULLY BEFORE
* REMOVING THE CALLS TO PT_SET BELOW
*/
void context_make_active(context_t *c)
{
// gdt_set_kernel_stack((void *)((uintptr_t)c->c_kstack + c->c_kstacksz));
pt_set(c->c_pml4);
/* Switch stacks and run the thread */
__asm__ volatile(
"movq %0,%%rbp\n\t" /* update rbp */
"movq %1,%%rsp\n\t" /* update rsp */
"push %2\n\t" /* save rip */
"ret" /* jump to new rip */
::"m"(c->c_rbp),
"m"(c->c_rsp), "m"(c->c_rip));
}
void context_switch(context_t *oldc, context_t *newc)
{
gdt_set_kernel_stack(
(void *)((uintptr_t)newc->c_kstack + newc->c_kstacksz));
// sanity check that core-specific data is being managed (paged in)
// correctly
KASSERT(oldc->c_pml4 == pt_get());
uintptr_t curthr_paddr =
pt_virt_to_phys_helper(oldc->c_pml4, (uintptr_t)&curthr);
uintptr_t new_curthr_paddr =
pt_virt_to_phys_helper(newc->c_pml4, (uintptr_t)&curthr);
kthread_t *prev_curthr = curthr;
pt_set(newc->c_pml4);
KASSERT(pt_get() == newc->c_pml4);
KASSERT(curthr_paddr == new_curthr_paddr);
KASSERT(prev_curthr == curthr);
/*
* Save the current value of the stack pointer and the frame pointer into
* the old context. Set the instruction pointer to the return address
* (whoever called us).
*/
__asm__ volatile(
"pushfq;" /* save RFLAGS on the stack */
"pushq %%rbp \n" /* save base pointer */
"pushq %%rbx \n" /* save other callee-saved registers */
"pushq %%r12 \n"
"pushq %%r13 \n"
"pushq %%r14 \n"
"pushq %%r15 \n"
"movq %%rsp, %0 \n" /* save RSP into oldc */
"movq %2, %%rsp \n" /* restore RSP from newc */
"pushq %%rax\n\t"
"movabs $1f, %%rax \n\t" /* save RIP into oldc (saves the label '1'
below) */
"mov %%rax, %1\n\t"
"popq %%rax\n\t"
"pushq %3 \n\t" /* restore RIP */
"ret \n\t"
"1:\t" /* this is where oldc starts executing later */
"popq %%r15 \n\t" /* restore callee-saved registers */
"popq %%r14 \n\t"
"popq %%r13 \n\t"
"popq %%r12 \n\t"
"popq %%rbx \n\t"
"popq %%rbp \n\t" /* restore base pointer */
"popfq" /* restore RFLAGS */
: "=m"(oldc->c_rsp), "=m"(oldc->c_rip)
: "m"(newc->c_rsp), "m"(newc->c_rip));
}
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