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/**
* @file autostack.c
* @author Hanjie Wu (hanjiew)
* @brief autostack implementation
* @date 2023-02-22
*
*/
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <simics.h>
#include <syscall.h>
#include <thr_internals.h>
#include <ureg.h>
/**
* @brief test if the page fault is caused by page not present
*/
#define IS_PF_NP(error_code) (((error_code)&0x1) == 0)
/**
* @brief a stack size which is enough for our swexn handlers
*/
#define EX_STACK_SIZE (1 << 14)
char ex_stack[EX_STACK_SIZE];
void* ex_stack_end = &ex_stack[sizeof(ex_stack)];
/**
* @brief a stack size which is enough for common programs
*/
#define AUTOSYACK_SIZE (1 << 24)
/**
* @brief size limit of autostack growth
*/
const static unsigned int stack_limit = AUTOSYACK_SIZE;
/**
* @brief autostack swexn handler
*/
static void swexn_handler(void* arg, ureg_t* reg) {
/* check cause */
if (reg->cause == SWEXN_CAUSE_PAGEFAULT && IS_PF_NP(reg->error_code)) {
/* check stack limit */
if (reg->cr2 < main_tcb.stack_lo &&
reg->cr2 > main_tcb.stack_lo - stack_limit) {
uintptr_t aligned = reg->cr2 & PAGE_ALIGN_MASK;
if (new_pages((void*)aligned, (int)(main_tcb.stack_lo - aligned)) !=
0) {
task_vanish(-2);
}
main_tcb.stack_lo = aligned;
swexn(ex_stack_end, swexn_handler, NULL, reg);
}
}
task_vanish(-2);
}
/**
* @brief install autostack handler
*/
void install_autostack(void* stack_high, void* stack_low) {
/* use main_tcb to record stack limits */
main_tcb.stack_hi = (unsigned int)stack_high;
main_tcb.stack_lo = (unsigned int)stack_low;
main_tcb.tid = gettid();
main_tcb.is_main = 1;
rb_insert_tcb(&main_tcb);
swexn(ex_stack_end, swexn_handler, NULL, NULL);
}
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