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/** @file station.c
*
* @brief Exercises clock interrupts in a charming fashion.
*
* @author de0u
*
* PebPeb-only executable -- it doesn't work on hardware.
*
*/
#include <common_kern.h>
/* libc includes. */
#include <malloc.h>
#include <simics.h> /* lprintf() */
#include <stdio.h>
/* multiboot header file */
#include <multiboot.h> /* boot_info */
/* memory includes. */
#include <lmm.h> /* lmm_remove_free() */
/* x86 specific includes */
#include <x86/asm.h> /* enable_interrupts() */
#include <x86/cr.h>
#include <x86/interrupt_defines.h> /* interrupt_setup() */
#include <x86/page.h>
#include <x86/seg.h> /* install_user_segs() */
#include <hvcall.h>
#include <malloc_internal.h>
#include <video_defines.h>
#define DEBUG
#include <contracts.h>
#include <assert.h>
#include <string.h>
/* https://classictrainsongs.com/down_by_station/down_by_the_station.htm */
char *lyrics[] = {
"Down by the station early in the morning,\n",
"See the little puffer bellies all in a row.\n",
"See the station master turn the little handle,\n",
"Chug, chug, toot, toot, off we go.\n",
NULL
};
void
twiddle(void)
{
volatile int accumulator = 0;
while (accumulator != -1)
++accumulator;
panic("Uh oh, overflow, population, common group");
}
#define DELAY_TICKS 10 // If you make this much larger, what happens next will shock you!
volatile int tick = 0;
volatile int line = 0;
void
tickback(void)
{
if (++tick == DELAY_TICKS) {
tick = 0;
hv_print(strlen(lyrics[line]), (unsigned char *)lyrics[line]);
++line;
if (lyrics[line] == NULL)
hv_exit(0);
}
hv_enable_interrupts();
twiddle();
}
/** @brief Kernel entrypoint.
*
* This is the entrypoint for the kernel.
*
* @return Does not return
*/
int
kernel_main(mbinfo_t *mbinfo, int argc, char **argv, char **envp)
{
if (!hv_isguest()) {
lprintf("I am NOT supposed to be here!!!");
panic("This payload is guest-only");
return (-1);
}
hv_setidt(HV_TICKBACK, tickback, HV_SETIDT_PRIVILEGED);
hv_setidt(HV_KEYBOARD, tickback, HV_SETIDT_PRIVILEGED);
hv_enable_interrupts();
twiddle();
return (-99);
}
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