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#include "misc.h"
#ifdef CONFIG_RANDOMIZE_BASE
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#include <asm/msr.h>
#include <asm/archrandom.h>
#define I8254_PORT_CONTROL 0x43
#define I8254_PORT_COUNTER0 0x40
#define I8254_CMD_READBACK 0xC0
#define I8254_SELECT_COUNTER0 0x02
#define I8254_STATUS_NOTREADY 0x40
static inline u16 i8254(void)
{
u16 status, timer;
do {
outb(I8254_PORT_CONTROL,
I8254_CMD_READBACK | I8254_SELECT_COUNTER0);
status = inb(I8254_PORT_COUNTER0);
timer = inb(I8254_PORT_COUNTER0);
timer |= inb(I8254_PORT_COUNTER0) << 8;
} while (status & I8254_STATUS_NOTREADY);
return timer;
}
static unsigned long get_random_long(void)
{
unsigned long random;
if (has_cpuflag(X86_FEATURE_RDRAND)) {
debug_putstr("KASLR using RDRAND...\n");
if (rdrand_long(&random))
return random;
}
if (has_cpuflag(X86_FEATURE_TSC)) {
uint32_t raw;
debug_putstr("KASLR using RDTSC...\n");
rdtscl(raw);
/* Only use the low bits of rdtsc. */
random = raw & 0xffff;
} else {
debug_putstr("KASLR using i8254...\n");
random = i8254();
}
/* Extend timer bits poorly... */
random |= (random << 16);
#ifdef CONFIG_X86_64
random |= (random << 32);
#endif
return random;
}
unsigned char *choose_kernel_location(unsigned char *input,
unsigned long input_size,
unsigned char *output,
unsigned long output_size)
{
unsigned long choice = (unsigned long)output;
if (cmdline_find_option_bool("nokaslr")) {
debug_putstr("KASLR disabled...\n");
goto out;
}
/* XXX: choose random location. */
out:
return (unsigned char *)choice;
}
#endif /* CONFIG_RANDOMIZE_BASE */