diff options
Diffstat (limited to 'arch/x86/boot')
| -rw-r--r-- | arch/x86/boot/compressed/aslr.c | 53 | ||||
| -rw-r--r-- | arch/x86/boot/compressed/misc.h | 2 |
2 files changed, 55 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c index b73cc66d201..14b24e0e549 100644 --- a/arch/x86/boot/compressed/aslr.c +++ b/arch/x86/boot/compressed/aslr.c @@ -1,6 +1,59 @@ #include "misc.h" #ifdef CONFIG_RANDOMIZE_BASE +#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, diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index 9077af7fd0b..0782eb0b6e3 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -52,6 +52,8 @@ unsigned char *choose_kernel_location(unsigned char *input, unsigned long input_size, unsigned char *output, unsigned long output_size); +/* cpuflags.c */ +bool has_cpuflag(int flag); #else static inline unsigned char *choose_kernel_location(unsigned char *input, |