| Ingo Molnar | b2b062b | 2009-01-18 18:37:14 +0100 | [diff] [blame^] | 1 | #ifndef _ASM_STACKPROTECTOR_H |
| 2 | #define _ASM_STACKPROTECTOR_H 1 |
| 3 | |
| 4 | #include <asm/tsc.h> |
| 5 | #include <asm/pda.h> |
| 6 | |
| 7 | /* |
| 8 | * Initialize the stackprotector canary value. |
| 9 | * |
| 10 | * NOTE: this must only be called from functions that never return, |
| 11 | * and it must always be inlined. |
| 12 | */ |
| 13 | static __always_inline void boot_init_stack_canary(void) |
| 14 | { |
| 15 | u64 canary; |
| 16 | u64 tsc; |
| 17 | |
| 18 | /* |
| 19 | * If we're the non-boot CPU, nothing set the PDA stack |
| 20 | * canary up for us - and if we are the boot CPU we have |
| 21 | * a 0 stack canary. This is a good place for updating |
| 22 | * it, as we wont ever return from this function (so the |
| 23 | * invalid canaries already on the stack wont ever |
| 24 | * trigger). |
| 25 | * |
| 26 | * We both use the random pool and the current TSC as a source |
| 27 | * of randomness. The TSC only matters for very early init, |
| 28 | * there it already has some randomness on most systems. Later |
| 29 | * on during the bootup the random pool has true entropy too. |
| 30 | */ |
| 31 | get_random_bytes(&canary, sizeof(canary)); |
| 32 | tsc = __native_read_tsc(); |
| 33 | canary += tsc + (tsc << 32UL); |
| 34 | |
| 35 | current->stack_canary = canary; |
| 36 | write_pda(stack_canary, canary); |
| 37 | } |
| 38 | |
| 39 | #endif |