| .. | .. | 
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| 13 | 13 |   * On x86_64, %gs is shared by percpu area and stack canary.  All | 
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| 14 | 14 |   * percpu symbols are zero based and %gs points to the base of percpu | 
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| 15 | 15 |   * area.  The first occupant of the percpu area is always | 
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| 16 |  | - * irq_stack_union which contains stack_canary at offset 40.  Userland  | 
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 | 16 | + * fixed_percpu_data which contains stack_canary at offset 40.  Userland  | 
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| 17 | 17 |   * %gs is always saved and restored on kernel entry and exit using | 
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| 18 | 18 |   * swapgs, so stack protector doesn't add any complexity there. | 
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| 19 | 19 |   * | 
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| .. | .. | 
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| 65 | 65 |   */ | 
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| 66 | 66 |  static __always_inline void boot_init_stack_canary(void) | 
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| 67 | 67 |  { | 
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| 68 |  | -	u64 uninitialized_var(canary);  | 
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 | 68 | +	u64 canary;  | 
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| 69 | 69 |  	u64 tsc; | 
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| 70 | 70 |   | 
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| 71 | 71 |  #ifdef CONFIG_X86_64 | 
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| 72 |  | -	BUILD_BUG_ON(offsetof(union irq_stack_union, stack_canary) != 40);  | 
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 | 72 | +	BUILD_BUG_ON(offsetof(struct fixed_percpu_data, stack_canary) != 40);  | 
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| 73 | 73 |  #endif | 
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| 74 | 74 |  	/* | 
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| 75 | 75 |  	 * We both use the random pool and the current TSC as a source | 
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| 76 | 76 |  	 * of randomness. The TSC only matters for very early init, | 
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| 77 | 77 |  	 * there it already has some randomness on most systems. Later | 
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| 78 | 78 |  	 * on during the bootup the random pool has true entropy too. | 
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| 79 |  | -	 * For preempt-rt we need to weaken the randomness a bit, as  | 
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| 80 |  | -	 * we can't call into the random generator from atomic context  | 
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| 81 |  | -	 * due to locking constraints. We just leave canary  | 
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| 82 |  | -	 * uninitialized and use the TSC based randomness on top of it.  | 
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| 83 | 79 |  	 */ | 
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| 84 |  | -#ifndef CONFIG_PREEMPT_RT_FULL  | 
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| 85 | 80 |  	get_random_bytes(&canary, sizeof(canary)); | 
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| 86 |  | -#endif  | 
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| 87 | 81 |  	tsc = rdtsc(); | 
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| 88 | 82 |  	canary += tsc + (tsc << 32UL); | 
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| 89 | 83 |  	canary &= CANARY_MASK; | 
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| 90 | 84 |   | 
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| 91 | 85 |  	current->stack_canary = canary; | 
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| 92 | 86 |  #ifdef CONFIG_X86_64 | 
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| 93 |  | -	this_cpu_write(irq_stack_union.stack_canary, canary);  | 
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 | 87 | +	this_cpu_write(fixed_percpu_data.stack_canary, canary);  | 
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| 94 | 88 |  #else | 
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| 95 | 89 |  	this_cpu_write(stack_canary.canary, canary); | 
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 | 90 | +#endif  | 
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 | 91 | +}  | 
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 | 92 | +  | 
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 | 93 | +static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)  | 
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 | 94 | +{  | 
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 | 95 | +#ifdef CONFIG_X86_64  | 
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 | 96 | +	per_cpu(fixed_percpu_data.stack_canary, cpu) = idle->stack_canary;  | 
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 | 97 | +#else  | 
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 | 98 | +	per_cpu(stack_canary.canary, cpu) = idle->stack_canary;  | 
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| 96 | 99 |  #endif | 
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| 97 | 100 |  } | 
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| 98 | 101 |   | 
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| .. | .. | 
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| 125 | 128 |  static inline void setup_stack_canary_segment(int cpu) | 
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| 126 | 129 |  { } | 
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| 127 | 130 |   | 
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 | 131 | +static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)  | 
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 | 132 | +{ }  | 
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 | 133 | +  | 
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| 128 | 134 |  static inline void load_stack_canary_segment(void) | 
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| 129 | 135 |  { | 
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| 130 | 136 |  #ifdef CONFIG_X86_32 | 
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