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| 2 | |
| 3 | * GCC stack protector support.
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| 4 | *
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| 5 | * Stack protector works by putting a predefined pattern at the start of
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| 6 | * the stack frame and verifying that it hasn't been overwritten when
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| 7 | * returning from the function. The pattern is called the stack canary
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| 8 | * and is a unique value for each task.
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| 9 |
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| 10 |
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| 11 | #ifndef _ASM_STACKPROTECTOR_H
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| 12 | #define _ASM_STACKPROTECTOR_H 1
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| 13 |
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| 14 | #ifdef CONFIG_STACKPROTECTOR
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| 15 |
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| 16 | #include <asm/tsc.h>
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| 17 | #include <asm/processor.h>
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| 18 | #include <asm/percpu.h>
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| 19 | #include <asm/desc.h>
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| 20 |
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| 21 | #include <linux/sched.h>
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| 22 |
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| 23 | DECLARE_PER_CPU_CACHE_HOT(unsigned long, __stack_chk_guard);
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| 24 |
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| 25 | |
| 26 | * Initialize the stackprotector canary value.
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| 27 | *
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| 28 | * NOTE: this must only be called from functions that never return
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| 29 | * and it must always be inlined.
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| 30 | *
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| 31 | * In addition, it should be called from a compilation unit for which
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| 32 | * stack protector is disabled. Alternatively, the caller should not end
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| 33 | * with a function call which gets tail-call optimized as that would
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| 34 | * lead to checking a modified canary value.
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| 35 |
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| 36 | static __always_inline void boot_init_stack_canary(void)
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| 37 | {
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| 38 | unsigned long canary = get_random_canary();
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| 39 |
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| 40 | current->stack_canary = canary;
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| 41 | this_cpu_write(__stack_chk_guard, canary);
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| 42 | }
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| 43 |
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| 44 | static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
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| 45 | {
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| 46 | per_cpu(__stack_chk_guard, cpu) = idle->stack_canary;
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| 47 | }
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| 48 |
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| 49 | #else
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| 50 |
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| 51 |
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| 52 |
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| 53 | static inline void cpu_init_stack_canary(int cpu, struct task_struct *idle)
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| 54 | { }
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| 55 |
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| 56 | #endif
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| 57 | #endif
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