| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
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| 2 | /* |
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| 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 | /* |
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| 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 /* STACKPROTECTOR */ |
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| 50 | |
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| 51 | /* dummy boot_init_stack_canary() is defined in linux/stackprotector.h */ |
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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 /* STACKPROTECTOR */ |
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| 57 | #endif /* _ASM_STACKPROTECTOR_H */ |
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| 58 | |
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