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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 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 stack canary
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| 8 | * and gcc expects it to be defined by a global variable called
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| 9 | * "__stack_chk_guard" on ARM. This prevents SMP systems from using a
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| 10 | * different value for each task unless we enable a GCC plugin that
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| 11 | * replaces these symbol references with references to each task's own
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| 12 | * value.
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| 13 |
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| 14 |
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| 15 | #ifndef _ASM_STACKPROTECTOR_H
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| 16 | #define _ASM_STACKPROTECTOR_H 1
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| 17 |
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| 18 | #include <asm/thread_info.h>
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| 19 |
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| 20 | extern unsigned long __stack_chk_guard;
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| 21 |
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| 22 | |
| 23 | * Initialize the stackprotector canary value.
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| 24 | *
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| 25 | * NOTE: this must only be called from functions that never return,
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| 26 | * and it must always be inlined.
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| 27 |
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| 28 | static __always_inline void boot_init_stack_canary(void)
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| 29 | {
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| 30 | unsigned long canary = get_random_canary();
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| 31 |
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| 32 | current->stack_canary = canary;
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| 33 | #ifndef CONFIG_STACKPROTECTOR_PER_TASK
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| 34 | __stack_chk_guard = current->stack_canary;
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| 35 | #endif
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| 36 | }
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| 37 |
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| 38 | #endif
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