| 1 |
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| 2 | #ifndef __ASM_GENERIC_ACCESS_OK_H__
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| 3 | #define __ASM_GENERIC_ACCESS_OK_H__
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| 4 |
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| 5 | |
| 6 | * Checking whether a pointer is valid for user space access.
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| 7 | * These definitions work on most architectures, but overrides can
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| 8 | * be used where necessary.
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| 9 |
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| 10 |
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| 11 | |
| 12 | * architectures with compat tasks have a variable TASK_SIZE and should
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| 13 | * override this to a constant.
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| 14 |
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| 15 | #ifndef TASK_SIZE_MAX
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| 16 | #define TASK_SIZE_MAX TASK_SIZE
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| 17 | #endif
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| 18 |
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| 19 | #ifndef __access_ok
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| 20 | |
| 21 | * 'size' is a compile-time constant for most callers, so optimize for
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| 22 | * this case to turn the check into a single comparison against a constant
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| 23 | * limit and catch all possible overflows.
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| 24 | * On architectures with separate user address space (m68k, s390, parisc,
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| 25 | * sparc64) or those without an MMU, this should always return true.
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| 26 | *
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| 27 | * This version was originally contributed by Jonas Bonn for the
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| 28 | * OpenRISC architecture, and was found to be the most efficient
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| 29 | * for constant 'size' and 'limit' values.
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| 30 |
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| 31 | static inline int __access_ok(const void __user *ptr, unsigned long size)
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| 32 | {
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| 33 | unsigned long limit = TASK_SIZE_MAX;
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| 34 | unsigned long addr = (unsigned long)ptr;
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| 35 |
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| 36 | if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) ||
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| 37 | !IS_ENABLED(CONFIG_MMU))
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| 38 | return true;
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| 39 |
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| 40 | return (size <= limit) && (addr <= (limit - size));
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| 41 | }
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| 42 | #endif
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| 43 |
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| 44 | #ifndef access_ok
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| 45 | #define access_ok(addr, size) likely(__access_ok(addr, size))
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| 46 | #endif
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| 47 |
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| 48 | #endif
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