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![Linus Torvalds](/assets/img/avatar_default.png)
Every in-kernel use of this function defined it to KERNEL_DS (either as an actual define, or as an inline function). It's an entirely historical artifact, and long long long ago used to actually read the segment selector valueof '%ds' on x86. Which in the kernel is always KERNEL_DS. Inspired by a patch from Jann Horn that just did this for a very small subset of users (the ones in fs/), along with Al who suggested a script. I then just took it to the logical extreme and removed all the remaining gunk. Roughly scripted with git grep -l '(get_ds())' -- :^tools/ | xargs sed -i 's/(get_ds())/(KERNEL_DS)/' git grep -lw 'get_ds' -- :^tools/ | xargs sed -i '/^#define get_ds()/d' plus manual fixups to remove a few unusual usage patterns, the couple of inline function cases and to fix up a comment that had become stale. The 'get_ds()' function remains in an x86 kvm selftest, since in user space it actually does something relevant. Inspired-by: Jann Horn <jannh@google.com> Inspired-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
203 lines
6 KiB
C
203 lines
6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_UACCESS_H
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#define _ASM_UACCESS_H
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/*
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* User space memory access functions
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*/
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#include <linux/compiler.h>
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#include <linux/string.h>
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#include <asm/asi.h>
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#include <asm/spitfire.h>
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#include <asm/extable_64.h>
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#include <asm/processor.h>
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/*
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* Sparc64 is segmented, though more like the M68K than the I386.
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* We use the secondary ASI to address user memory, which references a
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* completely different VM map, thus there is zero chance of the user
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* doing something queer and tricking us into poking kernel memory.
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*
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* What is left here is basically what is needed for the other parts of
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* the kernel that expect to be able to manipulate, erum, "segments".
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* Or perhaps more properly, permissions.
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*
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* "For historical reasons, these macros are grossly misnamed." -Linus
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*/
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#define KERNEL_DS ((mm_segment_t) { ASI_P })
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#define USER_DS ((mm_segment_t) { ASI_AIUS }) /* har har har */
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#define get_fs() ((mm_segment_t){(current_thread_info()->current_ds)})
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#define segment_eq(a, b) ((a).seg == (b).seg)
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#define set_fs(val) \
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do { \
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current_thread_info()->current_ds = (val).seg; \
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__asm__ __volatile__ ("wr %%g0, %0, %%asi" : : "r" ((val).seg)); \
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} while(0)
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/*
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* Test whether a block of memory is a valid user space address.
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* Returns 0 if the range is valid, nonzero otherwise.
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*/
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static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
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{
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if (__builtin_constant_p(size))
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return addr > limit - size;
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addr += size;
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if (addr < size)
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return true;
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return addr > limit;
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}
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#define __range_not_ok(addr, size, limit) \
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({ \
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__chk_user_ptr(addr); \
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__chk_range_not_ok((unsigned long __force)(addr), size, limit); \
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})
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static inline int __access_ok(const void __user * addr, unsigned long size)
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{
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return 1;
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}
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static inline int access_ok(const void __user * addr, unsigned long size)
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{
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return 1;
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}
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void __retl_efault(void);
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/* Uh, these should become the main single-value transfer routines..
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* They automatically use the right size if we just have the right
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* pointer type..
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*
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* This gets kind of ugly. We want to return _two_ values in "get_user()"
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* and yet we don't want to do any pointers, because that is too much
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* of a performance impact. Thus we have a few rather ugly macros here,
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* and hide all the ugliness from the user.
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*/
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#define put_user(x, ptr) ({ \
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unsigned long __pu_addr = (unsigned long)(ptr); \
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__chk_user_ptr(ptr); \
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__put_user_nocheck((__typeof__(*(ptr)))(x), __pu_addr, sizeof(*(ptr)));\
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})
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#define get_user(x, ptr) ({ \
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unsigned long __gu_addr = (unsigned long)(ptr); \
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__chk_user_ptr(ptr); \
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__get_user_nocheck((x), __gu_addr, sizeof(*(ptr)), __typeof__(*(ptr)));\
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})
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#define __put_user(x, ptr) put_user(x, ptr)
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#define __get_user(x, ptr) get_user(x, ptr)
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struct __large_struct { unsigned long buf[100]; };
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#define __m(x) ((struct __large_struct *)(x))
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#define __put_user_nocheck(data, addr, size) ({ \
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register int __pu_ret; \
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switch (size) { \
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case 1: __put_user_asm(data, b, addr, __pu_ret); break; \
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case 2: __put_user_asm(data, h, addr, __pu_ret); break; \
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case 4: __put_user_asm(data, w, addr, __pu_ret); break; \
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case 8: __put_user_asm(data, x, addr, __pu_ret); break; \
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default: __pu_ret = __put_user_bad(); break; \
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} \
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__pu_ret; \
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})
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#define __put_user_asm(x, size, addr, ret) \
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__asm__ __volatile__( \
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"/* Put user asm, inline. */\n" \
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"1:\t" "st"#size "a %1, [%2] %%asi\n\t" \
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"clr %0\n" \
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"2:\n\n\t" \
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".section .fixup,#alloc,#execinstr\n\t" \
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".align 4\n" \
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"3:\n\t" \
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"sethi %%hi(2b), %0\n\t" \
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"jmpl %0 + %%lo(2b), %%g0\n\t" \
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" mov %3, %0\n\n\t" \
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".previous\n\t" \
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".section __ex_table,\"a\"\n\t" \
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".align 4\n\t" \
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".word 1b, 3b\n\t" \
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".previous\n\n\t" \
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: "=r" (ret) : "r" (x), "r" (__m(addr)), \
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"i" (-EFAULT))
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int __put_user_bad(void);
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#define __get_user_nocheck(data, addr, size, type) ({ \
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register int __gu_ret; \
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register unsigned long __gu_val; \
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switch (size) { \
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case 1: __get_user_asm(__gu_val, ub, addr, __gu_ret); break; \
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case 2: __get_user_asm(__gu_val, uh, addr, __gu_ret); break; \
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case 4: __get_user_asm(__gu_val, uw, addr, __gu_ret); break; \
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case 8: __get_user_asm(__gu_val, x, addr, __gu_ret); break; \
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default: \
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__gu_val = 0; \
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__gu_ret = __get_user_bad(); \
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break; \
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} \
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data = (__force type) __gu_val; \
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__gu_ret; \
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})
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#define __get_user_asm(x, size, addr, ret) \
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__asm__ __volatile__( \
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"/* Get user asm, inline. */\n" \
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"1:\t" "ld"#size "a [%2] %%asi, %1\n\t" \
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"clr %0\n" \
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"2:\n\n\t" \
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".section .fixup,#alloc,#execinstr\n\t" \
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".align 4\n" \
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"3:\n\t" \
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"sethi %%hi(2b), %0\n\t" \
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"clr %1\n\t" \
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"jmpl %0 + %%lo(2b), %%g0\n\t" \
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" mov %3, %0\n\n\t" \
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".previous\n\t" \
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".section __ex_table,\"a\"\n\t" \
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".align 4\n\t" \
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".word 1b, 3b\n\n\t" \
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".previous\n\t" \
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: "=r" (ret), "=r" (x) : "r" (__m(addr)), \
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"i" (-EFAULT))
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int __get_user_bad(void);
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unsigned long __must_check raw_copy_from_user(void *to,
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const void __user *from,
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unsigned long size);
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unsigned long __must_check raw_copy_to_user(void __user *to,
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const void *from,
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unsigned long size);
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#define INLINE_COPY_FROM_USER
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#define INLINE_COPY_TO_USER
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unsigned long __must_check raw_copy_in_user(void __user *to,
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const void __user *from,
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unsigned long size);
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unsigned long __must_check __clear_user(void __user *, unsigned long);
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#define clear_user __clear_user
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__must_check long strnlen_user(const char __user *str, long n);
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struct pt_regs;
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unsigned long compute_effective_address(struct pt_regs *,
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unsigned int insn,
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unsigned int rd);
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#endif /* _ASM_UACCESS_H */
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