riscv: split the declaration of __copy_user
We use a single __copy_user assembly function to copy memory both from and to userspace. While this works, it triggers sparse errors because we're implicitly casting between the kernel and user address spaces by calling __copy_user. This patch splits the C declaration into a pair of functions, __asm_copy_{to,from}_user, that have sane semantics WRT __user. This split make things fine from sparse's point of view. The assembly implementation keeps a single definition but add a double ENTRY() for it, one for __asm_copy_to_user and another one for __asm_copy_from_user. The result is a spare-safe implementation that pays no performance or code size penalty. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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@ -392,19 +392,21 @@ do { \
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})
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extern unsigned long __must_check __copy_user(void __user *to,
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extern unsigned long __must_check __asm_copy_to_user(void __user *to,
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const void *from, unsigned long n);
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extern unsigned long __must_check __asm_copy_from_user(void *to,
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const void __user *from, unsigned long n);
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static inline unsigned long
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raw_copy_from_user(void *to, const void __user *from, unsigned long n)
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{
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return __copy_user(to, from, n);
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return __asm_copy_to_user(to, from, n);
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}
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static inline unsigned long
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raw_copy_to_user(void __user *to, const void *from, unsigned long n)
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{
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return __copy_user(to, from, n);
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return __asm_copy_from_user(to, from, n);
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}
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extern long strncpy_from_user(char *dest, const char __user *src, long count);
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@ -13,6 +13,7 @@
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* Assembly functions that may be used (directly or indirectly) by modules
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*/
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EXPORT_SYMBOL(__clear_user);
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EXPORT_SYMBOL(__copy_user);
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EXPORT_SYMBOL(__asm_copy_to_user);
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EXPORT_SYMBOL(__asm_copy_from_user);
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EXPORT_SYMBOL(memset);
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EXPORT_SYMBOL(memcpy);
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@ -13,7 +13,8 @@ _epc:
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.previous
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.endm
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ENTRY(__copy_user)
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ENTRY(__asm_copy_to_user)
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ENTRY(__asm_copy_from_user)
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/* Enable access to user memory */
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li t6, SR_SUM
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@ -63,7 +64,8 @@ ENTRY(__copy_user)
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addi a0, a0, 1
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bltu a1, a3, 5b
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j 3b
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ENDPROC(__copy_user)
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ENDPROC(__asm_copy_to_user)
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ENDPROC(__asm_copy_from_user)
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ENTRY(__clear_user)
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