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x86: uaccess: move 32-bit and 64-bit parts into proper <asm/uaccess_N.h> header

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The x86 <asm/uaccess.h> file has grown features that are specific to
x86-64 like LAM support and the related access_ok() changes.  They
really should be in the <asm/uaccess_64.h> file and not pollute the
generic x86 header.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds
2023-05-02 16:39:59 -07:00
parent 6ccdc91d6a
commit b9bd9f605c
3 changed files with 82 additions and 85 deletions
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87
arch/x86/include/asm/uaccess.h
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@@ -16,83 +16,10 @@
#include <asm/extable.h>
#include <asm/tlbflush.h>
#ifdef CONFIG_ADDRESS_MASKING
/*
* Mask out tag bits from the address.
*
* Magic with the 'sign' allows to untag userspace pointer without any branches
* while leaving kernel addresses intact.
*/
static inline unsigned long __untagged_addr(unsigned long addr)
{
long sign;
/*
* Refer tlbstate_untag_mask directly to avoid RIP-relative relocation
* in alternative instructions. The relocation gets wrong when gets
* copied to the target place.
*/
asm (ALTERNATIVE("",
"sar $63, %[sign]\n\t" /* user_ptr ? 0 : -1UL */
"or %%gs:tlbstate_untag_mask, %[sign]\n\t"
"and %[sign], %[addr]\n\t", X86_FEATURE_LAM)
: [addr] "+r" (addr), [sign] "=r" (sign)
: "m" (tlbstate_untag_mask), "[sign]" (addr));
return addr;
}
#define untagged_addr(addr) ({ \
unsigned long __addr = (__force unsigned long)(addr); \
(__force __typeof__(addr))__untagged_addr(__addr); \
})
static inline unsigned long __untagged_addr_remote(struct mm_struct *mm,
unsigned long addr)
{
long sign = addr >> 63;
mmap_assert_locked(mm);
addr &= (mm)->context.untag_mask | sign;
return addr;
}
#define untagged_addr_remote(mm, addr) ({ \
unsigned long __addr = (__force unsigned long)(addr); \
(__force __typeof__(addr))__untagged_addr_remote(mm, __addr); \
})
#ifdef CONFIG_X86_32
# include <asm/uaccess_32.h>
#else
#define untagged_addr(addr) (addr)
#endif
#ifdef CONFIG_X86_64
/*
* On x86-64, we may have tag bits in the user pointer. Rather than
* mask them off, just change the rules for __access_ok().
*
* Make the rule be that 'ptr+size' must not overflow, and must not
* have the high bit set. Compilers generally understand about
* unsigned overflow and the CF bit and generate reasonable code for
* this. Although it looks like the combination confuses at least
* clang (and instead of just doing an "add" followed by a test of
* SF and CF, you'll see that unnecessary comparison).
*
* For the common case of small sizes that can be checked at compile
* time, don't even bother with the addition, and just check that the
* base pointer is ok.
*/
static inline bool __access_ok(const void __user *ptr, unsigned long size)
{
if (__builtin_constant_p(size <= PAGE_SIZE) && size <= PAGE_SIZE) {
return (long)ptr >= 0;
} else {
unsigned long sum = size + (unsigned long)ptr;
return (long) sum >= 0 && sum >= (unsigned long)ptr;
}
}
#define __access_ok __access_ok
# include <asm/uaccess_64.h>
#endif
#include <asm-generic/access_ok.h>
@@ -583,14 +510,6 @@ extern struct movsl_mask {
#define ARCH_HAS_NOCACHE_UACCESS 1
#ifdef CONFIG_X86_32
unsigned long __must_check clear_user(void __user *mem, unsigned long len);
unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
# include <asm/uaccess_32.h>
#else
# include <asm/uaccess_64.h>
#endif
/*
* The "unsafe" user accesses aren't really "unsafe", but the naming
* is a big fat warning: you have to not only do the access_ok()