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-rw-r--r--arch/x86/include/asm/uaccess_64.h18
1 files changed, 3 insertions, 15 deletions
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 20411e69e67f..e5b23e917f41 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -15,25 +15,17 @@
#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));
+ "and %%gs:tlbstate_untag_mask, %[addr]\n\t", X86_FEATURE_LAM)
+ : [addr] "+r" (addr) : "m" (tlbstate_untag_mask));
return addr;
}
@@ -46,12 +38,8 @@ static inline unsigned long __untagged_addr(unsigned long 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;
+ return addr & (mm)->context.untag_mask;
}
#define untagged_addr_remote(mm, addr) ({ \