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-rw-r--r--arch/arm/include/asm/assembler.h11
-rw-r--r--arch/arm/include/asm/uaccess.h26
2 files changed, 37 insertions, 0 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index b17ee03d280b..88286dd483ff 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -467,6 +467,17 @@ THUMB( orr \reg , \reg , #PSR_T_BIT )
#endif
.endm
+ .macro uaccess_mask_range_ptr, addr:req, size:req, limit:req, tmp:req
+#ifdef CONFIG_CPU_SPECTRE
+ sub \tmp, \limit, #1
+ subs \tmp, \tmp, \addr @ tmp = limit - 1 - addr
+ addhs \tmp, \tmp, #1 @ if (tmp >= 0) {
+ subhss \tmp, \tmp, \size @ tmp = limit - (addr + size) }
+ movlo \addr, #0 @ if (tmp < 0) addr = NULL
+ csdb
+#endif
+ .endm
+
.macro uaccess_disable, tmp, isb=1
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
/*
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 1191e7da8fab..c136eef8f690 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -100,6 +100,32 @@ static inline void set_fs(mm_segment_t fs)
__typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
/*
+ * Sanitise a uaccess pointer such that it becomes NULL if addr+size
+ * is above the current addr_limit.
+ */
+#define uaccess_mask_range_ptr(ptr, size) \
+ ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
+static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
+ size_t size)
+{
+ void __user *safe_ptr = (void __user *)ptr;
+ unsigned long tmp;
+
+ asm volatile(
+ " sub %1, %3, #1\n"
+ " subs %1, %1, %0\n"
+ " addhs %1, %1, #1\n"
+ " subhss %1, %1, %2\n"
+ " movlo %0, #0\n"
+ : "+r" (safe_ptr), "=&r" (tmp)
+ : "r" (size), "r" (current_thread_info()->addr_limit)
+ : "cc");
+
+ csdb();
+ return safe_ptr;
+}
+
+/*
* Single-value transfer routines. They automatically use the right
* size if we just have the right pointer type. Note that the functions
* which read from user space (*get_*) need to take care not to leak