1 files changed, 39 insertions, 1 deletions
diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c
index 228d681a8715..6e0528831cd3 100644
--- a/arch/arm64/mm/extable.c
+++ b/arch/arm64/mm/extable.c
@@ -8,8 +8,33 @@
 #include <linux/uaccess.h>
 
 #include <asm/asm-extable.h>
+#include <asm/esr.h>
 #include <asm/ptrace.h>
 
+static bool cpy_faulted_on_uaccess(const struct exception_table_entry *ex,
+				   unsigned long esr)
+{
+	bool uaccess_is_write = FIELD_GET(EX_DATA_UACCESS_WRITE, ex->data);
+	bool fault_on_write = esr & ESR_ELx_WNR;
+
+	return uaccess_is_write == fault_on_write;
+}
+
+bool insn_may_access_user(unsigned long addr, unsigned long esr)
+{
+	const struct exception_table_entry *ex = search_exception_tables(addr);
+
+	if (!ex)
+		return false;
+
+	switch (ex->type) {
+	case EX_TYPE_UACCESS_CPY:
+		return cpy_faulted_on_uaccess(ex, esr);
+	default:
+		return true;
+	}
+}
+
 static inline unsigned long
 get_ex_fixup(const struct exception_table_entry *ex)
 {
@@ -29,6 +54,17 @@ static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
 	return true;
 }
 
+static bool ex_handler_uaccess_cpy(const struct exception_table_entry *ex,
+				   struct pt_regs *regs, unsigned long esr)
+{
+	/* Do not fix up faults on kernel memory accesses */
+	if (!cpy_faulted_on_uaccess(ex, esr))
+		return false;
+
+	regs->pc = get_ex_fixup(ex);
+	return true;
+}
+
 static bool
 ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
 				  struct pt_regs *regs)
@@ -56,7 +92,7 @@ ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
 	return true;
 }
 
-bool fixup_exception(struct pt_regs *regs)
+bool fixup_exception(struct pt_regs *regs, unsigned long esr)
 {
 	const struct exception_table_entry *ex;
 
@@ -70,6 +106,8 @@ bool fixup_exception(struct pt_regs *regs)
 	case EX_TYPE_UACCESS_ERR_ZERO:
 	case EX_TYPE_KACCESS_ERR_ZERO:
 		return ex_handler_uaccess_err_zero(ex, regs);
+	case EX_TYPE_UACCESS_CPY:
+		return ex_handler_uaccess_cpy(ex, regs, esr);
 	case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
 		return ex_handler_load_unaligned_zeropad(ex, regs);
 	}