Merge 4.4.163 into android-4.4

[sagit-ice-cold/kernel_xiaomi_msm8998.git] / arch / arm64 / mm / fault.c

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index be7f841..fb987b0 100644 (file)
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -134,6 +134,11 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
 }
 #endif
 
+static bool is_el1_instruction_abort(unsigned int esr)
+{
+       return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
+}
+
 /*
  * The kernel tried to access some page that wasn't present.
  */
@@ -142,8 +147,9 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
 {
        /*
         * Are we prepared to handle this kernel fault?
+        * We are almost certainly not prepared to handle instruction faults.
         */
-       if (fixup_exception(regs))
+       if (!is_el1_instruction_abort(esr) && fixup_exception(regs))
                return;
 
        /*
@@ -205,8 +211,6 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re
 #define VM_FAULT_BADMAP                0x010000
 #define VM_FAULT_BADACCESS     0x020000
 
-#define ESR_LNX_EXEC           (1 << 24)
-
 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
                           unsigned int mm_flags, unsigned long vm_flags,
                           struct task_struct *tsk)
@@ -245,6 +249,26 @@ out:
        return fault;
 }
 
+static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs)
+{
+       unsigned int ec       = ESR_ELx_EC(esr);
+       unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
+
+       if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR)
+               return false;
+
+       if (system_uses_ttbr0_pan())
+               return fsc_type == ESR_ELx_FSC_FAULT &&
+                       (regs->pstate & PSR_PAN_BIT);
+       else
+               return fsc_type == ESR_ELx_FSC_PERM;
+}
+
+static bool is_el0_instruction_abort(unsigned int esr)
+{
+       return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
+}
+
 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
                                   struct pt_regs *regs)
 {
@@ -271,19 +295,24 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
        if (user_mode(regs))
                mm_flags |= FAULT_FLAG_USER;
 
-       if (esr & ESR_LNX_EXEC) {
+       if (is_el0_instruction_abort(esr)) {
                vm_flags = VM_EXEC;
        } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
                vm_flags = VM_WRITE;
                mm_flags |= FAULT_FLAG_WRITE;
        }
 
-       /*
-        * PAN bit set implies the fault happened in kernel space, but not
-        * in the arch's user access functions.
-        */
-       if (IS_ENABLED(CONFIG_ARM64_PAN) && (regs->pstate & PSR_PAN_BIT))
-               goto no_context;
+       if (addr < USER_DS && is_permission_fault(esr, regs)) {
+               /* regs->orig_addr_limit may be 0 if we entered from EL0 */
+               if (regs->orig_addr_limit == KERNEL_DS)
+                       die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
+
+               if (is_el1_instruction_abort(esr))
+                       die("Attempting to execute userspace memory", regs, esr);
+
+               if (!search_exception_tables(regs->pc))
+                       die("Accessing user space memory outside uaccess.h routines", regs, esr);
+       }
 
        /*
         * As per x86, we may deadlock here. However, since the kernel only
@@ -435,7 +464,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
        return 1;
 }
 
-static struct fault_info {
+static const struct fault_info {
        int     (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
        int     sig;
        int     code;
@@ -625,3 +654,17 @@ int cpu_enable_pan(void *__unused)
        return 0;
 }
 #endif /* CONFIG_ARM64_PAN */
+
+#ifdef CONFIG_ARM64_UAO
+/*
+ * Kernel threads have fs=KERNEL_DS by default, and don't need to call
+ * set_fs(), devtmpfs in particular relies on this behaviour.
+ * We need to enable the feature at runtime (instead of adding it to
+ * PSR_MODE_EL1h) as the feature may not be implemented by the cpu.
+ */
+int cpu_enable_uao(void *__unused)
+{
+       asm(SET_PSTATE_UAO(1));
+       return 0;
+}
+#endif /* CONFIG_ARM64_UAO */