Merge branch 'akpm' (patches from Andrew)

[cascardo/linux.git] / arch / arm64 / mm / fault.c

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 97135b6..95df28b 100644 (file)
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -192,6 +192,14 @@ out:
        return fault;
 }
 
+static inline int permission_fault(unsigned int esr)
+{
+       unsigned int ec       = (esr & ESR_ELx_EC_MASK) >> ESR_ELx_EC_SHIFT;
+       unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
+
+       return (ec == ESR_ELx_EC_DABT_CUR && fsc_type == ESR_ELx_FSC_PERM);
+}
+
 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
                                   struct pt_regs *regs)
 {
@@ -225,12 +233,13 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
                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 (permission_fault(esr) && (addr < USER_DS)) {
+               if (get_fs() == KERNEL_DS)
+                       die("Accessing user space memory with fs=KERNEL_DS", 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
@@ -568,3 +577,16 @@ void cpu_enable_pan(void *__unused)
        config_sctlr_el1(SCTLR_EL1_SPAN, 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.
+ */
+void cpu_enable_uao(void *__unused)
+{
+       asm(SET_PSTATE_UAO(1));
+}
+#endif /* CONFIG_ARM64_UAO */