1 files changed, 38 insertions, 8 deletions

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 6de1fd3d0097..f236bcd5485d 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -37,8 +37,10 @@ struct pt_regs {
 	unsigned short __esh;
 	unsigned short fs;
 	unsigned short __fsh;
+	/* On interrupt, gs and __gsh store the vector number. */
 	unsigned short gs;
 	unsigned short __gsh;
+	/* On interrupt, this is the error code. */
 	unsigned long orig_ax;
 	unsigned long ip;
 	unsigned short cs;
@@ -144,7 +146,7 @@ static inline int v8086_mode(struct pt_regs *regs)
 static inline bool user_64bit_mode(struct pt_regs *regs)
 {
 #ifdef CONFIG_X86_64
-#ifndef CONFIG_PARAVIRT
+#ifndef CONFIG_PARAVIRT_XXL
 	/*
 	 * On non-paravirt systems, this is the only long mode CPL 3
 	 * selector.  We do not allow long mode selectors in the LDT.
@@ -237,23 +239,51 @@ static inline int regs_within_kernel_stack(struct pt_regs *regs,
 }
 
 /**
+ * regs_get_kernel_stack_nth_addr() - get the address of the Nth entry on stack
+ * @regs:	pt_regs which contains kernel stack pointer.
+ * @n:		stack entry number.
+ *
+ * regs_get_kernel_stack_nth() returns the address of the @n th entry of the
+ * kernel stack which is specified by @regs. If the @n th entry is NOT in
+ * the kernel stack, this returns NULL.
+ */
+static inline unsigned long *regs_get_kernel_stack_nth_addr(struct pt_regs *regs, unsigned int n)
+{
+	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
+
+	addr += n;
+	if (regs_within_kernel_stack(regs, (unsigned long)addr))
+		return addr;
+	else
+		return NULL;
+}
+
+/* To avoid include hell, we can't include uaccess.h */
+extern long probe_kernel_read(void *dst, const void *src, size_t size);
+
+/**
  * regs_get_kernel_stack_nth() - get Nth entry of the stack
  * @regs:	pt_regs which contains kernel stack pointer.
  * @n:		stack entry number.
  *
  * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
- * is specified by @regs. If the @n th entry is NOT in the kernel stack,
+ * is specified by @regs. If the @n th entry is NOT in the kernel stack
  * this returns 0.
  */
 static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 						      unsigned int n)
 {
-	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
-	addr += n;
-	if (regs_within_kernel_stack(regs, (unsigned long)addr))
-		return *addr;
-	else
-		return 0;
+	unsigned long *addr;
+	unsigned long val;
+	long ret;
+
+	addr = regs_get_kernel_stack_nth_addr(regs, n);
+	if (addr) {
+		ret = probe_kernel_read(&val, addr, sizeof(val));
+		if (!ret)
+			return val;
+	}
+	return 0;
 }
 
 #define arch_has_single_step()	(1)