ptrace,x86: force IRET path after a ptrace_stop()

[jlayton/linux.git] / arch / x86 / include / asm / ptrace.h

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 14fd6fd75a19b8d62c983e7120fadbf151eb5043..6205f0c434dbabcb72f7135821c614420904c1da 100644 (file)
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -231,6 +231,22 @@ static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 
 #define ARCH_HAS_USER_SINGLE_STEP_INFO
 
+/*
+ * When hitting ptrace_stop(), we cannot return using SYSRET because
+ * that does not restore the full CPU state, only a minimal set.  The
+ * ptracer can change arbitrary register values, which is usually okay
+ * because the usual ptrace stops run off the signal delivery path which
+ * forces IRET; however, ptrace_event() stops happen in arbitrary places
+ * in the kernel and don't force IRET path.
+ *
+ * So force IRET path after a ptrace stop.
+ */
+#define arch_ptrace_stop_needed(code, info)                            \
+({                                                                     \
+       set_thread_flag(TIF_NOTIFY_RESUME);                             \
+       false;                                                          \
+})
+
 struct user_desc;
 extern int do_get_thread_area(struct task_struct *p, int idx,
                              struct user_desc __user *info);