From 4a6d70c9505fef1d8906b1d61db3de5d8ecf9454 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 24 Apr 2012 16:31:07 -0400 Subject: ftrace/x86: Remove the complex ftrace NMI handling code As ftrace function tracing would require modifying code that could be executed in NMI context, which is not stopped with stop_machine(), ftrace had to do a complex algorithm with various stages of setup and memory barriers to make it work. With the new breakpoint method, this is no longer required. The changes to the code can be done without any problem in NMI context, as well as without stop machine altogether. Remove the complex code as it is no longer needed. Also, a lot of the notrace annotations could be removed from the NMI code as it is now safe to trace them. With the exception of do_nmi itself, which does some special work to handle running in the debug stack. The breakpoint method can cause NMIs to double nest the debug stack if it's not setup properly, and that is done in do_nmi(), thus that function must not be traced. (Note the arch sh may want to do the same) Cc: Paul Mundt Cc: H. Peter Anvin Signed-off-by: Steven Rostedt --- arch/x86/Kconfig | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/x86/Kconfig') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 1d14cc6b79a..1324139612e 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -40,7 +40,6 @@ config X86 select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_GRAPH_FP_TEST select HAVE_FUNCTION_TRACE_MCOUNT_TEST - select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE select HAVE_SYSCALL_TRACEPOINTS select HAVE_KVM select HAVE_ARCH_KGDB -- cgit v1.2.3-70-g09d2