On Thu, 16 Mar 2017 08:56:28 -0500 Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > Paul Menzel reported a warning: > > WARNING: CPU: 0 PID: 774 at /build/linux-ROBWaj/linux-4.9.13/kernel/trace/trace_functions_graph.c:233 ftrace_return_to_handler+0x1aa/0x1e0 > Bad frame pointer: expected f6919d98, received f6919db0 > from func acpi_pm_device_sleep_wake return to c43b6f9d > > The warning means that function graph tracing is broken for the > acpi_pm_device_sleep_wake() function. That's because the acpi Makefile > unconditionally sets the '-Os' gcc flag to optimize for size. That's an > issue because mcount-based function graph tracing is incompatible with > '-Os' on x86, thanks to the following gcc bug: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109 > > I have another patch pending which will ensure that mcount-based > function graph tracing is never used with CONFIG_CC_OPTIMIZE_FOR_SIZE on > x86. > > But this patch is needed in addition to that one because the ACPI > Makefile overrides that config option for no apparent reason. It has > had this flag since the beginning of git history, and there's no related > comment, so I don't know why it's there. As far as I can tell, there's > no reason for it to be there. The appropriate behavior is for it to > honor CONFIG_CC_OPTIMIZE_FOR_{SIZE,PERFORMANCE} like the rest of the > kernel. > > Reported-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx> > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > --- > drivers/acpi/Makefile | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile > index a391bbc..d94f92f 100644 > --- a/drivers/acpi/Makefile > +++ b/drivers/acpi/Makefile > @@ -2,7 +2,6 @@ > # Makefile for the Linux ACPI interpreter > # > > -ccflags-y := -Os Unless somebody can come up with a real reason to have this, Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> -- Steve > ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT > > # -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
