Messages in this thread | | | Date | Tue, 21 Mar 2017 21:44:03 +0100 | From | Paul Menzel <> | Subject | Re: [PATCH] acpi: fix incompatibility with mcount-based function graph tracing |
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Dear Josh,
On 2017-03-16 14:56, Josh Poimboeuf 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@molgen.mpg.de> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > --- > 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 > ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT > > #
I checked out Linux 4.9.16, applied your patch on top, and copied the Debian 4.9 Linux kernel configuration, did `make menuconfig`, disabled building debugging symbols, and executed `ARCH=i386 make -j40 deb-pkg`.
I installed that package on the Lenovo X60, and the result with tracing enabled has improved. The system suspends without a crash. Unfortunately, instead of resuming when pressing the power button, it starts from scratch. Suspend and resume without tracing enabled works though.
I’ll try to collect logs, but I don’t know, if there will be any, if the system just resets.
Maybe, this can be reproduced in QEMU?
Kind regards,
Paul
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