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authorJosh Poimboeuf <jpoimboe@redhat.com>2017-03-16 08:56:28 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-04-08 09:53:31 +0200
commit3342857ac074768e14e361392ac09fbbd70d840e (patch)
treeb683382155997a42fe8911a6796133e4a2020bee
parentab48ab614b8c83f3a3b0f83f7882b1d2766962d3 (diff)
ACPI: Fix incompatibility with mcount-based function graph tracing
commit 61b79e16c68d703dde58c25d3935d67210b7d71b upstream. 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> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/acpi/Makefile1
1 files changed, 0 insertions, 1 deletions
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 675eaf337178..b9cebca376f9 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
#