From: Mark Rutland mark.rutland@arm.com
[ Upstream commit 8f9e0a52810dd83406c768972d022c37e7a18f1f ]
The ACPICA code has been built with '-Os' since the beginning of git history, though there's no explanatory comment as to why.
This is unfortunate as GCC drops the alignment specificed by '-falign-functions=N' when '-Os' is used, as reported in GCC bug 88345:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345
This prevents CONFIG_FUNCTION_ALIGNMENT and CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B from having their expected effect on the ACPICA code. This is doubly unfortunate as in subsequent patches arm64 will depend upon CONFIG_FUNCTION_ALIGNMENT for its ftrace implementation.
Drop the '-Os' flag when building the ACPICA code. With this removed, the code builds cleanly and works correctly in testing so far.
I've tested this by selecting CONFIG_DEBUG_FORCE_FUNCTION_ALIGN_64B=y, building and booting a kernel using ACPI, and looking for misaligned text symbols:
* arm64:
Before, v6.2-rc3: # uname -rm 6.2.0-rc3 aarch64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 5009
Before, v6.2-rc3 + fixed __cold: # uname -rm 6.2.0-rc3-00001-g2a2bedf8bfa9 aarch64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 919
After: # uname -rm 6.2.0-rc3-00002-g267bddc38572 aarch64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 323 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | grep acpi | wc -l 0
* x86_64:
Before, v6.2-rc3: # uname -rm 6.2.0-rc3 x86_64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 11537
Before, v6.2-rc3 + fixed __cold: # uname -rm 6.2.0-rc3-00001-g2a2bedf8bfa9 x86_64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 2805
After: # uname -rm 6.2.0-rc3-00002-g267bddc38572 x86_64 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | wc -l 1357 # grep ' [Tt] ' /proc/kallsyms | grep -iv '[048c]0 [Tt] ' | grep acpi | wc -l 0
With the patch applied, the remaining unaligned text labels are a combination of static call trampolines and labels in assembly, which can be dealt with in subsequent patches.
Signed-off-by: Mark Rutland mark.rutland@arm.com Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Cc: Florent Revest revest@chromium.org Cc: Len Brown lenb@kernel.org Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Robert Moore robert.moore@intel.com Cc: Steven Rostedt rostedt@goodmis.org Cc: Will Deacon will@kernel.org Cc: linux-acpi@vger.kernel.org Link: https://lore.kernel.org/r/20230123134603.1064407-4-mark.rutland@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/acpica/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/acpi/acpica/Makefile b/drivers/acpi/acpica/Makefile index e05232da05888..1e8e4e7a29cb3 100644 --- a/drivers/acpi/acpica/Makefile +++ b/drivers/acpi/acpica/Makefile @@ -3,7 +3,7 @@ # Makefile for ACPICA Core interpreter #
-ccflags-y := -Os -D_LINUX -DBUILDING_ACPICA +ccflags-y := -D_LINUX -DBUILDING_ACPICA ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT
# use acpi.o to put all files here into acpi.o modparam namespace