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    Subject[PATCH AUTOSEL 6.2 21/53] ACPI: Don't build ACPICA with '-Os'
    Date
    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 9e0d95d76fff7..30f3fc13c29d1 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
    --
    2.39.0
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