Re: [PATCH v3 01/60] arm64: kernel: Disable latent_entropy GCC plugin in early C runtime

Mark Rutland
2023-04-28T10:39:52Z

On Tue, Mar 07, 2023 at 03:04:23PM +0100, Ard Biesheuvel wrote:
> Avoid build issues in the early C code related to the latent_entropy GCC
> plugin, by incorporating the C flags fragment that disables it.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Just to check, are you seeing issues today? IIUC the plugin only instruments
functions which are explicitly marked with __latent_entropy, and if we're
seeing that happen unexpectedly (or due to that being applying to __meminit /
__init), we might need to do likewise for other noinstr code.

Regardless, for this patch:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
> arch/arm64/kernel/pi/Makefile | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/kernel/pi/Makefile b/arch/arm64/kernel/pi/Makefile
> index 4c0ea3cd4ea406b6..c844a0546d7f0e62 100644
> --- a/arch/arm64/kernel/pi/Makefile
> +++ b/arch/arm64/kernel/pi/Makefile
> @@ -3,6 +3,7 @@
>
> KBUILD_CFLAGS := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) -fpie \
> -Os -DDISABLE_BRANCH_PROFILING $(DISABLE_STACKLEAK_PLUGIN) \
> + $(DISABLE_LATENT_ENTROPY_PLUGIN) \
> $(call cc-option,-mbranch-protection=none) \
> -I$(srctree)/scripts/dtc/libfdt -fno-stack-protector \
> -include $(srctree)/include/linux/hidden.h \
> --
> 2.39.2
>
>