On Mon, Jul 27, 2020 at 09:05:59AM -0700, Nathan Chancellor wrote:
On Mon, Jul 27, 2020 at 03:07:57PM +0200, gregkh@linuxfoundation.org wrote:
The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ca9b31f6bb9c6aa9b4e5f0792f39a97bbffb8c51 Mon Sep 17 00:00:00 2001 From: Fangrui Song maskray@google.com Date: Tue, 21 Jul 2020 10:31:23 -0700 Subject: [PATCH] Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross compilation
When CROSS_COMPILE is set (e.g. aarch64-linux-gnu-), if $(CROSS_COMPILE)elfedit is found at /usr/bin/aarch64-linux-gnu-elfedit, GCC_TOOLCHAIN_DIR will be set to /usr/bin/. --prefix= will be set to /usr/bin/ and Clang as of 11 will search for both $(prefix)aarch64-linux-gnu-$needle and $(prefix)$needle.
GCC searchs for $(prefix)aarch64-linux-gnu/$version/$needle, $(prefix)aarch64-linux-gnu/$needle and $(prefix)$needle. In practice, $(prefix)aarch64-linux-gnu/$needle rarely contains executables.
To better model how GCC's -B/--prefix takes in effect in practice, newer Clang (since https://github.com/llvm/llvm-project/commit/3452a0d8c17f7166f479706b293caf6a...) only searches for $(prefix)$needle. Currently it will find /usr/bin/as instead of /usr/bin/aarch64-linux-gnu-as.
Set --prefix= to $(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) (/usr/bin/aarch64-linux-gnu-) so that newer Clang can find the appropriate cross compiling GNU as (when -no-integrated-as is in effect).
Cc: stable@vger.kernel.org Reported-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Fangrui Song maskray@google.com Reviewed-by: Nathan Chancellor natechancellor@gmail.com Tested-by: Nathan Chancellor natechancellor@gmail.com Tested-by: Nick Desaulniers ndesaulniers@google.com Link: https://github.com/ClangBuiltLinux/linux/issues/1099 Reviewed-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Masahiro Yamada masahiroy@kernel.org
diff --git a/Makefile b/Makefile index 676f1cfb1d56..9d9d4166c0be 100644 --- a/Makefile +++ b/Makefile @@ -567,7 +567,7 @@ ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),) ifneq ($(CROSS_COMPILE),) CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) -CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR) +CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) endif ifneq ($(GCC_TOOLCHAIN),)
Patch attached.
Now queued up, thanks!
greg k-h