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From: Nathan Chancellor <natechancellor@gmail.com>
To: gregkh@linuxfoundation.org
Cc: maskray@google.com, masahiroy@kernel.org,
	ndesaulniers@google.com, stable@vger.kernel.org
Subject: Re: FAILED: patch "[PATCH] Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross" failed to apply to 4.4-stable tree
Date: Mon, 27 Jul 2020 09:05:59 -0700	[thread overview]
Message-ID: <20200727160559.GA1386610@ubuntu-n2-xlarge-x86> (raw)
In-Reply-To: <159585527713469@kroah.com>

[-- Attachment #1: Type: text/plain, Size: 2799 bytes --]

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/3452a0d8c17f7166f479706b293caf6ac76ffd90)
> 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.

Cheers,
Nathan

[-- Attachment #2: 0001-Makefile-Fix-GCC_TOOLCHAIN_DIR-prefix-for-Clang-cros.patch --]
[-- Type: text/x-diff, Size: 2523 bytes --]

From daab2c7d8578f450e6f96b72f01c85abcb46e525 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Tue, 21 Jul 2020 10:31:23 -0700
Subject: [PATCH 4.4] Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross
 compilation

commit ca9b31f6bb9c6aa9b4e5f0792f39a97bbffb8c51 upstream.

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/3452a0d8c17f7166f479706b293caf6ac76ffd90)
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>
[nc: Adjust context, CLANG_FLAGS does not exist in 4.4]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 46178c83906c..de97963888fc 100644
--- a/Makefile
+++ b/Makefile
@@ -607,7 +607,7 @@ ifeq ($(cc-name),clang)
 ifneq ($(CROSS_COMPILE),)
 CLANG_TARGET	:= --target=$(notdir $(CROSS_COMPILE:%-=%))
 GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
-CLANG_PREFIX	:= --prefix=$(GCC_TOOLCHAIN_DIR)
+CLANG_PREFIX	:= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
 GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
 endif
 ifneq ($(GCC_TOOLCHAIN),)

base-commit: 554bbfc0d87fcbc842a18997c2a11a772dc3f003
-- 
2.28.0.rc1


  reply	other threads:[~2020-07-27 16:06 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-27 13:07 FAILED: patch "[PATCH] Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross" failed to apply to 4.4-stable tree gregkh
2020-07-27 16:05 ` Nathan Chancellor [this message]
2020-07-29 11:53   ` Greg KH

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