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Date:   Wed, 13 May 2020 20:01:49 -0700
From:   Nathan Chancellor <natechancellor@gmail.com>
To:     kbuild test robot <lkp@intel.com>
Cc:     kbuild-all@lists.01.org, clang-built-linux@googlegroups.com,
        linux-kernel@vger.kernel.org, Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: ld.lld: error: undefined symbol: kb_cs
Message-ID: <20200514030149.GA1841966@ubuntu-s3-xlarge-x86>
References: <202005140845.lthaPgxR%lkp@intel.com>
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On Thu, May 14, 2020 at 08:13:48AM +0800, kbuild test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   24085f70a6e1b0cb647ec92623284641d8270637
> commit: 5990cdee689c6885b27c6d969a3d58b09002b0bc lib/mpi: Fix building for powerpc with clang

I am certain that this patch did nothing to cause this... Maybe exposed
it but not the root cause.

> date:   3 weeks ago
> config: powerpc-randconfig-r034-20200514 (attached as .config)
> compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 310d32cb80a611e6384a921e85607fea05841f26)
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install powerpc cross compiling tool for clang build
>         # apt-get install binutils-powerpc-linux-gnu
>         git checkout 5990cdee689c6885b27c6d969a3d58b09002b0bc
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
> >> ld.lld: error: undefined symbol: kb_cs
> >>> referenced by i8042-ppcio.h:28 (drivers/input/serio/i8042-ppcio.h:28)
> >>> input/serio/i8042.o:(__i8042_command) in archive drivers/built-in.a
> >>> referenced by i8042-ppcio.h:28 (drivers/input/serio/i8042-ppcio.h:28)
> >>> input/serio/i8042.o:(__i8042_command) in archive drivers/built-in.a
> >>> referenced by i8042-ppcio.h:28 (drivers/input/serio/i8042-ppcio.h:28)
> >>> input/serio/i8042.o:(__i8042_command) in archive drivers/built-in.a
> >>> referenced 45 more times
> --
> >> ld.lld: error: undefined symbol: kb_data
> >>> referenced by i8042.c:309 (drivers/input/serio/i8042.c:309)
> >>> input/serio/i8042.o:(__i8042_command) in archive drivers/built-in.a
> >>> referenced by i8042-ppcio.h:33 (drivers/input/serio/i8042-ppcio.h:33)
> >>> input/serio/i8042.o:(__i8042_command) in archive drivers/built-in.a
> >>> referenced by i8042.c:319 (drivers/input/serio/i8042.c:319)
> >>> input/serio/i8042.o:(__i8042_command) in archive drivers/built-in.a
> >>> referenced 15 more times

kb_cs and kb_data are declared as extern void pointers when
CONFIG_WALNUT is set, which this config does. However, it looks like
the definitions of these variables were removed in
commit  917f0af9e5a9 ("powerpc: Remove arch/ppc and include/asm-ppc"),
way back in 2.6.27-rc1... So presumably, this has been broken for 12
years and nobody noticed? Probably means there is a good amount of dead
code that can be removed, or we could just avoid ever selecting this
driver with CONFIG_WALNUT (if it does not actually work without the
special handling from i8042-ppcio.h) while removing the dead code.

Cheers,
Nathan

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 924c541a9260..59b2f655e39e 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -138,7 +138,7 @@ config PPC
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_KEEP_MEMBLOCK
 	select ARCH_MIGHT_HAVE_PC_PARPORT
-	select ARCH_MIGHT_HAVE_PC_SERIO
+	select ARCH_MIGHT_HAVE_PC_SERIO if !WALNUT
 	select ARCH_OPTIONAL_KERNEL_RWX		if ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_USE_BUILTIN_BSWAP
diff --git a/drivers/input/serio/i8042-ppcio.h b/drivers/input/serio/i8042-ppcio.h
deleted file mode 100644
index 391f94d9e47d..000000000000
--- a/drivers/input/serio/i8042-ppcio.h
+++ /dev/null
@@ -1,57 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-#ifndef _I8042_PPCIO_H
-#define _I8042_PPCIO_H
-
-
-#if defined(CONFIG_WALNUT)
-
-#define I8042_KBD_IRQ 25
-#define I8042_AUX_IRQ 26
-
-#define I8042_KBD_PHYS_DESC "walnutps2/serio0"
-#define I8042_AUX_PHYS_DESC "walnutps2/serio1"
-#define I8042_MUX_PHYS_DESC "walnutps2/serio%d"
-
-extern void *kb_cs;
-extern void *kb_data;
-
-#define I8042_COMMAND_REG (*(int *)kb_cs)
-#define I8042_DATA_REG (*(int *)kb_data)
-
-static inline int i8042_read_data(void)
-{
-	return readb(kb_data);
-}
-
-static inline int i8042_read_status(void)
-{
-	return readb(kb_cs);
-}
-
-static inline void i8042_write_data(int val)
-{
-	writeb(val, kb_data);
-}
-
-static inline void i8042_write_command(int val)
-{
-	writeb(val, kb_cs);
-}
-
-static inline int i8042_platform_init(void)
-{
-	i8042_reset = I8042_RESET_ALWAYS;
-	return 0;
-}
-
-static inline void i8042_platform_exit(void)
-{
-}
-
-#else
-
-#include "i8042-io.h"
-
-#endif
-
-#endif /* _I8042_PPCIO_H */
diff --git a/drivers/input/serio/i8042.h b/drivers/input/serio/i8042.h
index 38dc27ad3c18..eb376700dfff 100644
--- a/drivers/input/serio/i8042.h
+++ b/drivers/input/serio/i8042.h
@@ -17,8 +17,6 @@
 #include "i8042-ip22io.h"
 #elif defined(CONFIG_SNI_RM)
 #include "i8042-snirm.h"
-#elif defined(CONFIG_PPC)
-#include "i8042-ppcio.h"
 #elif defined(CONFIG_SPARC)
 #include "i8042-sparcio.h"
 #elif defined(CONFIG_X86) || defined(CONFIG_IA64)