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Subject: Re: drivers/infiniband/core/.tmp_gl_uverbs_main.o:undefined reference
 to `__user_bad'
From:   Randy Dunlap <rdunlap@infradead.org>
To:     kbuild test robot <lkp@intel.com>,
        Jason Gunthorpe <jgg@mellanox.com>
Cc:     kbuild-all@01.org, linux-kernel@vger.kernel.org,
        Leon Romanovsky <leonro@mellanox.com>,
        Michal Simek <monstr@monstr.eu>
References: <201902281750.jbpT0s0R%fengguang.wu@intel.com>
 <646013c8-5fcd-e7ab-0a87-3e0620563dfb@infradead.org>
Message-ID: <f19db95e-be92-302c-2aef-19c4f3f5c8b0@infradead.org>
Date:   Sun, 4 Aug 2019 21:50:50 -0700
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On 4/2/19 7:38 PM, Randy Dunlap wrote:
> On 2/28/19 1:03 AM, kbuild test robot wrote:
>> Hi Jason,
>>
>> FYI, the error/warning still remains.
>>
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> head:   7d762d69145a54d169f58e56d6dac57a5508debc
>> commit: 3a6532c9af1a7836da2d597f1aaca73cb16c3b97 RDMA/uverbs: Use uverbs_attr_bundle to pass udata for write
>> date:   3 months ago
>> config: microblaze-allyesconfig (attached as .config)
>> compiler: microblaze-linux-gcc (GCC) 8.2.0
>> reproduce:
>>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>         chmod +x ~/bin/make.cross
>>         git checkout 3a6532c9af1a7836da2d597f1aaca73cb16c3b97
>>         # save the attached .config to linux build tree
>>         GCC_VERSION=8.2.0 make.cross ARCH=microblaze 
>>
>> All errors (new ones prefixed by >>):
>>
>>    `.exit.data' referenced in section `.exit.text' of drivers/tty/n_hdlc.o: defined in discarded section `.exit.data' of drivers/tty/n_hdlc.o
>>    `.exit.data' referenced in section `.exit.text' of drivers/tty/n_hdlc.o: defined in discarded section `.exit.data' of drivers/tty/n_hdlc.o
>>    drivers/infiniband/core/uverbs_main.o: In function `ib_uverbs_write':
>>>> drivers/infiniband/core/.tmp_gl_uverbs_main.o:(.text+0x13a4): undefined reference to `__user_bad'
>>    drivers/android/binder.o: In function `binder_thread_write':
>>    drivers/android/.tmp_gl_binder.o:(.text+0xda6c): undefined reference to `__user_bad'
>>    drivers/android/.tmp_gl_binder.o:(.text+0xda98): undefined reference to `__user_bad'
>>    drivers/android/.tmp_gl_binder.o:(.text+0xdf10): undefined reference to `__user_bad'
>>    drivers/android/.tmp_gl_binder.o:(.text+0xe498): undefined reference to `__user_bad'
>>    drivers/android/binder.o:drivers/android/.tmp_gl_binder.o:(.text+0xea78): more undefined references to `__user_bad' follow
>>
>> ---
>> 0-DAY kernel test infrastructure                Open Source Technology Center
>> https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
> 
> Hi Michal,
> 
> Would you comment on this, please?

[crickets]

> Jason has said more than once that these build errors are because
> arch/microblaze does not support get_user() of size 8 (bytes),
> although it does support a put_user() of size 8.
> 
> 
> See a previous report & comment at
> https://lore.kernel.org/lkml/20190101200742.GA5757@mellanox.com/
> 
> 
> thanks.

I currently don't have a cross-build environment set up, so I haven't
built this yet, but a patch like this might fix this nagging issue.

(It's clearly not high priority since arch/microblaze/ mostly seems to be
not well-maintained.)

---
From: Randy Dunlap <rdunlap@infradead.org>

arch/microblaze/ is missing support for get_user() of size 8 bytes,
so add it by using __copy_from_user().

Fixes these build errors:
   drivers/infiniband/core/uverbs_main.o: In function `ib_uverbs_write':
   drivers/infiniband/core/.tmp_gl_uverbs_main.o:(.text+0x13a4): undefined reference to `__user_bad'
   drivers/android/binder.o: In function `binder_thread_write':
   drivers/android/.tmp_gl_binder.o:(.text+0xda6c): undefined reference to `__user_bad'
   drivers/android/.tmp_gl_binder.o:(.text+0xda98): undefined reference to `__user_bad'
   drivers/android/.tmp_gl_binder.o:(.text+0xdf10): undefined reference to `__user_bad'
   drivers/android/.tmp_gl_binder.o:(.text+0xe498): undefined reference to `__user_bad'
   drivers/android/binder.o:drivers/android/.tmp_gl_binder.o:(.text+0xea78): more undefined references to `__user_bad' follow

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
---
 arch/microblaze/include/asm/uaccess.h |    6 ++++++
 1 file changed, 6 insertions(+)

--- lnx-53-rc3.orig/arch/microblaze/include/asm/uaccess.h
+++ lnx-53-rc3/arch/microblaze/include/asm/uaccess.h
@@ -186,6 +186,9 @@ extern long __user_bad(void);
 			__get_user_asm("lw", __gu_addr, __gu_val,	\
 				       __gu_err);			\
 			break;						\
+		case 8:							\
+			__gu_err = __copy_from_user(&__gu_val, __gu_addr, 8);\
+			break;						\
 		default:						\
 			__gu_err = __user_bad();			\
 			break;						\
@@ -212,6 +215,9 @@ extern long __user_bad(void);
 	case 4:								\
 		__get_user_asm("lw", (ptr), __gu_val, __gu_err);	\
 		break;							\
+	case 8:								\
+		__gu_err = __copy_from_user(&__gu_val, ptr, 8);		\
+		break;							\
 	default:							\
 		/* __gu_val = 0; __gu_err = -EINVAL;*/ __gu_err = __user_bad();\
 	}								\