Date:   Wed, 24 Jun 2020 18:45:47 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Richard Weinberger <richard.weinberger@...il.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Richard Weinberger <richard@....at>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Prasad Sodagudi <psodagud@...eaurora.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Amit Daniel Kachhap <amit.kachhap@....com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        clang-built-linux@...glegroups.com,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH drivers/misc 0/4] lkdtm: Various clean ups

On 6/24/20 3:35 PM, Randy Dunlap wrote:
> On 6/24/20 3:23 PM, Randy Dunlap wrote:
>> On 6/24/20 3:01 PM, Richard Weinberger wrote:
>>> On Wed, Jun 24, 2020 at 11:29 PM Randy Dunlap <rdunlap@...radead.org> wrote:
>>>>
>>>> On 6/24/20 1:36 PM, Kees Cook wrote:
>>>>> On Wed, Jun 24, 2020 at 09:23:25AM +0200, Richard Weinberger wrote:
>>>>>> ----- Ursprüngliche Mail -----
>>>>>>>>> Regardless, it seems arch/x86/um/asm/desc.h is not needed any more?
>>>>>>>
>>>>>>>> True that, we can rip the file.
>>>>>>>
>>>>>>> Has anyone fixed the uml build errors?
>>>>>>
>>>>>> I didn't realize that this is a super urgent issue. ;-)
>>>>>>
>>>>>> Kees, if you want you can carry a patch in your series, I'll ack it.
>>>>>> Otherwise I can also do a patch and bring it via the uml tree upstream
>>>>>> as soon more fixes queued up.
>>>>>
>>>>> I think the lkdtm change will tweak this bug, so I'm happy to carry the
>>>>> patch (I just haven't had time to create and test one). Is it really
>>>>> just as simple as removing arch/x86/um/asm/desc.h?
>>>>>
>>>>
>>>> I just tried that and the build is still failing, so No, it's not that simple.
>>>>
>>>> But thanks for offering.
>>>>
>>>> I'll just ignore the UML build errors for now.
>>>
>>> This is a allyesconfig?
>>> I just gave CONFIG_LKDTM=y a try, builds fine here.
>>>
>>
>> I'm building linux-next and it fails.
> 
> More specifically, uml for i386 fails. x86_64 is OK.
> The problem is with the <asm/desc.h> file.
> I'm tampering with it...

I'm not getting anywhere with this. Too many mazes of tiny twisty passages.

>>> But the desc.h in uml is still in vain and can be deleted AFAICT.

Looks like lkdtm/bugs.c needs to get/use arch/x86/include/asm/processor.h
but it actually uses arch/x86/um/asm/processor*.h, which does not have the
needed structs etc.


Here are the build errors and warnings that I am seeing with allmodconfig:


  CC [M]  drivers/misc/lkdtm/bugs.o
In file included from ../arch/x86/include/asm/desc.h:11:0,
                 from ../drivers/misc/lkdtm/bugs.c:17:
../arch/x86/include/asm/cpu_entry_area.h:65:42: error: invalid application of ‘sizeof’ to incomplete type ‘struct x86_hw_tss’
  unsigned long stack[(PAGE_SIZE - sizeof(struct x86_hw_tss)) / sizeof(unsigned long)];
                                          ^~~~~~
../arch/x86/include/asm/cpu_entry_area.h:66:20: error: field ‘tss’ has incomplete type
  struct x86_hw_tss tss;
                    ^~~
../arch/x86/include/asm/cpu_entry_area.h:89:26: error: field ‘entry_stack_page’ has incomplete type
  struct entry_stack_page entry_stack_page;
                          ^~~~~~~~~~~~~~~~
../arch/x86/include/asm/cpu_entry_area.h:100:20: error: field ‘tss’ has incomplete type
  struct tss_struct tss;
                    ^~~
In file included from ../drivers/misc/lkdtm/bugs.c:17:0:
../arch/x86/include/asm/desc.h:45:25: error: ‘GDT_ENTRIES’ undeclared here (not in a function); did you mean ‘LDT_ENTRIES’?
  struct desc_struct gdt[GDT_ENTRIES];
                         ^~~~~~~~~~~
                         LDT_ENTRIES
../arch/x86/include/asm/desc.h: In function ‘__set_tss_desc’:
../arch/x86/include/asm/desc.h:186:10: error: ‘__KERNEL_TSS_LIMIT’ undeclared (first use in this function); did you mean ‘__KERNEL__’?
          __KERNEL_TSS_LIMIT);
          ^~~~~~~~~~~~~~~~~~
          __KERNEL__
../arch/x86/include/asm/desc.h:186:10: note: each undeclared identifier is reported only once for each function it appears in
../arch/x86/include/asm/desc.h: In function ‘native_set_ldt’:
../arch/x86/include/asm/desc.h:202:40: error: ‘GDT_ENTRY_LDT’ undeclared (first use in this function); did you mean ‘GDT_ENTRY_INIT’?
   write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_LDT,
                                        ^
../arch/x86/include/asm/desc.h:123:75: note: in definition of macro ‘write_gdt_entry’
 #define write_gdt_entry(dt, entry, desc, type) native_write_gdt_entry(dt, entry, desc, type)
                                                                           ^~~~~
../arch/x86/include/asm/desc.h: In function ‘native_load_tr_desc’:
../arch/x86/include/asm/desc.h:259:31: error: ‘GDT_ENTRY_TSS’ undeclared (first use in this function); did you mean ‘GDT_ENTRIES’?
  asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));
                               ^~~~~~~~~~~~~
                               GDT_ENTRIES
../arch/x86/include/asm/desc.h: In function ‘native_load_tls’:
../arch/x86/include/asm/desc.h:278:33: error: ‘struct thread_struct’ has no member named ‘tls_array’
   gdt[GDT_ENTRY_TLS_MIN + i] = t->tls_array[i];
                                 ^~
In file included from ../arch/x86/include/asm/string.h:3:0,
                 from ../include/linux/string.h:20,
                 from ../arch/x86/um/asm/processor_32.h:9,
                 from ../arch/x86/um/asm/processor.h:10,
                 from ../include/linux/rcupdate.h:30,
                 from ../include/linux/rculist.h:11,
                 from ../include/linux/pid.h:5,
                 from ../include/linux/sched.h:14,
                 from ../drivers/misc/lkdtm/bugs.c:10:
../arch/x86/include/asm/desc.h: In function ‘force_reload_TR’:
../arch/x86/include/asm/desc.h:288:18: error: ‘GDT_ENTRY_TSS’ undeclared (first use in this function); did you mean ‘GDT_ENTRIES’?
  memcpy(&tss, &d[GDT_ENTRY_TSS], sizeof(tss_desc));
                  ^
../arch/x86/include/asm/string_32.h:182:45: note: in definition of macro ‘memcpy’
 #define memcpy(t, f, n) __builtin_memcpy(t, f, n)
                                             ^
In file included from ../include/linux/kernel.h:11:0,
                 from ../drivers/misc/lkdtm/lkdtm.h:7,
                 from ../drivers/misc/lkdtm/bugs.c:8:
../arch/x86/include/asm/desc.h: In function ‘invalidate_tss_limit’:
../arch/x86/include/asm/desc.h:327:32: error: ‘TIF_IO_BITMAP’ undeclared (first use in this function); did you mean ‘CONFIG_SBITMAP’?
  if (unlikely(test_thread_flag(TIF_IO_BITMAP)))
                                ^
../include/linux/compiler.h:78:42: note: in definition of macro ‘unlikely’
 # define unlikely(x) __builtin_expect(!!(x), 0)
                                          ^
../arch/x86/include/asm/desc.h:327:15: note: in expansion of macro ‘test_thread_flag’
  if (unlikely(test_thread_flag(TIF_IO_BITMAP)))
               ^~~~~~~~~~~~~~~~
In file included from ../drivers/misc/lkdtm/bugs.c:17:0:
../arch/x86/include/asm/desc.h: At top level:
../arch/x86/include/asm/desc.h:334:0: warning: "LDT_empty" redefined
 #define LDT_empty(info)     \
 
In file included from ../arch/um/include/asm/mmu.h:10:0,
                 from ../include/linux/mm_types.h:18,
                 from ../include/linux/sched/signal.h:13,
                 from ../drivers/misc/lkdtm/bugs.c:11:
../arch/x86/um/asm/mm_context.h:65:0: note: this is the location of the previous definition
 #define LDT_empty(info) (_LDT_empty(info))
 
In file included from ../drivers/misc/lkdtm/bugs.c:17:0:
../arch/x86/include/asm/desc.h: In function ‘get_cpu_gdt_rw’:
../arch/x86/include/asm/desc.h:54:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^


-- 
~Randy
Reported-by: Randy Dunlap <rdunlap@...radead.org>

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