Re: [PATCH v3 22/23] powerpc/vdso: Migrate native signals to generic vdso_base

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 17/06/2021 à 08:36, Christophe Leroy a écrit :
> 
> 
> Le 11/06/2021 à 20:02, Dmitry Safonov a écrit :
>> Generic way to track the land vma area.
>> Stat speaks for itself.
>>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Signed-off-by: Dmitry Safonov <dima@arista.com>
> 
> 
> Build failure:
> 
>    CC      arch/powerpc/kernel/asm-offsets.s
> In file included from ./include/linux/mmzone.h:21,
>                   from ./include/linux/gfp.h:6,
>                   from ./include/linux/xarray.h:14,
>                   from ./include/linux/radix-tree.h:19,
>                   from ./include/linux/fs.h:15,
>                   from ./include/linux/compat.h:17,
>                   from arch/powerpc/kernel/asm-offsets.c:14:
> ./include/linux/mm_types.h: In function 'init_vdso_base':
> ./include/linux/mm_types.h:522:28: error: 'TASK_SIZE_MAX' undeclared (first use in this function); 
> did you mean 'XATTR_SIZE_MAX'?
>    522 | #define UNMAPPED_VDSO_BASE TASK_SIZE_MAX
>        |                            ^~~~~~~~~~~~~
> ./include/linux/mm_types.h:627:40: note: in expansion of macro 'UNMAPPED_VDSO_BASE'
>    627 |         mm->vdso_base = (void __user *)UNMAPPED_VDSO_BASE;
>        |                                        ^~~~~~~~~~~~~~~~~~
> ./include/linux/mm_types.h:522:28: note: each undeclared identifier is reported only once for each 
> function it appears in
>    522 | #define UNMAPPED_VDSO_BASE TASK_SIZE_MAX
>        |                            ^~~~~~~~~~~~~
> ./include/linux/mm_types.h:627:40: note: in expansion of macro 'UNMAPPED_VDSO_BASE'
>    627 |         mm->vdso_base = (void __user *)UNMAPPED_VDSO_BASE;
>        |                                        ^~~~~~~~~~~~~~~~~~
> make[2]: *** [arch/powerpc/kernel/asm-offsets.s] Error 1
> make[1]: *** [prepare0] Error 2
> make: *** [__sub-make] Error 2
> 

Fixed by moving TASK_SIZE_MAX into asm/task_size_32.h and asm/task_size_64.h

diff --git a/arch/powerpc/include/asm/task_size_32.h b/arch/powerpc/include/asm/task_size_32.h
index de7290ee770f..03af9e6bb5cd 100644
--- a/arch/powerpc/include/asm/task_size_32.h
+++ b/arch/powerpc/include/asm/task_size_32.h
@@ -7,6 +7,7 @@
  #endif

  #define TASK_SIZE (CONFIG_TASK_SIZE)
+#define TASK_SIZE_MAX		TASK_SIZE

  /*
   * This decides where the kernel will search for a free chunk of vm space during
diff --git a/arch/powerpc/include/asm/task_size_64.h b/arch/powerpc/include/asm/task_size_64.h
index c993482237ed..bfdb98c0ef43 100644
--- a/arch/powerpc/include/asm/task_size_64.h
+++ b/arch/powerpc/include/asm/task_size_64.h
@@ -49,6 +49,7 @@
  						TASK_SIZE_USER64)

  #define TASK_SIZE TASK_SIZE_OF(current)
+#define TASK_SIZE_MAX		TASK_SIZE_USER64

  #define TASK_UNMAPPED_BASE_USER32 (PAGE_ALIGN(TASK_SIZE_USER32 / 4))
  #define TASK_UNMAPPED_BASE_USER64 (PAGE_ALIGN(DEFAULT_MAP_WINDOW_USER64 / 4))
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 22c79ab40006..5823140d39f1 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -8,13 +8,6 @@
  #include <asm/extable.h>
  #include <asm/kup.h>

-#ifdef __powerpc64__
-/* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
-#define TASK_SIZE_MAX		TASK_SIZE_USER64
-#else
-#define TASK_SIZE_MAX		TASK_SIZE
-#endif
-
  static inline bool __access_ok(unsigned long addr, unsigned long size)
  {
  	return addr < TASK_SIZE_MAX && size <= TASK_SIZE_MAX - addr;