Re: [PATCH] parisc: Fix extraction of hash lock bits in syscall.S

[John David Anglin <dave.anglin@bell.net>]

On 2021-11-19 10:56 a.m., Helge Deller wrote:
> * John David Anglin<dave.anglin@bell.net>:
>> The extru instruction leaves the most significant 32 bits of the target register in an undefined
>> state on PA 2.0 systems.  If any of these bits are nonzero, this will break the calculation of the
>> lock pointer.
>>
>> Fix by using extrd,u instruction on 64-bit kernels.
> I wonder if we shouldn't introduce an extru_safe() macro.
> The name doesn't matter, but that way we can get rid of the ifdefs and
> use it in other places as well, e.g. as seen below.
> Thoughs?
Seems like a good idea.

Only question is this hunk

@@ -366,17 +366,9 @@
       */
      .macro        L2_ptep    pmd,pte,index,va,fault
  #if CONFIG_PGTABLE_LEVELS == 3
-    extru        \va,31-ASM_PMD_SHIFT,ASM_BITS_PER_PMD,\index
+    extru_safe    \va,31-ASM_PMD_SHIFT,ASM_BITS_PER_PMD,\index
  #else
-# if defined(CONFIG_64BIT)
-    extrd,u        \va,63-ASM_PGDIR_SHIFT,ASM_BITS_PER_PGD,\index
-  #else
-  # if PAGE_SIZE > 4096
-    extru        \va,31-ASM_PGDIR_SHIFT,32-ASM_PGDIR_SHIFT,\index
-  # else
-    extru        \va,31-ASM_PGDIR_SHIFT,ASM_BITS_PER_PGD,\index
-  # endif
-# endif
+    extru_safe    \va,31-ASM_PGDIR_SHIFT,ASM_BITS_PER_PGD,\index
  #endif
      dep             %r0,31,PAGE_SHIFT,\pmd  /* clear offset */
  #if CONFIG_PGTABLE_LEVELS < 3

where we lose the PAGE_SIZE > 4096 shift.

Dave

-- 
John David Anglin  dave.anglin@bell.net