Re: [PATCH 6.10 000/809] 6.10.3-rc3 review

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

On 2024-08-08 5:50 p.m., John David Anglin wrote:
> The mode likely problem is the shladd instruction in the following macro in entry.S:
>
>         .macro          L2_ptep pmd,pte,index,va,fault
> #if CONFIG_PGTABLE_LEVELS == 3
>         extru_safe      \va,31-ASM_PMD_SHIFT,ASM_BITS_PER_PMD,\index
> #else
>         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
>         copy            %r0,\pte
> #endif
>         ldw,s           \index(\pmd),\pmd
>         bb,>=,n         \pmd,_PxD_PRESENT_BIT,\fault
>         dep             %r0,31,PxD_FLAG_SHIFT,\pmd /* clear flags */
>         SHLREG          \pmd,PxD_VALUE_SHIFT,\pmd
>         extru_safe      \va,31-PAGE_SHIFT,ASM_BITS_PER_PTE,\index
>         dep             %r0,31,PAGE_SHIFT,\pmd  /* clear offset */
>         shladd          \index,BITS_PER_PTE_ENTRY,\pmd,\pmd /* pmd is now pte */
>         .endm
>
> I believe the shladd instruction should be changed to shladd,l (shift left and add logical).
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index ab23e61a6f01..1ec60406f841 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -399,7 +399,7 @@
      SHLREG        \pmd,PxD_VALUE_SHIFT,\pmd
      extru_safe    \va,31-PAGE_SHIFT,ASM_BITS_PER_PTE,\index
      dep        %r0,31,PAGE_SHIFT,\pmd  /* clear offset */
-    shladd        \index,BITS_PER_PTE_ENTRY,\pmd,\pmd /* pmd is now pte */
+    shladd,l    \index,BITS_PER_PTE_ENTRY,\pmd,\pmd /* pmd is now pte */
      .endm

      /* Look up PTE in a 3-Level scheme. */

Boots okay.  Fixing the addi instruction is harder and it would take some time to test.

Dave

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