Re: [PATCH 3/6] 8xx: invalidate non present TLBs

Benjamin Herrenschmidt [off-list ref] wrote on 07/10/2009 23:18:05:

On Wed, 2009-10-07 at 22:46 +0200, Joakim Tjernlund wrote:

quoted

8xx sometimes need to load a invalid/non-present TLBs in
it DTLB asm handler.
These must be invalidated separaly as linux mm don't.

not sure about the dsisr test here, what is the point ?

Without this patch I get about twice as many DTLB errors( on 2.4)

I have also noted that all my dcbst DTLB has the store bit set:
  trap:300 address:10030b8c, dar:10030b8c,err:42000000 dcbst

Thare are comments in the kernel that dcbst wrongly
generates TLB Errors with store set on 8xx. Is this really so?
Should dcbst always trap as a load?

 Jocke

Cheers,
Ben.

quoted

---
 arch/powerpc/mm/fault.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 7699394..72941c7 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c

@@ -39,7 +39,7 @@
 #include <asm/uaccess.h>
 #include <asm/tlbflush.h>
 #include <asm/siginfo.h>
-
+#include <mm/mmu_decl.h>

 #ifdef CONFIG_KPROBES
 static inline int notify_page_fault(struct pt_regs *regs)

@@ -243,6 +243,12 @@ good_area:
       goto bad_area;
 #endif /* CONFIG_6xx */
 #if defined(CONFIG_8xx)
+   /* 8xx sometimes need to load a invalid/non-present TLBs.
+    * These must be invalidated separately as linux mm don't.
+    */
+   if (error_code & 0x40000000) /* no translation? */
+      _tlbil_va(address);
+
         /* The MPC8xx seems to always set 0x80000000, which is
          * "undefined".  Of those that can be set, this is the only
          * one which seems bad.