powerpc/book3e: Flush IPROT protected TLB entries leftover by firmware

When we set up the TLB for ourselves on Book3E, we need to flush out any
old mappings established by the firmware or bootloader.  At present we
attempt this with a tlbilx to flush everything, but this will leave behind
any entries with the IPROT bit set.

There are several good reason firmware might establish mappings with IPROT,
and in fact ePAPR compliant firmwares are required to establish their
initial mapped area with IPROT.

This patch, therefore adds more complex code to scan through the TLB upon
entry and flush away any entries that are not our own.

Signed-off-by: Jack Miller <jack@codezen.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 44 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 8fe0fc233f02..23bd83b20be4 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -886,8 +886,51 @@ have_hes:
         bctr
 
 1:      /* We are now running at PAGE_OFFSET, clean the TLB of everything
-         * else (XXX we should scan for bolted crap from the firmware too)
+         * else (including IPROTed things left by firmware)
+         * r4 = TLBnCFG
+         * r3 = current address (more or less)
          */
+
+        li      r5,0
+        mtspr   SPRN_MAS6,r5
+        tlbsx   0,r3
+
+        rlwinm  r9,r4,0,TLBnCFG_N_ENTRY
+        rlwinm  r10,r4,8,0xff
+        addi    r10,r10,-1      /* Get inner loop mask */
+
+        li      r3,1
+
+        mfspr   r5,SPRN_MAS1
+        rlwinm  r5,r5,0,(~(MAS1_VALID|MAS1_IPROT))
+
+        mfspr   r6,SPRN_MAS2
+        rldicr  r6,r6,0,51              /* Extract EPN */
+
+        mfspr   r7,SPRN_MAS0
+        rlwinm  r7,r7,0,0xffff0fff      /* Clear HES and WQ */
+
+        rlwinm  r8,r7,16,0xfff          /* Extract ESEL */
+
+2:      add     r4,r3,r8
+        and     r4,r4,r10
+
+        rlwimi  r7,r4,16,MAS0_ESEL_MASK
+
+        mtspr   SPRN_MAS0,r7
+        mtspr   SPRN_MAS1,r5
+        mtspr   SPRN_MAS2,r6
+        tlbwe
+
+        addi    r3,r3,1
+        and.    r4,r3,r10
+
+        bne     3f
+        addis   r6,r6,(1<<30)@h
+3:
+        cmpw    r3,r9
+        blt     2b
+
         PPC_TLBILX(0,0,0)
         sync
         isync