On Apr 18, 2011, at 4:40 PM, Benjamin Herrenschmidt wrote:

On Mon, 2011-04-18 at 07:43 -0500, Kumar Gala wrote:

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On Apr 15, 2011, at 3:32 AM, Michael Ellerman wrote:
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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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An erratum on A2 can lead to the bolted entry we insert for the =

linear

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mapping being evicted, to avoid that write the bolted entry to way =

3.

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Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <redacted>
---
arch/powerpc/kernel/exceptions-64e.S |    5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
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diff --git a/arch/powerpc/kernel/exceptions-64e.S =

b/arch/powerpc/kernel/exceptions-64e.S

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index 5c43063..e6c0926 100644

--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S

@@ -864,8 +864,9 @@ have_hes:

	 * that will have to be made dependent on whether we are running =

under

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	 * a hypervisor I suppose.
	 */
-	ori	r3,r3,MAS0_HES | MAS0_WQ_ALLWAYS
-	mtspr	SPRN_MAS0,r3
+	ori	r11,r3,MAS0_WQ_ALLWAYS
+	oris	r11,r11,MAS0_ESEL(3)@h /* Use way 3: workaround A2 =

erratum 376 */

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+	mtspr	SPRN_MAS0,r11
	lis	r3,(MAS1_VALID | MAS1_IPROT)@h
	ori	r3,r3,BOOK3E_PAGESZ_1GB << MAS1_TSIZE_SHIFT
	mtspr	SPRN_MAS1,r3

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Seems like this should have a MMU Feature bit or something for A2.

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Too early. We haven't detected the CPU and are establishing the =

initial

TLB entry here.

How about wrapping with CONFIG_PPC_A2

Any reason why that wouldn't work on something else anyways ?

No, I wasn't paying attention to what this code exactly was (not enough =
context in the diff), I see its our initial setup so not a big deal.  =
Was thinking this was run-time exception handler code.

- k