linux-kernel - [PATCH] powerpc/8xx: fix setting of pagetable for Abatron BDI debug tool.

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Message-Id: <9b1d38ef4c4d26f9ef9b6a69a37949a4eee722df.1547025153.git.christophe.leroy@c-s.fr>
Date:   Wed,  9 Jan 2019 20:30:07 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/8xx: fix setting of pagetable for Abatron BDI debug
 tool.

Commit 8c8c10b90d88 ("powerpc/8xx: fix handling of early NULL pointer
dereference") moved the loading of r6 earlier in the code. As some
functions are called inbetween, r6 needs to be loaded again with the
address of swapper_pg_dir in order to set PTE pointers for
the Abatron BDI.

Fixes: 8c8c10b90d88 ("powerpc/8xx: fix handling of early NULL pointer dereference")
Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/kernel/head_8xx.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index aea5f367e4fe..ab0e6f1c98b0 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -885,11 +885,12 @@ start_here:
 
 	/* set up the PTE pointers for the Abatron bdiGDB.
 	*/
-	tovirt(r6,r6)
 	lis	r5, abatron_pteptrs@h
 	ori	r5, r5, abatron_pteptrs@l
 	stw	r5, 0xf0(0)	/* Must match your Abatron config file */
 	tophys(r5,r5)
+	lis	r6, swapper_pg_dir@h
+	ori	r6, r6, swapper_pg_dir@l
 	stw	r6, 0(r5)
 
 /* Now turn on the MMU for real! */
-- 
2.13.3