Subject: [PATCH AUTOSEL 5.15 24/44] powerpc/40x: Map 32Mbytes of memory at startup

From: Sasha Levin <[email-masked]>
Date: Mon, 17 Jan 2022 12:01:07 -0500

From: Christophe Leroy <[email-masked]>

[ Upstream commit 06e7cbc29e97b4713b4ea6def04ae8501a7d1a59 ]

As reported by Carlo, 16Mbytes is not enough with modern kernels
that tend to be a bit big, so map another 16M page at boot.

Signed-off-by: Christophe Leroy <[email-masked]>
Signed-off-by: Michael Ellerman <[email-masked]>
Link: https://lore.kernel.org/r/89b5f974[email-masked]
Signed-off-by: Sasha Levin <[email-masked]>
---
 arch/powerpc/kernel/head_40x.S | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 7d72ee5ab387c..e783860bea838 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -27,6 +27,7 @@
 
 #include <linux/init.h>
 #include <linux/pgtable.h>
+#include <linux/sizes.h>
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/mmu.h>
@@ -650,7 +651,7 @@ start_here:
 	b	.		/* prevent prefetch past rfi */
 
 /* Set up the initial MMU state so we can do the first level of
- * kernel initialization.  This maps the first 16 MBytes of memory 1:1
+ * kernel initialization.  This maps the first 32 MBytes of memory 1:1
  * virtual to physical and more importantly sets the cache mode.
  */
 initial_mmu:
@@ -687,6 +688,12 @@ initial_mmu:
 	tlbwe	r4,r0,TLB_DATA		/* Load the data portion of the entry */
 	tlbwe	r3,r0,TLB_TAG		/* Load the tag portion of the entry */
 
+	li	r0,62			/* TLB slot 62 */
+	addis	r4,r4,SZ_16M@h
+	addis	r3,r3,SZ_16M@h
+	tlbwe	r4,r0,TLB_DATA		/* Load the data portion of the entry */
+	tlbwe	r3,r0,TLB_TAG		/* Load the tag portion of the entry */
+
 	isync
 
 	/* Establish the exception vector base
-- 
2.34.1