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

From: Sasha Levin
Date: Mon Jan 17 2022 - 12:04:06 EST


From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>

[ 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 <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/89b5f974a7fa5011206682cd092e2c905530ff46.1632755552.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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