[PATCH v3 06/10] powerpc/fsl_booke: Enable reloading of TLBCAM without switching to AS1

From: Christophe Leroy
Date: Mon Oct 25 2021 - 17:49:45 EST


Avoid switching to AS1 when reloading TLBCAM after init for
STRICT_KERNEL_RWX.

When we setup AS1 we expect the entire accessible memory to be mapped
through one entry, this is not the case anymore at the end of init.

We are not changing the size of TLBCAMs, only flags, so no need to
switch to AS1.

So change loadcam_multi() to not switch to AS1 when the given
temporary tlb entry in 0.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
v3: No change
v2: No change
---
arch/powerpc/mm/nohash/tlb_low.S | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/nohash/tlb_low.S b/arch/powerpc/mm/nohash/tlb_low.S
index 5add4a51e51f..dd39074de9af 100644
--- a/arch/powerpc/mm/nohash/tlb_low.S
+++ b/arch/powerpc/mm/nohash/tlb_low.S
@@ -369,7 +369,7 @@ _GLOBAL(_tlbivax_bcast)
* extern void loadcam_entry(unsigned int index)
*
* Load TLBCAM[index] entry in to the L2 CAM MMU
- * Must preserve r7, r8, r9, r10 and r11
+ * Must preserve r7, r8, r9, r10, r11, r12
*/
_GLOBAL(loadcam_entry)
mflr r5
@@ -401,7 +401,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_BIG_PHYS)
*
* r3 = first entry to write
* r4 = number of entries to write
- * r5 = temporary tlb entry
+ * r5 = temporary tlb entry (0 means no switch to AS1)
*/
_GLOBAL(loadcam_multi)
mflr r8
@@ -409,6 +409,8 @@ _GLOBAL(loadcam_multi)
mfmsr r11
andi. r11,r11,MSR_IS
bne 10f
+ mr. r12, r5
+ beq 10f

/*
* Set up temporary TLB entry that is the same as what we're
@@ -446,6 +448,8 @@ _GLOBAL(loadcam_multi)
/* Don't return to AS=0 if we were in AS=1 at function start */
andi. r11,r11,MSR_IS
bne 3f
+ cmpwi r12, 0
+ beq 3f

/* Return to AS=0 and clear the temporary entry */
mfmsr r6
--
2.31.1