2020-01-23 11:21:21

by Laurentiu Tudor

Subject: [PATCH] powerpc/fsl_booke: avoid creating duplicate tlb1 entry

In the current implementation, the call to loadcam_multi() is wrapped
between switch_to_as1() and restore_to_as0() calls so, when it tries
to create its own temporary AS=1 TLB1 entry, it ends up duplicating the
existing one created by switch_to_as1(). Add a check to skip creating
the temporary entry if already running in AS=1.

Fixes: d9e1831a4202 ("powerpc/85xx: Load all early TLB entries at once")
Signed-off-by: Laurentiu Tudor <[email protected]>
Cc: [email protected]
---
arch/powerpc/mm/nohash/tlb_low.S | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/nohash/tlb_low.S b/arch/powerpc/mm/nohash/tlb_low.S
index 2ca407cedbe7..eaeee402f96e 100644
--- a/arch/powerpc/mm/nohash/tlb_low.S
+++ b/arch/powerpc/mm/nohash/tlb_low.S
@@ -397,7 +397,7 @@ _GLOBAL(set_context)
* extern void loadcam_entry(unsigned int index)
*
* Load TLBCAM[index] entry in to the L2 CAM MMU
- * Must preserve r7, r8, r9, and r10
+ * Must preserve r7, r8, r9, r10 and r11
*/
_GLOBAL(loadcam_entry)
mflr r5
@@ -433,6 +433,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_BIG_PHYS)
*/
_GLOBAL(loadcam_multi)
mflr r8
+ /* Don't switch to AS=1 if already there */
+ mfmsr r11
+ andi. r11,r11,MSR_IS
+ bne 10f

/*
* Set up temporary TLB entry that is the same as what we're
@@ -458,6 +462,7 @@ _GLOBAL(loadcam_multi)
mtmsr r6
isync

+10:
mr r9,r3
add r10,r3,r4
2: bl loadcam_entry
@@ -466,6 +471,10 @@ _GLOBAL(loadcam_multi)
mr r3,r9
blt 2b

+ /* Don't return to AS=0 if we were in AS=1 at function start */
+ andi. r11,r11,MSR_IS
+ bne 3f
+
/* Return to AS=0 and clear the temporary entry */
mfmsr r6
rlwinm. r6,r6,0,~(MSR_IS|MSR_DS)
@@ -481,6 +490,7 @@ _GLOBAL(loadcam_multi)
tlbwe
isync

+3:
mtlr r8
blr
#endif
--
2.17.1

2020-02-29 23:11:34

by Crystal Wood

Subject: Re: [PATCH] powerpc/fsl_booke: avoid creating duplicate tlb1 entry

On Thu, 2020-01-23 at 11:19 +0000, Laurentiu Tudor wrote:
> In the current implementation, the call to loadcam_multi() is wrapped
> between switch_to_as1() and restore_to_as0() calls so, when it tries
> to create its own temporary AS=1 TLB1 entry, it ends up duplicating the
> existing one created by switch_to_as1(). Add a check to skip creating
> the temporary entry if already running in AS=1.
>
> Fixes: d9e1831a4202 ("powerpc/85xx: Load all early TLB entries at once")
> Signed-off-by: Laurentiu Tudor <[email protected]>
> Cc: [email protected]
> ---
> arch/powerpc/mm/nohash/tlb_low.S | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)

Assuming you've tested this on all combinations of 32/64 relocatable and not:

Acked-by: Scott Wood <[email protected]>

-Scott

2020-03-17 13:15:57

by Michael Ellerman

Subject: Re: [PATCH] powerpc/fsl_booke: avoid creating duplicate tlb1 entry

On Thu, 2020-01-23 at 11:19:25 UTC, Laurentiu Tudor wrote:
> In the current implementation, the call to loadcam_multi() is wrapped
> between switch_to_as1() and restore_to_as0() calls so, when it tries
> to create its own temporary AS=3D1 TLB1 entry, it ends up duplicating the
> existing one created by switch_to_as1(). Add a check to skip creating
> the temporary entry if already running in AS=3D1.
>
> Fixes: d9e1831a4202 ("powerpc/85xx: Load all early TLB entries at once")
> Signed-off-by: Laurentiu Tudor <[email protected]>
> Cc: [email protected]

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/aa4113340ae6c2811e046f08c2bc21011d20a072

cheers