Re: [PATCH v3 31/41] powerpc/32: Dismantle EXC_XFER_STD/LITE/TEMPLATE

[LEROY Christophe]

Le 01/08/2021 à 03:21, Finn Thain a écrit :
> On Sat, 31 Jul 2021, Christophe Leroy wrote:
>
> > > Stan Johnson contacted me about a regression in mainline that he
> > > observed on his G3 Powerbooks. Using 'git bisect' we determined that
> > > this patch was the cause of the regression, i.e. commit 4c0104a83fc3
> > > ("powerpc/32: Dismantle EXC_XFER_STD/LITE/TEMPLATE").
> > >
> > > When testing 4c0104a83fc and all subsequent builds, various user
> > > processes were liable to segfault. Here is the console log that Stan
> > > provided:
> >
> > Hi, i will be able to look at that more in details next week, however I
> > have a few preliminary qurstions.
> >
> > Can you reliabily reproduce the problem with the said commit, and can
> > you reliabily run without problem with the parent commit ?
>
> Yes and yes. (I already asked Stan to establish those things before I
> contacted the list.)

I think I found the problem with that commit. Can you retry with the 
following change:

diff --git a/arch/powerpc/kernel/head_book3s_32.S 
b/arch/powerpc/kernel/head_book3s_32.S
index 0a3d7d4a9ec4..a294103a91a1 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -299,7 +299,7 @@ ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
 	EXCEPTION_PROLOG_1
 	EXCEPTION_PROLOG_2 0x300 DataAccess handle_dar_dsisr=1
 	prepare_transfer_to_handler
-	lwz	r5, _DSISR(r11)
+	lwz	r5, _DSISR(r1)
 	andis.	r0, r5, DSISR_DABRMATCH@h
 	bne-	1f
 	bl	do_page_fault
---
Thanks
Christophe