Re: [PATCH v3 31/41] powerpc/32: Dismantle EXC_XFER_STD/LITE/TEMPLATE
From: Finn Thain <fthain@linux-m68k.org>
Date: 2021-08-03 00:43:28
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lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
On Mon, 2 Aug 2021, LEROY Christophe wrote:
quoted hunk ↗ jump to hunk
Le 01/08/2021 à 03:21, Finn Thain a écrit :quoted
On Sat, 31 Jul 2021, Christophe Leroy wrote:quoted
quoted
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.Sb/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
That patch doesn't apply to mainline. This version might help.
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 764edd860ed4..68e5c0a7e99d 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S@@ -300,7 +300,7 @@ ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE) EXCEPTION_PROLOG_1 EXCEPTION_PROLOG_2 INTERRUPT_DATA_STORAGE 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