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Message-ID: <20220725125256.cg6su4d2ageylvp6@pali>
Date: Mon, 25 Jul 2022 14:52:56 +0200
From: Pali Rohár <pali@...nel.org>
To: Michael Ellerman <mpe@...erman.id.au>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Regression: Linux v5.15+ does not boot on Freescale P2020
On Monday 25 July 2022 18:20:01 Michael Ellerman wrote:
> Pali Rohár <pali@...nel.org> writes:
> > On Saturday 23 July 2022 14:42:22 Christophe Leroy wrote:
> >> Le 22/07/2022 à 11:09, Pali Rohár a écrit :
> >> > Trying to boot mainline Linux kernel v5.15+, including current version
> >> > from master branch, on Freescale P2020 does not work. Kernel does not
> >> > print anything to serial console, seems that it does not work and after
> >> > timeout watchdog reset the board.
> >>
> >> Can you provide more information ? Which defconfig or .config, which
> >> version of gcc, etc ... ?
> >
> > I used default defconfig for mpc85xx with gcc 8, compilation for e500
> > cores.
> >
> > If you need exact .config content I can send it during week.
> >
> >> > I run git bisect and it found following commit:
> >> >
> >> > 9401f4e46cf6965e23738f70e149172344a01eef is the first bad commit
> >> > commit 9401f4e46cf6965e23738f70e149172344a01eef
> >> > Author: Christophe Leroy <christophe.leroy@...roup.eu>
> >> > Date: Tue Mar 2 08:48:11 2021 +0000
> >> >
> >> > powerpc: Use lwarx/ldarx directly instead of PPC_LWARX/LDARX macros
> >> >
> >> > Force the eh flag at 0 on PPC32.
> >> >
> >> > Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> >> > Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> >> > Link: https://lore.kernel.org/r/1fc81f07cabebb875b963e295408cc3dd38c8d85.1614674882.git.christophe.leroy@csgroup.eu
> >> >
> >> > :040000 040000 fe6747e45736dfcba74914a9445e5f70f5120600 96358d08b65d3200928a973efb5b969b3d45f2b0 M arch
> >> >
> >> >
> >> > If I revert this commit then kernel boots correctly. It also boots fine
> >> > if I revert this commit on top of master branch.
> >> >
> >> > Freescale P2020 has two 32-bit e500 powerpc cores.
> >> >
> >> > Any idea why above commit is causing crash of the kernel? And why it is
> >> > needed? Could eh flag set to 0 cause deadlock?
> >>
> >> Setting the eh flag to 0 is not supposed to be a change introduced by
> >> that commit. Indeed that commit is not supposed to change anything at
> >> all in the generated code.
> >
> > My understanding of that commit is that it changed eh flag parameter
> > from 1 to 0 for 32-bit powerpc, including also p2020.
>
> Can you compare the disassembly before and after and find a place where
> an instruction has changed?
>
> cheers
Yes, of course. Here is diff between output from objdump -d vmlinux.
original version --- is from git master branch and modified version +++
is the original version with reverted above problematic commit.
So the +++ version is the one which is working.
--- vmlinux.master.dump 2022-07-25 14:43:45.922239496 +0200
+++ vmlinux.revert.dump 2022-07-25 14:43:49.238259296 +0200
@@ -1,5 +1,5 @@
-vmlinux.master: file format elf32-powerpc
+vmlinux.revert: file format elf32-powerpc
Disassembly of section .head.text:
@@ -11213,7 +11213,7 @@ c000b850: 3f a0 c1 0f lis r29,-1611
c000b854: 81 02 00 04 lwz r8,4(r2)
c000b858: 3b fd 10 68 addi r31,r29,4200
c000b85c: 39 40 00 01 li r10,1
-c000b860: 7d 20 f8 29 lwarx r9,0,r31,1
+c000b860: 7d 20 f8 28 lwarx r9,0,r31
c000b864: 2c 09 00 00 cmpwi r9,0
c000b868: 40 82 00 10 bne c000b878 <die+0x68>
c000b86c: 7d 40 f9 2d stwcx. r10,0,r31
@@ -11227,7 +11227,7 @@ c000b888: 81 3e 00 1c lwz r9,28(r30
c000b88c: 7f 88 48 00 cmpw cr7,r8,r9
c000b890: 41 9e 00 38 beq cr7,c000b8c8 <die+0xb8>
c000b894: 39 40 00 01 li r10,1
-c000b898: 7d 20 f8 29 lwarx r9,0,r31,1
+c000b898: 7d 20 f8 28 lwarx r9,0,r31
c000b89c: 2c 09 00 00 cmpwi r9,0
c000b8a0: 40 82 00 10 bne c000b8b0 <die+0xa0>
c000b8a4: 7d 40 f9 2d stwcx. r10,0,r31
@@ -186495,7 +186495,7 @@ c00b173c: 3b 40 00 00 li r26,0
c00b1740: 3a e0 00 00 li r23,0
c00b1744: 7e c0 00 a6 mfmsr r22
c00b1748: 7c 00 01 46 wrteei 0
-c00b174c: 7f a0 c0 29 lwarx r29,0,r24,1
+c00b174c: 7f a0 c0 28 lwarx r29,0,r24
c00b1750: 2c 1d 00 00 cmpwi r29,0
c00b1754: 40 82 00 10 bne c00b1764 <rcu_gp_init+0x15c>
c00b1758: 7f 20 c1 2d stwcx. r25,0,r24
@@ -187821,7 +187821,7 @@ c00b2b7c: 3f e0 c1 0b lis r31,-1611
c00b2b80: 38 c0 00 01 li r6,1
c00b2b84: 3b ff c5 20 addi r31,r31,-15072
c00b2b88: 38 ff 02 20 addi r7,r31,544
-c00b2b8c: 7d 00 38 29 lwarx r8,0,r7,1
+c00b2b8c: 7d 00 38 28 lwarx r8,0,r7
c00b2b90: 2c 08 00 00 cmpwi r8,0
c00b2b94: 40 82 00 10 bne c00b2ba4 <rcu_cpu_starting+0xc0>
c00b2b98: 7c c0 39 2d stwcx. r6,0,r7
@@ -187947,7 +187947,7 @@ c00b2d6c: 3f a0 c1 0b lis r29,-1611
c00b2d70: 39 00 00 01 li r8,1
c00b2d74: 3b bd c5 20 addi r29,r29,-15072
c00b2d78: 39 3d 02 20 addi r9,r29,544
-c00b2d7c: 7d 40 48 29 lwarx r10,0,r9,1
+c00b2d7c: 7d 40 48 28 lwarx r10,0,r9
c00b2d80: 2c 0a 00 00 cmpwi r10,0
c00b2d84: 40 82 00 10 bne c00b2d94 <rcu_report_dead+0x90>
c00b2d88: 7d 00 49 2d stwcx. r8,0,r9
@@ -2527838,7 +2527838,7 @@ c096b0e4: 4e 80 00 20 blr
c096b0e8 <_raw_spin_trylock>:
c096b0e8: 94 21 ff f0 stwu r1,-16(r1)
c096b0ec: 39 40 00 01 li r10,1
-c096b0f0: 7d 20 18 29 lwarx r9,0,r3,1
+c096b0f0: 7d 20 18 28 lwarx r9,0,r3
c096b0f4: 2c 09 00 00 cmpwi r9,0
c096b0f8: 40 82 00 10 bne c096b108 <_raw_spin_trylock+0x20>
c096b0fc: 7d 40 19 2d stwcx. r10,0,r3
@@ -2527853,7 +2527853,7 @@ c096b11c: 4e 80 00 20 blr
c096b120 <_raw_read_trylock>:
c096b120: 94 21 ff f0 stwu r1,-16(r1)
-c096b124: 7d 20 18 29 lwarx r9,0,r3,1
+c096b124: 7d 20 18 28 lwarx r9,0,r3
c096b128: 35 29 00 01 addic. r9,r9,1
c096b12c: 40 81 00 10 ble c096b13c <_raw_read_trylock+0x1c>
c096b130: 7d 20 19 2d stwcx. r9,0,r3
@@ -2527869,7 +2527869,7 @@ c096b150: 4e 80 00 20 blr
c096b154 <_raw_write_trylock>:
c096b154: 94 21 ff f0 stwu r1,-16(r1)
c096b158: 39 40 ff ff li r10,-1
-c096b15c: 7d 20 18 29 lwarx r9,0,r3,1
+c096b15c: 7d 20 18 28 lwarx r9,0,r3
c096b160: 2c 09 00 00 cmpwi r9,0
c096b164: 40 82 00 10 bne c096b174 <_raw_write_trylock+0x20>
c096b168: 7d 40 19 2d stwcx. r10,0,r3
@@ -2527888,7 +2527888,7 @@ c096b190: 81 22 00 00 lwz r9,0(r2)
c096b194: 39 29 02 00 addi r9,r9,512
c096b198: 91 22 00 00 stw r9,0(r2)
c096b19c: 39 40 00 01 li r10,1
-c096b1a0: 7d 20 18 29 lwarx r9,0,r3,1
+c096b1a0: 7d 20 18 28 lwarx r9,0,r3
c096b1a4: 2c 09 00 00 cmpwi r9,0
c096b1a8: 40 82 00 10 bne c096b1b8 <_raw_spin_lock_bh+0x2c>
c096b1ac: 7d 40 19 2d stwcx. r10,0,r3
@@ -2527940,7 +2527940,7 @@ c096b240: 81 22 00 00 lwz r9,0(r2)
c096b244: 39 29 02 00 addi r9,r9,512
c096b248: 91 22 00 00 stw r9,0(r2)
c096b24c: 39 40 00 01 li r10,1
-c096b250: 7d 20 18 29 lwarx r9,0,r3,1
+c096b250: 7d 20 18 28 lwarx r9,0,r3
c096b254: 2c 09 00 00 cmpwi r9,0
c096b258: 40 82 00 10 bne c096b268 <_raw_spin_trylock_bh+0x34>
c096b25c: 7d 40 19 2d stwcx. r10,0,r3
@@ -2527997,7 +2527997,7 @@ c096b304: 94 21 ff f0 stwu r1,-16(r1
c096b308: 81 22 00 00 lwz r9,0(r2)
c096b30c: 39 29 02 00 addi r9,r9,512
c096b310: 91 22 00 00 stw r9,0(r2)
-c096b314: 7d 20 18 29 lwarx r9,0,r3,1
+c096b314: 7d 20 18 28 lwarx r9,0,r3
c096b318: 35 29 00 01 addic. r9,r9,1
c096b31c: 40 81 00 10 ble c096b32c <_raw_read_lock_bh+0x28>
c096b320: 7d 20 19 2d stwcx. r9,0,r3
@@ -2528018,7 +2528018,7 @@ c096b350: 81 22 00 00 lwz r9,0(r2)
c096b354: 39 29 02 00 addi r9,r9,512
c096b358: 91 22 00 00 stw r9,0(r2)
c096b35c: 39 40 ff ff li r10,-1
-c096b360: 7d 20 18 29 lwarx r9,0,r3,1
+c096b360: 7d 20 18 28 lwarx r9,0,r3
c096b364: 2c 09 00 00 cmpwi r9,0
c096b368: 40 82 00 10 bne c096b378 <_raw_write_lock_bh+0x2c>
c096b36c: 7d 40 19 2d stwcx. r10,0,r3
@@ -2528035,7 +2528035,7 @@ c096b394: 4b ff ff f4 b c096b388
c096b398 <_raw_read_lock>:
c096b398: 94 21 ff f0 stwu r1,-16(r1)
-c096b39c: 7d 20 18 29 lwarx r9,0,r3,1
+c096b39c: 7d 20 18 28 lwarx r9,0,r3
c096b3a0: 35 29 00 01 addic. r9,r9,1
c096b3a4: 40 81 00 10 ble c096b3b4 <_raw_read_lock+0x1c>
c096b3a8: 7d 20 19 2d stwcx. r9,0,r3
@@ -2528053,7 +2528053,7 @@ c096b3d0: 4b ff ff f4 b c096b3c4
c096b3d4 <_raw_read_lock_irq>:
c096b3d4: 94 21 ff f0 stwu r1,-16(r1)
c096b3d8: 7c 00 01 46 wrteei 0
-c096b3dc: 7d 20 18 29 lwarx r9,0,r3,1
+c096b3dc: 7d 20 18 28 lwarx r9,0,r3
c096b3e0: 35 29 00 01 addic. r9,r9,1
c096b3e4: 40 81 00 10 ble c096b3f4 <_raw_read_lock_irq+0x20>
c096b3e8: 7d 20 19 2d stwcx. r9,0,r3
@@ -2528073,7 +2528073,7 @@ c096b414: 94 21 ff f0 stwu r1,-16(r1
c096b418: 7c 6a 1b 78 mr r10,r3
c096b41c: 7c 60 00 a6 mfmsr r3
c096b420: 7c 00 01 46 wrteei 0
-c096b424: 7d 20 50 29 lwarx r9,0,r10,1
+c096b424: 7d 20 50 28 lwarx r9,0,r10
c096b428: 35 29 00 01 addic. r9,r9,1
c096b42c: 40 81 00 10 ble c096b43c <_raw_read_lock_irqsave+0x28>
c096b430: 7d 20 51 2d stwcx. r9,0,r10
@@ -2528091,7 +2528091,7 @@ c096b458: 4b ff ff f4 b c096b44c
c096b45c <_raw_spin_lock>:
c096b45c: 94 21 ff f0 stwu r1,-16(r1)
c096b460: 39 40 00 01 li r10,1
-c096b464: 7d 20 18 29 lwarx r9,0,r3,1
+c096b464: 7d 20 18 28 lwarx r9,0,r3
c096b468: 2c 09 00 00 cmpwi r9,0
c096b46c: 40 82 00 10 bne c096b47c <_raw_spin_lock+0x20>
c096b470: 7d 40 19 2d stwcx. r10,0,r3
@@ -2528110,7 +2528110,7 @@ c096b49c <_raw_spin_lock_irq>:
c096b49c: 94 21 ff f0 stwu r1,-16(r1)
c096b4a0: 7c 00 01 46 wrteei 0
c096b4a4: 39 40 00 01 li r10,1
-c096b4a8: 7d 20 18 29 lwarx r9,0,r3,1
+c096b4a8: 7d 20 18 28 lwarx r9,0,r3
c096b4ac: 2c 09 00 00 cmpwi r9,0
c096b4b0: 40 82 00 10 bne c096b4c0 <_raw_spin_lock_irq+0x24>
c096b4b4: 7d 40 19 2d stwcx. r10,0,r3
@@ -2528131,7 +2528131,7 @@ c096b4e4: 7c 6a 1b 78 mr r10,r3
c096b4e8: 7c 60 00 a6 mfmsr r3
c096b4ec: 7c 00 01 46 wrteei 0
c096b4f0: 39 00 00 01 li r8,1
-c096b4f4: 7d 20 50 29 lwarx r9,0,r10,1
+c096b4f4: 7d 20 50 28 lwarx r9,0,r10
c096b4f8: 2c 09 00 00 cmpwi r9,0
c096b4fc: 40 82 00 10 bne c096b50c <_raw_spin_lock_irqsave+0x2c>
c096b500: 7d 00 51 2d stwcx. r8,0,r10
@@ -2528149,7 +2528149,7 @@ c096b528: 4b ff ff f4 b c096b51c
c096b52c <_raw_write_lock_nested>:
c096b52c: 94 21 ff f0 stwu r1,-16(r1)
c096b530: 39 40 ff ff li r10,-1
-c096b534: 7d 20 18 29 lwarx r9,0,r3,1
+c096b534: 7d 20 18 28 lwarx r9,0,r3
c096b538: 2c 09 00 00 cmpwi r9,0
c096b53c: 40 82 00 10 bne c096b54c <_raw_write_lock_nested+0x20>
c096b540: 7d 40 19 2d stwcx. r10,0,r3
@@ -2528167,7 +2528167,7 @@ c096b568: 4b ff ff f4 b c096b55c
c096b56c <_raw_write_lock>:
c096b56c: 94 21 ff f0 stwu r1,-16(r1)
c096b570: 39 40 ff ff li r10,-1
-c096b574: 7d 20 18 29 lwarx r9,0,r3,1
+c096b574: 7d 20 18 28 lwarx r9,0,r3
c096b578: 2c 09 00 00 cmpwi r9,0
c096b57c: 40 82 00 10 bne c096b58c <_raw_write_lock+0x20>
c096b580: 7d 40 19 2d stwcx. r10,0,r3
@@ -2528186,7 +2528186,7 @@ c096b5ac <_raw_write_lock_irq>:
c096b5ac: 94 21 ff f0 stwu r1,-16(r1)
c096b5b0: 7c 00 01 46 wrteei 0
c096b5b4: 39 40 ff ff li r10,-1
-c096b5b8: 7d 20 18 29 lwarx r9,0,r3,1
+c096b5b8: 7d 20 18 28 lwarx r9,0,r3
c096b5bc: 2c 09 00 00 cmpwi r9,0
c096b5c0: 40 82 00 10 bne c096b5d0 <_raw_write_lock_irq+0x24>
c096b5c4: 7d 40 19 2d stwcx. r10,0,r3
@@ -2528207,7 +2528207,7 @@ c096b5f4: 7c 6a 1b 78 mr r10,r3
c096b5f8: 7c 60 00 a6 mfmsr r3
c096b5fc: 7c 00 01 46 wrteei 0
c096b600: 39 00 ff ff li r8,-1
-c096b604: 7d 20 50 29 lwarx r9,0,r10,1
+c096b604: 7d 20 50 28 lwarx r9,0,r10
c096b608: 2c 09 00 00 cmpwi r9,0
c096b60c: 40 82 00 10 bne c096b61c <_raw_write_lock_irqsave+0x2c>
c096b610: 7d 00 51 2d stwcx. r8,0,r10
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