On Monday 25 July 2022 18:20:01 Michael Ellerman wrote: > Pali Rohár <p...@kernel.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.le...@csgroup.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.le...@csgroup.eu> > >> > Signed-off-by: Michael Ellerman <m...@ellerman.id.au> > >> > Link: > >> > https://lore.kernel.org/r/1fc81f07cabebb875b963e295408cc3dd38c8d85.1614674882.git.christophe.le...@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
