linux-kernel - Re: [PATCH] powerpc/ptrace: Don't return error when getting/setting FP regs without CONFIG_PPC_FPU

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Message-Id: <161745070512.936361.2043800315190251594.b4-ty@ellerman.id.au>
Date:   Sat, 03 Apr 2021 22:51:45 +1100
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] powerpc/ptrace: Don't return error when getting/setting FP regs without CONFIG_PPC_FPU_REGS

On Wed, 31 Mar 2021 14:14:58 +0000 (UTC), Christophe Leroy wrote:
> An #ifdef CONFIG_PPC_FPU_REGS is missing in arch_ptrace() leading
> to the following Oops because [REGSET_FPR] entry is not initialised in
> native_regsets[].
> 
> [   41.917608] BUG: Unable to handle kernel instruction fetch
> [   41.922849] Faulting instruction address: 0xff8fd228
> [   41.927760] Oops: Kernel access of bad area, sig: 11 [#1]
> [   41.933089] BE PAGE_SIZE=4K PREEMPT CMPC885
> [   41.940753] Modules linked in:
> [   41.943768] CPU: 0 PID: 366 Comm: gdb Not tainted 5.12.0-rc5-s3k-dev-01666-g7aac86a0f057-dirty #4835
> [   41.952800] NIP:  ff8fd228 LR: c004d9e0 CTR: ff8fd228
> [   41.957790] REGS: caae9df0 TRAP: 0400   Not tainted  (5.12.0-rc5-s3k-dev-01666-g7aac86a0f057-dirty)
> [   41.966741] MSR:  40009032 <EE,ME,IR,DR,RI>  CR: 82004248  XER: 20000000
> [   41.973540]
> [   41.973540] GPR00: c004d9b4 caae9eb0 c1b64f60 c1b64520 c0713cd4 caae9eb8 c1bacdfc 00000004
> [   41.973540] GPR08: 00000200 ff8fd228 c1bac700 00001032 28004242 1061aaf4 00000001 106d64a0
> [   41.973540] GPR16: 00000000 00000000 7fa0a774 10610000 7fa0aef9 00000000 10610000 7fa0a538
> [   41.973540] GPR24: 7fa0a580 7fa0a570 c1bacc00 c1b64520 c1bacc00 caae9ee8 00000108 c0713cd4
> [   42.009685] NIP [ff8fd228] 0xff8fd228
> [   42.013300] LR [c004d9e0] __regset_get+0x100/0x124
> [   42.018036] Call Trace:
> [   42.020443] [caae9eb0] [c004d9b4] __regset_get+0xd4/0x124 (unreliable)
> [   42.026899] [caae9ee0] [c004da94] copy_regset_to_user+0x5c/0xb0
> [   42.032751] [caae9f10] [c002f640] sys_ptrace+0xe4/0x588
> [   42.037915] [caae9f30] [c0011010] ret_from_syscall+0x0/0x28
> [   42.043422] --- interrupt: c00 at 0xfd1f8e4
> [   42.047553] NIP:  0fd1f8e4 LR: 1004a688 CTR: 00000000
> [   42.052544] REGS: caae9f40 TRAP: 0c00   Not tainted  (5.12.0-rc5-s3k-dev-01666-g7aac86a0f057-dirty)
> [   42.061494] MSR:  0000d032 <EE,PR,ME,IR,DR,RI>  CR: 48004442  XER: 00000000
> [   42.068551]
> [   42.068551] GPR00: 0000001a 7fa0a040 77dad7e0 0000000e 00000170 00000000 7fa0a078 00000004
> [   42.068551] GPR08: 00000000 108deb88 108dda40 106d6010 44004442 1061aaf4 00000001 106d64a0
> [   42.068551] GPR16: 00000000 00000000 7fa0a774 10610000 7fa0aef9 00000000 10610000 7fa0a538
> [   42.068551] GPR24: 7fa0a580 7fa0a570 1078fe00 1078fd70 1078fd70 00000170 0fdd3244 0000000d
> [   42.104696] NIP [0fd1f8e4] 0xfd1f8e4
> [   42.108225] LR [1004a688] 0x1004a688
> [   42.111753] --- interrupt: c00
> [   42.114768] Instruction dump:
> [   42.117698] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
> [   42.125443] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
> [   42.133195] ---[ end trace d35616f22ab2100c ]---
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/ptrace: Don't return error when getting/setting FP regs without CONFIG_PPC_FPU_REGS
      https://git.kernel.org/powerpc/c/3618250c8399cb36f4a0fbc48610a178307e1c64

cheers