From 8361dadbae8bf2054221110c795f0859dc99954f Mon Sep 17 00:00:00 2001 From: Reza Arbab Date: Fri, 21 Jun 2019 10:25:53 +0530 Subject: [PATCH] powerpc/64s: Save r13 in machine_check_common_early Testing my memcpy_mcsafe() work in progress with an injected UE, I get an error like this immediately after the function returns: BUG: Unable to handle kernel data access at 0x7fff84dec8f8 Faulting instruction address: 0xc0080000009c00b0 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Radix MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: mce(O+) vmx_crypto crc32c_vpmsum CPU: 0 PID: 1375 Comm: modprobe Tainted: G O 5.1.0-rc6 #267 NIP: c0080000009c00b0 LR: c0080000009c00a8 CTR: c000000000095f90 REGS: c0000000ee197790 TRAP: 0300 Tainted: G O (5.1.0-rc6) MSR: 900000000280b033 CR: 88002826 XER: 00040000 CFAR: c000000000095f8c DAR: 00007fff84dec8f8 DSISR: 40000000 IRQMASK: 0 GPR00: 000000006c6c6568 c0000000ee197a20 c0080000009c8400 fffffffffffffff2 GPR04: c0080000009c02e0 0000000000000006 0000000000000000 c000000003c834c8 GPR08: 0080000000000000 776a6681b7fb5100 0000000000000000 c0080000009c01c8 GPR12: c000000000095f90 00007fff84debc00 000000004d071440 0000000000000000 GPR16: 0000000100000601 c0080000009e0000 c000000000c98dd8 c000000000c98d98 GPR20: c000000003bba970 c0080000009c04d0 c0080000009c0618 c0000000001e5820 GPR24: 0000000000000000 0000000000000100 0000000000000001 c000000003bba958 GPR28: c0080000009c02e8 c0080000009c0318 c0080000009c02e0 0000000000000000 NIP [c0080000009c00b0] cause_ue+0xa8/0xe8 [mce] LR [c0080000009c00a8] cause_ue+0xa0/0xe8 [mce] To fix, ensure that r13 is properly restored after an MCE. Signed-off-by: Reza Arbab --- arch/powerpc/kernel/exceptions-64s.S | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 311f1392a2ec37..932d8d05892ca5 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -265,6 +265,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE) EXC_REAL_END(machine_check, 0x200, 0x100) EXC_VIRT_NONE(0x4200, 0x100) TRAMP_REAL_BEGIN(machine_check_common_early) + SET_SCRATCH0(r13) /* save r13 */ EXCEPTION_PROLOG_1(PACA_EXMC, NOTEST, 0x200) /* * Register contents: