Messages in this thread | | | Date | Thu, 10 Nov 2016 12:50:04 -0500 | From | Yazen Ghannam <> | Subject | Re: [tip:ras/core] x86/RAS: Simplify SMCA HWID descriptor struct |
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> static void get_smca_bank_info(unsigned int bank) > { > unsigned int i, hwid_mcatype, cpu = smp_processor_id(); > - struct smca_hwid_mcatype *type; > + struct smca_hwid *s_hwid; > u32 high, instance_id; > - u16 hwid, mcatype; > > /* Collect bank_info using CPU 0 for now. */ > if (cpu) > @@ -162,14 +157,13 @@ static void get_smca_bank_info(unsigned int bank) > return; > } > > - hwid = high & MCI_IPID_HWID; > - mcatype = (high & MCI_IPID_MCATYPE) >> 16; > - hwid_mcatype = HWID_MCATYPE(hwid, mcatype); > + hwid_mcatype = HWID_MCATYPE(high & MCI_IPID_HWID, > + (high & MCI_IPID_MCATYPE) >> 16); >
Sorry for catching this late, but it seems this change doesn't compile correctly. This causes the value of hwid_mcatype to be incorrect, so we will never match a bank to its type.
I see this with GCC 4.8.5 and 5.4.0.
There are no warnings or issues when building or booting just that the behavior is incorrect.
Disassembly of above change: db: 8b 45 e0 mov -0x20(%rbp),%eax de: 41 89 c4 mov %eax,%r12d e1: 25 00 00 ff 0f and $0xfff0000,%eax e6: 41 c1 ec 10 shr $0x10,%r12d ea: 41 09 c4 or %eax,%r12d
Disassembly of original code: 286: 8b 45 d0 mov -0x30(%rbp),%eax 289: 41 89 c5 mov %eax,%r13d 28c: c1 e8 10 shr $0x10,%eax 28f: 41 81 e5 ff 0f 00 00 and $0xfff,%r13d 296: 41 c1 e5 10 shl $0x10,%r13d 29a: 41 09 c5 or %eax,%r13d
Adding extra parentheses in HWID_MCATYPE() gives the same assembly as the original code and fixes the behavior.
> + hwid_mcatype = HWID_MCATYPE((high & MCI_IPID_HWID)), > + ((high & MCI_IPID_MCATYPE) >> 16));
Thanks, Yazen
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