Messages in this thread | | | Date | Mon, 8 May 2023 17:31:40 -0700 | Subject | Re: [PATCH v6 07/12] x86/cpu/keylocker: Load an internal wrapping key at boot-time | From | "Chang S. Bae" <> |
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On 5/8/2023 2:56 PM, Dave Hansen wrote: > On 5/8/23 11:18, Chang S. Bae wrote: >> On 5/5/2023 4:05 PM, Eric Biggers wrote: >>> On Mon, Apr 10, 2023 at 03:59:31PM -0700, Chang S. Bae wrote: >>>> +#ifdef CONFIG_X86_KEYLOCKER >>>> +void setup_keylocker(struct cpuinfo_x86 *c); >>>> +void destroy_keylocker_data(void); >>>> +#else >>>> +#define setup_keylocker(c) do { } while (0) >>>> +#define destroy_keylocker_data() do { } while (0) >>>> +#endif >>> >>> Shouldn't the !CONFIG_X86_KEYLOCKER stubs be static inline functions >>> instead of >>> macros, so that type checking works? >> >> I think either way works here. This macro is just for nothing. > > Chang, I do prefer the 'static inline' as a general rule. Think of this: > > static inline void setup_keylocker(struct cpuinfo_x86 *c) {} > > versus: > > #define setup_keylocker(c) do { } while (0) > > Imagine some dope does: > > char c; > ... > setup_keylocker(c); > > With the macro, they'll get no type warning. The inline actually makes > it easier to find bugs because folks will get _some_ type checking no > matter how they compile the code.
Ah, when the prototype with one or more arguments, 'static inline' allows the check. Then it is not an 'either-way' thing.
Looking at the x86 code, there are some seemingly related:
$ git grep "do { } while (0)" arch/x86 | grep -v "()" arch/x86/include/asm/kprobes.h:#define flush_insn_slot(p) do { } while (0) arch/x86/include/asm/mc146818rtc.h:#define lock_cmos(reg) do { } while (0) arch/x86/include/asm/pgtable.h:#define flush_tlb_fix_spurious_fault(vma, address, ptep) do { } while (0) arch/x86/include/asm/preempt.h:#define init_task_preempt_count(p) do { } while (0) arch/x86/kvm/ioapic.h:#define ASSERT(x) do { } while (0) arch/x86/kvm/mmu/mmu_internal.h:#define pgprintk(x...) do { } while (0) arch/x86/kvm/mmu/mmu_internal.h:#define rmap_printk(x...) do { } while (0) arch/x86/kvm/mmu/mmu_internal.h:#define MMU_WARN_ON(x) do { } while (0)
Now I feel owed for some potential cleanup work.
Thanks, Chang
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