On Fri, Mar 19 2021 at 17:17, Thomas Gleixner wrote:
> On Wed, Mar 17 2021 at 11:12, Andy Lutomirski wrote:
>> +
>> +#define DEBUG_ENTRY_WARN_ONCE(condition, format...) do {} while (0)
>
> So we have a stub for !DEBUG
>
>> +static __always_inline void kentry_cpu_depth_add(unsigned int n) {}
>> +static void kentry_cpu_depth_check(unsigned int n) {}
>> +static __always_inline void kentry_cpu_depth_sub(unsigned int n) {}
>> +
>> +#endif
>> +
>> /* See comment for enter_from_user_mode() in entry-common.h */
>> static __always_inline void __enter_from_user_mode(struct pt_regs *regs)
>> {
>> + kentry_cpu_depth_add(1);
>> arch_check_user_regs(regs);
>> lockdep_hardirqs_off(CALLER_ADDR0);
>>
>> @@ -22,6 +78,14 @@ static __always_inline void __enter_from_user_mode(struct
>> pt_regs *regs)
>>
>> instrumentation_begin();
>> trace_hardirqs_off_finish();
>> +
>> +#ifdef CONFIG_DEBUG_ENTRY
>
> Why do we need that #ifdeffery all over the place?
>
>> + DEBUG_ENTRY_WARN_ONCE(
>> + this_cpu_read(kentry_cpu_depth) != 1,
>> + "kentry: __enter_from_user_mode() called while kentry thought
>> the CPU was in the kernel (%u)",
>> + this_cpu_read(kentry_cpu_depth));
Because you directly access kentry_cpu_depth which makes the compiler
unhappy.
And of course at the other place where you guard it with IS_ENABLED() it
fails to build with CONFIG_DEBUG_ENTRY=n
kernel/entry/common.c:158:10: error: ‘struct task_struct’ has no member named
‘kentry_in_syscall’
current->kentry_in_syscall = true;
This is V4 of this series... Oh well.
tglx
