Re: [PATCH v2 00/13] objtool: Detect and warn about indirect calls in __nocfi functions

Xin Li
2025-05-02T06:13:28Z

On 5/1/2025 11:59 AM, Sean Christopherson wrote:
>> Ok maybe I'm being dense, but what is left other than simply calling
>> __fred_entry_from_kvm() as a normal C function?
>>
>> I'm on the go so there might be something in the code I'm missing, but on the
>> surface...?
> I'm sure it's doable, though I'd be more than a little nervous about diverging
> from what FRED=y does, e.g. in case code somewhere expects the stack to look
> exactly like a real FRED event.

__fred_entry_from_kvm() accepts a pt_regs structure pointer, with event
type and vector in FRED stack frame. They are set up in the assembly.

> And since we'd still need the assembly to support FRED=y, I don't see any point
> in adding more code when it's trivially easy to have asm_fred_entry_from_kvm()
> skip ERETS.

Yeah, your change seems minimized to me.