Re: [PATCH] x86/entry: Improve system call entry comments

From: Andy Lutomirski
Date: Tue Mar 08 2016 - 13:45:52 EST

On Tue, Mar 8, 2016 at 10:40 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 03/08/16 02:30, Ingo Molnar wrote:
>>>>> + *
>>>>> + * This is considered a slow path. It is not used by modern libc
>>>>> + * implementations on modern hardware except during process startup.
>>>>> + *
>>> Sadly I believe Android still uses int $0x80 in the upstream version.
>> I don't see how that fact conflicts with my statement: on 64-bit kernels INT $0x80
>> will (of course) work, but will land on another entry point: entry_INT80_compat(),
>> not entry_INT80_32().
>> On 32-bit kernels the INT $0x80 entry point is entry_INT80_32().
> It doesn't. I was referring to the above quote. Trying to fix that.

s/modern/most, perhaps?

I'm hoping that some day Bionic goes away and gets replaced by musl.

Of course, musl doesn't always use fast syscalls because it needs a
vdso facility that doesn't currently exist. I'll deal with that

> -hpa

Andy Lutomirski
AMA Capital Management, LLC