Hi Thomas, On 24/06/2019 01:34, Thomas Gleixner wrote: > Vincenzo, > > On Fri, 21 Jun 2019, Vincenzo Frascino wrote: >> vDSO (virtual dynamic shared object) is a mechanism that the Linux >> kernel provides as an alternative to system calls to reduce where >> possible the costs in terms of cycles. >> This is possible because certain syscalls like gettimeofday() do >> not write any data and return one or more values that are stored >> in the kernel, which makes relatively safe calling them directly >> as a library function. >> >> Even if the mechanism is pretty much standard, every architecture >> in the last few years ended up implementing their own vDSO library >> in the architectural code. > > .... > >> This implementation contains the portings to the common library for: arm64, >> compat mode for arm64, arm, mips, x86_64, x32, compat mode for x86_64 and >> i386. > > I picked up the core implementation and the ARM64 and x86 conversion. I did > some refinements in several places, coding style, naming conventions, > comments and changelogs including subject prefixes. Please double check! > I tested your changes and they seem OK (git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso). ... > As you can see from the commit dates, this has soaked for some time in a > WIP branch and I did extensive regression testing. So far so good. > > Thanks a lot for going through several iterations. It's a very much > appreciated effort! > It has been a lot of fun and I learned many many things about the vDSOs and the kernel that I did not know before. Thanks to you for your patience and guidance. > Especially with the upcoming time namespaces this will avoid a lot of > duplicated and pointlessly different horrors all over the architecture > space. Any architecture which wants to gain that support needs to convert > to the generic VDSO first. > > As you have become the dude who knows almost everything about VDSO > including all the nasty pitfalls, I propose the patch below. > Thanks for this, it means a lot to me. > Thanks, > > tglx > > 8<------------ > Subject: MAINTAINERS: Add entry for the generic VDSO library > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Date: Mon, 24 Jun 2019 02:03:50 +0200 > > Asign the following folks in alphabetic order: > > - Andy for being the VDSO wizard of x86 and in general. He's also the > performance monitor of choice and the code in the generic library is > heavily influenced by his previous x86 VDSO work. > > - Thomas for being the dude who has to deal with any form of time(r) > nonsense anyway > > - Vincenzo for being the poor sod who went through all the different > architecture implementations in order to unify them. A lot of knowledge > gained from VDSO implementation details to the intricacies of taming the > build system. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > --- > MAINTAINERS | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -6665,6 +6665,18 @@ L: kvm@xxxxxxxxxxxxxxx > S: Supported > F: drivers/uio/uio_pci_generic.c > > +GENERIC VDSO LIBRARY: > +M: Andy Lutomirksy <luto@xxxxxxxxxx> > +M: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > +M: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> > +L: linux-kernel@xxxxxxxxxxxxxxx > +T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/vdso > +S: Maintained > +F: lib/vdso > +F: kernel/time/vsyscall.c > +F: include/vdso > +F: include/asm-generic/vdso/vsyscall.h > + > GENWQE (IBM Generic Workqueue Card) > M: Frank Haverkamp <haver@xxxxxxxxxxxxx> > S: Supported > -- Regards, Vincenzo
