Le 09/11/2023 à 11:18, Michael Ellerman a écrit : > "Arnd Bergmann" <arnd@xxxxxxxx> writes: >> On Wed, Nov 8, 2023, at 19:31, Christophe Leroy wrote: >>> Le 08/11/2023 à 13:58, Arnd Bergmann a écrit : >> >>> powerpc has functions doing more or less the same, they are called >>> __c_kernel_clock_gettime() and alike with their prototypes siting in >>> arch/powerpc/include/asm/vdso/gettimeofday.h >>> >>> Should those prototypes be moved to include/vdso/gettime.h too and >>> eventually renamed, or are they considered too powerpc specific ? >> >> I don't actually know, my initial interpretation was that >> these function names are part of the user ABI for the vdso, >> but I never looked closely enough at how vdso works to >> be sure what the actual ABI is. > > AFAIK the ABI is just the symbols we export, as defined in the linker > script: > > /* > * This controls what symbols we export from the DSO. > */ > VERSION > { > VDSO_VERSION_STRING { > global: > __kernel_get_syscall_map; > __kernel_gettimeofday; > __kernel_clock_gettime; > __kernel_clock_getres; > __kernel_get_tbfreq; > __kernel_sync_dicache; > __kernel_sigtramp_rt64; > __kernel_getcpu; > __kernel_time; > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/kernel/vdso/vdso64.lds.S?h=v6.6&#n117 > >> If __c_kernel_clock_gettime() etc are not part of the user-facing >> ABI, I think renaming them for consistency with the other >> architectures would be best. > > The __c symbols are not part of the ABI, so we could rename them. > > At the moment though they don't have the same prototype as the generic > versions, because we find the VDSO data in asm and pass it to the C > functions, eg: > > int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz, > const struct vdso_data *vd); > > I think we can rework that though, by implementing > __arch_get_vdso_data() and getting the vdso_data in C. Then we'd be able > to share the prototypes. I think it would not a been good idea, it would be less performant, for explanation see commit https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e876f0b69dc993e86ca7795e63e98385aa9a7ef3 Christophe