Christophe Leroy <christophe.leroy@xxxxxx> writes: > The VDSO datapage and the text pages are always located immediately > next to each other, so it can be hardcoded without an indirection > through __kernel_datapage_offset > > In order to ease things, move the data page in front like other > arches, that way there is no need to know the size of the library > to locate the data page. > > Before: > clock-getres-realtime-coarse: vdso: 714 nsec/call > clock-gettime-realtime-coarse: vdso: 792 nsec/call > clock-gettime-realtime: vdso: 1243 nsec/call > > After: > clock-getres-realtime-coarse: vdso: 699 nsec/call > clock-gettime-realtime-coarse: vdso: 784 nsec/call > clock-gettime-realtime: vdso: 1231 nsec/call > > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx> > --- > v7: > - Moved the removal of the tmp param of __get_datapage() > in a subsequent patch > - Included the addition of the offset param to __get_datapage() > in the further preparatory patch > --- > arch/powerpc/include/asm/vdso_datapage.h | 8 ++-- > arch/powerpc/kernel/vdso.c | 53 ++++-------------------- > arch/powerpc/kernel/vdso32/datapage.S | 3 -- > arch/powerpc/kernel/vdso32/vdso32.lds.S | 7 +--- > arch/powerpc/kernel/vdso64/datapage.S | 3 -- > arch/powerpc/kernel/vdso64/vdso64.lds.S | 7 +--- > 6 files changed, 16 insertions(+), 65 deletions(-) > > diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h > index b9ef6cf50ea5..11886467dfdf 100644 > --- a/arch/powerpc/include/asm/vdso_datapage.h > +++ b/arch/powerpc/include/asm/vdso_datapage.h > @@ -118,10 +118,12 @@ extern struct vdso_data *vdso_data; > > .macro get_datapage ptr, tmp > bcl 20, 31, .+4 > +999: > mflr \ptr > - addi \ptr, \ptr, (__kernel_datapage_offset - (.-4))@l > - lwz \tmp, 0(\ptr) > - add \ptr, \tmp, \ptr > +#if CONFIG_PPC_PAGE_SHIFT > 14 > + addis \ptr, \ptr, (_vdso_datapage - 999b)@ha > +#endif > + addi \ptr, \ptr, (_vdso_datapage - 999b)@l > .endm > > #endif /* __ASSEMBLY__ */ > diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c > index f38f26e844b6..d33fa22ddbed 100644 > --- a/arch/powerpc/kernel/vdso.c > +++ b/arch/powerpc/kernel/vdso.c > @@ -190,7 +190,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) > * install_special_mapping or the perf counter mmap tracking code > * will fail to recognise it as a vDSO (since arch_vma_name fails). > */ > - current->mm->context.vdso_base = vdso_base; > + current->mm->context.vdso_base = vdso_base + PAGE_SIZE; I merged this but then realised it breaks the display of the vdso in /proc/self/maps. ie. the vdso vma gets no name: # cat /proc/self/maps 110f90000-110fa0000 r-xp 00000000 08:03 17021844 /usr/bin/cat 110fa0000-110fb0000 r--p 00000000 08:03 17021844 /usr/bin/cat 110fb0000-110fc0000 rw-p 00010000 08:03 17021844 /usr/bin/cat 126000000-126030000 rw-p 00000000 00:00 0 [heap] 7fffa8790000-7fffa87d0000 rw-p 00000000 00:00 0 7fffa87d0000-7fffa8830000 r--p 00000000 08:03 17521786 /usr/lib/locale/en_AU.utf8/LC_CTYPE 7fffa8830000-7fffa8840000 r--p 00000000 08:03 16958337 /usr/lib/locale/en_AU.utf8/LC_NUMERIC 7fffa8840000-7fffa8850000 r--p 00000000 08:03 8501358 /usr/lib/locale/en_AU.utf8/LC_TIME 7fffa8850000-7fffa8ad0000 r--p 00000000 08:03 16870886 /usr/lib/locale/en_AU.utf8/LC_COLLATE 7fffa8ad0000-7fffa8ae0000 r--p 00000000 08:03 8509433 /usr/lib/locale/en_AU.utf8/LC_MONETARY 7fffa8ae0000-7fffa8af0000 r--p 00000000 08:03 25383753 /usr/lib/locale/en_AU.utf8/LC_MESSAGES/SYS_LC_MESSAGES 7fffa8af0000-7fffa8b00000 r--p 00000000 08:03 17521790 /usr/lib/locale/en_AU.utf8/LC_PAPER 7fffa8b00000-7fffa8b10000 r--p 00000000 08:03 8501354 /usr/lib/locale/en_AU.utf8/LC_NAME 7fffa8b10000-7fffa8b20000 r--p 00000000 08:03 8509431 /usr/lib/locale/en_AU.utf8/LC_ADDRESS 7fffa8b20000-7fffa8b30000 r--p 00000000 08:03 8509434 /usr/lib/locale/en_AU.utf8/LC_TELEPHONE 7fffa8b30000-7fffa8b40000 r--p 00000000 08:03 17521787 /usr/lib/locale/en_AU.utf8/LC_MEASUREMENT 7fffa8b40000-7fffa8b50000 r--s 00000000 08:03 25623315 /usr/lib64/gconv/gconv-modules.cache 7fffa8b50000-7fffa8d40000 r-xp 00000000 08:03 25383789 /usr/lib64/libc-2.30.so 7fffa8d40000-7fffa8d50000 r--p 001e0000 08:03 25383789 /usr/lib64/libc-2.30.so 7fffa8d50000-7fffa8d60000 rw-p 001f0000 08:03 25383789 /usr/lib64/libc-2.30.so 7fffa8d60000-7fffa8d70000 r--p 00000000 08:03 8509432 /usr/lib/locale/en_AU.utf8/LC_IDENTIFICATION 7fffa8d70000-7fffa8d90000 r-xp 00000000 00:00 0 <--- missing 7fffa8d90000-7fffa8dc0000 r-xp 00000000 08:03 25383781 /usr/lib64/ld-2.30.so 7fffa8dc0000-7fffa8dd0000 r--p 00020000 08:03 25383781 /usr/lib64/ld-2.30.so 7fffa8dd0000-7fffa8de0000 rw-p 00030000 08:03 25383781 /usr/lib64/ld-2.30.so 7fffc31c0000-7fffc31f0000 rw-p 00000000 00:00 0 [stack] And it's also going to break the logic in arch_unmap() to detect if we're unmapping (part of) the VDSO. And it will break arch_remap() too. And the logic to recognise the signal trampoline in arch/powerpc/perf/callchain_*.c as well. So I'm going to rebase and drop this for now. Basically we have a bunch of places that assume that vdso_base is == the start of the VDSO vma, and also that the code starts there. So that will need some work to tease out all those assumptions and make them work with this change. cheers
