On Wed, Dec 17, 2025 at 9:16 PM Brian Gerst <[email protected]> wrote: > > On Tue, Dec 16, 2025 at 4:26 PM H. Peter Anvin <[email protected]> wrote: > > > > Currently the vdso doesn't include .note.gnu.property or a GNU noexec > > stack annotation (the -z noexecstack in the linker script is > > ineffective because we specify PHDRs explicitly.) > > > > The motivation is that the dynamic linker currently do not check > > these. > > > > However, this is a weak excuse: the vdso*.so are also supposed to be > > usable at link libraries, and there is no reason why the dynamic > > linker might not want or need to check these in the future, so add > > them back in -- it is trivial enough. > > > > Use symbolic constants for the PHDR permission flags. > > > > [ v4: drop unrelated formatting changes ] > > > > Signed-off-by: H. Peter Anvin (Intel) <[email protected]> > > --- > > arch/x86/entry/vdso/common/vdso-layout.lds.S | 38 ++++++++++++-------- > > 1 file changed, 23 insertions(+), 15 deletions(-) > > > > diff --git a/arch/x86/entry/vdso/common/vdso-layout.lds.S > > b/arch/x86/entry/vdso/common/vdso-layout.lds.S > > index ec1ac191a057..a1e30be3e83d 100644 > > --- a/arch/x86/entry/vdso/common/vdso-layout.lds.S > > +++ b/arch/x86/entry/vdso/common/vdso-layout.lds.S > > @@ -47,18 +47,18 @@ SECTIONS > > *(.gnu.linkonce.b.*) > > } :text > > > > - /* > > - * Discard .note.gnu.property sections which are unused and have > > - * different alignment requirement from vDSO note sections. > > - */ > > - /DISCARD/ : { > > + .note.gnu.property : { > > *(.note.gnu.property) > > - } > > - .note : { *(.note.*) } :text :note > > - > > - .eh_frame_hdr : { *(.eh_frame_hdr) } :text > > :eh_frame_hdr > > - .eh_frame : { KEEP (*(.eh_frame)) } :text > > + } :text :note :gnu_property > > + .note : { > > + *(.note*) > > + } :text :note > > > > + .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr > > + .eh_frame : { > > + KEEP (*(.eh_frame)) > > + *(.eh_frame.*) > > + } :text > > > > /* > > * Text is well-separated from actual data: there's plenty of > > @@ -87,15 +87,23 @@ SECTIONS > > * Very old versions of ld do not recognize this name token; use the > > constant. > > */ > > #define PT_GNU_EH_FRAME 0x6474e550 > > +#define PT_GNU_STACK 0x6474e551 > > +#define PT_GNU_PROPERTY 0x6474e553 > > Do we even still support the old linkers that need these constants?
Digging into the binutils source, PT_GNU_EH_FRAME and PT_GNU_STACK were added to the parser around bintils-2.15. PT_GNU_PROPERTY was added in binutils-2.38, which is newer than the minimum supported version of binutils-2.30. Probably better to just leave them then. Brian Gerst
