On Mon, 2022-10-10 at 11:29 +1100, Benjamin Gray wrote: > > A function symbol may set a value in the st_other field to indicate > > the TOC should be treated as caller-saved. The linker should > > ensure> the > > current TOC is saved before calling it and restore the TOC> > > afterwards, > > much like external calls.
As I suggested on the last revision, worth mentioning here that it's the '.localentry <NAME>, 1' directive we're talking about here. > > > > This is necessary for supporting V2 ABI static calls that do not > > preserve the TOC. > > > > Signed-off-by: Benjamin Gray <bg...@linux.ibm.com> > > --- > > arch/powerpc/kernel/module_64.c | 14 +++++++++++++- > > 1 file changed, 13 insertions(+), 1 deletion(-) > > > > diff --git a/arch/powerpc/kernel/module_64.c> > > b/arch/powerpc/kernel/module_64.c > > index 7e45dc98df8a..83a6f6e22e3b 100644 > > --- a/arch/powerpc/kernel/module_64.c > > +++ b/arch/powerpc/kernel/module_64.c > > @@ -55,6 +55,12 @@ static unsigned int local_entry_offset(const> > > Elf64_Sym *sym) > > * of function and try to derive r2 from it). */ > > return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other); > > } > > + > > +static bool need_r2save_stub(unsigned char st_other) > > +{ > > + return (st_other & STO_PPC64_LOCAL_MASK) == (1 <<> > > STO_PPC64_LOCAL_BIT); > > +} > > + > > #else > > > > static func_desc_t func_desc(unsigned long addr) > > @@ -66,6 +72,11 @@ static unsigned int local_entry_offset(const> > > Elf64_Sym *sym) > > return 0; > > } > > > > +static bool need_r2save_stub(unsigned char st_other) > > +{ > > + return false; > > +} > > + > > void *dereference_module_function_descriptor(struct module *mod,> > > void *ptr) > > { > > if (ptr < (void *)mod->arch.start_opd || > > @@ -632,7 +643,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, > > case R_PPC_REL24: > > /* FIXME: Handle weak symbols here --RR */ > > if (sym->st_shndx == SHN_UNDEF || > > - sym->st_shndx == SHN_LIVEPATCH) { > > + sym->st_shndx == SHN_LIVEPATCH || > > + need_r2save_stub(sym->st_other)) { > > /* External: go via stub */ Perhaps this comment should be updated to mention that there are non- external but external-like calls? Otherwise Reviewed-by: Andrew Donnellan <a...@linux.ibm.com> > > value = stub_for_addr(sechdrs, > > value,> me, > > strtab +> sym- > > >st_name); -- Andrew Donnellan OzLabs, ADL Canberra a...@linux.ibm.com IBM Australia Limited