On Fri, Apr 28, 2023 at 10:28:19AM +0000, Christophe Leroy wrote:
> > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > index 5b600bbf2389..d67b80251eec 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -131,6 +131,27 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
> > for (insn = next_insn_same_sec(file, insn); insn; \
> > insn = next_insn_same_sec(file, insn))
> >
> > +static struct instruction *find_insn_containing(struct objtool_file *file,
> > + struct section *sec,
> > + unsigned long offset)
> > +{
> > + struct instruction *insn;
> > +
> > + insn = find_insn(file, sec, 0);
> > + if (!insn)
> > + return NULL;
> > +
> > + sec_for_each_insn_from(file, insn) {
> > + if (insn->offset > offset)
> > + return NULL;
> > + if (insn->offset <= offset && (insn->offset + insn->len) > offset)
> > + return insn;
> > + }
> > +
> > + return NULL;
> > +}
Urgh, this is horrendous crap. Yes you're only using it in case of a
warning, but adding a function like this makes it appear like it's
actually sane to use.
A far better implementation -- but still not stellar -- would be
something like:
sym = find_symbol_containing(sec, offset);
if (!sym)
// fail
sym_for_each_insn(file, sym, insn) {
...
}
But given insn_hash uses sec_offset_hash() you can do something similar
to find_reloc_by_dest_range()
start = offset - (INSN_MAX_SIZE - 1);
for_offset_range(o, start, start + INSN_MAX_SIZE) {
hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, o)) {
if (insn->sec != sec)
continue;
if (insn->offset <= offset &&
insn->offset + inns->len > offset)
return insn;
}
}
return NULL;
> > +
> > +
> > static inline struct symbol *insn_call_dest(struct instruction *insn)
> > {
> > if (insn->type == INSN_JUMP_DYNAMIC ||
> > @@ -4529,6 +4550,61 @@ static int validate_reachable_instructions(struct objtool_file *file)
> > return 0;
> > }
> >
> > +static int is_in_pvh_code(struct instruction *insn)
> > +{
> > + struct symbol *sym = insn->sym;
> > +
> > + return sym && !strcmp(sym->name, "pvh_start_xen");
> > +}
> > +
> > +static int validate_pie(struct objtool_file *file)
> > +{
> > + struct section *sec;
> > + struct reloc *reloc;
> > + struct instruction *insn;
> > + int warnings = 0;
> > +
> > + for_each_sec(file, sec) {
> > + if (!sec->reloc)
> > + continue;
> > + if (!(sec->sh.sh_flags & SHF_ALLOC))
> > + continue;
> > +
> > + list_for_each_entry(reloc, &sec->reloc->reloc_list, list) {
> > + switch (reloc->type) {
> > + case R_X86_64_NONE:
> > + case R_X86_64_PC32:
> > + case R_X86_64_PLT32:
> > + case R_X86_64_64:
> > + case R_X86_64_PC64:
> > + case R_X86_64_GOTPCREL:
> > + break;
> > + case R_X86_64_32:
> > + case R_X86_64_32S:
>
> That looks very specific to X86, should it go at another place ?
>
> If it can work for any architecture, can you add generic macros, just
> like commit c1449735211d ("objtool: Use macros to define arch specific
> reloc types") then commit c984aef8c832 ("objtool/powerpc: Add --mcount
> specific implementation") ?
Yes, this should be something like arch_PIE_reloc() or so. Similar to
arch_pc_relative_reloc().
