[PATCH v6 08/14] aarch64: enable BTI at runtime

[Szabolcs Nagy]

The 07/11/2020 08:58, Richard Henderson wrote:
> On 7/1/20 7:39 AM, Szabolcs Nagy wrote:
> > +  unsigned prot = PROT_READ | PROT_EXEC | PROT_BTI;
> > +
> > +  for (phdr = map->l_phdr; phdr < &map->l_phdr[map->l_phnum]; ++phdr)
> > +    if (phdr->p_type == PT_LOAD && (phdr->p_flags & PF_X))
> > +      {
> > +	ElfW(Addr) start = phdr->p_vaddr + map->l_addr;
> > +	ElfW(Addr) len = phdr->p_memsz;
> > +	if (__mprotect ((void *) start, len, prot) < 0)
> 
> Spend an extra cycle or two and honor the exact set of p_flags?
> 
> If I construct an executable but non-readable PT_LOAD segment, that should be
> fine.  RWX with BTI would undoubtedly be an unusual case, but perhaps not
> implausible in the context of a JIT with a statically allocated buffer.

i will commit the attached fix tomorrow
unless there are comments on it.

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