svn commit: r339876 - head/libexec/rtld-elf
Michael Tuexen
Michael.Tuexen at macmic.franken.de
Tue Oct 30 10:17:44 UTC 2018
> On 29. Oct 2018, at 22:08, Alex Richardson <arichardson at FreeBSD.org> wrote:
>
> Author: arichardson
> Date: Mon Oct 29 21:08:02 2018
> New Revision: 339876
> URL: https://svnweb.freebsd.org/changeset/base/339876
>
> Log:
> rtld: set obj->textsize correctly
>
> With lld-generated binaries the first PT_LOAD will usually be a read-only
> segment unless you pass --no-rosegment. For those binaries the textsize is
> determined by the next PT_LOAD. To allow both LLD and bfd 2.17 binaries to
> be parsed correctly use the end of the last PT_LOAD that is marked as
> executable instead.
>
> I noticed that the value was wrong while adding some debug prints for some rtld
> changes for CHERI binaries. `obj->textsize` only seems to be used by PPC so the
> effect is untested. However, the value before was definitely wrong and the new
> result matches the phdrs.
I build kernel and world with a revision later than this on a PPC. Buildword
ends up with a world where almost all binaries are segfaulting.... Especially gdb
(but svn, ls or so all segfault).
Best regards
Michael
>
> Reviewed By: kib
> Approved By: brooks (mentor)
> Differential Revision: https://reviews.freebsd.org/D17117
>
> Modified:
> head/libexec/rtld-elf/map_object.c
> head/libexec/rtld-elf/rtld.c
>
> Modified: head/libexec/rtld-elf/map_object.c
> ==============================================================================
> --- head/libexec/rtld-elf/map_object.c Mon Oct 29 21:03:43 2018 (r339875)
> +++ head/libexec/rtld-elf/map_object.c Mon Oct 29 21:08:02 2018 (r339876)
> @@ -93,6 +93,7 @@ map_object(int fd, const char *path, const struct stat
> Elf_Addr note_end;
> char *note_map;
> size_t note_map_len;
> + Elf_Addr text_end;
>
> hdr = get_elf_header(fd, path, sb);
> if (hdr == NULL)
> @@ -116,6 +117,7 @@ map_object(int fd, const char *path, const struct stat
> note_map = NULL;
> segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
> stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
> + text_end = 0;
> while (phdr < phlimit) {
> switch (phdr->p_type) {
>
> @@ -130,6 +132,10 @@ map_object(int fd, const char *path, const struct stat
> path, nsegs);
> goto error;
> }
> + if ((segs[nsegs]->p_flags & PF_X) == PF_X) {
> + text_end = MAX(text_end,
> + round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz));
> + }
> break;
>
> case PT_PHDR:
> @@ -280,8 +286,7 @@ map_object(int fd, const char *path, const struct stat
> }
> obj->mapbase = mapbase;
> obj->mapsize = mapsize;
> - obj->textsize = round_page(segs[0]->p_vaddr + segs[0]->p_memsz) -
> - base_vaddr;
> + obj->textsize = text_end - base_vaddr;
> obj->vaddrbase = base_vaddr;
> obj->relocbase = mapbase - base_vaddr;
> obj->dynamic = (const Elf_Dyn *) (obj->relocbase + phdyn->p_vaddr);
>
> Modified: head/libexec/rtld-elf/rtld.c
> ==============================================================================
> --- head/libexec/rtld-elf/rtld.c Mon Oct 29 21:03:43 2018 (r339875)
> +++ head/libexec/rtld-elf/rtld.c Mon Oct 29 21:08:02 2018 (r339876)
> @@ -1390,13 +1390,15 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t e
> if (nsegs == 0) { /* First load segment */
> obj->vaddrbase = trunc_page(ph->p_vaddr);
> obj->mapbase = obj->vaddrbase + obj->relocbase;
> - obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
> - obj->vaddrbase;
> } else { /* Last load segment */
> obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
> obj->vaddrbase;
> }
> nsegs++;
> + if ((ph->p_flags & PF_X) == PF_X) {
> + obj->textsize = MAX(obj->textsize,
> + round_page(ph->p_vaddr + ph->p_memsz) - obj->vaddrbase);
> + }
> break;
>
> case PT_DYNAMIC:
>
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