Re: svn commit: r339876 - head/libexec/rtld-elf
On Tue, Oct 30, 2018 at 03:32:40PM +, Alexander Richardson wrote: > On Tue, 30 Oct 2018 at 10:17, Michael Tuexen > wrote: > > > > > On 29. Oct 2018, at 22:08, Alex Richardson > > > 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 > > This is rather surprising since if anything the range of the icache > flush should increase rather than decrease after this change. > > I can only see this causing a behaviour change if we actually need to > flush more than just the executable segments. > Is it possible that some binary/library contains a non-executable > segment as the first PT_LOAD? > Or is there some linker script that adds custom PHDRS? > Could it be that there is a hole between start of the object mapping and the last PT_LOADable segment eligible for execution ? ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
Re: svn commit: r339876 - head/libexec/rtld-elf
On Tue, 30 Oct 2018 at 10:17, Michael Tuexen
wrote:
>
> > On 29. Oct 2018, at 22:08, Alex Richardson 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
This is rather surprising since if anything the range of the icache
flush should increase rather than decrease after this change.
I can only see this causing a behaviour change if we actually need to
flush more than just the executable segments.
Is it possible that some binary/library contains a non-executable
segment as the first PT_LOAD?
Or is there some linker script that adds custom PHDRS?
Alex
> >
> > 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.cMon Oct 29 21:03:43 2018
> > (r339875)
> > +++ head/libexec/rtld-elf/map_object.cMon 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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Re: svn commit: r339876 - head/libexec/rtld-elf
> On 29. Oct 2018, at 22:08, Alex Richardson 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.cMon Oct 29 21:03:43 2018
> (r339875)
> +++ head/libexec/rtld-elf/map_object.cMon 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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svn commit: r339876 - head/libexec/rtld-elf
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.
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.cMon Oct 29 21:03:43 2018
(r339875)
+++ head/libexec/rtld-elf/rtld.cMon 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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