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PR22758, FAIL: Run pr22393-2

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We can't map different disk pages into the same memory page; The last
page mapped will simply overwrite any previous pages.  The
executable/non-executable new_segment test ignored this fact, leading
to a ld.so segfault on hppa when .dynamic is overwritten with zeros.

This patch moves existing tests for demand paging with lma on the same
memory page, to a new test performed before any case where we want a
new segment due to protection or loadable conflicts.

	PR 22758
	* elf.c (_bfd_elf_map_sections_to_segments): Don't start a new
	segment when demand paged with lma on the same page.  Test this
	before load/non-load, executable/non-executable,
	writable/non-writable tests and simplify.  Delete bogus relro
	condition in writable/non-writable test.  Delete outdated
	comment.  Formatting.
This commit is contained in:
Alan Modra
2018-01-30 16:02:32 +10:30
parent fc413dc467
commit 76cb3a89a6
2 changed files with 26 additions and 24 deletions
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10
bfd/ChangeLog
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@ -1,3 +1,13 @@
2018-01-30 Alan Modra <amodra@gmail.com>
PR 22758
* elf.c (_bfd_elf_map_sections_to_segments): Don't start a new
segment when demand paged with lma on the same page. Test this
before load/non-load, executable/non-executable,
writable/non-writable tests and simplify. Delete bogus relro
condition in writable/non-writable test. Delete outdated
comment. Formatting.
2018-01-30 Alan Modra <amodra@gmail.com> 2018-01-30 Alan Modra <amodra@gmail.com>
* elflink.c (bfd_elf_define_start_stop): Make __start and __stop * elflink.c (bfd_elf_define_start_stop): Make __start and __stop

40
bfd/elf.c
View File

@ -4727,33 +4727,35 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
the previous section, then we need a new segment. */ the previous section, then we need a new segment. */
new_segment = TRUE; new_segment = TRUE;
} }
else if ((abfd->flags & D_PAGED) != 0
&& (((last_hdr->lma + last_size - 1) & -maxpagesize)
== (hdr->lma & -maxpagesize)))
{
/* If we are demand paged then we can't map two disk
pages onto the same memory page. */
new_segment = FALSE;
}
/* In the next test we have to be careful when last_hdr->lma is close /* In the next test we have to be careful when last_hdr->lma is close
to the end of the address space. If the aligned address wraps to the end of the address space. If the aligned address wraps
around to the start of the address space, then there are no more around to the start of the address space, then there are no more
pages left in memory and it is OK to assume that the current pages left in memory and it is OK to assume that the current
section can be included in the current segment. */ section can be included in the current segment. */
else if ((BFD_ALIGN (last_hdr->lma + last_size, maxpagesize) + maxpagesize else if ((BFD_ALIGN (last_hdr->lma + last_size, maxpagesize)
> last_hdr->lma) + maxpagesize > last_hdr->lma)
&& (BFD_ALIGN (last_hdr->lma + last_size, maxpagesize) + maxpagesize && (BFD_ALIGN (last_hdr->lma + last_size, maxpagesize)
<= hdr->lma)) + maxpagesize <= hdr->lma))
{ {
/* If putting this section in this segment would force us to /* If putting this section in this segment would force us to
skip a page in the segment, then we need a new segment. */ skip a page in the segment, then we need a new segment. */
new_segment = TRUE; new_segment = TRUE;
} }
else if ((last_hdr->flags & (SEC_LOAD | SEC_THREAD_LOCAL)) == 0 else if ((last_hdr->flags & (SEC_LOAD | SEC_THREAD_LOCAL)) == 0
&& (hdr->flags & (SEC_LOAD | SEC_THREAD_LOCAL)) != 0 && (hdr->flags & (SEC_LOAD | SEC_THREAD_LOCAL)) != 0)
&& ((abfd->flags & D_PAGED) == 0
|| (((last_hdr->lma + last_size - 1) & -maxpagesize)
!= (hdr->lma & -maxpagesize))))
{ {
/* We don't want to put a loaded section after a /* We don't want to put a loaded section after a
nonloaded (ie. bss style) section in the same segment nonloaded (ie. bss style) section in the same segment
as that will force the non-loaded section to be loaded. as that will force the non-loaded section to be loaded.
Consider .tbss sections as loaded for this purpose. Consider .tbss sections as loaded for this purpose. */
However, like the writable/non-writable case below,
if they are on the same page then they must be put
in the same segment. */
new_segment = TRUE; new_segment = TRUE;
} }
else if ((abfd->flags & D_PAGED) == 0) else if ((abfd->flags & D_PAGED) == 0)
@ -4770,20 +4772,10 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
new_segment = TRUE; new_segment = TRUE;
} }
else if (! writable else if (! writable
&& (hdr->flags & SEC_READONLY) == 0 && (hdr->flags & SEC_READONLY) == 0)
&& ((info != NULL
&& info->relro_end > info->relro_start)
|| (((last_hdr->lma + last_size - 1) & -maxpagesize)
!= (hdr->lma & -maxpagesize))))
{ {
/* We don't want to put a writable section in a read only /* We don't want to put a writable section in a read only
segment, unless they are on the same page in memory segment. */
anyhow and there is no RELRO segment. We already
know that the last section does not bring us past the
current section on the page, so the only case in which
the new section is not on the same page as the previous
section is when the previous section ends precisely on
a page boundary. */
new_segment = TRUE; new_segment = TRUE;
} }
else else