In rtld's map_object(), use pread(..., 0) rather than read() to read the
ELF header from the front of the file. As all other I/O on the binary
is done using mmap(), this avoids the need for seek pri

In rtld's map_object(), use pread(..., 0) rather than read() to read the
ELF header from the front of the file. As all other I/O on the binary
is done using mmap(), this avoids the need for seek privileges on the
file descriptor during run-time linking.

MFC after: 1 month
Sponsored by: Google

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- MFC @196061

Only perform .bss mapping and cleaning operations when segment file size
is not equal to its memory size.

This eliminates unneeded clearing of the text segment that often
happens due to text end not

Only perform .bss mapping and cleaning operations when segment file size
is not equal to its memory size.

This eliminates unneeded clearing of the text segment that often
happens due to text end not being page-aligned.

For instance,
$ readelf -l /lib/libedit.so.6
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x00000000 0x00000000 0x139e1 0x139e1 R E 0x1000
LOAD 0x014000 0x00014000 0x00014000 0x00f04 0x00f14 RW 0x1000
DYNAMIC 0x014cc4 0x00014cc4 0x00014cc4 0x000d0 0x000d0 RW 0x4
$ procstat -v $$ (for /bin/sh)
68585 0x28097000 0x280aa000 r-x 6 0 21 14 CN vn /lib/libedit.so.6
68585 0x280aa000 0x280ab000 r-x 1 0 1 0 CN vn /lib/libedit.so.6 <==
68585 0x280ab000 0x280ac000 rwx 1 0 1 0 CN vn /lib/libedit.so.6
Note the splitted map entry marked by '<=='.

Reviewed by: kan
Approved by: re (kensmith)
MFC after: 1 month

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- Merge from HEAD

Currently, when mapping an object, rtld reserves the whole address space
for the mapping by the object' file with the protection and mode of
the first loadable segment over the whole region. Then, it

Currently, when mapping an object, rtld reserves the whole address space
for the mapping by the object' file with the protection and mode of
the first loadable segment over the whole region. Then, it maps other
segments at the appropriate addresses inside the region.

On amd64, due to default alignment of the segments being 1Gb, the
subsequent segment mappings leave the holes in the region, that usually
contain mapping of the object' file past eof. Such mappings prevent
wiring of the address space, because the pages cannot be faulted in.

Change the way the mapping of the ELF objects is constructed, by first
mapping PROT_NONE anonymous memory over the whole range, and then
mapping the segments of the object over it. Take advantage of this new
order and allocate .bss by changing the protection of the range instead
of remapping.

Note that we cannot simply keep the holes between segments, because
other mappings may be made there. Among other issues, when the dso is
unloaded, rtld unmaps the whole region, deleting unrelated mappings.

The kernel ELF image activator does put the holes between segments, but
this is not critical for now because kernel loads only executable image
and interpreter, both cannot be unloaded. This will be fixed later, if
needed.

Reported and tested by: Hans Ottevanger <fbsdhackers beasties demon nl>
Suggested and reviewed by: kan, alc

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Update comment to the reality, rtld supports any number of loadable segments.
Fix spacing.

Reviewed by: kan

Implement the dynamic string token substitution in the rpath and
soneeded pathes. The $ORIGIN, $OSNAME, $OSREL and $PLATFORM tokens
are supported. Enabling the substitution requires DF_ORIGIN flag in

Implement the dynamic string token substitution in the rpath and
soneeded pathes. The $ORIGIN, $OSNAME, $OSREL and $PLATFORM tokens
are supported. Enabling the substitution requires DF_ORIGIN flag in
DT_FLAGS or DF_1_ORIGIN if DF_FLAGS_1, that may be set with -z origin
gnu ld flag. Translation is unconditionally disabled for setuid/setgid
processes.

The $ORIGIN translation relies on the AT_EXECPATH auxinfo supplied
by kernel.

Requested by: maho
Tested by: maho, pho
Reviewed by: kan

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Implement dl_iterate_phdr function.
Convert boolean flags in internal Obj_Entry structure into bitfields.
Properly check for loaded segment alignment in map_object.

Implement ELF symbol versioning using GNU semantics. This code aims
to be compatible with symbol versioning support as implemented by
GNU libc and documented by http://people.redhat.com/~drepper/symb

Implement ELF symbol versioning using GNU semantics. This code aims
to be compatible with symbol versioning support as implemented by
GNU libc and documented by http://people.redhat.com/~drepper/symbol-versioning
and LSB 3.0.

Implement dlvsym() function to allow lookups for a specific version of
a given symbol.

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Attempt to free any static TLS space used by a shared library when it
is unloaded. This allows applications which load and unload libraries
like libGL.so.1 several times to work properly.

MFC after:

Attempt to free any static TLS space used by a shared library when it
is unloaded. This allows applications which load and unload libraries
like libGL.so.1 several times to work properly.

MFC after: 2 days

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Add support for Thread Local Storage.

- Add support for DT_FLAGS.
- Define various things from the most recent ELF spec.

Simplify map_object() by breaking out the ELF header validation bits
into a separate function.

Fix signed/unsigned comparison warnings.

Free obj->priv field in obj_free functions. This field is NULL
on all architectures except ia64, which uses it to keep function
description table.

Change the way ELF coredumps are handled. Instead of unconditionally
skipping read-only pages, which can result in valuable non-text-related
data not getting dumped, the ELF loader and the dynamic l

Change the way ELF coredumps are handled. Instead of unconditionally
skipping read-only pages, which can result in valuable non-text-related
data not getting dumped, the ELF loader and the dynamic loader now mark
read-only text pages NOCORE and the coredump code only checks (primarily) for
complete inaccessibility of the page or NOCORE being set.

Certain applications which map large amounts of read-only data will
produce much larger cores. A new sysctl has been added,
debug.elf_legacy_coredump, which will revert to the old behavior.

This commit represents collaborative work by all parties involved.
The PR contains a program demonstrating the problem.

PR: kern/45994
Submitted by: "Peter Edwards" <pmedwards@eircom.net>, Archie Cobbs <archie@dellroad.org>
Reviewed by: jdp, dillon
MFC after: 7 days

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Add support for binaries with arbitrary number of PT_LOAD sections.

Reviewed by: peter

Add ia64 support. Various adjustments were made to existing targets to
cope with a few interface changes required by the ia64. In particular,
function pointers on ia64 need special treatment in rtld.

Get the actual pathname of the dynamic linker from the executable's
PT_INTERP program header entry, to ensure that gdb always finds
the right dynamic linker.

Use obj->relocbase to simplify a few cal

Get the actual pathname of the dynamic linker from the executable's
PT_INTERP program header entry, to ensure that gdb always finds
the right dynamic linker.

Use obj->relocbase to simplify a few calculations where appropriate.

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When checking to see if a shared object is already loaded, look for
a device/inode match if no pathname match is found.

Revamp the symbol lookup algorithm to cope better with objects
loaded separately by dlopen that have global symbols with identical
names. Viewing each dlopened object as a DAG which is linked by its

Revamp the symbol lookup algorithm to cope better with objects
loaded separately by dlopen that have global symbols with identical
names. Viewing each dlopened object as a DAG which is linked by its
DT_NEEDED entries in the dynamic table, the search order is as
follows:

* If the referencing object was linked with -Bsymbolic, search it
internally.
* Search all dlopened DAGs containing the referencing object.
* Search all objects loaded at program start up.
* Search all objects which were dlopened() using the RTLD_GLOBAL
flag (which is now supported too).

The search terminates as soon as a strong definition is found.
Lacking that, the first weak definition is used.

These rules match those of Solaris, as best I could determine them
from its vague manual pages and the results of experiments I performed.

PR: misc/12438

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$Id$ -> $FreeBSD$

Change many asserts into normal errors. They were all for conditions
caused by invalid shared objects rather than by internal errors.

Enable format string mismatch checking for _rtld_error().

Add alpha support.

Submitted by: John Birrell <jb@cimlogic.com.au> (with extra hacks by me)
Obtained from: Probably NetBSD

Import the ELF dynamic linker. This is the ElfKit version with
quite a few enhancements and bug fixes. There are still some known
deficiencies, but it should be adequate to get us started with ELF.

Import the ELF dynamic linker. This is the ElfKit version with
quite a few enhancements and bug fixes. There are still some known
deficiencies, but it should be adequate to get us started with ELF.

Submitted by: John Polstra <jdp@polstra.com>

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