MFC: r328834

o Let rtld(1) set up psABI user trap handlers prior to executing the
objects' init functions instead of doing the setup via a constructor
in libc as the init functions may already depend on these handlers
to be in place. This gets us rid of:
- the undefined order in which libc constructors as __guard_setup()
and jemalloc_constructor() are executed WRT __sparc_utrap_setup(),
- the requirement to link libc last so __sparc_utrap_setup() gets
called prior to constructors in other libraries (see r122883).
For static binaries, crt1.o still sets up the user trap handlers.
o Move misplaced prototypes for MD functions in to the MD prototype
section of rtld.h.
o Sprinkle nitems().

MFC r308689:
Pass CPUID[1] %edx (cpu_feature), %ecx (cpu_feature2) and
CPUID[7].%ebx (cpu_stdext_feature), %ecx (cpu_stdext_feature2) to the
ifunc resolvers on x86.

MFC r308925:
Adjust r308689 to make rtld compilable with either in-tree or
(hopefully) stock gcc 4.2.1 on i386 and other arches.

MFC r257811 (by markj):
Include rtld itself when iterating over loaded ELF objects in
dl_iterate_phdr(3).

MFC r294373:
Do not call callbacks for dl_iterate_phdr(3) with the rtld bind and
phdr locks locked.

MFC r294470 (by kan):
Fix initlist_add_object invocation parameters.

MFC r294936 (by kan):
Do not unlock rtld_phdr_lock over callback invocations.

MFC r270798:
Process STT_GNU_IFUNC when doing non-plt relocations.

MFC r270802:
Only do the second pass over non-plt relocations when the first pass
found IFUNCs.

Approved by: re (gjb)

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Revert r253748,253749

This WIP should not have been committed yet.

Pointyhat to: avg

remove needless inclusion of machine/cpu.h in userland

MFC after: 21 days

Avoid use of register variables, which some compilers (e.g. clang)
don't like. It makes the code a little clearer as well.

MFC after: 1 week

Add GNU hash support for rtld.

Based on dragonflybsd support for GNU hash by John Marino <draco marino st>
Reviewed by: kan
Tested by: bapt
MFC after: 2 weeks

Use xmalloc() instead of malloc() in the places where malloc() calls
are assumed to not fail.

Make the xcalloc() calling conventions follow the calloc(3) calling
conventions and replace unchecked calls to calloc() with calls to
xcalloc().

Remove redundand declarations from xmalloc.c, which are already
present in rtld.h.

Reviewed by: kan
Discussed with: bde
MFC after: 2 weeks

Fix several problems with our ELF filters implementation.

Do not relocate twice an object which happens to be needed by loaded
binary (or dso) and some filtee opened due to symbol resolution when
relocating need objects. Record the state of the relocation
processing in Obj_Entry and short-circuit relocate_objects() if
current object already processed.

Do not call constructors for filtees loaded during the early
relocation processing before image is initialized enough to run
user-provided code. Filtees are loaded using dlopen_object(), which
normally performs relocation and initialization. If filtee is
lazy-loaded during the relocation of dso needed by the main object,
dlopen_object() runs too earlier, when most runtime services are not
yet ready.

Postpone the constructors call to the time when main binary and
depended libraries constructors are run, passing the new flag
RTLD_LO_EARLY to dlopen_object(). Symbol lookups callers inform
symlook_* functions about early stage of initialization with
SYMLOOK_EARLY. Pass flags through all functions participating in
object relocation.

Use the opportunity and fix flags argument to find_symdef() in
arch-specific reloc.c to use proper name SYMLOOK_IN_PLT instead of
true, which happen to have the same numeric value.

Reported and tested by: theraven
Reviewed by: kan
MFC after: 2 weeks

Add support for preinit, init and fini arrays. Some ABIs, in
particular on ARM, do require working init arrays.

Traditional FreeBSD crt1 calls _init and _fini of the binary, instead
of allowing runtime linker to arrange the calls. This was probably
done to have the same crt code serve both statically and dynamically
linked binaries. Since ABI mandates that first is called preinit
array functions, then init, and then init array functions, the init
have to be called from rtld now.

To provide binary compatibility to old FreeBSD crt1, which calls _init
itself, rtld only calls intializers and finalizers for main binary if
binary has a note indicating that new crt was used for linking. Add
parsing of ELF notes to rtld, and cache p_osrel value since we parsed
it anyway.

The patch is inspired by init_array support for DragonflyBSD, written
by John Marino.

Reviewed by: kan
Tested by: andrew (arm, previous version), flo (sparc64, previous version)
MFC after: 3 weeks

Additional icache paranoia: non-PLT relocations can modify the text segment.
It is then important to make sure the icache is synchronized again to
prevent (rare) random seg faults and illegal instructions.

MFC after: 3 days

Add support for STT_GNU_IFUNC and R_MACHINE_IRELATIVE GNU extensions to
rtld on 386 and amd64. This adds runtime bits neccessary for the use
of the dispatch functions from the dynamically-linked executables and
shared libraries.

To allow use of external references from the dispatch function, resolution
of the R_MACHINE_IRESOLVE relocations in PLT is postponed until GOT entries
for PLT are prepared, and normal resolution of the GOT entries is finished.
Similar to how it is done by GNU, IRELATIVE relocations are resolved in
advance, instead of normal lazy handling for PLT.

Move the init_pltgot() call before the relocations for the object are
processed.

MFC after: 3 weeks

Remove dead code that snuck in from the 32-bit PowerPC version of this
file. The error being checked for does not exist on 64-bit systems.

Turn off default generation of userland dot symbols on powerpc64 now that
we have a binutils that supports it. Kernel dot symbols remain on to assist
DDB.

When loading dso without PT_GNU_STACK phdr, only call
__pthread_map_stacks_exec() on architectures that allow executable
stacks.

Reported and tested by: marcel (ia64)

Mark rtld on PowerPC as not requiring executable stack.

Reviewed and tested by: nwhitehorn

Add support for R_PPC64_UADDR64 relocations.

Fix an error in the ABI in rtld_bind_start(). When passing arguments to a
C function, the caller's stack frame must have room to store all of the
arguments to that function. While here, fix stack frame alignment issues.

Without this change, the compiler will save r3 and r4 into the caller's
stack frame before calling setjmp() in _rtld_bind(). These would then
overwrite arguments to the newly-bound function, causing eventual failures.

Implement support for ELF filters in rtld. Both normal and auxillary
filters are implemented.

Filtees are loaded on demand, unless LD_LOADFLTR environment variable
is set or -z loadfltr was specified during the linking. This forces
rtld to upgrade read-locked rtld_bind_lock to write lock when it
encounters an object with filter during symbol lookup.

Consolidate common arguments of the symbol lookup functions in the
SymLook structure. Track the state of the rtld locks in the
RtldLockState structure. Pass local RtldLockState through the rtld
symbol lookup calls to allow lock upgrades.

Reviewed by: kan
Tested by: Mykola Dzham <i levsha me>, nwhitehorn (powerpc)

Check for undefined weak symbols during PLT binding on powerpc64, and do
not attempt to copy NULL function descriptors. This fixes LD_BIND_NOW on
powerpc64 after r211706.

Reviewed by: kib

RTLD support for powerpc64. A few small modifications to the Makefile
and symbol map are required to support various consequences of the dot
symbol scheme:

- Symbols beginning with a dot are reserved, so start private symbols with
an underscore.
- In order to set RTLD breakpoints, gdb must be able to locate the text
entry point, not the data section function descriptor, so add
.r_debug_state to the symbol map on powerpc64.

Obtained from: projects/ppc64

Only use the cache after the early stage of loading. This is
because calling mmap() etc. may use GOT which is not set up
yet. Use calloc() instead of mmap() in cases where this
was the case before (sparc64, powerpc, arm).

Submitted by: Dimitry Andric (dimitry andric com)
Reviewed by: kan
Approved by: ed (mentor)

Support the extended PLT format used when objects have more than 8192
PLT relocations on PPC32.

Now that the kernel defines CACHE_LINE_SIZE in machine/param.h, use
that definition in the custom locking code for the run-time linker
rather than local definitions.

Pointed out by: tinderbox
MFC after: 2 weeks

Include an extra header to get a function prototype.

Unbreak the dynamic linker by not creating a cache for rtld-elf
itself. It needs mmap(2), which now needs getosreldate(3) and
which in turn uses a global variable to cache the result. This
cannot be done before linking is done.

See also: ../sparc64/reloc.c:1.15
Approved by: re (kensmith)

o Fix the static TLS relocation. We were subtracting the size of
the TCB.
o Use NULL for null pointer argument.
o Replace magic 8 with TLS_TCB_SIZE.

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.

Remove these unused files before any other archs include the same bogus
file.

Implement TLS relocations for powerpc.

Approved by: grehan (mentor)

Add stubs for powerpc TLS.

Submitted by: ssouhlal

Allow threading libraries to register their own locking
implementation in case default one provided by rtld is
not suitable.

Consolidate various identical MD lock implementation into
a single file using appropriate machine/atomic.h.

Approved by: re (scottl)

No need to zero fill memory, mmapped anonymously. Kernel will
return pre-zeroed pages itself.

Noticed by: jake

rtld support for PowerPC. Mostly obtained from NetBSD, with mods
for binutils 2.13

Reviewed by: benno

Approved by: re (blanket)