On architectures that use RELA relocations it is safe to rerun the ifunc
resolvers on after all CPUs have started, but while they are sill parked.
On arm64 with big.LITTLE this is needed as some SoCs have shipped with
different ID register values the big and little clusters meaning we were
unable to rely on the register values from the boot CPU.
Add support for rerunning the resolvers on arm64 and amd64 as these are
both RELA using architectures.
Reviewed by: kib
Sponsored by: Innovate UK
Differential Revision: https://reviews.freebsd.org/D25455
It turns out relocating the symbol table itself can cause issues, like fbt
crashing because it applies the offsets to the kernel twice.
This had been previously brought up in rS333447 when the stoffs hack was
added, but I had been unaware of this and reimplemented symtab relocation.
Instead of relocating the symbol table, keep track of the relocation base
in ddb, so the ddb symbols behave like the kernel linker-provided symbols.
This is intended to be NFC on platforms other than PowerPC, which do not
use fully relocatable kernels. (The relbase will always be 0)
* Remove the rest of the stoffs hack.
* Remove my half-baked displace_symbol_table() function.
* Extend ddb initialization to cope with having a relocation offset on the
kernel symbol table.
* Fix my kernel-as-initrd hack to work with booke64 by using a temporary
mapping to access the data.
* Fix another instance of __powerpc__ that is actually RELOCATABLE_KERNEL.
* Change the behavior or X_db_symbol_values to apply the relocation base
when updating valp, to match link_elf_symbol_values() behavior.
Reviewed by: jhibbits
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D25223
This is a general cleanup of the relocatable kernel support on powerpc,
needed to enable kernel ifuncs.
* Fix some relocatable issues in the kernel linker, and change to using
a RELOCATABLE_KERNEL #define instead of #ifdef __powerpc__ for parts that
other platforms can use in the future if they wish to have ET_DYN kernels.
* Get rid of the DB_STOFFS hack now that the kernel is relocated to the DMAP
properly across the board on powerpc64.
* Add powerpc64 and powerpc32 ifunc functionality.
* Allow AIM64 virtual mode OF kernels to run from the DMAP like other AIM64
by implementing a virtual mode restart. This fixes the runtime address on
PowerMac G5.
* Fix symbol relocation problems on post-relocation kernels by relocating
the symbol table.
* Add an undocumented method for supplying kernel symbols on powernv and
other powerpc machines using linux-style kernel/initrd loading -- If
you pass the kernel in as the initrd as well, the copy resident in initrd
will be used as a source for symbols when initializing the debugger.
This method is subject to removal once we have a better way of doing this.
Approved by: jhibbits
Relnotes: yes
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D23156
When I implemented MD DYNAMIC parsing, I was originally passing a
linker_file_t so that the MD code could relocate pointers.
However, it turns out this isn't even filled in until later, so it was
always 0.
Just pass the load base (ef->address) directly, as that's really the only
thing we were interested in in the first place.
This fixes a crash on RB800 where it was trying to write to an unmapped
address when updating the GOT.
Reviewed by: jhibbits
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D24105
Quiet a variety of Wwrite-strings warnings in sys/kern at low-impact
sites. This patch avoids addressing certain others which would need to
plumb const through structure definitions.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D23798
This change adds 2 new SYSCTLs, to retrieve the original and relocated KERNBASE
values. This provides an easy, architecture independent way to calculate the
running kernel displacement (current/load address minus original base address).
The initial goal for this change is to add a new libkvm function that returns
the kernel displacement, both for live kernels and crashdumps. This would in
turn be used by kgdb to find out how to relocate kernel symbols (if needed).
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D23284
Filesystems which want to use it in limited capacity can employ the
VOP_UNLOCK_FLAGS macro.
Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D21427
Due to clang and LLD's tendency to use a PLT for builtins, and as they
don't have full support for EABI, we sometimes have to deal with a PLT in
.ko files in a clang-built kernel.
As such, augment the in-kernel linker to support jump table processing.
As there is no particular reason to support lazy binding in kernel modules,
only implement Secure-PLT immediate binding.
As part of these changes, add elf_cpu_parse_dynamic() to the MD API of the
in-kernel linker (except on platforms that use raw object files.)
The new function will allow MD code to act on MD tags in _DYNAMIC.
Use this new function in the PowerPC MD code to ensure BSS-PLT modules using
PLT will be rejected during insertion, and to poison the runtime resolver to
ensure we get a clear panic reason if a call is made to the resolver.
Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D22608
The arm kernel stack unwinder has apparently never been able to unwind when
the path of execution leads through a kernel module. There was code that
tried to handle modules by looking for the unwind data in them, but it did
so by trying to find symbols which have never existed in arm kernel
modules. That caused the unwind code to panic, and because part of panic
handling calls into the unwind code, that just created a recursion loop.
Locating the unwind data in a loaded module requires accessing the Elf
section headers to find the SHT_ARM_EXIDX section. For preloaded modules
those headers are present in a metadata blob. For dynamically loaded
modules, the headers are present only while the loading is in progress; the
memory is freed once the module is ready to use. For that reason, there is
new code in kern/link_elf.c, wrapped in #ifdef __arm__, to extract the
unwind info while the headers are loaded. The values are saved into new
fields in the linker_file structure which are also conditional on __arm__.
In arm/unwind.c there is new code to locally cache the per-module info
needed to find the unwind tables. The local cache is crafted for lockless
read access, because the unwind code often needs to run in context where
sleeping is not allowed. A large comment block describes the local cache
list, so I won't repeat it all here.
With an upcoming change the amd64 kernel will map preloaded files RW
instead of RWX, so the kernel linker must adjust protections
appropriately using pmap_change_prot().
Reviewed by: kib
MFC after: 1 month
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21860
- Ensure that the end of the mapping passed to vm_page_wire() is
page-aligned. vm_page_wire() expects this.
- Wire pages before reading data into them.
- Apply protections specified in the segment descriptor using
vm_map_protect() once relocation processing is done.
- On amd64, ensure that we load KLDs above KERNBASE, since they
are compiled with the "kernel" memory model by default.
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21756
This is required for DPCPU and VNET data variable definitions to work when
KLDs are linked as DSOs. R_X86_64_RELATIVE relocations should not appear
in object files, so assert this in elf_relocaddr().
Reviewed by: kib
MFC after: 1 month
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21755
Apply a linker script when linking i386 kernel modules to apply padding
to a set_pcpu or set_vnet section. The padding value is kind-of random
and is used to catch modules not compiled with the linker-script, so
possibly still having problems leading to kernel panics.
This is needed as the code generated on certain architectures for
non-simple-types, e.g., an array can generate an absolute relocation
on the edge (just outside) the section and thus will not be properly
relocated. Adding the padding to the end of the section will ensure
that even absolute relocations of complex types will be inside the
section, if they are the last object in there and hence relocation will
work properly and avoid panics such as observed with carp.ko or ipsec.ko.
There is a rather lengthy discussion of various options to apply in
the mentioned PRs and their depends/blocks, and the review.
There seems no best solution working across multiple toolchains and
multiple version of them, so I took the liberty of taking one,
as currently our users (and our CI system) are hitting this on
just i386 and we need some solution. I wish we would have a proper
fix rather than another "hack".
Also backout r340009 which manually, temporarily fixed CARP before 12.0-R
"by chance" after a lead-up of various other link-elf.c and related fixes.
PR: 230857,238012
With suggestions from: arichardson (originally last year)
Tested by: lwhsu
Event: Waterloo Hackathon 2019
Reported by: lwhsu, olivier
MFC after: 6 weeks
Differential Revision: https://reviews.freebsd.org/D17512
we fail during module load because the pcpu or vnet module sections are
full. We did return a proper error but not leaving any indication to
the user as to what the actual problem was.
Even worse, on 12/13 currently we are seeing an unrelated error (ENOSYS
instead of ENOSPC, which gets skipped over in kern_linker.c) to be
printed which made problem diagnostics even harder.
PR: 228854
MFC after: 3 days
returns the section start and stop locations as well as a count if the
caller asks for them.
There was only one out-of-file consumer of count which did not actually
use it and hence was eliminated in r339407.
In r194784 parse_dpcpu(), and in r195699 parse_vnet() (a copy of the
former) started to use the link_elf_lookup_set() interface internally
also asking for the count.
count is computed as the difference of the void **stop - void **start
locations and as such, if the absoulte numbers
(stop - start) % sizeof(void *) != 0
a round-down happens, e.g., **stop 0x1003 - **start 0x1000 => count 0.
To get the section size instead of "count is the number of pointer
elements in the section", the parse_*() functions do a
count *= sizeof(void *).
They use the result to allocate memory and copy the section data
into the "master" and per-instance memory regions with a size of
count.
As a result of count possibly round-down this can miss the last
bytes of the section. The good news is that we do not touch
out of bounds memory during these operations (we may at a later stage
if the last bytes would overflow the master sections).
Given relocation in elf_relocaddr() works based on the absolute
numbers of start and stop, this means that we can possibly try to
access relocated data which was never copied and hence we get
random garbage or at best zeroed memory.
Stop the two (last) consumers of count (the parse_*() functions)
from using count as well, and calculate the section size based on
the absolute numbers of stop and start and use the proper size for
the memory allocation and data copies. This will make the symbols
in the last bytes of the pcpu or vnet sections be presented as
expected.
PR: 232289
Approved by: re (gjb)
MFC after: 2 weeks
The change is a no-op for architectures which don't ifunc memset,
memcpy nor memmove.
Convert places which need them. Xen bits by royger.
Reviewed by: kib
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17487
Tested with ifunc resolvers in the kernel and module with calls from
kernel to kernel, module to kernel, and module to module.
Reviewed by: kib (previous version)
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D17370
The boot-time ifunc resolver assumes that it only needs to apply
IRELATIVE relocations to PLT entries. With an upcoming optimization,
this assumption no longer holds, so add the support required to handle
PC-relative relocations targeting GNU_IFUNC symbols.
- Provide a custom symbol lookup routine that can be used in early boot.
The default lookup routine uses kobj, which is not functional at that
point.
- Apply all existing relocations during boot rather than filtering
IRELATIVE relocations.
- Ensure that we continue to apply ifunc relocations in a second pass
when loading a kernel module.
Reviewed by: kib
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D16749
The basename will never match against the preload metadata, so these
calls previously had no effect.
Reviewed by: kib, royger
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D16330
Evaluate cpu_stdext_feature early to have moved link_elf_ireloc() see
correct flags, most important is SMAP.
Tested by: mjg
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D15367
Required MD bits are only provided for x86.
Reviewed by: jhb (previous version, as part of the larger patch)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D13838
This reduces noise when kernel is compiled by newer GCC versions,
such as one used by external toolchain ports.
Reviewed by: kib, andrew(sys/arm and sys/arm64), emaste(partial), erj(partial)
Reviewed by: jhb (sys/dev/pci/* sys/kern/vfs_aio.c and sys/kern/kern_synch.c)
Differential Revision: https://reviews.freebsd.org/D10385
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
vim overzealously removed some trailing `+' and I didn't check the
diff
MFC after: 1 week
X-MFC with: r292640
Pointyhat to: ngie
Sponsored by: EMC / Isilon Storage Division
not be found. Otherwise, relocations against such symbols will be silently
ignored instead of causing an error to be raised.
Reviewed by: kib
MFC after: 1 week
linkers no longer raise an error when undefined weak symbols are
found, but relocate as if the symbol value was 0. Note that we do not
repeat the mistake of userspace dynamic linker of making the symbol
lookup prefer non-weak symbol definition over the weak one, if both
are available. In fact, kernel linker uses the first definition
found, and ignores duplicates.
Signature of the elf_lookup() and elf_obj_lookup() functions changed
to split result/error code and the symbol address returned.
Otherwise, it is impossible to return zero address as the symbol
value, to MD relocation code. This explains the mechanical changes in
elf_machdep.c sources.
The powerpc64 R_PPC_JMP_SLOT handler did not checked error from the
lookup() call, the patch leaves the code as is (untested).
Reported by: glebius
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Add a check to preload_search_info to make sure mod is set. Most of the
callers of preload_search_info don't check that the mod parameter is
set, which can cause page faults. While at it, remove some now unnecessary
checks before calling preload_search_info.
Sponsored by: Citrix Systems R&D
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D3440
It is not network-specific code and would
be better as part of libkern instead.
Move zlib.h and zutil.h from net/ to sys/
Update includes to use sys/zlib.h and sys/zutil.h instead of net/
Submitted by: Steve Kiernan stevek@juniper.net
Obtained from: Juniper Networks, Inc.
GitHub Pull Request: https://github.com/freebsd/freebsd/pull/28
Relnotes: yes
executables. The goal here, not yet accomplished, is to let the e500 kernel
run under QEMU by setting KERNBASE to something that fits in low memory and
then having the kernel relocate itself at runtime.
This involves:
1. Have the loader pass the start and size of the .ctors section to the
kernel in 2 new metadata elements.
2. Have the linker backends look for and record the start and size of
the .ctors section in dynamically loaded modules.
3. Have the linker backends call the constructors as part of the final
work of initializing preloaded or dynamically loaded modules.
Note that LLVM appends the priority of the constructors to the name of
the .ctors section. Not so when compiling with GCC. The code currently
works for GCC and not for LLVM.
Submitted by: Dmitry Mikulin <dmitrym@juniper.net>
Obtained from: Juniper Networks, Inc.
This includes:
o All directories named *ia64*
o All files named *ia64*
o All ia64-specific code guarded by __ia64__
o All ia64-specific makefile logic
o Mention of ia64 in comments and documentation
This excludes:
o Everything under contrib/
o Everything under crypto/
o sys/xen/interface
o sys/sys/elf_common.h
Discussed at: BSDcan
an address in the first 2GB of the process's address space. This flag should
have the same semantics as the same flag on Linux.
To facilitate this, add a new parameter to vm_map_find() that specifies an
optional maximum virtual address. While here, fix several callers of
vm_map_find() to use a VMFS_* constant for the findspace argument instead of
TRUE and FALSE.
Reviewed by: alc
Approved by: re (kib)
In particular, do not lock Giant conditionally when calling into the
filesystem module, remove the VFS_LOCK_GIANT() and related
macros. Stop handling buffers belonging to non-mpsafe filesystems.
The VFS_VERSION is bumped to indicate the interface change which does
not result in the interface signatures changes.
Conducted and reviewed by: attilio
Tested by: pho
global variables are placed. When a module is loaded by link_elf
linker its variables from "set_vnet" linker set are copied to the
kernel "set_vnet" ("modspace") and all references to these variables
inside the module are relocated accordingly.
The issue is when a module is loaded that has references to global
variables from another, previously loaded module: these references are
not relocated so an invalid address is used when the module tries to
access the variable. The example is V_layer3_chain, defined in ipfw
module and accessed from ipfw_nat.
The same issue is with DPCPU variables, which use "set_pcpu" linker
set.
Fix this making the link_elf linker on a module load recognize
"external" DPCPU/VNET variables defined in the previously loaded
modules and relocate them accordingly. For this set_pcpu_list and
set_vnet_list are used, where the addresses of modules' "set_pcpu" and
"set_vnet" linker sets are stored.
Note, archs that use link_elf_obj (amd64) were not affected by this
issue.
Reviewed by: jhb, julian, zec (initial version)
MFC after: 1 month
Add the sysctl debug.iosize_max_clamp, enabled by default. Setting the
sysctl to zero allows to perform the SSIZE_MAX-sized i/o requests from
the usermode.
Discussed with: bde, das (previous versions)
MFC after: 1 month
