Refactor booke critical registers saving into a few macros
and move it into the exception prolog directly.
Keep the dedicated transfert_to_handler entry point for the
moment allthough they are empty. They will be removed in a
later patch to reduce churn.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/269171496f1f5f22afa621695bded22976c9d48d.1615552867.git.christophe.leroy@csgroup.eu
The space in the head section is rather constrained by the fact that
exception vectors are spread every 0x100 bytes and sometimes we
need to have "out of line" code because it doesn't fit.
Now that we are enabling MMU early in the prolog, take that opportunity
to jump somewhere else in the .text section where we don't have any
space constraint.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/38b31ca4bc782a4985bc7952a675404d7ff27c24.1615552867.git.christophe.leroy@csgroup.eu
For consistency, add in the macro the label used by exception prolog
to branch to stack overflow processing.
While at it, enclose the macro in #ifdef CONFIG_VMAP_STACK on the 8xx
as already done on book3s/32.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/cf80056f5b946572ad98aea9d915dd25b23beda6.1615552867.git.christophe.leroy@csgroup.eu
The check of the emergency context initialisation in
vmap_stack_overflow is buggy for the SMP case, as it
compares r1 with 0 while in the SMP case r1 is offseted
by the CPU id.
Instead of fixing it, just perform static initialisation
of the first emergency context.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4a67ba422be75713286dca0c86ee0d3df2eb6dfa.1615552867.git.christophe.leroy@csgroup.eu
On 40x and 8xx, kernel text is pinned.
On book3s/32, kernel text is mapped by BATs.
Enable instruction translation at the same time as data translation, it
makes things simpler.
In syscall handler, MSR_RI can also be set at the same time because
srr0/srr1 are already saved and r1 is set properly.
On booke, translation is always on, so at the end all PPC32
have translation on early. Just update msr.
Also update comment in power_save_ppc32_restore().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5269c7e5f5d2117358af3a89744d75a116be27b0.1615552867.git.christophe.leroy@csgroup.eu
8xx requires to tag the DAR with a magic value in order to
fixup DAR on faults generated by 'dcbX', as the 8xx
forgets to update the DAR for those faults.
Do the tagging as early as possible, that is before enabling MMU.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/853a2e28ca7c5fc85617037030f99fe6070c9536.1615552867.git.christophe.leroy@csgroup.eu
If the code can use a stack in vm area, it can also use a
stack in linear space.
Simplify code by removing old non VMAP stack code on PPC32.
That means the data translation is now re-enabled early in
exception prolog in all cases, not only when using VMAP stacks.
While we are touching EXCEPTION_PROLOG macros, remove the
unused for_rtas parameter in EXCEPTION_PROLOG_1.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7cd6440c60a7e8f4f035b245c57720f51e225aae.1615552866.git.christophe.leroy@csgroup.eu
ksp_limit is there to help detect stack overflows.
That is specific to ppc32 as it was removed from ppc64 in
commit cbc9565ee8 ("powerpc: Remove ksp_limit on ppc64").
There are other means for detecting stack overflows.
As ppc64 has proven to not need it, ppc32 should be able to do
without it too.
Lets remove it and simplify exception handling.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d789c3385b22e07bedc997613c0d26074cb513e7.1615552866.git.christophe.leroy@csgroup.eu
Ensure normal exception handler are able to manage stuff with
MMU enabled. For that we use CONFIG_VMAP_STACK related code
allthough there is no intention to really activate CONFIG_VMAP_STACK
on powerpc 40x for the moment.
40x uses SPRN_DEAR instead of SPRN_DAR and SPRN_ESR instead of
SPRN_DSISR. Take it into account in common macros.
40x MSR value doesn't fit on 15 bits, use LOAD_REG_IMMEDIATE() in
common macros that will be used also with 40x.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/01963af2b83037bca270d7bf1336ffcf35da8282.1615552866.git.christophe.leroy@csgroup.eu
In order the enable MMU early in exception prolog, implement
CONFIG_VMAP_STACK principles in critical exception prolog.
There is no intention to use CONFIG_VMAP_STACK on 40x,
but related code will be used to enable MMU early in exception
in a later patch.
Also address (critirq_ctx - PAGE_OFFSET) directly instead of
using tophys() in order to win one instruction.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3fd75ee54c48307119acdbf66cfea966c1463bbd.1615552866.git.christophe.leroy@csgroup.eu
SPRN_SPRG_SCRATCH5 is used to save SPRN_PID.
SPRN_SPRG_SCRATCH6 is already available.
SPRN_PID is only 8 bits. We have r12 that contains CR.
We only need to preserve CR0, so we have space available in r12
to save PID.
Keep PID in r12 and free up SPRN_SPRG_SCRATCH5.
Then In TLB miss handlers, instead of using SPRN_SPRG_SCRATCH0 and
SPRN_SPRG_SCRATCH1, use SPRN_SPRG_SCRATCH5 and SPRN_SPRG_SCRATCH6
to avoid future conflicts with normal exception prologs.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4cdaa85d38e14d594ba902424060ec55babf2c42.1615552866.git.christophe.leroy@csgroup.eu
As per ISA 3.1, prefixed instruction should not cross 64-byte
boundary. So don't allow Uprobe on such prefixed instruction.
There are two ways probed instruction is changed in mapped pages.
First, when Uprobe is activated, it searches for all the relevant
pages and replace instruction in them. In this case, if that probe
is on the 64-byte unaligned prefixed instruction, error out
directly. Second, when Uprobe is already active and user maps a
relevant page via mmap(), instruction is replaced via mmap() code
path. But because Uprobe is invalid, entire mmap() operation can
not be stopped. In this case just print an error and continue.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210311091538.368590-1-ravi.bangoria@linux.ibm.com
Usually sigset_t is exactly 8B which is a "trivial" size and does not
warrant using __copy_from_user(). Use __get_user() directly in
anticipation of future work to remove the trivial size optimizations
from __copy_from_user().
The ppc32 implementation of get_sigset_t() previously called
copy_from_user() which, unlike __copy_from_user(), calls access_ok().
Replacing this w/ __get_user() (no access_ok()) is fine here since both
callsites in signal_32.c are preceded by an earlier access_ok().
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-11-cmr@codefail.de
Add uaccess blocks and use the 'unsafe' versions of functions doing user
access where possible to reduce the number of times uaccess has to be
opened/closed.
Co-developed-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-10-cmr@codefail.de
Add uaccess blocks and use the 'unsafe' versions of functions doing user
access where possible to reduce the number of times uaccess has to be
opened/closed.
There is no 'unsafe' version of copy_siginfo_to_user, so move it
slightly to allow for a "longer" uaccess block.
Co-developed-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-9-cmr@codefail.de
Previously restore_sigcontext() performed a costly KUAP switch on every
uaccess operation. These repeated uaccess switches cause a significant
drop in signal handling performance.
Rewrite restore_sigcontext() to assume that a userspace read access
window is open by replacing all uaccess functions with their 'unsafe'
versions. Modify the callers to first open, call
unsafe_restore_sigcontext(), and then close the uaccess window.
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-8-cmr@codefail.de
Previously setup_sigcontext() performed a costly KUAP switch on every
uaccess operation. These repeated uaccess switches cause a significant
drop in signal handling performance.
Rewrite setup_sigcontext() to assume that a userspace write access window
is open by replacing all uaccess functions with their 'unsafe' versions.
Modify the callers to first open, call unsafe_setup_sigcontext() and
then close the uaccess window.
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-7-cmr@codefail.de
Both rt_sigreturn() and handle_rt_signal_64() contain TM-related ifdefs
which break-up an if/else block. Provide stubs for the ifdef-guarded TM
functions and remove the need for an ifdef in rt_sigreturn().
Rework the remaining TM ifdef in handle_rt_signal64() similar to
commit f1cf4f93de ("powerpc/signal32: Remove ifdefery in middle of if/else").
Unlike in the commit for ppc32, the ifdef can't be removed entirely
since uc_transact in sigframe depends on CONFIG_PPC_TRANSACTIONAL_MEM.
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-6-cmr@codefail.de
The majority of setup_sigcontext() can be refactored to execute in an
"unsafe" context assuming an open uaccess window except for some
non-inline function calls. Move these out into a separate
prepare_setup_sigcontext() function which must be called first and
before opening up a uaccess window. Non-inline function calls should be
avoided during a uaccess window for a few reasons:
- KUAP should be enabled for as much kernel code as possible.
Opening a uaccess window disables KUAP which means any code
executed during this time contributes to a potential attack
surface.
- Non-inline functions default to traceable which means they are
instrumented for ftrace. This adds more code which could run
with KUAP disabled.
- Powerpc does not currently support the objtool UACCESS checks.
All code running with uaccess must be audited manually which
means: less code -> less work -> fewer problems (in theory).
A follow-up commit converts setup_sigcontext() to be "unsafe".
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-4-cmr@codefail.de
Reuse the "safe" implementation from signal.c but call unsafe_get_user()
directly in a loop to avoid the intermediate copy into a local buffer.
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-3-cmr@codefail.de
Use user access block in gpr32_set_common() instead of
repetitive __get_user() which imply repetitive KUAP open/close.
To get it clean, force inlining of the small set of tiny functions
called inside the block.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bdcb8652c3bb4ab5b8b3bfd08147434be8fc04c9.1615398498.git.christophe.leroy@csgroup.eu
"offsetof(struct pt_regs, msr) == offsetof(struct user_pt_regs, msr)"
checked in pt_regs_check() twice in a row. Remove the second check.
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210305112807.26299-1-efremov@linux.com
asm/tm.h included in traps.c is duplicated. It is also included on
the 62nd line.
asm/udbg.h included in setup-common.c is duplicated. It is also
included on the 61st line.
asm/bug.h included in arch/powerpc/include/asm/book3s/64/mmu-hash.h
is duplicated. It is also included on the 12th line.
asm/tlbflush.h included in arch/powerpc/include/asm/pgtable.h is
duplicated. It is also included on the 11th line.
asm/page.h included in arch/powerpc/include/asm/thread_info.h is
duplicated. It is also included on the 13th line.
Signed-off-by: Zhang Yunkai <zhang.yunkai@zte.com.cn>
[mpe: Squash together from multiple commits]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
If identical_pvr_fixup() is not inlined, there are two modpost warnings:
WARNING: modpost: vmlinux.o(.text+0x54e8): Section mismatch in reference
from the function identical_pvr_fixup() to the function
.init.text:of_get_flat_dt_prop()
The function identical_pvr_fixup() references
the function __init of_get_flat_dt_prop().
This is often because identical_pvr_fixup lacks a __init
annotation or the annotation of of_get_flat_dt_prop is wrong.
WARNING: modpost: vmlinux.o(.text+0x551c): Section mismatch in reference
from the function identical_pvr_fixup() to the function
.init.text:identify_cpu()
The function identical_pvr_fixup() references
the function __init identify_cpu().
This is often because identical_pvr_fixup lacks a __init
annotation or the annotation of identify_cpu is wrong.
identical_pvr_fixup() calls two functions marked as __init and is only
called by a function marked as __init so it should be marked as __init
as well. At the same time, remove the inline keywork as it is not
necessary to inline this function. The compiler is still free to do so
if it feels it is worthwhile since commit 889b3c1245 ("compiler:
remove CONFIG_OPTIMIZE_INLINING entirely").
Fixes: 14b3d926a2 ("[POWERPC] 4xx: update 440EP(x)/440GR(x) identical PVR issue workaround")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://github.com/ClangBuiltLinux/linux/issues/1316
Link: https://lore.kernel.org/r/20210302200829.2680663-1-nathan@kernel.org
If fadump_calculate_reserve_size() is not inlined, there is a modpost
warning:
WARNING: modpost: vmlinux.o(.text+0x5196c): Section mismatch in
reference from the function fadump_calculate_reserve_size() to the
function .init.text:parse_crashkernel()
The function fadump_calculate_reserve_size() references
the function __init parse_crashkernel().
This is often because fadump_calculate_reserve_size lacks a __init
annotation or the annotation of parse_crashkernel is wrong.
fadump_calculate_reserve_size() calls parse_crashkernel(), which is
marked as __init and fadump_calculate_reserve_size() is called from
within fadump_reserve_mem(), which is also marked as __init.
Mark fadump_calculate_reserve_size() as __init to fix the section
mismatch. Additionally, remove the inline keyword as it is not necessary
to inline this function; the compiler is still free to do so if it feels
it is worthwhile since commit 889b3c1245 ("compiler: remove
CONFIG_OPTIMIZE_INLINING entirely").
Fixes: 11550dc0a0 ("powerpc/fadump: reuse crashkernel parameter for fadump memory reservation")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://github.com/ClangBuiltLinux/linux/issues/1300
Link: https://lore.kernel.org/r/20210302195013.2626335-1-nathan@kernel.org
With some defconfig including CONFIG_CC_OPTIMIZE_FOR_SIZE,
(for instance mvme5100_defconfig and ps3_defconfig), gcc 5
generates a call to _restgpr_31_x.
Until recently it went unnoticed, but
commit 42ed6d56ad ("powerpc/vdso: Block R_PPC_REL24 relocations")
made it rise to the surface.
Provide that function (copied from lib/crtsavres.S) in
gettimeofday.S
Fixes: ab037dd87a ("powerpc/vdso: Switch VDSO to generic C implementation.")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a7aa198a88bcd33c6e35e99f70f86c7b7f2f9440.1615270757.git.christophe.leroy@csgroup.eu
unrecoverable_exception() is called from interrupt handlers or
after an interrupt handler has failed.
Make it a standard function to avoid doubling the actions
performed on interrupt entry (e.g.: user time accounting).
Fixes: 3a96570ffc ("powerpc: convert interrupt handlers to use wrappers")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ae96c59fa2cb7f24a8929c58cfa2c909cb8ff1f1.1615291471.git.christophe.leroy@csgroup.eu
Nick's patch cleaning up the SRR specifiers in exception-64s.S missed
a single instance of EXC_HV_OR_STD. Clean that up.
Caught by clang's integrated assembler.
Fixes: 3f7fbd97d0 ("powerpc/64s/exception: Clean up SRR specifiers")
Signed-off-by: Daniel Axtens <dja@axtens.net>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210225031006.1204774-2-dja@axtens.net
Rather than storing the iterator information in the registered
kmsg_dumper structure, create a separate iterator structure. The
kmsg_dump_iter structure can reside on the stack of the caller, thus
allowing lockless use of the kmsg_dump functions.
Update code that accesses the kernel logs using the kmsg_dumper
structure to use the new kmsg_dump_iter structure. For kmsg_dumpers,
this also means adding a call to kmsg_dump_rewind() to initialize
the iterator.
All this is in preparation for removal of @logbuf_lock.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org> # pstore
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210303101528.29901-13-john.ogness@linutronix.de
As reported by kernel test robot, a randconfig with high amount of
debuging options can lead to build failure for undefined reference
to replay_soft_interrupts() on ppc32.
This is due to gcc not seeing that __prep_irq_for_enabled_exit()
always returns true on ppc32 because it doesn't inline it for
some reason.
Force inlining of __prep_irq_for_enabled_exit() to fix the build.
Fixes: 344bb20b15 ("powerpc/syscall: Make interrupt.c buildable on PPC32")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/53f3a1f719441761000c41154602bf097d4350b5.1614148356.git.christophe.leroy@csgroup.eu
On book3s/32, page protection is defined by the PP bits in the PTE
which provide the following protection depending on the access
keys defined in the matching segment register:
- PP 00 means RW with key 0 and N/A with key 1.
- PP 01 means RW with key 0 and RO with key 1.
- PP 10 means RW with both key 0 and key 1.
- PP 11 means RO with both key 0 and key 1.
Since the implementation of kernel userspace access protection,
PP bits have been set as follows:
- PP00 for pages without _PAGE_USER
- PP01 for pages with _PAGE_USER and _PAGE_RW
- PP11 for pages with _PAGE_USER and without _PAGE_RW
For kernelspace segments, kernel accesses are performed with key 0
and user accesses are performed with key 1. As PP00 is used for
non _PAGE_USER pages, user can't access kernel pages not flagged
_PAGE_USER while kernel can.
For userspace segments, both kernel and user accesses are performed
with key 0, therefore pages not flagged _PAGE_USER are still
accessible to the user.
This shouldn't be an issue, because userspace is expected to be
accessible to the user. But unlike most other architectures, powerpc
implements PROT_NONE protection by removing _PAGE_USER flag instead of
flagging the page as not valid. This means that pages in userspace
that are not flagged _PAGE_USER shall remain inaccessible.
To get the expected behaviour, just mimic other architectures in the
TLB miss handler by checking _PAGE_USER permission on userspace
accesses as if it was the _PAGE_PRESENT bit.
Note that this problem only is only for 603 cores. The 604+ have
an hash table, and hash_page() function already implement the
verification of _PAGE_USER permission on userspace pages.
Fixes: f342adca3a ("powerpc/32s: Prepare Kernel Userspace Access Protection")
Cc: stable@vger.kernel.org # v5.2+
Reported-by: Christoph Plattner <christoph.plattner@thalesgroup.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4a0c6e3bb8f0c162457bf54d9bc6fd8d7b55129f.1612160907.git.christophe.leroy@csgroup.eu
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Merge tag 'io_uring-worker.v3-2021-02-25' of git://git.kernel.dk/linux-block
Pull io_uring thread rewrite from Jens Axboe:
"This converts the io-wq workers to be forked off the tasks in question
instead of being kernel threads that assume various bits of the
original task identity.
This kills > 400 lines of code from io_uring/io-wq, and it's the worst
part of the code. We've had several bugs in this area, and the worry
is always that we could be missing some pieces for file types doing
unusual things (recent /dev/tty example comes to mind, userfaultfd
reads installing file descriptors is another fun one... - both of
which need special handling, and I bet it's not the last weird oddity
we'll find).
With these identical workers, we can have full confidence that we're
never missing anything. That, in itself, is a huge win. Outside of
that, it's also more efficient since we're not wasting space and code
on tracking state, or switching between different states.
I'm sure we're going to find little things to patch up after this
series, but testing has been pretty thorough, from the usual
regression suite to production. Any issue that may crop up should be
manageable.
There's also a nice series of further reductions we can do on top of
this, but I wanted to get the meat of it out sooner rather than later.
The general worry here isn't that it's fundamentally broken. Most of
the little issues we've found over the last week have been related to
just changes in how thread startup/exit is done, since that's the main
difference between using kthreads and these kinds of threads. In fact,
if all goes according to plan, I want to get this into the 5.10 and
5.11 stable branches as well.
That said, the changes outside of io_uring/io-wq are:
- arch setup, simple one-liner to each arch copy_thread()
implementation.
- Removal of net and proc restrictions for io_uring, they are no
longer needed or useful"
* tag 'io_uring-worker.v3-2021-02-25' of git://git.kernel.dk/linux-block: (30 commits)
io-wq: remove now unused IO_WQ_BIT_ERROR
io_uring: fix SQPOLL thread handling over exec
io-wq: improve manager/worker handling over exec
io_uring: ensure SQPOLL startup is triggered before error shutdown
io-wq: make buffered file write hashed work map per-ctx
io-wq: fix race around io_worker grabbing
io-wq: fix races around manager/worker creation and task exit
io_uring: ensure io-wq context is always destroyed for tasks
arch: ensure parisc/powerpc handle PF_IO_WORKER in copy_thread()
io_uring: cleanup ->user usage
io-wq: remove nr_process accounting
io_uring: flag new native workers with IORING_FEAT_NATIVE_WORKERS
net: remove cmsg restriction from io_uring based send/recvmsg calls
Revert "proc: don't allow async path resolution of /proc/self components"
Revert "proc: don't allow async path resolution of /proc/thread-self components"
io_uring: move SQPOLL thread io-wq forked worker
io-wq: make io_wq_fork_thread() available to other users
io-wq: only remove worker from free_list, if it was there
io_uring: remove io_identity
io_uring: remove any grabbing of context
...
- Fix false-positive build warnings for ARCH=ia64 builds
- Optimize dictionary size for module compression with xz
- Check the compiler and linker versions in Kconfig
- Fix misuse of extra-y
- Support DWARF v5 debug info
- Clamp SUBLEVEL to 255 because stable releases 4.4.x and 4.9.x
exceeded the limit
- Add generic syscall{tbl,hdr}.sh for cleanups across arches
- Minor cleanups of genksyms
- Minor cleanups of Kconfig
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Merge tag 'kbuild-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Fix false-positive build warnings for ARCH=ia64 builds
- Optimize dictionary size for module compression with xz
- Check the compiler and linker versions in Kconfig
- Fix misuse of extra-y
- Support DWARF v5 debug info
- Clamp SUBLEVEL to 255 because stable releases 4.4.x and 4.9.x
exceeded the limit
- Add generic syscall{tbl,hdr}.sh for cleanups across arches
- Minor cleanups of genksyms
- Minor cleanups of Kconfig
* tag 'kbuild-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (38 commits)
initramfs: Remove redundant dependency of RD_ZSTD on BLK_DEV_INITRD
kbuild: remove deprecated 'always' and 'hostprogs-y/m'
kbuild: parse C= and M= before changing the working directory
kbuild: reuse this-makefile to define abs_srctree
kconfig: unify rule of config, menuconfig, nconfig, gconfig, xconfig
kconfig: omit --oldaskconfig option for 'make config'
kconfig: fix 'invalid option' for help option
kconfig: remove dead code in conf_askvalue()
kconfig: clean up nested if-conditionals in check_conf()
kconfig: Remove duplicate call to sym_get_string_value()
Makefile: Remove # characters from compiler string
Makefile: reuse CC_VERSION_TEXT
kbuild: check the minimum linker version in Kconfig
kbuild: remove ld-version macro
scripts: add generic syscallhdr.sh
scripts: add generic syscalltbl.sh
arch: syscalls: remove $(srctree)/ prefix from syscall tables
arch: syscalls: add missing FORCE and fix 'targets' to make if_changed work
gen_compile_commands: prune some directories
kbuild: simplify access to the kernel's version
...
The irq stack switching was moved out of the ASM entry code in course of
the entry code consolidation. It ended up being suboptimal in various
ways.
- Make the stack switching inline so the stackpointer manipulation is not
longer at an easy to find place.
- Get rid of the unnecessary indirect call.
- Avoid the double stack switching in interrupt return and reuse the
interrupt stack for softirq handling.
- A objtool fix for CONFIG_FRAME_POINTER=y builds where it got confused
about the stack pointer manipulation.
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Merge tag 'x86-entry-2021-02-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 irq entry updates from Thomas Gleixner:
"The irq stack switching was moved out of the ASM entry code in course
of the entry code consolidation. It ended up being suboptimal in
various ways.
This reworks the X86 irq stack handling:
- Make the stack switching inline so the stackpointer manipulation is
not longer at an easy to find place.
- Get rid of the unnecessary indirect call.
- Avoid the double stack switching in interrupt return and reuse the
interrupt stack for softirq handling.
- A objtool fix for CONFIG_FRAME_POINTER=y builds where it got
confused about the stack pointer manipulation"
* tag 'x86-entry-2021-02-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix stack-swizzle for FRAME_POINTER=y
um: Enforce the usage of asm-generic/softirq_stack.h
x86/softirq/64: Inline do_softirq_own_stack()
softirq: Move do_softirq_own_stack() to generic asm header
softirq: Move __ARCH_HAS_DO_SOFTIRQ to Kconfig
x86: Select CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
x86/softirq: Remove indirection in do_softirq_own_stack()
x86/entry: Use run_sysvec_on_irqstack_cond() for XEN upcall
x86/entry: Convert device interrupts to inline stack switching
x86/entry: Convert system vectors to irq stack macro
x86/irq: Provide macro for inlining irq stack switching
x86/apic: Split out spurious handling code
x86/irq/64: Adjust the per CPU irq stack pointer by 8
x86/irq: Sanitize irq stack tracking
x86/entry: Fix instrumentation annotation
In the arch addition of PF_IO_WORKER, I missed parisc and powerpc for
some reason. Fix that up, ensuring they handle PF_IO_WORKER like they do
PF_KTHREAD in copy_thread().
Reported-by: Bruno Goncalves <bgoncalv@redhat.com>
Fixes: 4727dc20e0 ("arch: setup PF_IO_WORKER threads like PF_KTHREAD")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull idmapped mounts from Christian Brauner:
"This introduces idmapped mounts which has been in the making for some
time. Simply put, different mounts can expose the same file or
directory with different ownership. This initial implementation comes
with ports for fat, ext4 and with Christoph's port for xfs with more
filesystems being actively worked on by independent people and
maintainers.
Idmapping mounts handle a wide range of long standing use-cases. Here
are just a few:
- Idmapped mounts make it possible to easily share files between
multiple users or multiple machines especially in complex
scenarios. For example, idmapped mounts will be used in the
implementation of portable home directories in
systemd-homed.service(8) where they allow users to move their home
directory to an external storage device and use it on multiple
computers where they are assigned different uids and gids. This
effectively makes it possible to assign random uids and gids at
login time.
- It is possible to share files from the host with unprivileged
containers without having to change ownership permanently through
chown(2).
- It is possible to idmap a container's rootfs and without having to
mangle every file. For example, Chromebooks use it to share the
user's Download folder with their unprivileged containers in their
Linux subsystem.
- It is possible to share files between containers with
non-overlapping idmappings.
- Filesystem that lack a proper concept of ownership such as fat can
use idmapped mounts to implement discretionary access (DAC)
permission checking.
- They allow users to efficiently changing ownership on a per-mount
basis without having to (recursively) chown(2) all files. In
contrast to chown (2) changing ownership of large sets of files is
instantenous with idmapped mounts. This is especially useful when
ownership of a whole root filesystem of a virtual machine or
container is changed. With idmapped mounts a single syscall
mount_setattr syscall will be sufficient to change the ownership of
all files.
- Idmapped mounts always take the current ownership into account as
idmappings specify what a given uid or gid is supposed to be mapped
to. This contrasts with the chown(2) syscall which cannot by itself
take the current ownership of the files it changes into account. It
simply changes the ownership to the specified uid and gid. This is
especially problematic when recursively chown(2)ing a large set of
files which is commong with the aforementioned portable home
directory and container and vm scenario.
- Idmapped mounts allow to change ownership locally, restricting it
to specific mounts, and temporarily as the ownership changes only
apply as long as the mount exists.
Several userspace projects have either already put up patches and
pull-requests for this feature or will do so should you decide to pull
this:
- systemd: In a wide variety of scenarios but especially right away
in their implementation of portable home directories.
https://systemd.io/HOME_DIRECTORY/
- container runtimes: containerd, runC, LXD:To share data between
host and unprivileged containers, unprivileged and privileged
containers, etc. The pull request for idmapped mounts support in
containerd, the default Kubernetes runtime is already up for quite
a while now: https://github.com/containerd/containerd/pull/4734
- The virtio-fs developers and several users have expressed interest
in using this feature with virtual machines once virtio-fs is
ported.
- ChromeOS: Sharing host-directories with unprivileged containers.
I've tightly synced with all those projects and all of those listed
here have also expressed their need/desire for this feature on the
mailing list. For more info on how people use this there's a bunch of
talks about this too. Here's just two recent ones:
https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdfhttps://fosdem.org/2021/schedule/event/containers_idmap/
This comes with an extensive xfstests suite covering both ext4 and
xfs:
https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts
It covers truncation, creation, opening, xattrs, vfscaps, setid
execution, setgid inheritance and more both with idmapped and
non-idmapped mounts. It already helped to discover an unrelated xfs
setgid inheritance bug which has since been fixed in mainline. It will
be sent for inclusion with the xfstests project should you decide to
merge this.
In order to support per-mount idmappings vfsmounts are marked with
user namespaces. The idmapping of the user namespace will be used to
map the ids of vfs objects when they are accessed through that mount.
By default all vfsmounts are marked with the initial user namespace.
The initial user namespace is used to indicate that a mount is not
idmapped. All operations behave as before and this is verified in the
testsuite.
Based on prior discussions we want to attach the whole user namespace
and not just a dedicated idmapping struct. This allows us to reuse all
the helpers that already exist for dealing with idmappings instead of
introducing a whole new range of helpers. In addition, if we decide in
the future that we are confident enough to enable unprivileged users
to setup idmapped mounts the permission checking can take into account
whether the caller is privileged in the user namespace the mount is
currently marked with.
The user namespace the mount will be marked with can be specified by
passing a file descriptor refering to the user namespace as an
argument to the new mount_setattr() syscall together with the new
MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
of extensibility.
The following conditions must be met in order to create an idmapped
mount:
- The caller must currently have the CAP_SYS_ADMIN capability in the
user namespace the underlying filesystem has been mounted in.
- The underlying filesystem must support idmapped mounts.
- The mount must not already be idmapped. This also implies that the
idmapping of a mount cannot be altered once it has been idmapped.
- The mount must be a detached/anonymous mount, i.e. it must have
been created by calling open_tree() with the OPEN_TREE_CLONE flag
and it must not already have been visible in the filesystem.
The last two points guarantee easier semantics for userspace and the
kernel and make the implementation significantly simpler.
By default vfsmounts are marked with the initial user namespace and no
behavioral or performance changes are observed.
The manpage with a detailed description can be found here:
1d7b902e28
In order to support idmapped mounts, filesystems need to be changed
and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
patches to convert individual filesystem are not very large or
complicated overall as can be seen from the included fat, ext4, and
xfs ports. Patches for other filesystems are actively worked on and
will be sent out separately. The xfstestsuite can be used to verify
that port has been done correctly.
The mount_setattr() syscall is motivated independent of the idmapped
mounts patches and it's been around since July 2019. One of the most
valuable features of the new mount api is the ability to perform
mounts based on file descriptors only.
Together with the lookup restrictions available in the openat2()
RESOLVE_* flag namespace which we added in v5.6 this is the first time
we are close to hardened and race-free (e.g. symlinks) mounting and
path resolution.
While userspace has started porting to the new mount api to mount
proper filesystems and create new bind-mounts it is currently not
possible to change mount options of an already existing bind mount in
the new mount api since the mount_setattr() syscall is missing.
With the addition of the mount_setattr() syscall we remove this last
restriction and userspace can now fully port to the new mount api,
covering every use-case the old mount api could. We also add the
crucial ability to recursively change mount options for a whole mount
tree, both removing and adding mount options at the same time. This
syscall has been requested multiple times by various people and
projects.
There is a simple tool available at
https://github.com/brauner/mount-idmapped
that allows to create idmapped mounts so people can play with this
patch series. I'll add support for the regular mount binary should you
decide to pull this in the following weeks:
Here's an example to a simple idmapped mount of another user's home
directory:
u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt
u1001@f2-vm:/$ ls -al /home/ubuntu/
total 28
drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
drwxr-xr-x 4 root root 4096 Oct 28 04:00 ..
-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile
-rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ ls -al /mnt/
total 28
drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 .
drwxr-xr-x 29 root root 4096 Oct 28 22:01 ..
-rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile
-rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ touch /mnt/my-file
u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file
u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file
u1001@f2-vm:/$ ls -al /mnt/my-file
-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file
u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file
u1001@f2-vm:/$ getfacl /mnt/my-file
getfacl: Removing leading '/' from absolute path names
# file: mnt/my-file
# owner: u1001
# group: u1001
user::rw-
user:u1001:rwx
group::rw-
mask::rwx
other::r--
u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
getfacl: Removing leading '/' from absolute path names
# file: home/ubuntu/my-file
# owner: ubuntu
# group: ubuntu
user::rw-
user:ubuntu:rwx
group::rw-
mask::rwx
other::r--"
* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
xfs: support idmapped mounts
ext4: support idmapped mounts
fat: handle idmapped mounts
tests: add mount_setattr() selftests
fs: introduce MOUNT_ATTR_IDMAP
fs: add mount_setattr()
fs: add attr_flags_to_mnt_flags helper
fs: split out functions to hold writers
namespace: only take read lock in do_reconfigure_mnt()
mount: make {lock,unlock}_mount_hash() static
namespace: take lock_mount_hash() directly when changing flags
nfs: do not export idmapped mounts
overlayfs: do not mount on top of idmapped mounts
ecryptfs: do not mount on top of idmapped mounts
ima: handle idmapped mounts
apparmor: handle idmapped mounts
fs: make helpers idmap mount aware
exec: handle idmapped mounts
would_dump: handle idmapped mounts
...
