GCC assumes that stack is aligned to 16-byte on call sites [1].
Since GCC 8, GCC began using 16-byte aligned SSE instructions to
implement assignments to structs on stack. When
CC_OPTIMIZE_FOR_PERFORMANCE is enabled, this affects
os-Linux/sigio.c, write_sigio_thread:
struct pollfds *fds, tmp;
tmp = current_poll;
Note that struct pollfds is exactly 16 bytes in size.
GCC 8+ generates assembly similar to:
movdqa (%rdi),%xmm0
movaps %xmm0,-0x50(%rbp)
This is an issue, because movaps will #GP if -0x50(%rbp) is not
aligned to 16 bytes [2], and how rbp gets assigned to is via glibc
clone thread_start, then function prologue, going though execution
trace similar to (showing only relevant instructions):
sub $0x10,%rsi
mov %rcx,0x8(%rsi)
mov %rdi,(%rsi)
syscall
pop %rax
pop %rdi
callq *%rax
push %rbp
mov %rsp,%rbp
The stack pointer always points to the topmost element on stack,
rather then the space right above the topmost. On push, the
pointer decrements first before writing to the memory pointed to
by it. Therefore, there is no need to have the stack pointer
pointer always point to valid memory unless the stack is poped;
so the `- sizeof(void *)` in the code is unnecessary.
On the other hand, glibc reserves the 16 bytes it needs on stack
and pops itself, so by the call instruction the stack pointer
is exactly the caller-supplied sp. It then push the 16 bytes of
the return address and the saved stack pointer, so the base
pointer will be 16-byte aligned if and only if the caller
supplied sp is 16-byte aligned. Therefore, the caller must supply
a 16-byte aligned pointer, which `stack + UM_KERN_PAGE_SIZE`
already satisfies.
On a side note, musl is unaffected by this issue because it forces
16 byte alignment via `and $-16,%rsi` in its clone wrapper.
Similarly, glibc i386 is also unaffected because it has
`andl $0xfffffff0, %ecx`.
To reproduce this bug, enable CONFIG_UML_RTC and
CC_OPTIMIZE_FOR_PERFORMANCE. uml_rtc will call
add_sigio_fd which will then cause write_sigio_thread to either go
into segfault loop or panic with "Segfault with no mm".
Similarly, signal stacks will be aligned by the host kernel upon
signal delivery. `- sizeof(void *)` to sigaltstack is
unconventional and extraneous.
On a related note, initialization of longjmp buffers do require
`- sizeof(void *)`. This is to account for the return address
that would have been pushed to the stack at the call site.
The reason for uml to respect 16-byte alignment, rather than
telling GCC to assume 8-byte alignment like the host kernel since
commit d9b0cde91c ("x86-64, gcc: Use
-mpreferred-stack-boundary=3 if supported"), is because uml links
against libc. There is no reason to assume libc is also compiled
with that flag and assumes 8-byte alignment rather than 16-byte.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838
[2] https://c9x.me/x86/html/file_module_x86_id_180.html
Signed-off-by: YiFei Zhu <zhuyifei1999@gmail.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
1. Reflect host cpu flags into the UML instance so they can
be used to select the correct implementations for xor, crypto, etc.
2. Reflect host cache alignment into UML instance. This is
important when running 32 bit on a 64 bit host as 32 bit by
default aligns to 32 while the actual alignment should be 64.
Ditto for some Xeons which align at 128.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
We should be able to ndelay() from any context, even from an
interrupt context! However, this is broken (not functionally,
but locking-wise) in time-travel because we'll get into the
time-travel code and enable interrupts to handle messages on
other time-travel aware subsystems (only virtio for now).
Luckily, I've already reworked the time-travel aware signal
(interrupt) delivery for suspend/resume to have a time travel
handler, which runs directly in the context of the signal and
not from the Linux interrupt.
In order to fix this time-travel issue then, we need to do a
few things:
1) rework the signal handling code to call time-travel handlers
(only) if interrupts are disabled but signals aren't blocked,
instead of marking it only pending there. This is needed to
not deadlock other communication.
2) rework time-travel to not enable interrupts while it's
waiting for a message;
3) rework time-travel to not (just) disable interrupts but
rather block signals at a lower level while it needs them
disabled for communicating with the controller.
Finally, since now we can actually spend even virtual time
in interrupts-disabled sections, the delay warning when we
deliver a time-travel delayed interrupt is no longer valid,
things can (and should) now get delayed.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Use signals_enabled instead of always jumping through
a function call to read it, there's not much point in
that.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This mostly reverts the old commit 3963333fe6 ("uml: cover stubs
with a VMA") which had added a VMA to the existing PTEs. However,
there's no real reason to have the PTEs in the first place and the
VMA cannot be 'fixed' in place, which leads to bugs that userspace
could try to unmap them and be forcefully killed, or such. Also,
there's a bit of an ugly hole in userspace's address space.
Simplify all this: just install the stub code/page at the top of
the (inner) address space, i.e. put it just above TASK_SIZE. The
pages are simply hard-coded to be mapped in the userspace process
we use to implement an mm context, and they're out of reach of the
inner mmap/munmap/mprotect etc. since they're above TASK_SIZE.
Getting rid of the VMA also makes vma_merge() no longer hit one of
the VM_WARN_ON()s there because we installed a VMA while the code
assumes the stack VMA is the first one.
It also removes a lockdep warning about mmap_sem usage since we no
longer have uml_setup_stubs() and thus no longer need to do any
manipulation that would require mmap_sem in activate_mm().
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
The userspace stacks mostly have a stack (and in the case of the
syscall stub we can just set their stack pointer) that points to
the location of the stub data page already.
Rework the stubs to use the stack pointer to derive the start of
the data page, rather than requiring it to be hard-coded.
In the clone stub, also integrate the int3 into the stack remap,
since we really must not use the stack while we remap it.
This prepares for putting the stub at a variable location that's
not part of the normal address space of the userspace processes
running inside the UML machine.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
If the two are mixed up, then it looks as though the parent
returned an error if the child failed (before) the mmap(),
and then the resulting process never gets killed. Fix this
by splitting the child and parent errors, reporting and
using them appropriately.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
In some cases we can get to fix_range_common() with mmap_sem held,
and in others we get there without it being held. For example, we
get there with it held from sys_mprotect(), and without it held
from fork_handler().
Avoid any issues in this and simply defer killing the task until
it runs the next time. Do it on the mm so that another task that
shares the same mm can't continue running afterwards.
Cc: stable@vger.kernel.org
Fixes: 468f65976a ("um: Fix hung task in fix_range_common()")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Since we're basically debugging the userspace (it runs in ptrace)
it's useful to dump out the registers - but they're not readable,
so if something goes wrong it's hard to say what. Print the names
of registers in the register dump so it's easier to look at.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Changing os_idle_sleep() to use pause() (I accidentally described
it as an empty select() in the commit log because I had changed it
from that to pause() in a later revision) exposed a race condition
in the idle code. The following can happen:
timer_settime(0, 0, {it_interval={tv_sec=0, tv_nsec=0}, it_value={tv_sec=0, tv_nsec=624017}}, NULL) = 0
...
<SIGALRM is delivered but we're already on the way to idle>
pause()
and we now hang forever. This was previously possible as well, but
it could never cause UML to hang for more than a second since we
could only sleep for that much, so at most you'd notice a "hiccup"
in the UML. Obviously, any sort of external interrupt also "saves"
it and interrupts pause().
Fix this by properly handling the race, rather than papering over
it again:
- first, block SIGALRM, and obtain the old signal set
- check the timer
- suspend, waiting for any signal out of the old set, if, and only
if, the timer will fire in the future
- restore the old signal mask
This ensures race-free operation: as it's blocked, the signal won't
be delivered while we're looking at the timer even if it were to be
triggered right _after_ we've returned from timer_gettime() with a
non-zero value (telling us the timer will trigger). Thus, despite
getting to sigsuspend() because timer_gettime() told us we're still
waiting, we'll not hang because sigsuspend() will return immediately
due to the pending signal.
Fixes: 49da38a3ef ("um: Simplify os_idle_sleep() and sleep longer")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This reverts commit ef4459a6da ("um: allocate a guard page to
helper threads"), it's broken in multiple ways:
1) the free no longer matches the alloc; and
2) more importantly, the set_memory_ro() causes allocation of
page tables for the normal memory that doesn't have any,
and that later causes corruption and crashes (usually but
not always in vfree()).
We could fix the first bug and use vmalloc() to work around the
second, but set_memory_ro() actually doesn't do anything either
so I'll just revert that as well.
Reported-by: Benjamin Berg <benjamin@sipsolutions.net>
Fixes: ef4459a6da ("um: allocate a guard page to helper threads")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Lockdep (on 5.10-rc) points out that we're delivering IRQs while IRQs
are not even enabled, which clearly shouldn't happen. Defer the time
event IRQ delivery until they actually are enabled.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
If the sigio workaround needed to be applied to a file descriptor,
set_irq_wake() wouldn't work for it since it would get polled by
the thread instead of causing SIGIO, and thus could never really
cause a wakeup, since the thread notification FD wasn't marked as
being able to wake up the system.
Fix this by marking the thread's notification FD explicitly as a
wake source FD, i.e. not suppressing SIGIO for it in suspend. In
order to not cause spurious wakeups, we then need to remove all
FDs that shouldn't wake up the system from the polling thread. In
order to do this, add unlocked versions of ignore_sigio_fd() and
add_sigio_fd() (nothing else is happening in suspend, so this is
fine), and also modify ignore_sigio_fd() to return -ENOENT if the
FD wasn't originally in there. This doesn't matter because nothing
else currently checks the return value, but the irq code needs to
know which ones to restore the workaround for.
All told, this lets us use a timerfd for the RTC clock in the next
patch, which doesn't send SIGIO.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Ensure that file closes, connection closes, etc are propagated
as interrupts in the interrupt controller.
Fixes: ff6a17989c ("Epoll based IRQ controller")
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
We've been running into stack overflows in helper threads
corrupting memory (e.g. because somebody put printf() or
os_info() there), so to avoid those causing hard-to-debug
issues later on, allocate a guard page for helper thread
stacks and mark it read-only.
Unfortunately, the crash dump at that point is useless as
the stack tracer will try to backtrace the *kernel* thread,
not the helper thread, but at least we don't survive to a
random issue caused by corruption.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
UML userspace fetches siginfo and passes it to signal handlers
in UML. This is needed only for some of the signals, because
key handlers like SIGIO make no use of this variable.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
With all the previous bits in place, we can now also support
suspend to RAM, in the sense that everything is suspended,
not just most, including userspace, processes like in s2idle.
Since um_idle_sleep() now waits forever, we can simply call
that to "suspend" the system.
As before, you can wake it up using SIGUSR1 since we're just
in a pause() call that only needs to return.
In order to implement selective resume from certain devices,
and not have any arbitrary device interrupt wake up, suspend
interrupts by removing SIGIO notification (O_ASYNC) from all
the FDs that are not supposed to wake up the system. However,
swap out the handler so we don't actually handle the SIGIO as
an interrupt.
Since we're in pause(), the mere act of receiving SIGIO wakes
us up, and then after things have been restored enough, re-set
O_ASYNC for all previously suspended FDs, reinstall the proper
SIGIO handler, and send SIGIO to self to process anything that
might now be pending.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
In order to be able to experiment with suspend in UML, add the
minimal work to be able to suspend (s2idle) an instance of UML,
and be able to wake it back up from that state with the USR1
signal sent to the main UML process.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
There really is no reason to pass the amount of time we should
sleep, especially since it's just hard-coded to one second.
Additionally, one second isn't really all that long, and as we
are expecting to be woken up by a signal, we can sleep longer
and avoid doing some work every second, so replace the current
clock_nanosleep() with just an empty select() that can _only_
be woken up by a signal.
We can also remove the deliver_alarm() since we don't need to
do that when we got e.g. SIGIO that woke us up, and if we got
SIGALRM the signal handler will actually (have) run, so it's
just unnecessary extra work.
Similarly, in time-travel mode, just program the wakeup event
from idle to be S64_MAX, which is basically the most you could
ever simulate to. Of course, you should already have an event
in the list that's earlier and will cause a wakeup, normally
that's the regular timer interrupt, though in suspend it may
(later) also be an RTC event. Since actually getting to this
point would be a bug and you can't ever get out again, panic()
on it in the time control code.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
We don't actually use this in um_request_irq(), so it can
never be assigned. It's also not clear what that would be
useful for, so just remove it.
This results in quite a number of cleanups, all the way to
removing the "SIGIO on close" startup check, since the data
it assigns (pty_close_sigio) is not used anymore.
While at it, also make this an enum so we get a minimum of
type checking, and remove the IRQ_NONE hack in virtio since
we now no longer have the name twice.
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
If we run out of space, return an error instead of 0.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
The signal.c can't use heap for bit data located on stack. However,
by default a compiler warns us about overstepping stack frame size
threshold:
arch/um/os-Linux/signal.c: In function ‘sig_handler_common’:
arch/um/os-Linux/signal.c:51:1: warning: the frame size of 2960 bytes is larger than 2048 bytes [-Wframe-larger-than=]
51 | }
| ^
arch/um/os-Linux/signal.c: In function ‘timer_real_alarm_handler’:
arch/um/os-Linux/signal.c:95:1: warning: the frame size of 2960 bytes is larger than 2048 bytes [-Wframe-larger-than=]
95 | }
| ^
Due to above increase stack frame size threshold explicitly for signal.c
to avoid unnecessary warning.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: David Gow <davidgow@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
asprintf is not compatible with the existing uml memory allocation
mechanism. Its use on the "user" side of UML results in a corrupt slab
state.
Fixes: 0d4e5ac7e7 ("um: remove uses of variable length arrays")
Cc: stable@vger.kernel.org
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
pids are no longer limited to 16-bits, bump to 32-bits,
ie. 9 decimal characters. Additionally sizeof("/") already
returns 2 - ie. it already accounts for trailing zero.
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Linux UM Mailing List <linux-um@lists.infradead.org>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
musl toolchain and headers are a bit more strict. These fixes enable building
UML with musl as well as seem not to break on glibc.
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
We do not need to update the metadata (atime, mtime, etc)
on the UBD file and/or the COW file until UML exits.
UBD image mtime is checked in UML only when opening
the files. After that they are locked and used
exclusively by a single UML instance, so there is
no point wasting resources on updating metadata on
every sync. We can sync data only. The host will
always update mtime if a file has been modified upon
closing it.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
These two functions are otherwise unknown to the pedantic compiler.
Include the correct header to enable the build to succeed.
Signed-off-by: Zach van Rijn <me@zv.io>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This implements synchronized time-travel mode which - using a special
application on a unix socket - lets multiple machines take part in a
time-travelling simulation together.
The protocol for the unix domain socket is defined in the new file
include/uapi/linux/um_timetravel.h.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This file isn't really shared, it's only used on the kernel side,
not on the user side. Remove the include from the user-side and
move the file to a better place.
While at it, rename it to time-internal.h, it's not really just
timers but all kinds of things related to timekeeping.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
When building UML with glibc 2.17 installed, compilation
of arch/um/os-Linux/file.c fails due to failure to find
FALLOC_FL_PUNCH_HOLE and FALLOC_FL_KEEP_SIZE definitions.
It appears that /usr/include/bits/fcntl-linux.h (indirectly
included by /usr/include/fcntl.h) does not include falloc.h
with an older glibc, whereas a more up-to-date version
does.
Adding the direct include to file.c resolves the issue
and does not cause problems for more recent glibc.
Fixes: 50109b5a03 ("um: Add support for DISCARD in the UBD Driver")
Cc: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
sizeof gives us the size of the pointer variable, not of the
area it points to. So the number of bytes copied by umid_file_name()
is 8.
We should pass in the correct length of the file buffer.
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
The ubd code suffers from a possible y2038 overflow on 32-bit
architectures, both for the cow header and the os_file_modtime()
function.
Replace time_t with time64_t to extend the ubd_kern side as much
as possible.
Whether this makes a difference for the user side depends on
the host libc implementation that may use either 32-bit or 64-bit
time_t.
For the cow file format, the header contains an unsigned 32-bit
timestamp, which is good until y2106, passing this through a
'long long' gives us a consistent interpretation between 32-bit
and 64-bit um kernels.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
In the main() code, we eventually enable signals just before
exec() or exit(), in order to to not have signals pending and
delivered *after* the exec().
I've observed SIGSEGV loops at this point, and the reason seems
to be the irqflags tracing; this makes sense as the kernel is
no longer really functional at this point. Since there's really
no reason to use unblock_signals_trace() here (I had just done
a global search & replace), use the plain unblock_signals() in
this case to avoid going into the no longer functional kernel.
Fixes: 0dafcbe128 ("um: Implement TRACE_IRQFLAGS_SUPPORT")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Convert files to use SPDX header. All files are licensed under the GPLv2.
Signed-off-by: Alex Dewar <alex.dewar@gmx.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
This module allows virtio devices to be used over a vhost-user socket.
Signed-off-by: Erel Geron <erelx.geron@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
UML enables TRACE_IRQFLAGS_SUPPORT but doesn't actually implement
it. It seems to have been added for lockdep support, but that can't
actually really work well without IRQ flags tracing, as is also
very noisily reported when enabling CONFIG_DEBUG_LOCKDEP.
Implement it now.
Fixes: 711553efa5 ("[PATCH] uml: declare in Kconfig our partial LOCKDEP support")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
In timer_real_alarm_handler(), regs is only initialized if
the context argument is non-NULL, also initialize in the
other case.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
This entry is misleading, the actual signal handler is
another one that never uses sig_info.
Also remove the SIGALRM if inside sig_handler() for the
same reason.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
This makes the code clearer and lets the time travel patch have
the actual time used for these functions in just one place.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
There are some unused functions, and some others that have
unused arguments; clean up the timer code a bit.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
os_timer_one_shot() gets passed a value "unsigned long delta",
so must not have an "int ticks" as that actually ends up being
-1, and thus triggering a timer over and over again.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
While the affected code is run in user-mode, the build still warns
about it. Convert all uses of VLA to dynamic allocations.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Reverts commit b6024b21fe and
adjusts default stack sizing to cope with larger size of
floating point save registers on the newer Intel CPUs.
b6024b21fe replaced storing the
register state on the stack with kmalloc-ed storage. That has
a number of issues and a panic if that fails.
1. kmalloc/ATOMIC can fail. There was a latent hard crash
in all interrupt and fault handling as a result.
2. kmalloc in the interrupt path introduces a considerable
performance penalty for networking ~ 14% on iperf.
This commit restores uml to a stable state until a better
solution is found.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Support for DISCARD and WRITE_ZEROES in the ubd driver using
fallocate.
DISCARD is enabled by default and can be disabled using a new
UBD command line flag.
If the underlying fs on which the UBD image is stored does not
support DISCARD the support for both DISCARD and WRITE_ZEROES
is turned off.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Fixes:
arch/um/os-Linux/skas/process.c:613:1: warning: control reaches end of
non-void function [-Wreturn-type]
longjmp() never returns but gcc still warns that the end of the function
can be reached.
Add a return code and debug aid to detect this impossible case.
Signed-off-by: Richard Weinberger <richard@nod.at>
__uml_initcall() is not used and .uml.initcall.init section is empty:
$ grep -r '__uml_initcall('
arch/um/include/shared/init.h:#define __uml_initcall(fn) \
$ readelf -s ../umobj/linux | grep __uml_initcall
23214: 00000000603b75d8 0 NOTYPE GLOBAL DEFAULT 32 __uml_initcall_start
25337: 00000000603b75d8 0 NOTYPE GLOBAL DEFAULT 32 __uml_initcall_end
So it is unnecessary.
Signed-off-by: Alexander Pateenok <pateenoc@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Recent libcs have gotten a bit more strict, so we actually need to
include the right headers and use the right types. This enables UML to
compile again.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: stable@vger.kernel.org
Signed-off-by: Richard Weinberger <richard@nod.at>
1. Removes the need to walk the IRQ/Device list to determine
who triggered the IRQ.
2. Improves scalability (up to several times performance
improvement for cases with 10s of devices).
3. Improves UML baseline IO performance for one disk + one NIC
use case by up to 10%.
4. Introduces write poll triggered IRQs.
5. Prerequisite for introducing high performance mmesg family
of functions in network IO.
6. Fixes RNG shutdown which was leaking a file descriptor
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
glibc 2.26 removed the 'struct ucontext' to "improve" POSIX compliance
and break programs, including User Mode Linux. Fix User Mode Linux
by using POSIX ucontext_t.
This fixes:
arch/um/os-Linux/signal.c: In function 'hard_handler':
arch/um/os-Linux/signal.c:163:22: error: dereferencing pointer to incomplete type 'struct ucontext'
mcontext_t *mc = &uc->uc_mcontext;
arch/x86/um/stub_segv.c: In function 'stub_segv_handler':
arch/x86/um/stub_segv.c:16:13: error: dereferencing pointer to incomplete type 'struct ucontext'
&uc->uc_mcontext);
Cc: stable@vger.kernel.org
Signed-off-by: Krzysztof Mazur <krzysiek@podlesie.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
