linux-stable.git/arch/um/kernel, branch v5.4.151

um: Disable CONFIG_GCOV with MODULES

2021-05-22T09:38:28+00:00

[ Upstream commit ad3d19911632debc886ef4a992d41d6de7927006 ]

CONFIG_GCOV doesn't work with modules, and for various reasons
it cannot work, see also
https://lore.kernel.org/r/d36ea54d8c0a8dd706826ba844a6f27691f45d55.camel@sipsolutions.net

Make CONFIG_GCOV depend on !MODULES to avoid anyone
running into issues there. This also means we need
not export the gcov symbols.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger 
Signed-off-by: Sasha Levin

um: Mark all kernel symbols as local

2021-05-22T09:38:28+00:00

[ Upstream commit d5027ca63e0e778b641cf23e3f5c6d6212cf412b ]

Ritesh reported a bug [1] against UML, noting that it crashed on
startup. The backtrace shows the following (heavily redacted):

(gdb) bt
...
 #26 0x0000000060015b5d in sem_init () at ipc/sem.c:268
 #27 0x00007f89906d92f7 in ?? () from /lib/x86_64-linux-gnu/libcom_err.so.2
 #28 0x00007f8990ab8fb2 in call_init (...) at dl-init.c:72
...
 #40 0x00007f89909bf3a6 in nss_load_library (...) at nsswitch.c:359
...
 #44 0x00007f8990895e35 in _nss_compat_getgrnam_r (...) at nss_compat/compat-grp.c:486
 #45 0x00007f8990968b85 in __getgrnam_r [...]
 #46 0x00007f89909d6b77 in grantpt [...]
 #47 0x00007f8990a9394e in __GI_openpty [...]
 #48 0x00000000604a1f65 in openpty_cb (...) at arch/um/os-Linux/sigio.c:407
 #49 0x00000000604a58d0 in start_idle_thread (...) at arch/um/os-Linux/skas/process.c:598
 #50 0x0000000060004a3d in start_uml () at arch/um/kernel/skas/process.c:45
 #51 0x00000000600047b2 in linux_main (...) at arch/um/kernel/um_arch.c:334
 #52 0x000000006000574f in main (...) at arch/um/os-Linux/main.c:144

indicating that the UML function openpty_cb() calls openpty(),
which internally calls __getgrnam_r(), which causes the nsswitch
machinery to get started.

This loads, through lots of indirection that I snipped, the
libcom_err.so.2 library, which (in an unknown function, "??")
calls sem_init().

Now, of course it wants to get libpthread's sem_init(), since
it's linked against libpthread. However, the dynamic linker
looks up that symbol against the binary first, and gets the
kernel's sem_init().

Hajime Tazaki noted that "objcopy -L" can localize a symbol,
so the dynamic linker wouldn't do the lookup this way. I tried,
but for some reason that didn't seem to work.

Doing the same thing in the linker script instead does seem to
work, though I cannot entirely explain - it *also* works if I
just add "VERSION { { global: *; }; }" instead, indicating that
something else is happening that I don't really understand. It
may be that explicitly doing that marks them with some kind of
empty version, and that's different from the default.

Explicitly marking them with a version breaks kallsyms, so that
doesn't seem to be possible.

Marking all the symbols as local seems correct, and does seem
to address the issue, so do that. Also do it for static link,
nsswitch libraries could still be loaded there.

[1] https://bugs.debian.org/983379

Reported-by: Ritesh Raj Sarraf 
Signed-off-by: Johannes Berg 
Acked-By: Anton Ivanov 
Tested-By: Ritesh Raj Sarraf 
Signed-off-by: Richard Weinberger 
Signed-off-by: Sasha Levin

um: mm: check more comprehensively for stub changes

2021-03-04T09:26:50+00:00

commit 47da29763ec9a153b9b685bff9db659e4e09e494 upstream.

If userspace tries to change the stub, we need to kill it,
because otherwise it can escape the virtual machine. In a
few cases the stub checks weren't good, e.g. if userspace
just tries to

	mmap(0x100000 - 0x1000, 0x3000, ...)

it could succeed to get a new private/anonymous mapping
replacing the stubs. Fix this by checking everywhere, and
checking for _overlap_, not just direct changes.

Cc: stable@vger.kernel.org
Fixes: 3963333fe676 ("uml: cover stubs with a VMA")
Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger 
Signed-off-by: Greg Kroah-Hartman

um: change sigio_spinlock to a mutex

2020-11-05T10:43:14+00:00

[ Upstream commit f2d05059e15af3f70502074f4e3a504530af504a ]

Lockdep complains at boot:

=============================
[ BUG: Invalid wait context ]
5.7.0-05093-g46d91ecd597b #98 Not tainted
-----------------------------
swapper/1 is trying to lock:
0000000060931b98 (&desc[i].request_mutex){+.+.}-{3:3}, at: __setup_irq+0x11d/0x623
other info that might help us debug this:
context-{4:4}
1 lock held by swapper/1:
 #0: 000000006074fed8 (sigio_spinlock){+.+.}-{2:2}, at: sigio_lock+0x1a/0x1c
stack backtrace:
CPU: 0 PID: 1 Comm: swapper Not tainted 5.7.0-05093-g46d91ecd597b #98
Stack:
 7fa4fab0 6028dfd1 0000002a 6008bea5
 7fa50700 7fa50040 7fa4fac0 6028e016
 7fa4fb50 6007f6da 60959c18 00000000
Call Trace:
 [<60023a0e>] show_stack+0x13b/0x155
 [<6028e016>] dump_stack+0x2a/0x2c
 [<6007f6da>] __lock_acquire+0x515/0x15f2
 [<6007eb50>] lock_acquire+0x245/0x273
 [<6050d9f1>] __mutex_lock+0xbd/0x325
 [<6050dc76>] mutex_lock_nested+0x1d/0x1f
 [<6008e27e>] __setup_irq+0x11d/0x623
 [<6008e8ed>] request_threaded_irq+0x169/0x1a6
 [<60021eb0>] um_request_irq+0x1ee/0x24b
 [<600234ee>] write_sigio_irq+0x3b/0x76
 [<600383ca>] sigio_broken+0x146/0x2e4
 [<60020bd8>] do_one_initcall+0xde/0x281

Because we hold sigio_spinlock and then get into requesting
an interrupt with a mutex.

Change the spinlock to a mutex to avoid that.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger 
Signed-off-by: Sasha Levin

Revert "um: Enable CONFIG_CONSTRUCTORS"

2020-02-01T09:34:53+00:00

commit 87c9366e17259040a9118e06b6dc8de986e5d3d1 upstream.

This reverts commit 786b2384bf1c ("um: Enable CONFIG_CONSTRUCTORS").

There are two issues with this commit, uncovered by Anton in tests
on some (Debian) systems:

1) I completely forgot to call any constructors if CONFIG_CONSTRUCTORS
   isn't set. Don't recall now if it just wasn't needed on my system, or
   if I never tested this case.

2) With that fixed, it works - with CONFIG_CONSTRUCTORS *unset*. If I
   set CONFIG_CONSTRUCTORS, it fails again, which isn't totally
   unexpected since whatever wanted to run is likely to have to run
   before the kernel init etc. that calls the constructors in this case.

Basically, some constructors that gcc emits (libc has?) need to run
very early during init; the failure mode otherwise was that the ptrace
fork test already failed:

----------------------
$ ./linux mem=512M
Core dump limits :
	soft - 0
	hard - NONE
Checking that ptrace can change system call numbers...check_ptrace : child exited with exitcode 6, while expecting 0; status 0x67f
Aborted
----------------------

Thinking more about this, it's clear that we simply cannot support
CONFIG_CONSTRUCTORS in UML. All the cases we need now (gcov, kasan)
involve not use of the __attribute__((constructor)), but instead
some constructor code/entry generated by gcc. Therefore, we cannot
distinguish between kernel constructors and system constructors.

Thus, revert this commit.

Cc: stable@vger.kernel.org [5.4+]
Fixes: 786b2384bf1c ("um: Enable CONFIG_CONSTRUCTORS")
Reported-by: Anton Ivanov 
Signed-off-by: Johannes Berg 
Acked-by: Anton Ivanov 
Signed-off-by: Greg Kroah-Hartman 

Signed-off-by: Richard Weinberger

um: Implement copy_thread_tls

2020-01-14T19:08:35+00:00

commit 457677c70c7672a4586b0b8abc396cc1ecdd376d upstream.

This is required for clone3 which passes the TLS value through a
struct rather than a register.

Signed-off-by: Amanieu d'Antras 
Cc: linux-um@lists.infradead.org
Cc:  # 5.3.x
Link: https://lore.kernel.org/r/20200104123928.1048822-1-amanieu@gmail.com
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

um: irq: Fix LAST_IRQ usage in init_IRQ()

2019-09-16T06:38:58+00:00

LAST_IRQ was used incorrectly in init_IRQ.
Commit 09ccf0364ca3 forgot to update the for loop.
Fix this.

Fixes: 49da7e64f33e ("High Performance UML Vector Network Driver")
Fixes: 09ccf0364ca3 ("um: Fix off by one error in IRQ enumeration")
Signed-off-by: Erel Geron 
Signed-off-by: Johannes Berg 
Acked-by: Anton Ivanov 
Signed-off-by: Richard Weinberger

um: Add SPDX headers to files in arch/um/kernel/

2019-09-15T19:37:17+00:00

Convert files to use SPDX header. All files are licensed under the
GPLv2.

Signed-off-by: Alex Dewar 
Signed-off-by: Richard Weinberger

um: drivers: Add virtio vhost-user driver

2019-09-15T19:37:15+00:00

This module allows virtio devices to be used over a vhost-user socket.

Signed-off-by: Erel Geron 
Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: time-travel: Restrict time update in IRQ handler

2019-09-15T19:37:13+00:00

We currently do the time updates in the timer handler, even if
we just call the timer handler ourselves. In basic mode we must
in fact do it there since otherwise the OS timer signal won't
move time forward, but in inf-cpu mode we don't need to, and
it's harder to understand.

Restrict the update there to basic mode, adding a comment, and
do it before calling the timer_handler() in inf-cpu mode.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger