Commit Graph

1021 Commits

Author SHA1 Message Date
Tiwei Bie
cb055b2135 um: Do not propagate mem parameter to kernel
This parameter is UML specific and is unknown to kernel. It should not
be propagated to kernel, otherwise it will be passed to user space as
an environment option by kernel with a warning like:

Unknown kernel command line parameters "mem=2G", will be passed to user space.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20241011040441.1586345-3-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-23 09:52:48 +02:00
Tiwei Bie
a34d105350 um: Remove UML specific debug parameter
It does nothing but emit a warning when 'debug' is provided in the
kernel command line. It can be a bit annoying, as 'debug' is also a
valid kernel parameter to enable kernel debugging.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20241011040441.1586345-2-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-23 09:52:48 +02:00
Johannes Berg
188b64f288 um: remove fault_catcher infrastructure
This was perhaps intended to do _nofault copies, but the
real reason is lost to history. Remove this, it's not
needed, and using longjmp() out of the middle of the
signal handler with all the state it has modified is
not going to be a good idea anyway.

Link: https://patch.msgid.link/20241010224513.901c4d390b3e.Ia74742668b44603c1ca23dd36f90e964e6e7ee55@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-23 09:52:46 +02:00
Johannes Berg
14d4a7b516 um: make stub_exe _start() pure inline asm
Since __attribute__((naked)) cannot be used with functions
containing C statements, just generate the few instructions
it needs in assembly directly.

While at it, fix the stack usage ("1 + 2*x - 1" is odd) and
document what it must do, and why it must adjust the stack.

Fixes: 8508a5e0e9 ("um: Fix misaligned stack in stub_exe")
Link: https://lore.kernel.org/linux-um/CABVgOSntH-uoOFMP5HwMXjx_f1osMnVdhgKRKm4uz6DFm2Lb8Q@mail.gmail.com/
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-23 09:04:59 +02:00
David Gow
8508a5e0e9 um: Fix misaligned stack in stub_exe
The stub_exe could segfault when built with some compilers (e.g. gcc
13.2.0), as SSE instructions which relied on stack alignment could be
generated, but the stack was misaligned.

This seems to be due to the __start entry point being run with a 16-byte
aligned stack, but the x86_64 SYSV ABI wanting the stack to be so
aligned _before_ a function call (so it is misaligned when the function
is entered due to the return address being pushed). The function
prologue then realigns it. Because the entry point is never _called_,
and hence there is no return address, the prologue is therefore actually
misaligning it, and causing the generated movaps instructions to
SIGSEGV. This results in the following error:
start_userspace : expected SIGSTOP, got status = 139

Don't generate this prologue for __start by using
__attribute__((naked)), which resolves the issue.

Fixes: 32e8eaf263 ("um: use execveat to create userspace MMs")
Signed-off-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/linux-um/CABVgOS=boUoG6=LHFFhxEd8H8jDP1zOaPKFEjH+iy2n2Q5S2aQ@mail.gmail.com/
Link: https://patch.msgid.link/20241017231007.1500497-2-davidgow@google.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-18 10:37:52 +02:00
Nathan Chancellor
1e3071d629 um: Disable auto variable initialization for stub_exe.c
When automatic variable initialization is enabled via
CONFIG_INIT_STACK_ALL_{PATTERN,ZERO}, clang will insert a call to
memset() to initialize an object created with __builtin_alloca(). This
ultimately breaks the build when linking stub_exe because it is a
standalone executable that does not include or link against memset().

  ld: arch/um/kernel/skas/stub_exe.o: in function `_start':
  arch/um/kernel/skas/stub_exe.c:83:(.ltext+0x15): undefined reference to `memset'

Disable automatic variable initialization for stub_exe.c by passing the
default value of 'uninitialized' to '-ftrivial-auto-var-init', which
avoids generating the call to memset(). This code is small and runs
quickly as it is just designed to set up an environment, so stack
variable initialization is unnecessary overhead for little gain.

Fixes: 32e8eaf263 ("um: use execveat to create userspace MMs")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20241016-uml-fix-stub_exe-clang-v1-2-3d6381dc5a78@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-17 10:33:31 +02:00
Nathan Chancellor
89350defd1 um: Fix passing '-n' to linker for stub_exe
When building stub_exe with clang, there is an error because '-n' is not
a recognized flag by the clang driver (which is being used to invoke the
linker):

  clang: error: unknown argument: '-n'

'-n' should be passed along to the linker, as it is the short flag for
'--nmagic', so prefix it with '-Wl,'.

Fixes: 32e8eaf263 ("um: use execveat to create userspace MMs")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20241016-uml-fix-stub_exe-clang-v1-1-3d6381dc5a78@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-17 10:33:31 +02:00
Benjamin Berg
41ab5fe747 um: Switch to 4 level page tables on 64 bit
The larger memory space is useful to support more applications inside
UML. One example for this is ASAN instrumentation of userspace
applications which requires addresses that would otherwise not be
available.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-11-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:22 +02:00
Benjamin Berg
e167cc7a95 um: clear all memory in new userspace processes
With the change to use execve() we can now safely clear the memory up to
STUB_START as rseq will not be trying to use memory in that region. Also,
on 64 bit the previous changes should mean that there is no usable
memory range above the stub.

Make the change and remove the comment as it is not needed anymore.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-10-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:22 +02:00
Benjamin Berg
68b9883cc1 um: Discover host_task_size from envp
When loading the UML binary, the host kernel will place the stack at the
highest possible address. It will then map the program name and
environment variables onto the start of the stack.

As such, an easy way to figure out the host_task_size is to use the
highest pointer to an environment variable as a reference.

Ensure that this works by disabling address layout randomization and
re-executing UML in case it was enabled.

This increases the available TASK_SIZE for 64 bit UML considerably.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-9-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:22 +02:00
Benjamin Berg
830003c73d um: Limit TASK_SIZE to the addressable range
We may have a TASK_SIZE from the host that is bigger than UML is able to
address with a three-level pagetable on 64-bit. Guard against that by
clipping the maximum TASK_SIZE to the maximum addressable area.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-8-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:22 +02:00
Benjamin Berg
91f0a0c5cc um: Calculate stub data address relative to stub code
Instead of using the current stack pointer, we can also use the current
instruction to calculate where the stub data is. With this the stub data
only needs to be aligned to a full page boundary.

Changing this has the advantage that we do not have a hole in the memory
space above the stub data (which would need to be explicitly cleared).

Another motivation to do this is that with the planned addition of a
SECCOMP based userspace the stack pointer may not be fully trustworthy.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-7-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:22 +02:00
Benjamin Berg
77eb31b600 um: Add compile time assert that stub fits on a page
The code assumes that the stub code can fit into a single page. This is
unlikely to ever change, but add a link time assert instead so that
there will be no hard to debug error.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-6-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:21 +02:00
Benjamin Berg
801e00d3a1 um: Set parent death signal for userspace process
Enable PR_SET_PDEATHSIG so that the UML userspace process will be killed
when the kernel exits unexpectedly.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-4-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:21 +02:00
Benjamin Berg
32e8eaf263 um: use execveat to create userspace MMs
Using clone will not undo features that have been enabled by libc. An
example of this already happening is rseq, which could cause the kernel
to read/write memory of the userspace process. In the future the
standard library might also use mseal by default to protect itself,
which would also thwart our attempts at unmapping everything.

Solve all this by taking a step back and doing an execve into a tiny
static binary that sets up the minimal environment required for the
stub without using any standard library. That way we have a clean
execution environment that is fully under the control of UML.

Note that this changes things a bit as the FDs are not anymore shared
with the kernel. Instead, we explicitly share the FDs for the physical
memory and all existing iomem regions. Doing this is fine, as iomem
regions cannot be added at runtime.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240919124511.282088-3-benjamin@sipsolutions.net
[use pipe() instead of pipe2(), remove unneeded close() calls]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 13:37:16 +02:00
Benjamin Berg
c6ce72005d um: remove auxiliary FP registers
We do not need the extra save/restore of the FP registers when getting
the fault information. This was originally added in commit 2f56debd77
("uml: fix FP register corruption") but at that time the code was not
saving/restoring the FP registers when switching to userspace. This was
fixed in commit fbfe9c847e ("um: Save FPU registers between task
switches") and since then the auxiliary registers have not been useful.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20241004233821.2130874-1-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 12:10:30 +02:00
Benjamin Berg
5a6951273e um: always use the internal copy of the FP registers
When switching from userspace to the kernel, all registers including the
FP registers are copied into the kernel and restored later on. As such,
the true source for the FP register state is actually already in the
kernel and they should never be grabbed from the userspace process.

Change the various places to simply copy the data from the internal FP
register storage area. Note that on i386 the format of PTRACE_GETFPREGS
and PTRACE_GETFPXREGS is different enough that conversion would be
needed. With this patch, -EINVAL is returned if the non-native format is
requested.

The upside is, that this patchset fixes setting registers via ptrace
(which simply did not work before) as well as fixing setting floating
point registers using the mcontext on signal return on i386.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240913133845.964292-1-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 12:03:55 +02:00
Tiwei Bie
865e3845ee um: Fix the return value of elf_core_copy_task_fpregs
This function is expected to return a boolean value, which should be
true on success and false on failure.

Fixes: d1254b12c9 ("uml: fix x86_64 core dump crash")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240913023302.130300-1-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 12:02:40 +02:00
Tiwei Bie
242fef3610 um: Fix the definition for physmem_size
Currently physmem_size is defined as long long but declared locally
as unsigned long long before using it in separate .c files. Make them
match by defining physmem_size as unsigned long long and also move
the declaration to a common header to allow the compiler to check it.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240916045950.508910-5-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 12:02:13 +02:00
Tiwei Bie
cd05cbed42 um: Remove highmem leftovers
Highmem was only supported on UML/i386. And the support has been
removed by commit a98a6d864d ("um: Remove broken highmem support").
Remove the leftovers and stop UML from trying to setup highmem when
the sum of physmem_size and iomem_size exceeds max_physmem.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240916045950.508910-4-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 12:02:13 +02:00
Tiwei Bie
a98b7761f6 um: Fix potential integer overflow during physmem setup
This issue happens when the real map size is greater than LONG_MAX,
which can be easily triggered on UML/i386.

Fixes: fe205bdd13 ("um: Print minimum physical memory requirement")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240916045950.508910-3-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10 12:02:13 +02:00
Linus Torvalds
12cc5240f4 This pull request contains the following changes for UML:
- Removal of dead code (TT mode leftovers, etc.)
 - Fixes for the network vector driver
 - Fixes for time-travel mode
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Merge tag 'uml-for-linus-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull UML updates from Richard Weinberger:

 - Removal of dead code (TT mode leftovers, etc)

 - Fixes for the network vector driver

 - Fixes for time-travel mode

* tag 'uml-for-linus-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux:
  um: fix time-travel syscall scheduling hack
  um: Remove outdated asm/sysrq.h header
  um: Remove the declaration of user_thread function
  um: Remove the call to SUBARCH_EXECVE1 macro
  um: Remove unused mm_fd field from mm_id
  um: Remove unused fields from thread_struct
  um: Remove the redundant newpage check in update_pte_range
  um: Remove unused kpte_clear_flush macro
  um: Remove obsoleted declaration for execute_syscall_skas
  user_mode_linux_howto_v2: add VDE vector support in doc
  vector_user: add VDE support
  um: remove ARCH_NO_PREEMPT_DYNAMIC
  um: vector: Fix NAPI budget handling
  um: vector: Replace locks guarding queue depth with atomics
  um: remove variable stack array in os_rcv_fd_msg()
2024-09-27 12:48:48 -07:00
Johannes Berg
381d2f95c8 um: fix time-travel syscall scheduling hack
The schedule() call there really never did anything at
least since the introduction of the EEVDF scheduler,
but now I found a case where we permanently hang in a
loop of -ERESTARTNOINTR (due to locking.) Work around
it by making any syscalls with error return take time
(and then schedule after) so we cannot hang in such a
loop forever.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2024-09-12 20:46:23 +02:00
Tiwei Bie
ae0dc67c25 um: Remove outdated asm/sysrq.h header
This header no longer serves a purpose after show_trace was removed
by commit 9d1ee8ce92 ("um: Rewrite show_stack()").

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2024-09-12 20:44:11 +02:00
Tiwei Bie
bf67dbf4f7 um: Remove the call to SUBARCH_EXECVE1 macro
This macro has never been defined by any supported sub-architectures
in tree since it was introduced by commit 1d3468a664 ("[PATCH uml:
move _kern.c files").

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2024-09-12 20:42:22 +02:00
Tiwei Bie
59376fb2a7 um: Remove unused mm_fd field from mm_id
It's no longer used since the removal of the SKAS3/4 support.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2024-09-12 20:36:22 +02:00
Tiwei Bie
94090f418f um: Remove unused fields from thread_struct
These fields are no longer used since the removal of tt mode.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2024-09-12 20:35:35 +02:00
Tiwei Bie
669afa4e87 um: Remove the redundant newpage check in update_pte_range
The two checks have been identical since commit ef714f1502 ("um:
remove force_flush_all from fork_handler"). And the inner one isn't
necessary anymore.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2024-09-12 20:34:39 +02:00
Daniel Vetter
91dae758bd drm-misc-next for v6.12:
UAPI Changes:
 
 virtio:
 - Define DRM capset
 
 Cross-subsystem Changes:
 
 dma-buf:
 - heaps: Clean up documentation
 
 printk:
 - Pass description to kmsg_dump()
 
 Core Changes:
 
 CI:
 - Update IGT tests
 - Point upstream repo to GitLab instance
 
 modesetting:
 - Introduce Power Saving Policy property for connectors
 - Add might_fault() to drm_modeset_lock priming
 - Add dynamic per-crtc vblank configuration support
 
 panic:
 - Avoid build-time interference with framebuffer console
 
 docs:
 - Document Colorspace property
 
 scheduler:
 - Remove full_recover from drm_sched_start
 
 TTM:
 - Make LRU walk restartable after dropping locks
 - Allow direct reclaim to allocate local memory
 
 Driver Changes:
 
 amdgpu:
 - Support Power Saving Policy connector property
 
 ast:
 - astdp: Support AST2600 with VGA; Clean up HPD
 
 bridge:
 - Silence error message on -EPROBE_DEFER
 - analogix: Clean aup
 - bridge-connector: Fix double free
 - lt6505: Disable interrupt when powered off
 - tc358767: Make default DP port preemphasis configurable
 
 gma500:
 - Update i2c terminology
 
 ivpu:
 - Add MODULE_FIRMWARE()
 
 lcdif:
 - Fix pixel clock
 
 loongson:
 - Use GEM refcount over TTM's
 
 mgag200:
 - Improve BMC handling
 - Support VBLANK intterupts
 
 nouveau:
 - Refactor and clean up internals
 - Use GEM refcount over TTM's
 
 panel:
 - Shutdown fixes plus documentation
 - Refactor several drivers for better code sharing
 - boe-th101mb31ig002: Support for starry-er88577 MIPI-DSI panel plus
   DT; Fix porch parameter
 - edp: Support AOU B116XTN02.3, AUO B116XAN06.1, AOU B116XAT04.1,
   BOE NV140WUM-N41, BOE NV133WUM-N63, BOE NV116WHM-A4D, CMN N116BCA-EA2,
   CMN N116BCP-EA2, CSW MNB601LS1-4
 - himax-hx8394: Support Microchip AC40T08A MIPI Display panel plus DT
 - ilitek-ili9806e: Support Densitron DMT028VGHMCMI-1D TFT plus DT
 - jd9365da: Support Melfas lmfbx101117480 MIPI-DSI panel plus DT; Refactor
   for code sharing
 
 sti:
 - Fix module owner
 
 stm:
 - Avoid UAF wih managed plane and CRTC helpers
 - Fix module owner
 - Fix error handling in probe
 - Depend on COMMON_CLK
 - ltdc: Fix transparency after disabling plane; Remove unused interrupt
 
 tegra:
 - Call drm_atomic_helper_shutdown()
 
 v3d:
 - Clean up perfmon
 
 vkms:
 - Clean up
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Merge tag 'drm-misc-next-2024-08-01' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-next

drm-misc-next for v6.12:

UAPI Changes:

virtio:
- Define DRM capset

Cross-subsystem Changes:

dma-buf:
- heaps: Clean up documentation

printk:
- Pass description to kmsg_dump()

Core Changes:

CI:
- Update IGT tests
- Point upstream repo to GitLab instance

modesetting:
- Introduce Power Saving Policy property for connectors
- Add might_fault() to drm_modeset_lock priming
- Add dynamic per-crtc vblank configuration support

panic:
- Avoid build-time interference with framebuffer console

docs:
- Document Colorspace property

scheduler:
- Remove full_recover from drm_sched_start

TTM:
- Make LRU walk restartable after dropping locks
- Allow direct reclaim to allocate local memory

Driver Changes:

amdgpu:
- Support Power Saving Policy connector property

ast:
- astdp: Support AST2600 with VGA; Clean up HPD

bridge:
- Silence error message on -EPROBE_DEFER
- analogix: Clean aup
- bridge-connector: Fix double free
- lt6505: Disable interrupt when powered off
- tc358767: Make default DP port preemphasis configurable

gma500:
- Update i2c terminology

ivpu:
- Add MODULE_FIRMWARE()

lcdif:
- Fix pixel clock

loongson:
- Use GEM refcount over TTM's

mgag200:
- Improve BMC handling
- Support VBLANK intterupts

nouveau:
- Refactor and clean up internals
- Use GEM refcount over TTM's

panel:
- Shutdown fixes plus documentation
- Refactor several drivers for better code sharing
- boe-th101mb31ig002: Support for starry-er88577 MIPI-DSI panel plus
  DT; Fix porch parameter
- edp: Support AOU B116XTN02.3, AUO B116XAN06.1, AOU B116XAT04.1,
  BOE NV140WUM-N41, BOE NV133WUM-N63, BOE NV116WHM-A4D, CMN N116BCA-EA2,
  CMN N116BCP-EA2, CSW MNB601LS1-4
- himax-hx8394: Support Microchip AC40T08A MIPI Display panel plus DT
- ilitek-ili9806e: Support Densitron DMT028VGHMCMI-1D TFT plus DT
- jd9365da: Support Melfas lmfbx101117480 MIPI-DSI panel plus DT; Refactor
  for code sharing

sti:
- Fix module owner

stm:
- Avoid UAF wih managed plane and CRTC helpers
- Fix module owner
- Fix error handling in probe
- Depend on COMMON_CLK
- ltdc: Fix transparency after disabling plane; Remove unused interrupt

tegra:
- Call drm_atomic_helper_shutdown()

v3d:
- Clean up perfmon

vkms:
- Clean up

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
From: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240801121406.GA102996@linux.fritz.box
2024-08-08 18:58:46 +02:00
Jocelyn Falempe
e1a261ba59 printk: Add a short description string to kmsg_dump()
kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
callback.
This patch adds a new struct kmsg_dump_detail, that will hold the
reason and description, and pass it to the dump() callback.

To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
function and a macro for backward compatibility.

I've written this for drm_panic, but it can be useful for other
kmsg_dumper.
It allows to see the panic reason, like "sysrq triggered crash"
or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.

v2:
 * Use a struct kmsg_dump_detail to hold the reason and description
   pointer, for more flexibility if we want to add other parameters.
   (Kees Cook)
 * Fix powerpc/nvram_64 build, as I didn't update the forward
   declaration of oops_to_nvram()

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Kees Cook <kees@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240702122639.248110-1-jfalempe@redhat.com
2024-07-17 12:35:24 +02:00
Johannes Berg
86abcd6eeb um: register power-off handler
Otherwise we always get

 reboot: Power off not available: System halted instead

which is really quite pointless.

Link: https://patch.msgid.link/20240703173839.fcbb538c6686.I3d333f4773cff93c4337c4d128ee0b1b501b3dfa@changeid
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-04 12:03:20 +02:00
Anton Ivanov
cd01672d64 um: Enable preemption in UML
Since userspace state is saved in the MM process, kernel using
FPU still doesn't really need to do anything, so this really
is as simple as enabling preemption. The irq critical section
in sigio_handler() needs preempt_disable()/preempt_enable().

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Link: https://patch.msgid.link/20240702102549.d2fcea450854.I12f5a53d80ec1e425e66ef272b1e95cb523b608e@changeid
[rebase, remove FPU save/restore, fix x86/um Makefile,
 rewrite commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:10:43 +02:00
Benjamin Berg
bcf3d957c6 um: refactor TLB update handling
Conceptually, we want the memory mappings to always be up to date and
represent whatever is in the TLB. To ensure that, we need to sync them
over in the userspace case and for the kernel we need to process the
mappings.

The kernel will call flush_tlb_* if page table entries that were valid
before become invalid. Unfortunately, this is not the case if entries
are added.

As such, change both flush_tlb_* and set_ptes to track the memory range
that has to be synchronized. For the kernel, we need to execute a
flush_tlb_kern_* immediately but we can wait for the first page fault in
case of set_ptes. For userspace in contrast we only store that a range
of memory needs to be synced and do so whenever we switch to that
process.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240703134536.1161108-13-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:50 +02:00
Benjamin Berg
573a446fc8 um: simplify and consolidate TLB updates
The HVC update was mostly used to compress consecutive calls into one.
This is mostly relevant for userspace where it is already handled by the
syscall stub code.

Simplify the whole logic and consolidate it for both kernel and
userspace. This does remove the sequential syscall compression for the
kernel, however that shouldn't be the main factor in most runs.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240703134536.1161108-12-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:50 +02:00
Benjamin Berg
ef714f1502 um: remove force_flush_all from fork_handler
There should be no need for this. It may be that this used to work
around another issue where after a clone the MM was in a bad state.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240703134536.1161108-11-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:50 +02:00
Benjamin Berg
5168f6b4a4 um: Do not flush MM in flush_thread
There should be no need to flush the memory in flush_thread. Doing this
likely worked around some issue where memory was still incorrectly
mapped when creating or cloning an MM.

With the removal of the special clone path, that isn't relevant anymore.
However, add the flush into MM initialization so that any new userspace
MM is guaranteed to be clean.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240703134536.1161108-10-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:49 +02:00
Benjamin Berg
3c83170d7c um: Delay flushing syscalls until the thread is restarted
As running the syscalls is expensive due to context switches, we should
do so as late as possible in case more syscalls need to be queued later
on. This will also benefit a later move to a SECCOMP enabled userspace
as in that case the need for extra context switches is removed entirely.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Link: https://patch.msgid.link/20240703134536.1161108-9-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:49 +02:00
Benjamin Berg
a5d2cfe749 um: remove copy_context_skas0
The kernel flushes the memory ranges anyway for CoW and does not assume
that the userspace process has anything set up already. So, start with a
fresh process for the new mm context.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240703134536.1161108-8-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:49 +02:00
Benjamin Berg
7911b650a0 um: remove LDT support
The current LDT code has a few issues that mean it should be redone in a
different way once we always start with a fresh MM even when cloning.

In a new and better world, the kernel would just ensure its own LDT is
clear at startup. At that point, all that is needed is a simple function
to populate the LDT from another MM in arch_dup_mmap combined with some
tracking of the installed LDT entries for each MM.

Note that the old implementation was even incorrect with regard to
reading, as it copied out the LDT entries in the internal format rather
than converting them to the userspace structure.

Removal should be fine as the LDT is not used for thread-local storage
anymore.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20240703134536.1161108-7-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:49 +02:00
Benjamin Berg
76ed9158e1 um: Rework syscall handling
Rework syscall handling to be platform independent. Also create a clean
split between queueing of syscalls and flushing them out, removing the
need to keep state in the code that triggers the syscalls.

The code adds syscall_data_len to the global mm_id structure. This will
be used later to allow surrounding code to track whether syscalls still
need to run and if errors occurred.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Link: https://patch.msgid.link/20240703134536.1161108-5-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:49 +02:00
Benjamin Berg
dc26184a9d um: Create signal stack memory assignment in stub_data
When we switch to use seccomp, we need both the signal stack and other
data (i.e. syscall information) to co-exist in the stub data. To
facilitate this, start by defining separate memory areas for the stack
and syscall data.

This moves the signal stack onto a new page as the memory area is not
sufficient to hold both signal stack and syscall information.

Only change the signal stack setup for now, as the syscall code will be
reworked later.

Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Link: https://patch.msgid.link/20240703134536.1161108-3-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:48 +02:00
Johannes Berg
4561022588 um: time-travel: remove time_exit()
This function is unused and unneeded, remove it.

Link: https://patch.msgid.link/20240703130105.02b3a974acb7.I7264821f7cfa17ea713b7a3e4787aa41a3107d01@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 17:09:08 +02:00
Johannes Berg
bfb80d8bc9 um: add shared memory optimisation for time-travel=ext
With external time travel, a LOT of message can end up
being exchanged on the socket, taking a significant
amount of time just to do that.

Add a new shared memory optimisation to that, where a
number of changes are made:
 - the controller sends a client ID and a shared memory FD
   (and a logging FD we don't use) in the ACK message to
   the initial START
 - the shared memory holds the current time and the
   free_until value, so that there's no need to exchange
   messages for that
 - if the client that's running has shared memory support,
   any client (the running one included) can request the
   next time it wants to run inside the shared memory,
   rather than sending a message, by also updating the
   free_until value
 - when shared memory is enabled, RUN/WAIT messages no
   longer have an ACK, further cutting down on messages

Together, this can reduce the number of messages very
significantly, and reduce overall test/simulation run time.

Co-developed-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Link: https://patch.msgid.link/20240702192118.6ad0a083f574.Ie41206c8ce4507fe26b991937f47e86c24ca7a31@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:24:54 +02:00
Johannes Berg
5cde6096a4 um: generalize os_rcv_fd
Change os_rcv_fd() to os_rcv_fd_msg() that can more generally
receive any number of FDs in any kind of message.

Link: https://patch.msgid.link/20240702192118.40b78b2bfe4e.Ic6ec12d72630e5bcae1e597d6bd5c6f29f441563@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:24:25 +02:00
Mordechay Goodstein
6555acdefc um: time-travel: support time-travel protocol broadcast messages
Add a message type to the time-travel protocol to broadcast
a small (64-bit) value to all participants in a simulation.
The main use case is to have an identical message come to
all participants in a simulation, e.g. to separate out logs
for different tests running in a single simulation.

Down in the guts of time_travel_handle_message() we can't
use printk() and not even printk_deferred(), so just store
the message and print it at the start of the userspace()
function.

Unfortunately this means that other prints in the kernel
can actually bypass the message, but in most cases where
this is used, for example to separate test logs, userspace
will be involved. Also, even if we could use
printk_deferred(), we'd still need to flush it out in the
userspace() function since otherwise userspace messages
might cross it.

As a result, this is a reasonable compromise, there's no
need to have any core changes and it solves the main use
case we have for it.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Link: https://patch.msgid.link/20240702192118.c4093bc5b15e.I2ca8d006b67feeb866ac2017af7b741c9e06445a@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:24:22 +02:00
Wei Yang
5cd93c7532 um/mm: remove redundant assignment of max_low_pfn
Current calculation of max_low_pfn is introduced in commit af84eab208
("[PATCH] uml: fix LVM crash"). It is intended to set max_low_pfn to the
same value as max_pfn.

But I am not sure why the max_pfn is set to totalram_pages, which
represents the number of usable pages in system instead of an absolute
page frame number. (The change history stops there.)

While we have already calculate it in setup_physmem(), so not necessary
to do it again.

Also this would help changing totalram_pages accounting, since we plan
to move the accounting into __free_pages_core(). With this change,
totalram_pages may not represent the total usable pages at this point,
since some pages would be deferred initialized.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
CC: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Alasdair G Kergon <agk@redhat.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Mike Rapoport (IBM) <rppt@kernel.org>
CC: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Link: https://patch.msgid.link/20240615034150.2958-1-richard.weiyang@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:22:39 +02:00
Tiwei Bie
cb2759431a um: Remove /proc/sysemu support code
Currently /proc/sysemu will never be registered, as sysemu_supported
is initialized to zero implicitly and no code updates it. And there is
also nothing to configure via sysemu in UML anymore.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240527134024.1539848-3-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:21:57 +02:00
Tiwei Bie
6fdae1da76 um: Remove unused ncpus variable
It's no longer used. And uml_ncpus_setup doesn't exist anymore.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20240527134024.1539848-2-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:21:57 +02:00
Johannes Berg
7d0a8a490a um: time-travel: fix time-travel-start option
We need to have the = as part of the option so that the
value can be parsed properly. Also document that it must
be given in nanoseconds, not seconds.

Fixes: 065038706f ("um: Support time travel mode")
Link: https://patch.msgid.link/20240417102744.14b9a9d4eba0.Ib22e9136513126b2099d932650f55f193120cd97@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:21:16 +02:00
Benjamin Berg
c140a5bd5d um: irqs: process outstanding IRQs when unblocking signals
When in time-travel mode, the eventfd events are read even when signals
are blocked as SIGIO still needs to be processed. In this case, the
event is cleared on the eventfd but the IRQ still needs to be fired
later.

We did already ensure that the SIGIO handler is run again. However, the
FDs are configured to be level triggered, so that eventfd will not
notify again. As such, add some logic to mark the IRQ as pending and
process it at the next opportunity.

To avoid duplication, reuse the logic used for the suspend/resume case.
This does not really change anything except for delaying running the
IRQs with timetravel_handler at a slightly later point in time (and
possibly running non-timetravel IRQs that shouldn't happen earlier).
While at it, move marking as pending into irq_event_handler as that is
the more logical place for it to happen.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20231018123643.1255813-1-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-07-03 12:18:01 +02:00