kernel/arch/um/include/shared/as-layout.h, branch linux-rolling-stableHosts the 0x221E linux distro kernel.https://universe.0xinfinity.dev/distro/kernel/atom?h=linux-rolling-stable2025-10-27T15:37:12Zum: Make host_task_size a local variable2025-10-27T15:37:12ZTiwei Bietiwei.btw@antgroup.com2025-10-27T05:45:16Zurn:sha1:691ff5914835a65151f3793e8b4dea0b230d0b6b
Currently, host_task_size is a global variable, but it is only used
in linux_main() to compute stub_start and task_size. Make it a local
variable to limit its scope to where it is actually needed.
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20251027054519.1996090-2-tiwei.bie@linux.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: Centralize stub size calculations2025-09-10T12:23:52ZTiwei Bietiwei.btw@antgroup.com2025-08-27T00:57:03Zurn:sha1:e047f9af9d6948728614f7eea41ba53d5b767e9f
Currently, the stub size is calculated in multiple places. Define
a macro that performs the calculation so that the code is easier
to read and maintain.
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: Remove outdated comment about STUB_DATA_PAGES2025-09-10T12:23:49ZTiwei Bietiwei.btw@antgroup.com2025-08-27T00:57:02Zurn:sha1:b765d69a1adf83b969f1f0c8353b80c3c18ef2f7
STUB_DATA_PAGES is no longer required to be a power of two since
commit 91f0a0c5cc5b ("um: Calculate stub data address relative to
stub code"). Remove the outdated comment.
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: Replace __ASSEMBLY__ with __ASSEMBLER__ in the usermode headers2025-07-22T15:12:45ZThomas Huththuth@redhat.com2025-03-14T07:10:06Zurn:sha1:fc9ed2f6589dc2c11f05883e5c323be5f39fd241
While the GCC and Clang compilers already define __ASSEMBLER__
automatically when compiling assembly code, __ASSEMBLY__ is a
macro that only gets defined by the Makefiles in the kernel.
This can be very confusing when switching between userspace
and kernelspace coding, so let's standardize on the __ASSEMBLER__
macro that is provided by the compilers now.
This is a completely mechanical patch (done with a simple "sed -i"
statement).
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-um@lists.infradead.org
Signed-off-by: Thomas Huth <thuth@redhat.com>
Link: https://patch.msgid.link/20250314071013.1575167-36-thuth@redhat.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: mark rodata read-only and implement _nofault accesses2025-03-18T10:03:14ZJohannes Bergjohannes.berg@intel.com2025-02-10T16:09:25Zurn:sha1:d1d7f01f7cd35e16c6bcef5a0e31988b5c9980f9
Mark read-only data actually read-only (simple mprotect), and
to be able to test it also implement _nofault accesses. This
works by setting up a new "segv_continue" pointer in current,
and then when we hit a segfault we change the signal return
context so that we continue at that address. The code using
this sets it up so that it jumps to a label and then aborts
the access that way, returning -EFAULT.
It's possible to optimize the ___backtrack_faulted() thing by
using asm goto (compiler version dependent) and/or gcc's (not
sure if clang has it) &&label extension, but at least in one
attempt I made the && caused the compiler to not load -EFAULT
into the register in case of jumping to the &&label from the
fault handler. So leave it like this for now.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Co-developed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20250210160926.420133-2-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: move thread info into task2024-11-12T13:50:31ZBenjamin Bergbenjamin.berg@intel.com2024-11-11T10:29:10Zurn:sha1:2f681ba4b352cdd5658ed2a96062375a12839755
This selects the THREAD_INFO_IN_TASK option for UM and changes the way
that the current task is discovered. This is trivial though, as UML
already tracks the current task in cpu_tasks[] and this can be used to
retrieve it.
Also remove the signal handler code that copies the thread information
into the IRQ stack. It is obsolete now, which also means that the
mentioned race condition cannot happen anymore.
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Reviewed-by: Hajime Tazaki <thehajime@gmail.com>
Link: https://patch.msgid.link/20241111102910.46512-1-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: Discover host_task_size from envp2024-10-10T11:37:22ZBenjamin Bergbenjamin.berg@intel.com2024-09-19T12:45:09Zurn:sha1:68b9883cc16ec2ce699d832ef60241b1a4e47d33
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>
um: Fix the definition for physmem_size2024-10-10T10:02:13ZTiwei Bietiwei.btw@antgroup.com2024-09-16T04:59:50Zurn:sha1:242fef3610e3a38c53781d4d81d8e779021c0af5
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>
um: Remove highmem leftovers2024-10-10T10:02:13ZTiwei Bietiwei.btw@antgroup.com2024-09-16T04:59:49Zurn:sha1:cd05cbed42b73168b0772b83bc24769fea3871bf
Highmem was only supported on UML/i386. And the support has been
removed by commit a98a6d864d3b ("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>
um: Create signal stack memory assignment in stub_data2024-07-03T15:09:48ZBenjamin Bergbenjamin@sipsolutions.net2024-07-03T13:45:26Zurn:sha1:dc26184a9d4acde988e996a437b0301b81c1ae2d
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>