linux.git/arch/um/Makefile, branch for-next Linux kernel source tree um: always include kconfig.h and compiler-version.h 2024-11-07T16:36:30+00:00 Benjamin Berg benjamin.berg@intel.com 2024-11-03T15:05:03+00:00 2f278b59574ae222a14e4ae59964cb47edfeadd1 Since commit a95b37e20db9 ("kbuild: get <linux/compiler_types.h> out of <linux/kconfig.h>") we can safely include these files in userspace code. Doing so simplifies matters as options do not need to be exported via asm-offsets.h anymore. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20241103150506.1367695-2-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com> 
Since commit a95b37e20db9 ("kbuild: get <linux/compiler_types.h> out of
<linux/kconfig.h>") we can safely include these files in userspace code.
Doing so simplifies matters as options do not need to be exported via
asm-offsets.h anymore.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20241103150506.1367695-2-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
um: use execveat to create userspace MMs 2024-10-10T11:37:16+00:00 Benjamin Berg benjamin.berg@intel.com 2024-09-19T12:45:03+00:00 32e8eaf263d9be014ba1970444f745682fa9c6c0 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> 
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>
um: Makefile: use bash from the environment 2024-04-22T20:17:29+00:00 Yueh-Shun Li shamrocklee@posteo.net 2024-03-23T17:44:25+00:00 19ee69234a7281e4706d789c764f93be6fc7b5b2 Set Makefile SHELL to bash instead of /bin/bash for better portability. Some systems do not install binaries to /bin, and therefore do not provide /bin/bash. This includes Linux distros which intentionally avoid implementing the Filesystem Hierarchy Standard (FHS), such as NixOS and Guix System. The recipies inside arch/um/Makefile don't require top-level Bash to build, and setting "SHELL" to "bash" makes Make pick the Bash executable from the environment, hence this patch. Changes since last roll: - Rebase onto a more recent commit on the master branch. - Remove a dangling in-text citation from the change log. - Reword the change log. Signed-off-by: Yueh-Shun Li <shamrocklee@posteo.net> Reviewed-by: Johannes Berg <johannes@sipsolutions.net Signed-off-by: Richard Weinberger <richard@nod.at> 
Set Makefile SHELL to bash instead of /bin/bash for better portability.

Some systems do not install binaries to /bin, and therefore do not
provide /bin/bash. This includes Linux distros which intentionally avoid
implementing the Filesystem Hierarchy Standard (FHS), such as NixOS and
Guix System.

The recipies inside arch/um/Makefile don't require top-level Bash to
build, and setting "SHELL" to "bash" makes Make pick the Bash executable
from the environment, hence this patch.

Changes since last roll:
- Rebase onto a more recent commit on the master branch.
- Remove a dangling in-text citation from the change log.
- Reword the change log.

Signed-off-by: Yueh-Shun Li <shamrocklee@posteo.net>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Fix adding '-no-pie' for clang 2024-01-27T16:13:37+00:00 Nathan Chancellor nathan@kernel.org 2024-01-23T22:59:54+00:00 846cfbeed09b45d985079a9173cf390cc053715b The kernel builds with -fno-PIE, so commit 883354afbc10 ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: stable@vger.kernel.org Closes: https://github.com/ClangBuiltLinux/linux/issues/1982 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> 
The kernel builds with -fno-PIE, so commit 883354afbc10 ("um: link
vmlinux with -no-pie") added the compiler linker flag '-no-pie' via
cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer.

While this works for GCC, this does not work for clang because cc-option
uses '-c', which stops the pipeline right before linking, so '-no-pie'
is unconsumed and clang warns, causing cc-option to fail just as it
would if the option was entirely unsupported:

  $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null
  clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument]

A recent version of clang exposes this because it generates a relocation
under '-mcmodel=large' that is not supported in PIE mode:

  /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE
  /usr/sbin/ld: failed to set dynamic section sizes: bad value
  clang: error: linker command failed with exit code 1 (use -v to see invocation)

Remove the cc-option check altogether. It is wasteful to invoke the
compiler to check for '-no-pie' because only one supported compiler
version does not support it, GCC 5.x (as it is supported with the
minimum version of clang and GCC 6.1.0+). Use a combination of the
gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add
'-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all
compilers that support this. Furthermore, using gcc-min-version can help
turn this back into

  LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie

when the minimum version of GCC is bumped past 6.1.0.

Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/1982
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
um: use obj-y to descend into arch/um/*/ 2023-08-26T20:41:34+00:00 Masahiro Yamada masahiroy@kernel.org 2023-07-21T17:18:57+00:00 8f85f93bfd2d490251143577bd43b01b40acb8d7 The single build rule does not work with the core-y syntax. [1] Use the standard obj-y syntax. [1]: https://lore.kernel.org/linux-kbuild/d57ba55f-20a3-b836-783d-b49c8a161b6e@kernel.org/T/#m7bc402e1e038f00ebcf2e92ed7fcb8a52fc1ea44 Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Jiri Slaby <jirislaby@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
The single build rule does not work with the core-y syntax. [1]

Use the standard obj-y syntax.

[1]: https://lore.kernel.org/linux-kbuild/d57ba55f-20a3-b836-783d-b49c8a161b6e@kernel.org/T/#m7bc402e1e038f00ebcf2e92ed7fcb8a52fc1ea44

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Jiri Slaby <jirislaby@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Hard-code the result of 'uname -s' 2023-08-26T20:40:37+00:00 Masahiro Yamada masahiroy@kernel.org 2023-07-21T17:18:56+00:00 d32df1080f0199f3570a541fcfcf9b5974b771db We rely on 'uname -s' returning 'Linux' because there are os-Linux/ directories, but no other os-*/. Supporting a non-Linux host is unlikely to happen. Let's hard-code 'Linux'. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Richard Weinberger <richard@nod.at> 
We rely on 'uname -s' returning 'Linux' because there are os-Linux/
directories, but no other os-*/.

Supporting a non-Linux host is unlikely to happen.

Let's hard-code 'Linux'.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Use HOST_DIR for mrproper 2023-06-14T19:27:38+00:00 Kees Cook keescook@chromium.org 2023-06-06T22:24:45+00:00 a5a319ec2c2236bb96d147c16196d2f1f3799301 When HEADER_ARCH was introduced, the MRPROPER_FILES (then MRPROPER_DIRS) list wasn't adjusted, leaving SUBARCH as part of the path argument. This resulted in the "mrproper" target not cleaning up arch/x86/... when SUBARCH was specified. Since HOST_DIR is arch/$(HEADER_ARCH), use it instead to get the correct path. Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Azeem Shaikh <azeemshaikh38@gmail.com> Cc: linux-um@lists.infradead.org Fixes: 7bbe7204e937 ("um: merge Makefile-{i386,x86_64}") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230606222442.never.807-kees@kernel.org 
When HEADER_ARCH was introduced, the MRPROPER_FILES (then MRPROPER_DIRS)
list wasn't adjusted, leaving SUBARCH as part of the path argument.
This resulted in the "mrproper" target not cleaning up arch/x86/... when
SUBARCH was specified. Since HOST_DIR is arch/$(HEADER_ARCH), use it
instead to get the correct path.

Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Azeem Shaikh <azeemshaikh38@gmail.com>
Cc: linux-um@lists.infradead.org
Fixes: 7bbe7204e937 ("um: merge Makefile-{i386,x86_64}")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230606222442.never.807-kees@kernel.org
um: Support LTO 2023-02-13T09:14:31+00:00 Peter Foley pefoley2@pefoley.com 2023-01-13T17:03:00+00:00 83e913f52aba69149261742aa9ea4ceea7bf182d Only a handful of changes are necessary to get it to work. Signed-off-by: Peter Foley <pefoley2@pefoley.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
Only a handful of changes are necessary to get it to work.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: Use CFLAGS_vmlinux 2023-02-13T09:14:20+00:00 Peter Foley pefoley2@pefoley.com 2023-01-13T04:49:10+00:00 6aa56115c73b37270e53aa91984bdb8b60164ec7 link-vmlinux.sh doesn't use LDFLAGS_vmlinux when linking the kernel for UML. Move the LDFLAGS_EXESTACK options into CFLAGS_vmlinux so they're actually respected. e.g. /usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: warning: .tmp_vmlinux.kallsyms3.o: missing .note.GNU-stack section implies executable stack /usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker /usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: warning: vmlinux has a LOAD segment with RWX permissions Reviewed-by: David Gow <davidgow@google.com> Signed-off-by: Peter Foley <pefoley2@pefoley.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
link-vmlinux.sh doesn't use LDFLAGS_vmlinux when linking the kernel for
UML. Move the LDFLAGS_EXESTACK options into CFLAGS_vmlinux so they're
actually respected.

e.g.
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: warning: .tmp_vmlinux.kallsyms3.o: missing .note.GNU-stack section implies executable stack
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
/usr/lib/gcc/x86_64-pc-linux-gnu/12/../../../../x86_64-pc-linux-gnu/bin/ld: warning: vmlinux has a LOAD segment with RWX permissions

Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Peter Foley <pefoley2@pefoley.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
rust: arch/um: Use 'pie' relocation mode under UML 2023-02-10T20:27:32+00:00 David Gow davidgow@google.com 2022-12-17T04:44:34+00:00 905a77077573056d7af508f35373f66ed8b4a39e UML expects a position independent executable for some reason, so tell rustc to generate pie objects. Otherwise we get a bunch of relocations we can't deal with in libcore. Signed-off-by: David Gow <davidgow@google.com> Signed-off-by: Richard Weinberger <richard@nod.at> 
UML expects a position independent executable for some reason, so tell
rustc to generate pie objects. Otherwise we get a bunch of relocations
we can't deal with in libcore.

Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>