linux-toradex.git/arch/um/Makefile, branch v6.3

um: Support LTO

2023-02-13T09:14:31+00:00

Only a handful of changes are necessary to get it to work.

Signed-off-by: Peter Foley 
Signed-off-by: Richard Weinberger

um: Use CFLAGS_vmlinux

2023-02-13T09:14:20+00:00

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 
Signed-off-by: Peter Foley 
Signed-off-by: Richard Weinberger

rust: arch/um: Use 'pie' relocation mode under UML

2023-02-10T20:27:32+00:00

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 
Signed-off-by: Richard Weinberger

arch: um: Mark the stack non-executable to fix a binutils warning

2022-09-21T07:11:42+00:00

Since binutils 2.39, ld will print a warning if any stack section is
executable, which is the default for stack sections on files without a
.note.GNU-stack section.

This was fixed for x86 in commit ffcf9c5700e4 ("x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments"),
but remained broken for UML, resulting in several warnings:

/usr/bin/ld: warning: arch/x86/um/vdso/vdso.o: missing .note.GNU-stack section implies executable stack
/usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
/usr/bin/ld: warning: .tmp_vmlinux.kallsyms1 has a LOAD segment with RWX permissions
/usr/bin/ld: warning: .tmp_vmlinux.kallsyms1.o: missing .note.GNU-stack section implies executable stack
/usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
/usr/bin/ld: warning: .tmp_vmlinux.kallsyms2 has a LOAD segment with RWX permissions
/usr/bin/ld: warning: .tmp_vmlinux.kallsyms2.o: missing .note.GNU-stack section implies executable stack
/usr/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
/usr/bin/ld: warning: vmlinux has a LOAD segment with RWX permissions

Link both the VDSO and vmlinux with -z noexecstack, fixing the warnings
about .note.GNU-stack sections. In addition, pass --no-warn-rwx-segments
to dodge the remaining warnings about LOAD segments with RWX permissions
in the kallsyms objects. (Note that this flag is apparently not
available on lld, so hide it behind a test for BFD, which is what the
x86 patch does.)

Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ffcf9c5700e49c0aee42dcba9a12ba21338e8136
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107
Signed-off-by: David Gow 
Reviewed-by: Lukas Straub 
Tested-by: Lukas Straub 
Acked-by: Randy Dunlap  # build-tested
Signed-off-by: Richard Weinberger

Revert "um: clang: Strip out -mno-global-merge from USER_CFLAGS"

2022-04-01T15:05:28+00:00

This reverts commit 6580c5c18fb3df2b11c5e0452372f815deeff895.

This patch is buggy, as noted in the patch linked below. The root cause
has been solved by removing '-mno-global-merge' for the entire kernel.

Link: https://lore.kernel.org/r/20220322173547.677760-1-nathan@kernel.org/
Signed-off-by: Nathan Chancellor 
Reviewed-by: David Gow 
Reviewed-by: Kees Cook 
Signed-off-by: Masahiro Yamada

um: clang: Strip out -mno-global-merge from USER_CFLAGS

2022-03-11T09:51:41+00:00

The things built with USER_CFLAGS don't seem to recognise it as a
compiler option, and print a warning:
clang: warning: argument unused during compilation: '-mno-global-merge' [-Wunused-command-line-argument]

Fixes: 744814d2fa ("um: Allow builds with Clang")
Signed-off-by: David Gow 
Reviewed-by: Nathan Chancellor 
Signed-off-by: Richard Weinberger

kbuild: do not require sub-make for separate output tree builds

2021-08-09T23:23:39+00:00

As explained in commit 3204a7fb98a3 ("kbuild: prefix $(srctree)/ to some
included Makefiles"), I want to stop using --include-dir some day.

I already fixed up the top Makefile, but some arch Makefiles (mips, um,
x86) still include check-in Makefiles without $(srctree)/.

Fix them up so 'need-sub-make := 1' can go away for this case.

Signed-off-by: Masahiro Yamada

um: allow not setting extra rpaths in the linux binary

2021-06-17T19:54:15+00:00

There doesn't seem to be any reason for the rpath being set in
the binaries, at on systems that I tested on. On the other hand,
setting rpath is actually harming binaries in some cases, e.g.
if using nix-based compilation environments where /lib & /lib64
are not part of the actual environment.

Add a new Kconfig option (under EXPERT, for less user confusion)
that allows disabling the rpath additions.

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

kbuild: remove cc-option test of -fno-stack-protector

2020-07-07T02:13:10+00:00

Some Makefiles already pass -fno-stack-protector unconditionally.
For example, arch/arm64/kernel/vdso/Makefile, arch/x86/xen/Makefile.

No problem report so far about hard-coding this option. So, we can
assume all supported compilers know -fno-stack-protector.

GCC 4.8 and Clang support this option (https://godbolt.org/z/_HDGzN)

Get rid of cc-option from -fno-stack-protector.

Remove CONFIG_CC_HAS_STACKPROTECTOR_NONE, which is always 'y'.

Note:
arch/mips/vdso/Makefile adds -fno-stack-protector twice, first
unconditionally, and second conditionally. I removed the second one.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Kees Cook 
Acked-by: Ard Biesheuvel 
Reviewed-by: Nick Desaulniers

kbuild: remove {CLEAN,MRPROPER,DISTCLEAN}_DIRS

2020-05-25T15:03:15+00:00

Merge {CLEAN,MRPROPER,DISTCLEAN}_DIRS into {CLEAN,MRPROPER,DISTCLEAN}_FILES
because the difference is just the -r option passed to the 'rm' command.

Do likewise as commit 1634f2bfdb84 ("kbuild: remove clean-dirs syntax").

Signed-off-by: Masahiro Yamada