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Merge tag 'fork-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull fork cleanups from Christian Brauner:
"This is cleanup series from when we reworked a chunk of the process
creation paths in the kernel and switched to struct
{kernel_}clone_args.
High-level this does two main things:
- Remove the double export of both do_fork() and _do_fork() where
do_fork() used the incosistent legacy clone calling convention.
Now we only export _do_fork() which is based on struct
kernel_clone_args.
- Remove the copy_thread_tls()/copy_thread() split making the
architecture specific HAVE_COYP_THREAD_TLS config option obsolete.
This switches all remaining architectures to select
HAVE_COPY_THREAD_TLS and thus to the copy_thread_tls() calling
convention. The current split makes the process creation codepaths
more convoluted than they need to be. Each architecture has their own
copy_thread() function unless it selects HAVE_COPY_THREAD_TLS then it
has a copy_thread_tls() function.
The split is not needed anymore nowadays, all architectures support
CLONE_SETTLS but quite a few of them never bothered to select
HAVE_COPY_THREAD_TLS and instead simply continued to use copy_thread()
and use the old calling convention. Removing this split cleans up the
process creation codepaths and paves the way for implementing clone3()
on such architectures since it requires the copy_thread_tls() calling
convention.
After having made each architectures support copy_thread_tls() this
series simply renames that function back to copy_thread(). It also
switches all architectures that call do_fork() directly over to
_do_fork() and the struct kernel_clone_args calling convention. This
is a corollary of switching the architectures that did not yet support
it over to copy_thread_tls() since do_fork() is conditional on not
supporting copy_thread_tls() (Mostly because it lacks a separate
argument for tls which is trivial to fix but there's no need for this
function to exist.).
The do_fork() removal is in itself already useful as it allows to to
remove the export of both do_fork() and _do_fork() we currently have
in favor of only _do_fork(). This has already been discussed back when
we added clone3(). The legacy clone() calling convention is - as is
probably well-known - somewhat odd:
#
# ABI hall of shame
#
config CLONE_BACKWARDS
config CLONE_BACKWARDS2
config CLONE_BACKWARDS3
that is aggravated by the fact that some architectures such as sparc
follow the CLONE_BACKWARDSx calling convention but don't really select
the corresponding config option since they call do_fork() directly.
So do_fork() enforces a somewhat arbitrary calling convention in the
first place that doesn't really help the individual architectures that
deviate from it. They can thus simply be switched to _do_fork()
enforcing a single calling convention. (I really hope that any new
architectures will __not__ try to implement their own calling
conventions...)
Most architectures already have made a similar switch (m68k comes to
mind).
Overall this removes more code than it adds even with a good portion
of added comments. It simplifies a chunk of arch specific assembly
either by moving the code into C or by simply rewriting the assembly.
Architectures that have been touched in non-trivial ways have all been
actually boot and stress tested: sparc and ia64 have been tested with
Debian 9 images. They are the two architectures which have been
touched the most. All non-trivial changes to architectures have seen
acks from the relevant maintainers. nios2 with a custom built
buildroot image. h8300 I couldn't get something bootable to test on
but the changes have been fairly automatic and I'm sure we'll hear
people yell if I broke something there.
All other architectures that have been touched in trivial ways have
been compile tested for each single patch of the series via git rebase
-x "make ..." v5.8-rc2. arm{64} and x86{_64} have been boot tested
even though they have just been trivially touched (removal of the
HAVE_COPY_THREAD_TLS macro from their Kconfig) because well they are
basically "core architectures" and since it is trivial to get your
hands on a useable image"
* tag 'fork-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
arch: rename copy_thread_tls() back to copy_thread()
arch: remove HAVE_COPY_THREAD_TLS
unicore: switch to copy_thread_tls()
sh: switch to copy_thread_tls()
nds32: switch to copy_thread_tls()
microblaze: switch to copy_thread_tls()
hexagon: switch to copy_thread_tls()
c6x: switch to copy_thread_tls()
alpha: switch to copy_thread_tls()
fork: remove do_fork()
h8300: select HAVE_COPY_THREAD_TLS, switch to kernel_clone_args
nios2: enable HAVE_COPY_THREAD_TLS, switch to kernel_clone_args
ia64: enable HAVE_COPY_THREAD_TLS, switch to kernel_clone_args
sparc: unconditionally enable HAVE_COPY_THREAD_TLS
sparc: share process creation helpers between sparc and sparc64
sparc64: enable HAVE_COPY_THREAD_TLS
fork: fold legacy_clone_args_valid() into _do_fork()
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| .gitignore | ||
| arch_timer.c | ||
| armksyms.c | ||
| asm-offsets.c | ||
| atags_compat.c | ||
| atags_parse.c | ||
| atags_proc.c | ||
| atags.h | ||
| bios32.c | ||
| bugs.c | ||
| cpuidle.c | ||
| crash_dump.c | ||
| debug.S | ||
| devtree.c | ||
| dma-isa.c | ||
| dma.c | ||
| early_printk.c | ||
| efi.c | ||
| elf.c | ||
| entry-armv.S | ||
| entry-common.S | ||
| entry-ftrace.S | ||
| entry-header.S | ||
| entry-v7m.S | ||
| fiq.c | ||
| fiqasm.S | ||
| ftrace.c | ||
| head-common.S | ||
| head-inflate-data.c | ||
| head-nommu.S | ||
| head.S | ||
| hibernate.c | ||
| hw_breakpoint.c | ||
| hyp-stub.S | ||
| insn.c | ||
| io.c | ||
| irq.c | ||
| isa.c | ||
| iwmmxt.S | ||
| jump_label.c | ||
| kgdb.c | ||
| machine_kexec.c | ||
| Makefile | ||
| module-plts.c | ||
| module.c | ||
| module.lds | ||
| opcodes.c | ||
| paravirt.c | ||
| patch.c | ||
| perf_callchain.c | ||
| perf_event_v6.c | ||
| perf_event_v7.c | ||
| perf_event_xscale.c | ||
| perf_regs.c | ||
| pj4-cp0.c | ||
| process.c | ||
| psci_smp.c | ||
| ptrace.c | ||
| reboot.c | ||
| reboot.h | ||
| relocate_kernel.S | ||
| return_address.c | ||
| setup.c | ||
| signal.c | ||
| signal.h | ||
| sigreturn_codes.S | ||
| sleep.S | ||
| smccc-call.S | ||
| smp_scu.c | ||
| smp_tlb.c | ||
| smp_twd.c | ||
| smp.c | ||
| stacktrace.c | ||
| suspend.c | ||
| swp_emulate.c | ||
| sys_arm.c | ||
| sys_oabi-compat.c | ||
| tcm.c | ||
| thumbee.c | ||
| time.c | ||
| topology.c | ||
| traps.c | ||
| unwind.c | ||
| v7m.c | ||
| vdso.c | ||
| vmlinux-xip.lds.S | ||
| vmlinux.lds.h | ||
| vmlinux.lds.S | ||
| xscale-cp0.c | ||