linux.git/arch/powerpc/Makefile, branch master

powerpc: Enable Rust for ppc64le

2026-07-31T11:27:48+00:00

Enabling rust support for ppc64le.

Tested on pseries Power11:
╰─❯ dmesg | grep rust
[    0.225728] Initialise system trusted keyrings
[    0.270961] rust_minimal: Rust minimal sample (init)
[    0.270968] rust_minimal: Am I built-in? true
[    0.270974] rust_minimal: test_parameter: 1
[    0.270983] rust_misc_device: Initialising Rust Misc Device Sample
[    0.271012] rust_print: Rust printing macros sample (init)
[    0.271019] rust_print: Emergency message (level 0) without args
[    0.271023] rust_print: Alert message (level 1) without args
[    0.271026] rust_print: Critical message (level 2) without args
[    0.271030] rust_print: Error message (level 3) without args
[    0.271033] rust_print: Warning message (level 4) without args
[    0.271037] rust_print: Notice message (level 5) without args
[    0.271040] rust_print: Info message (level 6) without args
[    0.271043] rust_print: A line that is continued without args
[    0.271054] rust_print: Emergency message (level 0) with args
[    0.271064] rust_print: Alert message (level 1) with args
[    0.271072] rust_print: Critical message (level 2) with args
[    0.271077] rust_print: Error message (level 3) with args
[    0.271083] rust_print: Warning message (level 4) with args
[    0.271091] rust_print: Notice message (level 5) with args
[    0.271097] rust_print: Info message (level 6) with args
[    0.271102] rust_print: A line that is continued with args
[    0.271110] rust_print: 1
[    0.271113] rust_print: "hello, world"
[    0.271121] rust_print: [samples/rust/rust_print_main.rs:35:5] c = "hello, world"
[    0.271129] rust_print: Arc says 42
[    0.271130] rust_print: Arc says hello, world
[    0.271136] rust_print: "hello, world"
[    0.271198] usbcore: registered new interface driver rust_driver_usb
[    0.271207] rust_faux_driver: Initialising Rust Faux Device Sample
[    0.271227] faux_driver rust-faux-sample-device: Hello from faux device!
[    0.271297] rust_configfs: Rust configfs sample (init)

Reviewed-by: Link Mauve 
Tested-by: Link Mauve 
Reviewed-by: Christophe Leroy (CS GROUP) 
Tested-by: Venkat Rao Bagalkote 
Link: https://github.com/Rust-for-Linux/linux/issues/105
Link: https://github.com/linuxppc/issues/issues/451
Acked-by: Gary Guo 
Link: https://github.com/rust-lang/compiler-team/issues/987
Link: https://github.com/rust-lang/compiler-team/issues/988
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260708082454.1254320-8-mkchauras@gmail.com

rust: Add PowerPC support

2026-07-31T11:27:48+00:00

For now only Big Endian 32-bit PowerPC is supported, as that is the only
hardware I have.  This has been tested on the Nintendo Wii so far, but I
plan on also using it on the GameCube, Wii U and Apple G4.

These changes aren’t the only ones required to get the kernel to compile
and link on PowerPC, libcore will also have to be changed to not use
integer division to format u64, u128 and core::time::Duration, otherwise
__udivdi3() and __umoddi3() will have to be added.  I have tested this
change by replacing the three implementations with unimplemented!() and
it linked just fine.

Signed-off-by: Link Mauve 
Link: https://github.com/Rust-for-Linux/linux/issues/105
Link: https://github.com/linuxppc/issues/issues/451
Acked-by: Gary Guo 
Link: https://github.com/rust-lang/compiler-team/issues/986
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20260708082454.1254320-7-mkchauras@gmail.com

kbuild: Add missing $(objtree) prefix to powerpc crtsavres.o artifact

2025-09-01T08:11:57+00:00

In the upstream commit 214c0eea43b2ea66bcd6467ea57e47ce8874191b
("kbuild: add $(objtree)/ prefix to some in-kernel build artifacts")
artifacts required for building out-of-tree kernel modules had
$(objtree) prepended to them to prepare for building in other
directories.

When building external modules for powerpc,
arch/powerpc/lib/crtsavres.o is required for certain
configurations. This artifact is missing the prepended $(objtree).

Fixes: 13b25489b6f8 ("kbuild: change working directory to external module directory with M=")
Acked-by: Masahiro Yamada 
Reviewed-by: Nicolas Schier 
Tested-by: Nicolas Schier 
Signed-off-by: Kienan Stewart 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/20250218-buildfix-extmod-powerpc-v2-1-1e78fcf12b56@efficios.com

arch/powerpc: Remove .interp section in vmlinux

2025-07-22T08:51:19+00:00

When building with CONFIG_RELOCATABLE, there is a .interp section
which contains the name of the expected ELF interpreter:

Contents of section .interp:
 c0000000021c1bac 2f757372 2f6c6962 2f6c642e 736f2e31  /usr/lib/ld.so.1
 c0000000021c1bbc 00                                   .

That information is useless and even likely wrong. Remove it.

Link: https://github.com/linuxppc/issues/issues/434
Signed-off-by: Christophe Leroy 
Acked-by: Segher Boessenkool 
Signed-off-by: Madhavan Srinivasan 
Link: https://patch.msgid.link/eeaf8fd6628a75d19872ab31cf7e7179e2baef5e.1751366959.git.christophe.leroy@csgroup.eu

Merge tag 'kbuild-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2024-11-30T21:41:50+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Add generic support for built-in boot DTB files

 - Enable TAB cycling for dialog buttons in nconfig

 - Fix issues in streamline_config.pl

 - Refactor Kconfig

 - Add support for Clang's AutoFDO (Automatic Feedback-Directed
   Optimization)

 - Add support for Clang's Propeller, a profile-guided optimization.

 - Change the working directory to the external module directory for M=
   builds

 - Support building external modules in a separate output directory

 - Enable objtool for *.mod.o and additional kernel objects

 - Use lz4 instead of deprecated lz4c

 - Work around a performance issue with "git describe"

 - Refactor modpost

* tag 'kbuild-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (85 commits)
  kbuild: rename .tmp_vmlinux.kallsyms0.syms to .tmp_vmlinux0.syms
  gitignore: Don't ignore 'tags' directory
  kbuild: add dependency from vmlinux to resolve_btfids
  modpost: replace tdb_hash() with hash_str()
  kbuild: deb-pkg: add python3:native to build dependency
  genksyms: reduce indentation in export_symbol()
  modpost: improve error messages in device_id_check()
  modpost: rename alias symbol for MODULE_DEVICE_TABLE()
  modpost: rename variables in handle_moddevtable()
  modpost: move strstarts() to modpost.h
  modpost: convert do_usb_table() to a generic handler
  modpost: convert do_of_table() to a generic handler
  modpost: convert do_pnp_device_entry() to a generic handler
  modpost: convert do_pnp_card_entries() to a generic handler
  modpost: call module_alias_printf() from all do_*_entry() functions
  modpost: pass (struct module *) to do_*_entry() functions
  modpost: remove DEF_FIELD_ADDR_VAR() macro
  modpost: deduplicate MODULE_ALIAS() for all drivers
  modpost: introduce module_alias_printf() helper
  modpost: remove unnecessary check in do_acpi_entry()
  ...

kbuild: add $(objtree)/ prefix to some in-kernel build artifacts

2024-11-27T00:38:27+00:00

$(objtree) refers to the top of the output directory of kernel builds.

This commit adds the explicit $(objtree)/ prefix to build artifacts
needed for building external modules.

This change has no immediate impact, as the top-level Makefile
currently defines:

  objtree         := .

This commit prepares for supporting the building of external modules
in a different directory.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Nicolas Schier

powerpc/Makefile: Allow overriding CPP

2024-11-15T00:59:55+00:00

Unlike all other arches, powerpc doesn't allow the user to override CPP,
because it sets it unconditionally in the arch Makefile. This can lead
to strange build failures.

Instead add the required flags to KBUILD_CPPFLAGS, which are passed
to CPP, CC and AS invocations by the generic Makefile logic.

Reported-by: Arnd Bergmann 
Tested-by: Nathan Chancellor 
Reviewed-by: Nathan Chancellor 
Closes: https://lore.kernel.org/all/20240607061629.530301-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann 
[mpe: Rebase, write change log, add Arnd's SoB as communicated privately]
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241107112646.32401-1-mpe@ellerman.id.au

powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS

2024-10-31T00:00:55+00:00

Implement support for DYNAMIC_FTRACE_WITH_CALL_OPS similar to the
arm64 implementation.

This works by patching-in a pointer to an associated ftrace_ops
structure before each traceable function. If multiple ftrace_ops are
associated with a call site, then a special ftrace_list_ops is used to
enable iterating over all the registered ftrace_ops. If no ftrace_ops
are associated with a call site, then a special ftrace_nop_ops structure
is used to render the ftrace call as a no-op. ftrace trampoline can then
read the associated ftrace_ops for a call site by loading from an offset
from the LR, and branch directly to the associated function.

The primary advantage with this approach is that we don't have to
iterate over all the registered ftrace_ops for call sites that have a
single ftrace_ops registered. This is the equivalent of implementing
support for dynamic ftrace trampolines, which set up a special ftrace
trampoline for each registered ftrace_ops and have individual call sites
branch into those directly.

A secondary advantage is that this gives us a way to add support for
direct ftrace callers without having to resort to using stubs. The
address of the direct call trampoline can be loaded from the ftrace_ops
structure.

To support this, we reserve a nop before each function on 32-bit
powerpc. For 64-bit powerpc, two nops are reserved before each
out-of-line stub. During ftrace activation, we update this location with
the associated ftrace_ops pointer. Then, on ftrace entry, we load from
this location and call into ftrace_ops->func().

For 64-bit powerpc, we ensure that the out-of-line stub area is
doubleword aligned so that ftrace_ops address can be updated atomically.

Signed-off-by: Naveen N Rao 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-15-hbathini@linux.ibm.com

powerpc64/ftrace: Move ftrace sequence out of line

2024-10-31T00:00:54+00:00

Function profile sequence on powerpc includes two instructions at the
beginning of each function:
	mflr	r0
	bl	ftrace_caller

The call to ftrace_caller() gets nop'ed out during kernel boot and is
patched in when ftrace is enabled.

Given the sequence, we cannot return from ftrace_caller with 'blr' as we
need to keep LR and r0 intact. This results in link stack (return
address predictor) imbalance when ftrace is enabled. To address that, we
would like to use a three instruction sequence:
	mflr	r0
	bl	ftrace_caller
	mtlr	r0

Further more, to support DYNAMIC_FTRACE_WITH_CALL_OPS, we need to
reserve two instruction slots before the function. This results in a
total of five instruction slots to be reserved for ftrace use on each
function that is traced.

Move the function profile sequence out-of-line to minimize its impact.
To do this, we reserve a single nop at function entry using
-fpatchable-function-entry=1 and add a pass on vmlinux.o to determine
the total number of functions that can be traced. This is then used to
generate a .S file reserving the appropriate amount of space for use as
ftrace stubs, which is built and linked into vmlinux.

On bootup, the stub space is split into separate stubs per function and
populated with the proper instruction sequence. A pointer to the
associated stub is maintained in dyn_arch_ftrace.

For modules, space for ftrace stubs is reserved from the generic module
stub space.

This is restricted to and enabled by default only on 64-bit powerpc,
though there are some changes to accommodate 32-bit powerpc. This is
done so that 32-bit powerpc could choose to opt into this based on
further tests and benchmarks.

As an example, after this patch, kernel functions will have a single nop
at function entry:
:
	addis	r2,r12,467
	addi	r2,r2,-16028
	nop
	mfocrf	r11,8
	...

When ftrace is enabled, the nop is converted to an unconditional branch
to the stub associated with that function:
:
	addis	r2,r12,467
	addi	r2,r2,-16028
	b	ftrace_ool_stub_text_end+0x11b28
	mfocrf	r11,8
	...

The associated stub:
:
	mflr	r0
	bl	ftrace_caller
	mtlr	r0
	b	kernel_clone+0xc
	...

This change showed an improvement of ~10% in null_syscall benchmark on a
Power 10 system with ftrace enabled.

Signed-off-by: Naveen N Rao 
Signed-off-by: Hari Bathini 
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241030070850.1361304-13-hbathini@linux.ibm.com

powerpc/boot: Remove bogus reference to lilo

2024-10-29T12:01:47+00:00

The help text refers to lilo, but the install script does not run lilo
and never has. The reference to lilo seems to have come originally from
arch/ppc/Makefile, but it was not true there either.

Remove it.

Reported-by: Thorsten Leemhuis 
Link: https://fosstodon.org/@kernellogger/113032940928131612
Signed-off-by: Michael Ellerman 
Link: https://patch.msgid.link/20241009053806.135807-1-mpe@ellerman.id.au