powerpc: Enable Rust for ppc64le

Enabling rust support for ppc64le only.

Tested on powernv9:

$ uname -rm
6.19.0-rc8+ ppc64le

$ sudo modprobe rust_minimal
[  632.890850] rust_minimal: Rust minimal sample (init)
[  632.890881] rust_minimal: Am I built-in? false
[  632.890898] rust_minimal: test_parameter: 1

$ sudo rmmod rust_minimal
[  648.272832] rust_minimal: My numbers are [72, 108, 200]
[  648.272873] rust_minimal: Rust minimal sample (exit)

$ sudo modprobe rust_print
[  843.410391] rust_print: Rust printing macros sample (init)
[  843.410424] rust_print: Emergency message (level 0) without args
[  843.410451] rust_print: Alert message (level 1) without args
[  843.410477] rust_print: Critical message (level 2) without args
[  843.410503] rust_print: Error message (level 3) without args
[  843.410530] rust_print: Warning message (level 4) without args
[  843.410557] rust_print: Notice message (level 5) without args
[  843.410594] rust_print: Info message (level 6) without args
[  843.410617] rust_print: A line that is continued without args
[  843.410646] rust_print: Emergency message (level 0) with args
[  843.410675] rust_print: Alert message (level 1) with args
[  843.410691] rust_print: Critical message (level 2) with args
[  843.410727] rust_print: Error message (level 3) with args
[  843.410761] rust_print: Warning message (level 4) with args
[  843.410796] rust_print: Notice message (level 5) with args
[  843.410821] rust_print: Info message (level 6) with args
[  843.410854] rust_print: A line that is continued with args
[  843.410892] rust_print: 1
[  843.410895] rust_print: "hello, world"
[  843.410924] rust_print: [samples/rust/rust_print_main.rs:35:5] c = "hello, world"
[  843.410977] rust_print: Arc<dyn Display> says 42
[  843.410979] rust_print: Arc<dyn Display> says hello, world

$ sudo rmmod rust_print
[  843.411003] rust_print: "hello, world"
[  888.499935] rust_print: Rust printing macros sample (exit)

Reviewed-by: Link Mauve <linkmauve@linkmauve.fr>
Tested-by: Link Mauve <linkmauve@linkmauve.fr>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260210090023.2587534-4-mkchauras@gmail.com

Author: mkchauras

Documentation/rust/arch-support.rst

@@ -18,7 +18,7 @@ Architecture   Level of support  Constraints
 ``arm``        Maintained        ARMv7 Little Endian only.
 ``arm64``      Maintained        Little Endian only.
 ``loongarch``  Maintained        \-
-``powerpc``    Maintained        32-bit Big Endian only.
+``powerpc``    Maintained        64-bit Little Endian. 32-bit Big Endian.
 ``riscv``      Maintained        ``riscv64`` and LLVM/Clang only.
 ``um``         Maintained        \-
 ``x86``        Maintained        ``x86_64`` only.

arch/powerpc/Kconfig

@@ -285,6 +285,7 @@ config PPC
 	select HAVE_RELIABLE_STACKTRACE
 	select HAVE_RSEQ
 	select HAVE_RUST			if PPC32
+	select HAVE_RUST			if PPC64 && CPU_LITTLE_ENDIAN
 	select HAVE_SAMPLE_FTRACE_DIRECT	if HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	select HAVE_SETUP_PER_CPU_AREA		if PPC64

arch/powerpc/Makefile

@@ -61,7 +61,12 @@ else
 KBUILD_LDFLAGS_MODULE += $(objtree)/arch/powerpc/lib/crtsavres.o
 endif
 
-KBUILD_RUSTFLAGS += --target=powerpc-unknown-linux-gnu
+ifdef CONFIG_PPC64
+KBUILD_RUSTFLAGS	+= --target=powerpc64le-unknown-linux-gnu
+KBUILD_RUSTFLAGS	+= -Ctarget-feature=-mma,-vsx,-hard-float,-altivec
+else
+KBUILD_RUSTFLAGS	+= --target=powerpc-unknown-linux-gnu
+endif
 
 ifdef CONFIG_CPU_LITTLE_ENDIAN
 KBUILD_CPPFLAGS	+= -mlittle-endian

rust/Makefile

@@ -410,7 +410,13 @@ BINDGEN_TARGET_x86	:= x86_64-linux-gnu
 BINDGEN_TARGET_arm64	:= aarch64-linux-gnu
 BINDGEN_TARGET_arm	:= arm-linux-gnueabi
 BINDGEN_TARGET_loongarch	:= loongarch64-linux-gnusf
+
+ifdef CONFIG_PPC64
+BINDGEN_TARGET_powerpc	:= powerpc64le-linux-gnu
+else
 BINDGEN_TARGET_powerpc	:= powerpc-linux-gnu
+endif
+
 BINDGEN_TARGET_um	:= $(BINDGEN_TARGET_$(SUBARCH))
 BINDGEN_TARGET		:= $(BINDGEN_TARGET_$(SRCARCH))