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Message-ID: <da26fa6a-5262-45bf-890c-7afbf94d0897@kernel.org>
Date: Wed, 4 Feb 2026 18:11:13 +0100
From: "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
To: "Mukesh Kumar Chaurasiya (IBM)" <mkchauras@...il.com>,
maddy@...ux.ibm.com, mpe@...erman.id.au, npiggin@...il.com,
peterz@...radead.org, jpoimboe@...nel.org, jbaron@...mai.com,
rostedt@...dmis.org, ardb@...nel.org, ojeda@...nel.org,
boqun.feng@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com,
lossin@...nel.org, a.hindborg@...nel.org, aliceryhl@...gle.com,
tmgross@...ch.edu, dakr@...nel.org, nathan@...nel.org,
nick.desaulniers+lkml@...il.com, morbo@...gle.com, justinstitt@...gle.com,
linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
rust-for-linux@...r.kernel.org, llvm@...ts.linux.dev,
Link Mauve <linkmauve@...kmauve.fr>
Subject: Re: [PATCH] powerpc: Enable Rust for ppc64le
Hi Mukesh, hi Link,
Le 04/02/2026 à 05:24, Mukesh Kumar Chaurasiya (IBM) a écrit :
> [Vous ne recevez pas souvent de courriers de mkchauras@...il.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>
> Enabling rust support for ppc64 only.
Link Mauve has sent a patch for rust support on PPC32 a few hours before
you, see
https://lore.kernel.org/r/20260204030507.8203-1-linkmauve@linkmauve.fr
Could you coordinate together to provide something supporting both PPC32
and PPC64 ?
I see the following conflicts at the time being. I also have a few
comments down.
diff --git a/Documentation/rust/arch-support.rst
b/Documentation/rust/arch-support.rst
index 6e6a515d0899..70b9e192a7a0 100644
--- a/Documentation/rust/arch-support.rst
+++ b/Documentation/rust/arch-support.rst
@@ -18,6 +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.
``riscv`` Maintained ``riscv64`` and LLVM/Clang only.
``um`` Maintained \-
``x86`` Maintained ``x86_64`` only.
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b8d36a261009..80b2666fc5af 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -283,8 +283,10 @@ config PPC
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE
select HAVE_RSEQ
+ select HAVE_RUST if PPC32
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_RUST if PPC64
select HAVE_SETUP_PER_CPU_AREA if PPC64
select HAVE_SOFTIRQ_ON_OWN_STACK
select HAVE_STACKPROTECTOR if PPC32 && $(cc-option,$(m32-flag)
-mstack-protector-guard=tls -mstack-protector-guard-reg=r2
-mstack-protector-guard-offset=0)
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index a58b1029592c..ac6fe8cc4ece 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -61,6 +61,8 @@ else
KBUILD_LDFLAGS_MODULE += $(objtree)/arch/powerpc/lib/crtsavres.o
endif
+KBUILD_RUSTFLAGS += --target=powerpc-unknown-linux-gnu
+
ifdef CONFIG_CPU_LITTLE_ENDIAN
KBUILD_CPPFLAGS += -mlittle-endian
KBUILD_LDFLAGS += -EL
@@ -172,10 +174,11 @@ CFLAGS-y += $(CONFIG_TUNE_CPU)
asinstr := $(call as-instr,lis 9$(comma)foo@...h,-DHAVE_AS_ATHIGH=1)
-KBUILD_CPPFLAGS += -I $(srctree)/arch/powerpc $(asinstr)
-KBUILD_AFLAGS += $(AFLAGS-y)
-KBUILD_CFLAGS += $(CC_FLAGS_NO_FPU)
-KBUILD_CFLAGS += $(CFLAGS-y)
+KBUILD_CPPFLAGS += -I $(srctree)/arch/powerpc $(asinstr)
+KBUILD_AFLAGS += $(AFLAGS-y)
+KBUILD_CFLAGS += $(CC_FLAGS_NO_FPU)
+KBUILD_CFLAGS += $(CFLAGS-y)
+KBUILD_RUSTFLAGS += -Ctarget-feature=-mma,-vsx,-hard-float,-altivec
CHECKFLAGS += -m$(BITS) -D__powerpc__ -D__powerpc$(BITS)__
ifdef CONFIG_CPU_BIG_ENDIAN
diff --git a/arch/powerpc/include/asm/jump_label.h
b/arch/powerpc/include/asm/jump_label.h
index d4eaba459a0e..d2284c72d21b 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -15,14 +15,35 @@
#define JUMP_ENTRY_TYPE stringify_in_c(FTR_ENTRY_LONG)
#define JUMP_LABEL_NOP_SIZE 4
+<<<<<<< HEAD
+/* This macro is also expanded on the Rust side. */
+#define ARCH_STATIC_BRANCH_ASM(key, label) \
+ "1:\n\t" \
+ "nop # arch_static_branch\n\t" \
+ ".pushsection __jump_table, \"aw\"\n\t" \
+ ".long 1b - ., " label " - .\n\t" \
+ JUMP_ENTRY_TYPE key " - .\n\t" \
+ ".popsection \n\t"
+
static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
{
- asm goto("1:\n\t"
- "nop # arch_static_branch\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
- ".long 1b - ., %l[l_yes] - .\n\t"
- JUMP_ENTRY_TYPE "%c0 - .\n\t"
- ".popsection \n\t"
+ asm goto(ARCH_STATIC_BRANCH_ASM("%c0", "%l[l_yes]")
+=======
+#define JUMP_TABLE_ENTRY(key, label) \
+ ".pushsection __jump_table, \"aw\" \n\t" \
+ ".long 1b - ., " label " - . \n\t" \
+ JUMP_ENTRY_TYPE key " - . \n\t" \
+ ".popsection \n\t"
+
+#define ARCH_STATIC_BRANCH_ASM(key, label) \
+ "1: nop \n\t" \
+ JUMP_TABLE_ENTRY(key,label)
+
+static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
+{
+ asm goto(
+ ARCH_STATIC_BRANCH_ASM("%c0", "%l[l_yes]")
+>>>>>>> rust64
: : "i" (&((char *)key)[branch]) : : l_yes);
return false;
@@ -34,10 +55,7 @@ static __always_inline bool
arch_static_branch_jump(struct static_key *key, bool
{
asm goto("1:\n\t"
"b %l[l_yes] # arch_static_branch_jump\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
- ".long 1b - ., %l[l_yes] - .\n\t"
- JUMP_ENTRY_TYPE "%c0 - .\n\t"
- ".popsection \n\t"
+ JUMP_TABLE_ENTRY("%c0", "%l[l_yes]")
: : "i" (&((char *)key)[branch]) : : l_yes);
return false;
diff --git a/rust/Makefile b/rust/Makefile
index 5d357dce1704..9b72c1e96191 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -383,13 +383,19 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387
-mpreferred-stack-boundary=% \
-fno-inline-functions-called-once -fsanitize=bounds-strict \
-fstrict-flex-arrays=% -fmin-function-alignment=% \
-fzero-init-padding-bits=% -mno-fdpic \
- --param=% --param asan-% -fno-isolate-erroneous-paths-dereference
+ --param=% --param asan-% -fno-isolate-erroneous-paths-dereference \
+ -ffixed-r2 -mmultiple -mno-readonly-in-sdata
# Derived from `scripts/Makefile.clang`.
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
+<<<<<<< HEAD
+BINDGEN_TARGET_powerpc := powerpc-linux-gnu
+=======
+BINDGEN_TARGET_powerpc := powerpc64le-linux-gnu
+>>>>>>> rust64
BINDGEN_TARGET_um := $(BINDGEN_TARGET_$(SUBARCH))
BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH))
diff --git a/scripts/generate_rust_target.rs
b/scripts/generate_rust_target.rs
index 38b3416bb979..1860af50b926 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -188,6 +188,16 @@ fn main() {
panic!("arm uses the builtin rustc target");
} else if cfg.has("ARM64") {
panic!("arm64 uses the builtin rustc aarch64-unknown-none
target");
+ } else if cfg.has("PPC32") {
+ ts.push("arch", "powerpc");
+ ts.push("data-layout", "E-m:e-p:32:32-Fn32-i64:64-n32");
+ ts.push("features", "+soft-float");
+ ts.push("llvm-target", "powerpc-unknown-eabi");
+ if cfg.rustc_version_atleast(1, 91, 0) {
+ ts.push("target-pointer-width", 32);
+ } else {
+ ts.push("target-pointer-width", "32");
+ }
} else if cfg.has("RISCV") {
if cfg.has("64BIT") {
panic!("64-bit RISC-V uses the builtin rustc
riscv64-unknown-none-elf target");
@@ -256,6 +266,30 @@ fn main() {
}
} else if cfg.has("LOONGARCH") {
panic!("loongarch uses the builtin rustc
loongarch64-unknown-none-softfloat target");
+ } else if cfg.has("PPC64") {
+ ts.push("arch", "powerpc64");
+ ts.push(
+ "data-layout",
+ if cfg.has("CPU_LITTLE_ENDIAN") {
+ "e-m:e-Fn32-i64:64-n32:64-S128-v256:256:256-v512:512:512"
+ } else {
+ "E-m:e-Fn32-i64:64-n32:64-S128-v256:256:256-v512:512:512"
+ },
+ );
+ ts.push("features", "-mma,-altivec,-vsx,-hard-float");
+ ts.push(
+ "llvm-target",
+ if cfg.has("CPU_LITTLE_ENDIAN") {
+ "powerpc64le-linux-gnu"
+ } else {
+ "powerpc64-linux-gnu"
+ },
+ );
+ if cfg.rustc_version_atleast(1, 91, 0) {
+ ts.push("target-pointer-width", 64);
+ } else {
+ ts.push("target-pointer-width", "64");
+ }
} else {
panic!("Unsupported architecture");
}
[...]
> ---
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/Makefile | 9 +++++----
> arch/powerpc/include/asm/jump_label.h | 23 +++++++++++++----------
> rust/Makefile | 1 +
> scripts/generate_rust_target.rs | 24 ++++++++++++++++++++++++
> 5 files changed, 44 insertions(+), 14 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 9537a61ebae0..e9b8d761ed52 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -285,6 +285,7 @@ config PPC
> select HAVE_RSEQ
> 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_RUST if PPC64
Keep in alphabetic order
> select HAVE_SETUP_PER_CPU_AREA if PPC64
> select HAVE_SOFTIRQ_ON_OWN_STACK
> select HAVE_STACKPROTECTOR if PPC32 && $(cc-option,$(m32-flag) -mstack-protector-guard=tls -mstack-protector-guard-reg=r2 -mstack-protector-guard-offset=0)
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index a58b1029592c..7ad28cf0fd35 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -172,10 +172,11 @@ CFLAGS-y += $(CONFIG_TUNE_CPU)
>
> asinstr := $(call as-instr,lis 9$(comma)foo@...h,-DHAVE_AS_ATHIGH=1)
>
> -KBUILD_CPPFLAGS += -I $(srctree)/arch/powerpc $(asinstr)
> -KBUILD_AFLAGS += $(AFLAGS-y)
> -KBUILD_CFLAGS += $(CC_FLAGS_NO_FPU)
> -KBUILD_CFLAGS += $(CFLAGS-y)
> +KBUILD_CPPFLAGS += -I $(srctree)/arch/powerpc $(asinstr)
> +KBUILD_AFLAGS += $(AFLAGS-y)
> +KBUILD_CFLAGS += $(CC_FLAGS_NO_FPU)
> +KBUILD_CFLAGS += $(CFLAGS-y)
> +KBUILD_RUSTFLAGS += -Ctarget-feature=-mma,-vsx,-hard-float,-altivec
>
> CHECKFLAGS += -m$(BITS) -D__powerpc__ -D__powerpc$(BITS)__
> ifdef CONFIG_CPU_BIG_ENDIAN
> diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
> index d4eaba459a0e..a6b211502bfe 100644
> --- a/arch/powerpc/include/asm/jump_label.h
> +++ b/arch/powerpc/include/asm/jump_label.h
> @@ -15,14 +15,20 @@
> #define JUMP_ENTRY_TYPE stringify_in_c(FTR_ENTRY_LONG)
> #define JUMP_LABEL_NOP_SIZE 4
>
> +#define JUMP_TABLE_ENTRY(key, label) \
> + ".pushsection __jump_table, \"aw\" \n\t" \
> + ".long 1b - ., " label " - . \n\t" \
> + JUMP_ENTRY_TYPE key " - . \n\t" \
> + ".popsection \n\t"
> +
> +#define ARCH_STATIC_BRANCH_ASM(key, label) \
> + "1: nop \n\t" \
> + JUMP_TABLE_ENTRY(key,label)
> +
> static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
> {
> - asm goto("1:\n\t"
> - "nop # arch_static_branch\n\t"
> - ".pushsection __jump_table, \"aw\"\n\t"
> - ".long 1b - ., %l[l_yes] - .\n\t"
> - JUMP_ENTRY_TYPE "%c0 - .\n\t"
> - ".popsection \n\t"
> + asm goto(
> + ARCH_STATIC_BRANCH_ASM("%c0", "%l[l_yes]")
> : : "i" (&((char *)key)[branch]) : : l_yes);
>
> return false;
> @@ -34,10 +40,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
> {
> asm goto("1:\n\t"
> "b %l[l_yes] # arch_static_branch_jump\n\t"
> - ".pushsection __jump_table, \"aw\"\n\t"
> - ".long 1b - ., %l[l_yes] - .\n\t"
> - JUMP_ENTRY_TYPE "%c0 - .\n\t"
> - ".popsection \n\t"
> + JUMP_TABLE_ENTRY("%c0", "%l[l_yes]")
> : : "i" (&((char *)key)[branch]) : : l_yes);
>
> return false;
> diff --git a/rust/Makefile b/rust/Makefile
> index 5d357dce1704..7a6daa822cbc 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -390,6 +390,7 @@ 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
> +BINDGEN_TARGET_powerpc := powerpc64le-linux-gnu
This needs to depend on CONFIG_PPC64 and CONFIG_CPU_LITTLE_ENDIAN.
> BINDGEN_TARGET_um := $(BINDGEN_TARGET_$(SUBARCH))
> BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH))
>
> diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
> index 38b3416bb979..875579b37424 100644
> --- a/scripts/generate_rust_target.rs
> +++ b/scripts/generate_rust_target.rs
> @@ -256,6 +256,30 @@ fn main() {
> }
> } else if cfg.has("LOONGARCH") {
> panic!("loongarch uses the builtin rustc loongarch64-unknown-none-softfloat target");
> + } else if cfg.has("PPC64") {
Shouldn't this be done closer to PPC32 ?
> + ts.push("arch", "powerpc64");
> + ts.push(
> + "data-layout",
> + if cfg.has("CPU_LITTLE_ENDIAN") {
> + "e-m:e-Fn32-i64:64-n32:64-S128-v256:256:256-v512:512:512"
> + } else {
> + "E-m:e-Fn32-i64:64-n32:64-S128-v256:256:256-v512:512:512"
> + },
> + );
> + ts.push("features", "-mma,-altivec,-vsx,-hard-float");
> + ts.push(
> + "llvm-target",
> + if cfg.has("CPU_LITTLE_ENDIAN") {
> + "powerpc64le-linux-gnu"
> + } else {
> + "powerpc64-linux-gnu"
> + },
> + );
> + if cfg.rustc_version_atleast(1, 91, 0) {
> + ts.push("target-pointer-width", 64);
> + } else {
> + ts.push("target-pointer-width", "64");
> + }
> } else {
> panic!("Unsupported architecture");
> }
> --
> 2.52.0
>
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