[PATCH v5 0/6] s390: Enable Rust support and add required arch glue

[PATCH v5 0/6] s390: Enable Rust support and add required arch glue

[Jan Polensky]

Rust support on s390 requires a small set of architecture-specific pieces
before the generic Rust kernel infrastructure can be used.

The series wires up s390 as a Rust-capable 64-bit architecture, adds the
missing assembly interfaces needed by Rust for WARN/BUG reporting and for
static branches, adjusts bindgen parameters to avoid repr layout conflicts
caused by packed and aligned s390 structures, and fixes issues discovered
during testing.

s390 currently requires rustc with support for -Zpacked-stack, and the
minimum tool version gating is adjusted accordingly.

Link: https://github.com/Rust-for-Linux/linux/issues/2

Tested against: rustc 1.96.0 (ac68faa20 2026-05-25)

Changes since v4:
- Patch 4/6: Use kernel's memchr() instead of __builtin_memchr (Sashiko AI)

Changes since v3:
- Added patch 4/6: Add memchr wrapper preserving KASAN/FORTIFY_SOURCE (reported by Sashiko AI)
- Added patch 5/6: Fix KASAN stack-out-of-bounds in atomic helpers (reported by Miguel, suggested by Gary)
- Patch 6/6: Document CONFIG_EXPOLINE constraint in arch-support.rst (Sashiko AI feedback)
- Patch 6/6: Added Acked-by from Miguel Ojeda

Changes since v2:
- mflags: cleanup (thanks Gary)

Changes since v1:
- strip the -nightly suffix in min-tool-version.sh (thanks Miguel and Alice)
- ARCH_JUMP_TABLE_ENTRY() moved up to align comments properly (thanks Gary)
- removed MONCODE_BUG to prevent 0U in non-C context in assembler (noted by Sashiko - AI)
- prevent environment pollution by explicit initialization mflag := (noted by Sashiko - AI)

Jan Polensky (6):
  s390/bug: Provide ARCH_WARN_ASM for Rust WARN/BUG support
  s390/jump_label: Implement ARCH_STATIC_BRANCH_JUMP_ASM and
    ARCH_STATIC_BRANCH_ASM macros
  rust/bindgen_parameters: Mark s390 types as opaque to prevent repr
    conflicts
  rust: helpers: Add memchr wrapper for string operations
  s390/cmpxchg: Fix KASAN stack-out-of-bounds in atomic helpers
  s390: Enable Rust support

 Documentation/rust/arch-support.rst |  1 +
 arch/s390/Kconfig                   |  1 +
 arch/s390/Makefile                  | 28 ++++++++++++++----------
 arch/s390/include/asm/bug.h         | 12 +++++++++++
 arch/s390/include/asm/cmpxchg.h     |  8 +++----
 arch/s390/include/asm/jump_label.h  | 33 +++++++++++++++++------------
 rust/Makefile                       |  1 +
 rust/bindgen_parameters             |  7 ++++++
 rust/helpers/helpers.c              |  1 +
 rust/helpers/string.c               |  8 +++++++
 scripts/generate_rust_target.rs     |  2 ++
 scripts/min-tool-version.sh         |  6 +++++-
 12 files changed, 78 insertions(+), 30 deletions(-)
 create mode 100644 rust/helpers/string.c


base-commit: e43ffb69e0438cddd72aaa30898b4dc446f664f8
--
2.53.0

[PATCH v5 1/6] s390/bug: Provide ARCH_WARN_ASM for Rust WARN/BUG support

[Jan Polensky]

Rust WARN and BUG support relies on ARCH_WARN_ASM to emit __bug_table
entries. On s390 the macro is missing, so Rust code cannot generate
proper WARN/BUG metadata for the kernel's bug reporting infrastructure.

Define ARCH_WARN_ASM to produce the same assembly sequence and
__bug_table entry format as the existing s390 BUG handling, including
the monitor call. Define ARCH_WARN_REACHABLE as empty since s390 does
not provide reachability analysis for warning paths.

Acked-by: Gary Guo <gary@garyguo.net>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
 arch/s390/include/asm/bug.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/s390/include/asm/bug.h b/arch/s390/include/asm/bug.h
index 59017fd3d935..d8e65885e935 100644
--- a/arch/s390/include/asm/bug.h
+++ b/arch/s390/include/asm/bug.h
@@ -4,6 +4,7 @@
 
 #include <linux/compiler.h>
 #include <linux/const.h>
+#include <linux/stringify.h>
 
 #define	MONCODE_BUG	_AC(0, U)
 #define	MONCODE_BUG_ARG _AC(1, U)
@@ -121,6 +122,17 @@ do {									\
 #define HAVE_ARCH_BUG_FORMAT
 #define HAVE_ARCH_BUG_FORMAT_ARGS
 
+#define ARCH_WARN_ASM(file, line, flags, size)				\
+	".section .rodata.str,\"aMS\",@progbits,1\n"			\
+	"9:\n"								\
+	".asciz \"\"\n"		/* Empty string for compatibility */	\
+	".previous\n"							\
+	"0:\n"								\
+	__stringify(mc 0(%r0),0) "\n"					\
+	__BUG_ENTRY("9b", file, line, flags, size)
+
+#define ARCH_WARN_REACHABLE
+
 #endif /* CONFIG_BUG && CONFIG_CC_HAS_ASM_IMMEDIATE_STRINGS */
 #endif /* __ASSEMBLER__ */
 
-- 
2.53.0

[PATCH v5 2/6] s390/jump_label: Implement ARCH_STATIC_BRANCH_JUMP_ASM and ARCH_STATIC_BRANCH_ASM macros

[Jan Polensky]

Rust static branch support needs the s390 jump label instruction sequence
and __jump_table emission in a reusable form. The current implementation
embeds the sequence directly in the C asm goto blocks, which cannot be
shared with Rust.

Introduce ARCH_STATIC_BRANCH_ASM and ARCH_STATIC_BRANCH_JUMP_ASM to
describe the brcl sequences for the likely-false and likely-true cases
and to emit the same __jump_table entries as before. Switch the existing
C helpers to use the new macros to avoid duplication without changing
the generated code.

Acked-by: Gary Guo <gary@garyguo.net>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
 arch/s390/include/asm/jump_label.h | 33 +++++++++++++++++-------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
index d9cbc18f6b2e..0e28c90dc242 100644
--- a/arch/s390/include/asm/jump_label.h
+++ b/arch/s390/include/asm/jump_label.h
@@ -19,19 +19,29 @@
 #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd"
 #endif
 
+#define ARCH_JUMP_TABLE_ENTRY(key, label, local_label)	\
+	".pushsection __jump_table,\"aw\"\n"		\
+	".balign	8\n"				\
+	".long	" local_label "-.," label "-.\n"	\
+	".quad	" key "-.\n"				\
+	".popsection\n"
+
 /*
  * We use a brcl 0,<offset> instruction for jump labels so it
  * can be easily distinguished from a hotpatch generated instruction.
  */
+#define ARCH_STATIC_BRANCH_ASM(key, label)	\
+	"0:	brcl 0," label "\n"		\
+	ARCH_JUMP_TABLE_ENTRY(key, label, "0b")
+
+#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label)	\
+	"0:	brcl 15," label "\n"		\
+	ARCH_JUMP_TABLE_ENTRY(key, label, "0b")
+
 static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
 {
-	asm goto("0:	brcl 0,%l[label]\n"
-			  ".pushsection __jump_table,\"aw\"\n"
-			  ".balign	8\n"
-			  ".long	0b-.,%l[label]-.\n"
-			  ".quad	%0+%1-.\n"
-			  ".popsection\n"
-			  : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
+	asm goto(ARCH_STATIC_BRANCH_ASM("%0+%1", "%l[label]")
+		: : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
 	return false;
 label:
 	return true;
@@ -39,13 +49,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
 
 static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
 {
-	asm goto("0:	brcl 15,%l[label]\n"
-			  ".pushsection __jump_table,\"aw\"\n"
-			  ".balign	8\n"
-			  ".long	0b-.,%l[label]-.\n"
-			  ".quad	%0+%1-.\n"
-			  ".popsection\n"
-			  : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
+	asm goto(ARCH_STATIC_BRANCH_JUMP_ASM("%0+%1", "%l[label]")
+		: : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
 	return false;
 label:
 	return true;
-- 
2.53.0

[PATCH v5 3/6] rust/bindgen_parameters: Mark s390 types as opaque to prevent repr conflicts

[Jan Polensky]

Bindgen attempts to generate Rust layouts for a number of s390 structs
that are packed but contain, or transitively contain, aligned fields.
Rust rejects such layouts with E0588 ("packed type cannot transitively
contain a #[repr(align)] type").

Add the affected s390 types to the opaque type list so bindgen emits
opaque blob types instead of full representations. This matches existing
workarounds for x86 types such as alt_instr and x86_msi_data.

Link: https://lore.kernel.org/all/e5c7aa10-590d-0d20-dd3b-385bee2377e7@intel.com/
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
 rust/bindgen_parameters | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/rust/bindgen_parameters b/rust/bindgen_parameters
index 6f02d9720ad2..8402b0c93545 100644
--- a/rust/bindgen_parameters
+++ b/rust/bindgen_parameters
@@ -14,6 +14,13 @@
 --opaque-type alt_instr
 --opaque-type x86_msi_data
 --opaque-type x86_msi_addr_lo
+# s390-only: same packed/align issue as above (E0588).
+--opaque-type lowcore
+--opaque-type tod_clock
+--opaque-type tpi_info
+--opaque-type uv_cb.*
+--opaque-type uv_secret.*
+--opaque-type zpci_fib
 
 # If SMP is disabled, `arch_spinlock_t` is defined as a ZST which triggers a Rust
 # warning. We don't need to peek into it anyway.
-- 
2.53.0

[PATCH v5 4/6] rust: helpers: Add memchr wrapper for string operations

[Jan Polensky]

Add a dedicated string helper file with a memchr wrapper that uses the
kernel's instrumented memchr() function to ensure KASAN and FORTIFY_SOURCE
protections are preserved for Rust code.

Reported-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Link: https://lore.kernel.org/rust-for-linux/CANiq72mXAZc0sNM7ShX8VDVs_7zJddawP-e=wt+ERr1YUCcWUw@mail.gmail.com/
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
 rust/helpers/helpers.c | 1 +
 rust/helpers/string.c  | 8 ++++++++
 2 files changed, 9 insertions(+)
 create mode 100644 rust/helpers/string.c

diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 625921e27dfb..592b9bdb4e4a 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -88,6 +88,7 @@
 #include "signal.c"
 #include "slab.c"
 #include "spinlock.c"
+#include "string.c"
 #include "sync.c"
 #include "task.c"
 #include "time.c"
diff --git a/rust/helpers/string.c b/rust/helpers/string.c
new file mode 100644
index 000000000000..d04340dc9139
--- /dev/null
+++ b/rust/helpers/string.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/string.h>
+
+void *rust_helper_memchr(const void *s, int c, size_t n)
+{
+	return memchr(s, c, n);
+}
\ No newline at end of file
-- 
2.53.0

[PATCH v5 5/6] s390/cmpxchg: Fix KASAN stack-out-of-bounds in atomic helpers

[Jan Polensky]

The __arch_cmpxchg1, __arch_cmpxchg2, __arch_xchg1, and __arch_xchg2
functions emulate 1-byte and 2-byte atomic operations using 4-byte
cmpxchg instructions, since s390 lacks native 1/2-byte cmpxchg support.

When KASAN is enabled, the READ_ONCE() operations in these functions
trigger stack-out-of-bounds warnings because they perform 4-byte reads
when only 1 or 2 bytes should be accessed.

Mark these functions as __no_sanitize_or_inline to prevent KASAN
instrumentation while maintaining correct functionality.

This resolves the following KASAN error during rust_atomics KUnit tests:

  BUG: KASAN: stack-out-of-bounds in rust_helper_atomic_i8_xchg+0xb2/0xc0
  Read of size 4 at addr 001bff7ffdbefcf0 by task kunit_try_catch/142

Reported-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Link: https://lore.kernel.org/rust-for-linux/CANiq72m4GVWFYqnxNtCHTPu7XcGewHB5LNwOoayTfnXs9pPbNg@mail.gmail.com/
Suggested-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/rust-for-linux/DITFTAVVHTNQ.380OHUHGTOI6M@garyguo.net/
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
 arch/s390/include/asm/cmpxchg.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/cmpxchg.h b/arch/s390/include/asm/cmpxchg.h
index 008357996262..e6ac55cf3c17 100644
--- a/arch/s390/include/asm/cmpxchg.h
+++ b/arch/s390/include/asm/cmpxchg.h
@@ -35,7 +35,7 @@ static __always_inline u64 __csg_asm(u64 ptr, u64 old, u64 new)
 	return old;
 }
 
-static inline u8 __arch_cmpxchg1(u64 ptr, u8 old, u8 new)
+static __no_sanitize_or_inline u8 __arch_cmpxchg1(u64 ptr, u8 old, u8 new)
 {
 	union {
 		u8 b[4];
@@ -58,7 +58,7 @@ static inline u8 __arch_cmpxchg1(u64 ptr, u8 old, u8 new)
 	return old;
 }
 
-static inline u16 __arch_cmpxchg2(u64 ptr, u16 old, u16 new)
+static __no_sanitize_or_inline u16 __arch_cmpxchg2(u64 ptr, u16 old, u16 new)
 {
 	union {
 		u16 b[2];
@@ -173,7 +173,7 @@ static __always_inline u64 __arch_cmpxchg(u64 ptr, u64 old, u64 new, int size)
 
 void __xchg_called_with_bad_pointer(void);
 
-static inline u8 __arch_xchg1(u64 ptr, u8 x)
+static __no_sanitize_or_inline u8 __arch_xchg1(u64 ptr, u8 x)
 {
 	int shift = (3 ^ (ptr & 3)) << 3;
 	u32 mask, old, new;
@@ -188,7 +188,7 @@ static inline u8 __arch_xchg1(u64 ptr, u8 x)
 	return old >> shift;
 }
 
-static inline u16 __arch_xchg2(u64 ptr, u16 x)
+static __no_sanitize_or_inline u16 __arch_xchg2(u64 ptr, u16 x)
 {
 	int shift = (2 ^ (ptr & 2)) << 3;
 	u32 mask, old, new;
-- 
2.53.0

[PATCH v5 6/6] s390: Enable Rust support

[Jan Polensky]

Enable building Rust code on s390 by wiring the architecture into the
kernel Rust infrastructure.

Add s390 to the Rust arch support documentation, provide the s390 Rust
target and required compiler flags, and set the bindgen target for
arch/s390. Adjust the Rust target generation and minimum rustc version
gating so the s390 setup is handled explicitly.

The Rust toolchain uses the "s390x" triple naming for the 64 bit target.

Rust support is currently incompatible with CONFIG_EXPOLINE, which
relies on compiler support for the -mindirect-branch= and
-mfunction_return= options. Therefore, select HAVE_RUST only when
EXPOLINE is disabled.

Acked-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Jan Polensky <japo@linux.ibm.com>
---
 Documentation/rust/arch-support.rst |  1 +
 arch/s390/Kconfig                   |  1 +
 arch/s390/Makefile                  | 28 +++++++++++++++++-----------
 rust/Makefile                       |  1 +
 scripts/generate_rust_target.rs     |  2 ++
 scripts/min-tool-version.sh         |  6 +++++-
 6 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/Documentation/rust/arch-support.rst b/Documentation/rust/arch-support.rst
index 6e6a515d0899..4f980815e92a 100644
--- a/Documentation/rust/arch-support.rst
+++ b/Documentation/rust/arch-support.rst
@@ -19,6 +19,7 @@ Architecture   Level of support  Constraints
 ``arm64``      Maintained        Little Endian only.
 ``loongarch``  Maintained        \-
 ``riscv``      Maintained        ``riscv64`` and LLVM/Clang only.
+``s390``       Maintained        ``CONFIG_EXPOLINE`` must be disabled.
 ``um``         Maintained        \-
 ``x86``        Maintained        ``x86_64`` only.
 =============  ================  ==============================================
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index ecbcbb781e40..26951781d74d 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -248,6 +248,7 @@ config S390
 	select HAVE_RELIABLE_STACKTRACE
 	select HAVE_RETHOOK
 	select HAVE_RSEQ
+	select HAVE_RUST if !EXPOLINE
 	select HAVE_SAMPLE_FTRACE_DIRECT
 	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
 	select HAVE_SETUP_PER_CPU_AREA
diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 297976b41088..8b712cd85fcd 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -35,25 +35,31 @@ KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO),-g)
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_DEBUG_INFO_DWARF4), $(call cc-option, -gdwarf-4,))
 KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_NO_ARRAY_BOUNDS),-Wno-array-bounds)
 
+KBUILD_RUSTFLAGS += --target=s390x-unknown-none-softfloat -Zpacked-stack -Ctarget-feature=+backchain
+
 UTS_MACHINE	:= s390x
 STACK_SIZE	:= $(if $(CONFIG_KASAN),65536,$(if $(CONFIG_KMSAN),65536,16384))
 CHECKFLAGS	+= -D__s390__ -D__s390x__
 
 export LD_BFD
 
-mflags-$(CONFIG_MARCH_Z10)    := -march=z10
-mflags-$(CONFIG_MARCH_Z196)   := -march=z196
-mflags-$(CONFIG_MARCH_ZEC12)  := -march=zEC12
-mflags-$(CONFIG_MARCH_Z13)    := -march=z13
-mflags-$(CONFIG_MARCH_Z14)    := -march=z14
-mflags-$(CONFIG_MARCH_Z15)    := -march=z15
-mflags-$(CONFIG_MARCH_Z16)    := -march=z16
-mflags-$(CONFIG_MARCH_Z17)    := -march=z17
+march-name-$(CONFIG_MARCH_Z10)   := z10
+march-name-$(CONFIG_MARCH_Z196)  := z196
+march-name-$(CONFIG_MARCH_ZEC12) := zEC12
+march-name-$(CONFIG_MARCH_Z13)   := z13
+march-name-$(CONFIG_MARCH_Z14)   := z14
+march-name-$(CONFIG_MARCH_Z15)   := z15
+march-name-$(CONFIG_MARCH_Z16)   := z16
+march-name-$(CONFIG_MARCH_Z17)   := z17
 
-export CC_FLAGS_MARCH := $(mflags-y)
+mflags := -march=$(march-name-y)
 
-aflags-y += $(mflags-y)
-cflags-y += $(mflags-y)
+export CC_FLAGS_MARCH := $(mflags)
+
+aflags-y += $(mflags)
+cflags-y += $(mflags)
+
+KBUILD_RUSTFLAGS += -Ctarget-cpu=$(march-name-y)
 
 cflags-$(CONFIG_MARCH_Z10_TUNE)		+= -mtune=z10
 cflags-$(CONFIG_MARCH_Z196_TUNE)	+= -mtune=z196
diff --git a/rust/Makefile b/rust/Makefile
index b9e9f512cec3..77460502f576 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -403,6 +403,7 @@ 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_s390	:= s390x-linux-gnu
 # This is only for i386 UM builds, which need the 32-bit target not -m32
 BINDGEN_TARGET_i386	:= i386-linux-gnu
 BINDGEN_TARGET_um	:= $(BINDGEN_TARGET_$(SUBARCH))
diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 38b3416bb979..8f1df6819d0b 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -256,6 +256,8 @@ fn main() {
         }
     } else if cfg.has("LOONGARCH") {
         panic!("loongarch uses the builtin rustc loongarch64-unknown-none-softfloat target");
+    } else if cfg.has("S390") {
+        panic!("s390 uses the builtin rustc s390x-unknown-none-softfloat target");
     } else {
         panic!("Unsupported architecture");
     }
diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh
index b96ec2d379b6..296acf8f71aa 100755
--- a/scripts/min-tool-version.sh
+++ b/scripts/min-tool-version.sh
@@ -31,7 +31,11 @@ llvm)
 	fi
 	;;
 rustc)
-	echo 1.85.0
+	if [ "$SRCARCH" = "s390" ]; then
+		echo 1.96.0
+	else
+		echo 1.85.0
+	fi
 	;;
 bindgen)
 	echo 0.71.1
-- 
2.53.0

Re: [PATCH v5 0/6] s390: Enable Rust support and add required arch glue

[Heiko Carstens]

On Mon, Jun 01, 2026 at 07:46:19PM +0200, Jan Polensky wrote:
> Rust support on s390 requires a small set of architecture-specific pieces
> before the generic Rust kernel infrastructure can be used.
> 
> The series wires up s390 as a Rust-capable 64-bit architecture, adds the
> missing assembly interfaces needed by Rust for WARN/BUG reporting and for
> static branches, adjusts bindgen parameters to avoid repr layout conflicts
> caused by packed and aligned s390 structures, and fixes issues discovered
> during testing.

...

> Jan Polensky (6):
>   s390/bug: Provide ARCH_WARN_ASM for Rust WARN/BUG support
>   s390/jump_label: Implement ARCH_STATIC_BRANCH_JUMP_ASM and
>     ARCH_STATIC_BRANCH_ASM macros
>   rust/bindgen_parameters: Mark s390 types as opaque to prevent repr
>     conflicts
>   rust: helpers: Add memchr wrapper for string operations
>   s390/cmpxchg: Fix KASAN stack-out-of-bounds in atomic helpers
>   s390: Enable Rust support
> 
>  Documentation/rust/arch-support.rst |  1 +
>  arch/s390/Kconfig                   |  1 +
>  arch/s390/Makefile                  | 28 ++++++++++++++----------
>  arch/s390/include/asm/bug.h         | 12 +++++++++++
>  arch/s390/include/asm/cmpxchg.h     |  8 +++----
>  arch/s390/include/asm/jump_label.h  | 33 +++++++++++++++++------------
>  rust/Makefile                       |  1 +
>  rust/bindgen_parameters             |  7 ++++++
>  rust/helpers/helpers.c              |  1 +
>  rust/helpers/string.c               |  8 +++++++
>  scripts/generate_rust_target.rs     |  2 ++
>  scripts/min-tool-version.sh         |  6 +++++-
>  12 files changed, 78 insertions(+), 30 deletions(-)
>  create mode 100644 rust/helpers/string.c

Thanks a lot! For the whole series:
Acked-by: Heiko Carstens <hca@linux.ibm.com>

I guess Alexander will pick this up and route this via s390.

Re: [PATCH v5 0/6] s390: Enable Rust support and add required arch glue

[Alexander Gordeev]

On Mon, Jun 08, 2026 at 04:21:22PM +0200, Heiko Carstens wrote:
> I guess Alexander will pick this up and route this via s390.

Yes, I applied and scheduled it for -rc7.

Two new files fall under the Rust maintainers scope:

 rust/helpers/helpers.c | 1 +
 rust/helpers/string.c  | 8 ++++++++

Please, let me know if someone is against it.
Otherwise, an ack would be ideal ;)

Thanks!

Re: [PATCH v5 0/6] s390: Enable Rust support and add required arch glue

[Gary Guo]

On Mon Jun 8, 2026 at 3:36 PM BST, Alexander Gordeev wrote:
> On Mon, Jun 08, 2026 at 04:21:22PM +0200, Heiko Carstens wrote:
>> I guess Alexander will pick this up and route this via s390.
>
> Yes, I applied and scheduled it for -rc7.
>
> Two new files fall under the Rust maintainers scope:
>
>  rust/helpers/helpers.c | 1 +
>  rust/helpers/string.c  | 8 ++++++++
>
> Please, let me know if someone is against it.
> Otherwise, an ack would be ideal ;)

Thes string.c is missing __rust_helper and it is also missing a trailing
newline.

Sashiko's report is accurate here:
https://sashiko.dev/#/patchset/20260601174625.2910233-1-japo%40linux.ibm.com?part=4

Best,
Gary

>
> Thanks!

Re: [PATCH v5 0/6] s390: Enable Rust support and add required arch glue

[Jan Polensky]

On Mon, Jun 08, 2026 at 04:48:45PM +0100, Gary Guo wrote:
> On Mon Jun 8, 2026 at 3:36 PM BST, Alexander Gordeev wrote:
> > On Mon, Jun 08, 2026 at 04:21:22PM +0200, Heiko Carstens wrote:
> >> I guess Alexander will pick this up and route this via s390.
> >
> > Yes, I applied and scheduled it for -rc7.
> >
> > Two new files fall under the Rust maintainers scope:
> >
> >  rust/helpers/helpers.c | 1 +
> >  rust/helpers/string.c  | 8 ++++++++
> >
> > Please, let me know if someone is against it.
> > Otherwise, an ack would be ideal ;)
>
> Thes string.c is missing __rust_helper and it is also missing a trailing
> newline.
>
> Sashiko's report is accurate here:
> https://sashiko.dev/#/patchset/20260601174625.2910233-1-japo%40linux.ibm.com?part=4
>
> Best,
> Gary
>
> >
> > Thanks!
>
>
Hi Gary,

thanks for pointing this out.

I've added the missing __rust_helper. Regarding the trailing newline,
the file already ends with one locally:

  $ tail -c2 rust/helpers/string.c | hexdump -C
  00000000  7d 0a                                             |}.|

The other helpers are also mixed in this regard, so I kept it consistent.
If you prefer, I can send a v7 adjusting this as well.

Best regards,
Jan