[PATCH v2 2/2] arm64: uapi: Use __u128 instead of __uint128_t in UAPI headers

From: Will Deacon

Date: Fri Jun 26 2026 - 10:18:07 EST


The arm64 UAPI exposes '__uint128_t' types in the members of
'struct user_fpsimd_state', 'struct user_pac_address_keys' and in the
signal frame via 'struct fpsimd_context'. Since the alignment of such
a type appears to be non-portable (16 bytes on arm64, 8 bytes on s390),
prefer the '__u128' typedef from uapi/linux/types.h, which makes the
alignment explicit and allows the definitions to be reused by other
host architectures.

Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Nick Desaulniers <nick.desaulniers+lkml@xxxxxxxxx>
Cc: Steffen Eiden <seiden@xxxxxxxxxxxxx>
Cc: Andreas Grapentin <gra@xxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dave Martin <dave.martin@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
arch/arm64/include/uapi/asm/ptrace.h | 12 ++++++------
arch/arm64/include/uapi/asm/sigcontext.h | 6 +++---
2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 6fed93fb2536..15649a253a57 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -93,7 +93,7 @@ struct user_pt_regs {
};

struct user_fpsimd_state {
- __uint128_t vregs[32];
+ __u128 vregs[32];
__u32 fpsr;
__u32 fpcr;
__u32 __reserved[2];
@@ -258,14 +258,14 @@ struct user_pac_mask {
/* pointer authentication keys (NT_ARM_PACA_KEYS, NT_ARM_PACG_KEYS) */

struct user_pac_address_keys {
- __uint128_t apiakey;
- __uint128_t apibkey;
- __uint128_t apdakey;
- __uint128_t apdbkey;
+ __u128 apiakey;
+ __u128 apibkey;
+ __u128 apdakey;
+ __u128 apdbkey;
};

struct user_pac_generic_keys {
- __uint128_t apgakey;
+ __u128 apgakey;
};

/* ZA state (NT_ARM_ZA) */
diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h
index e29bf3e2d0cc..d250ca7a1d46 100644
--- a/arch/arm64/include/uapi/asm/sigcontext.h
+++ b/arch/arm64/include/uapi/asm/sigcontext.h
@@ -78,7 +78,7 @@ struct fpsimd_context {
struct _aarch64_ctx head;
__u32 fpsr;
__u32 fpcr;
- __uint128_t vregs[32];
+ __u128 vregs[32];
};

/*
@@ -266,8 +266,8 @@ struct gcs_context {
* - ---- -----------
* REGS the entire SVE context
*
- * ZREGS __uint128_t[SVE_NUM_ZREGS][vq] all Z-registers
- * ZREG __uint128_t[vq] individual Z-register Zn
+ * ZREGS __u128[SVE_NUM_ZREGS][vq] all Z-registers
+ * ZREG __u128[vq] individual Z-register Zn
*
* PREGS uint16_t[SVE_NUM_PREGS][vq] all P-registers
* PREG uint16_t[vq] individual P-register Pn
--
2.55.0.rc0.799.gd6f94ed593-goog