The rseq rseq_cs.ptr.{ptr32,padding} uapi endianness handling is entirely wrong on 32-bit little endian: a preprocessor logic mistake wrongly uses the big endian field layout on 32-bit little endian architectures. Fortunately, those ptr32 accessors were never used within the kernel, and only meant as a convenience for user-space. Remove those and replace the whole rseq_cs union by a __u64 type, as this is the only thing really needed to express the ABI. Document how 32-bit architectures are meant to interact with this field.
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| @@ -105,23 +105,11 @@ struct rseq { · 104 unmodified lines | |||
| 105 | * Read and set by the kernel. Set by user-space with single-copy | 105 | * Read and set by the kernel. Set by user-space with single-copy |
| 106 | * atomicity semantics. This field should only be updated by the | 106 | * atomicity semantics. This field should only be updated by the |
| 107 | * thread which registered this data structure. Aligned on 64-bit. | 107 | * thread which registered this data structure. Aligned on 64-bit. |
| 108 | * | ||
| 109 | * 32-bit architectures should update the low order bits of the | ||
| 110 | * rseq_cs field, leaving the high order bits initialized to 0. | ||
| 108 | */ | 111 | */ |
| 109 | union { | 112 | __u64 rseq_cs; |
| 110 | __u64 ptr64; | ||
| 111 | #ifdef __LP64__ | ||
| 112 | __u64 ptr; | ||
| 113 | #else | ||
| 114 | struct { | ||
| 115 | #if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || defined(__BIG_ENDIAN) | ||
| 116 | __u32 padding; /* Initialized to zero. */ | ||
| 117 | __u32 ptr32; | ||
| 118 | #else /* LITTLE */ | ||
| 119 | __u32 ptr32; | ||
| 120 | __u32 padding; /* Initialized to zero. */ | ||
| 121 | #endif /* ENDIAN */ | ||
| 122 | } ptr; | ||
| 123 | #endif | ||
| 124 | } rseq_cs; | ||
| 125 | 113 | ||
| 126 | /* | 114 | /* |
| 127 | * Restartable sequences flags field. | 115 | * Restartable sequences flags field. |