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| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2022-01-27 18:27:20 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-02-02 15:11:34 +0300 |
| commit | bfdf4e6208051ed7165b2e92035b4bf11f43eb63 (patch) | |
| tree | 69822a3cb551575eb6702833efccc29d961bd25b /include/uapi/linux/rseq.h | |
| parent | 5c105d55a9dc9e01535116ccfc26e703168a574f (diff) | |
| download | linux-bfdf4e6208051ed7165b2e92035b4bf11f43eb63.tar.xz | |
rseq: Remove broken uapi field layout on 32-bit little endian
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.
Fixes: ec9c82e03a74 ("rseq: uapi: Declare rseq_cs field as union, update includes")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220127152720.25898-1-mathieu.desnoyers@efficios.com
Diffstat (limited to 'include/uapi/linux/rseq.h')
| -rw-r--r-- | include/uapi/linux/rseq.h | 20 |
1 files changed, 4 insertions, 16 deletions
diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h index 9a402fdb60e9..77ee207623a9 100644 --- a/include/uapi/linux/rseq.h +++ b/include/uapi/linux/rseq.h @@ -105,23 +105,11 @@ struct rseq { * Read and set by the kernel. Set by user-space with single-copy * atomicity semantics. This field should only be updated by the * thread which registered this data structure. Aligned on 64-bit. + * + * 32-bit architectures should update the low order bits of the + * rseq_cs field, leaving the high order bits initialized to 0. */ - union { - __u64 ptr64; -#ifdef __LP64__ - __u64 ptr; -#else - struct { -#if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || defined(__BIG_ENDIAN) - __u32 padding; /* Initialized to zero. */ - __u32 ptr32; -#else /* LITTLE */ - __u32 ptr32; - __u32 padding; /* Initialized to zero. */ -#endif /* ENDIAN */ - } ptr; -#endif - } rseq_cs; + __u64 rseq_cs; /* * Restartable sequences flags field. |