| Message ID | 20240206162801.882585-5-mjeanson@efficios.com |
|---|---|
| State | New |
| Headers | show |
| Series | Extend rseq support | expand |
Michael Jeanson <mjeanson@efficios.com> writes: > Access to features following the original rseq ABI 20 bytes (after > 'flags') starting with 'node_id' must be gated by an rseq feature size > test. Are there any kernels that still provide auxvals that result in a 8 byte rseq area? I.e. perhaps an older kernel that doesn't support the feature area at all? > diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h > index b6c9deea6b..a63e4afbdb 100644 > --- a/sysdeps/unix/sysv/linux/rseq-internal.h > +++ b/sysdeps/unix/sysv/linux/rseq-internal.h > @@ -28,13 +28,17 @@ > #include <ldsodefs.h> > > /* rseq area registered with the kernel. Use a custom definition > - here to isolate from kernel struct rseq changes. The > - implementation of sched_getcpu needs acccess to the cpu_id field; > - the other fields are unused and not included here. */ > + here to isolate from kernel struct rseq changes. Access to fields > + beyond the 20 bytes of the original ABI (after 'flags') must be gated > + by a check of the feature size. */ If the answer to the first question is "yes" then this should be changed to say "8 bytes" etc. > struct rseq_area > { > uint32_t cpu_id_start; > uint32_t cpu_id; > + uint64_t rseq_cs; > + uint32_t flags; > + uint32_t node_id; > + uint32_t mm_cid; > }; Ok.
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h index b6c9deea6b..a63e4afbdb 100644 --- a/sysdeps/unix/sysv/linux/rseq-internal.h +++ b/sysdeps/unix/sysv/linux/rseq-internal.h @@ -28,13 +28,17 @@ #include <ldsodefs.h> /* rseq area registered with the kernel. Use a custom definition - here to isolate from kernel struct rseq changes. The - implementation of sched_getcpu needs acccess to the cpu_id field; - the other fields are unused and not included here. */ + here to isolate from kernel struct rseq changes. Access to fields + beyond the 20 bytes of the original ABI (after 'flags') must be gated + by a check of the feature size. */ struct rseq_area { uint32_t cpu_id_start; uint32_t cpu_id; + uint64_t rseq_cs; + uint32_t flags; + uint32_t node_id; + uint32_t mm_cid; }; static inline struct rseq_area *
The 'struct rseq_area' is used to define the offset of the various features available in the rseq ABI. Add fields that follow cpu_id (rseq_cs, flags, node_id, mm_cid) in preparation for their use. Access to features following the original rseq ABI 20 bytes (after 'flags') starting with 'node_id' must be gated by an rseq feature size test. Signed-off-by: Michael Jeanson <mjeanson@efficios.com> --- sysdeps/unix/sysv/linux/rseq-internal.h | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)