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| author |   Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2019-12-20 15:33:18 -0500 |
|---|---|---|
| committer |   Shuah Khan <skhan@linuxfoundation.org> | 2019-12-23 10:52:41 -0700 |
| commit | 2a1f40adfb54ca65dc4c93bad444dd23b800a76e (patch) | |
| tree | 284abbc081e5c549f99e3a1cec4eec74549ef8d5 /tools/testing | |
| parent | rseq/selftests: Fix: Namespace gettid() for compatibility with glibc 2.30 (diff) | |
| download | linux-dev-2a1f40adfb54ca65dc4c93bad444dd23b800a76e.tar.xz linux-dev-2a1f40adfb54ca65dc4c93bad444dd23b800a76e.zip | |
rseq/selftests: Clarify rseq_prepare_unload() helper requirements
The rseq.h UAPI now documents that the rseq_cs field must be cleared
before reclaiming memory that contains the targeted struct rseq_cs, but
also that the rseq_cs field must be cleared before reclaiming memory of
the code pointed to by the rseq_cs start_ip and post_commit_offset
fields.
While we can expect that use of dlclose(3) will typically unmap
both struct rseq_cs and its associated code at once, nothing would
theoretically prevent a JIT from reclaiming the code without
reclaiming the struct rseq_cs, which would erroneously allow the
kernel to consider new code which is not a rseq critical section
as a rseq critical section following a code reclaim.
Suggested-by: Florian Weimer <fw@deneb.enyo.de>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Florian Weimer <fw@deneb.enyo.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Paul Turner <pjt@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Diffstat (limited to 'tools/testing')
| -rw-r--r-- | tools/testing/selftests/rseq/rseq.h | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h index d40d60e7499e..3f63eb362b92 100644 --- a/tools/testing/selftests/rseq/rseq.h +++ b/tools/testing/selftests/rseq/rseq.h @@ -149,11 +149,13 @@ static inline void rseq_clear_rseq_cs(void) /* * rseq_prepare_unload() should be invoked by each thread executing a rseq * critical section at least once between their last critical section and - * library unload of the library defining the rseq critical section - * (struct rseq_cs). This also applies to use of rseq in code generated by - * JIT: rseq_prepare_unload() should be invoked at least once by each - * thread executing a rseq critical section before reclaim of the memory - * holding the struct rseq_cs. + * library unload of the library defining the rseq critical section (struct + * rseq_cs) or the code referred to by the struct rseq_cs start_ip and + * post_commit_offset fields. This also applies to use of rseq in code + * generated by JIT: rseq_prepare_unload() should be invoked at least once by + * each thread executing a rseq critical section before reclaim of the memory + * holding the struct rseq_cs or reclaim of the code pointed to by struct + * rseq_cs start_ip and post_commit_offset fields. */ static inline void rseq_prepare_unload(void) { |