diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2013-02-08 04:34:54 +0000 |
|---|---|---|
| committer | Riku Voipio <riku.voipio@linaro.org> | 2013-03-11 14:35:08 +0200 |
| commit | e9a970a8316f9f86a6c800a9a90175bd593f862c (patch) | |
| tree | f90441831fb0422a1d17ad50e79d2a55363035ab | |
| parent | a94b4987e243d9afebf56a098afeddae133276b5 (diff) | |
linux-user/syscall.c: Don't warn about unimplemented get_robust_list
The nature of the kernel ABI for the get_robust_list and set_robust_list
syscalls means we cannot implement them in QEMU. Make get_robust_list
silently return ENOSYS rather than using the default "print message and
then fail ENOSYS" code path, in the same way we already do for
set_robust_list, and add a comment documenting why we do this.
This silences warnings which were being produced for emulating
even trivial programs like 'ls' in x86-64-on-x86-64.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
| -rw-r--r-- | linux-user/syscall.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 6182a272ec..ee82a2da4e 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -8631,7 +8631,20 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, #ifdef TARGET_NR_set_robust_list case TARGET_NR_set_robust_list: - goto unimplemented_nowarn; + case TARGET_NR_get_robust_list: + /* The ABI for supporting robust futexes has userspace pass + * the kernel a pointer to a linked list which is updated by + * userspace after the syscall; the list is walked by the kernel + * when the thread exits. Since the linked list in QEMU guest + * memory isn't a valid linked list for the host and we have + * no way to reliably intercept the thread-death event, we can't + * support these. Silently return ENOSYS so that guest userspace + * falls back to a non-robust futex implementation (which should + * be OK except in the corner case of the guest crashing while + * holding a mutex that is shared with another process via + * shared memory). + */ + goto unimplemented_nowarn; #endif #if defined(TARGET_NR_utimensat) && defined(__NR_utimensat) |