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[Qemu-devel] [PATCH 36/37] linux-user/syscall.c: Don't warn about unimpl
From: |
Michael Roth |
Subject: |
[Qemu-devel] [PATCH 36/37] linux-user/syscall.c: Don't warn about unimplemented get_robust_list |
Date: |
Tue, 2 Apr 2013 16:45:41 -0500 |
From: Peter Maydell <address@hidden>
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 <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
Signed-off-by: Riku Voipio <address@hidden>
(cherry picked from commit e9a970a8316f9f86a6c800a9a90175bd593f862c)
Signed-off-by: Michael Roth <address@hidden>
---
linux-user/syscall.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index b682357..4e43a58 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8551,7 +8551,20 @@ 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)
--
1.7.9.5
- [Qemu-devel] [PATCH 22/37] virtio-ccw: Queue sanity check for notify hypercall., (continued)
- [Qemu-devel] [PATCH 22/37] virtio-ccw: Queue sanity check for notify hypercall., Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 20/37] qga/main.c: Don't use g_key_file_get/set_int64, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 23/37] qemu-bridge-helper: force usage of a very high MAC address for the bridge, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 24/37] configure: Require at least spice-protocol-0.12.3, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 25/37] pseries: Add cleanup hook for PAPR virtual LAN device, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 26/37] target-ppc: Fix CPU_POWERPC_MPC8547E, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 27/37] ide/macio: Fix macio DMA initialisation., Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 28/37] virtio-blk: fix unplug + virsh reboot, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 35/37] linux-user: make bogus negative iovec lengths fail EINVAL, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 34/37] linux-user: fix futex strace of FUTEX_CLOCK_REALTIME, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 36/37] linux-user/syscall.c: Don't warn about unimplemented get_robust_list,
Michael Roth <=
- [Qemu-devel] [PATCH 37/37] update seabios to 1.7.2.1, Michael Roth, 2013/04/02
- Re: [Qemu-devel] Patch Round-up for stable 1.4.1, freeze next Tuesday, Eric Blake, 2013/04/02
- [Qemu-devel] [PATCH 31/37] qcow2: flush refcount cache correctly in alloc_refcount_block(), Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 30/37] page_cache: fix memory leak, Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 32/37] qcow2: flush refcount cache correctly in qcow2_write_snapshots(), Michael Roth, 2013/04/02
- [Qemu-devel] [PATCH 29/37] Fix page_cache leak in cache_resize, Michael Roth, 2013/04/02