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Re: [Qemu-devel] [PATCH v2 00/28] linux-user: fix race between signals a
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v2 00/28] linux-user: fix race between signals and syscalls |
Date: |
Mon, 23 May 2016 19:55:57 +0100 |
Ping?
I have a second series based on top of this which is shaping up
nicely and it would be good to get this lot into master before
posting the second set...
thanks
-- PMM
On 12 May 2016 at 18:47, Peter Maydell <address@hidden> wrote:
> This patch series is an updated version of the original series
> sent by Timothy Baldwin in autumn of last year
> (https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg01388.html).
> I have attempted to address various code review comments made on that
> original patchset.
>
> Changes v1->v2:
> * more description in comments and commit messages of what is going on
> * implement restarting for all guest architectures (tilegx wasn't
> in the tree when v1 was sent out)
> * reordered the patches in the series a bit; in particular we add
> support for restarting syscalls to all targets and so we don't
> need the TARGET_USE_ERESTARTSYS define
> * fixed a bug in the Alpha restart code where we were incorrectly
> treating env->ir[IR_PV] as the PC, not env->pc
> * restrict scope of patchset to just providing and using the
> safe_syscall mechanism. (I plan to upstream the other race fixes
> in the second half of Timothy's patchset separately once this lot
> are in.)
> * avoid per-architecture if-ladders in configure and C code by
> creating a linux-user/host/$(HOSTARCH) type directory structure
> so the makefiles can pull in the right files for the host
> automatically
> * added patches to use safe_syscall for futex, select and pselect
> (in particular fixing futex() allows binaries that use the Boehm
> garbage collector, like the Mono runtime, to work)
> * include a patch which sets r14 on exit from microblaze syscalls,
> which I think clarifies how that architecture does things
> (though it is not ABI-wise strictly required)
> * fixed bug in wrapping of waitid syscall -- it has five args, not four
> * switched safe_syscall() to use a "return -1 and set errno"
> convention for failure; this matches syscall(), and seemed to
> me to be more intuitive for switching code around and for when
> there's a mix of code paths using safe_syscall() and directly
> calling libc functions (though it does mean that we push error
> numbers into errno and then fish them out again later)
> * added the magic GNU-stack rune that avoids incorrectly tainting
> our whole binary as "needs an executable stack" when an asm
> file is linked into it
>
> Notes:
> * safe_syscall is supported for all guest architectures, but
> only the x86_64 host architecture; adding the asm fragment
> for our other hosts should be straightforward
> * there are a fair number of other system calls that should be
> using safe_syscall too
> In both cases I thought it was better to avoid making this patchset
> any larger or later; we can easily do these in later patches if
> the general concept and mechanism has made it into master.
>
>
> I've tested mostly by running the LTP test suite for 32-bit ARM
> guests; this patchset neither improves nor worsens our pass rate.
>
> I think the fixing of select/pselect ought to deal with hangs when
> running cmake (https://bugs.launchpad.net/qemu/+bug/955379), but
> I have no reliable reproducer for that bug so can't say for sure.
> The "Mono hangs due to it using Boehm GC" bug is
> https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/530000
> and that is definitely fixed by this patchset.
>
>
> thanks
> -- PMM
>
> Peter Maydell (5):
> linux-user: Consistently return host errnos from do_openat()
> linux-user: Support for restarting system calls for tilegx targets
> linux-user: Set r14 on exit from microblaze syscall
> linux-user: Use safe_syscall for pselect, select syscalls
> linux-user: Use safe_syscall for futex syscall
>
> Timothy E Baldwin (23):
> linux-user: Check array bounds in errno conversion
> linux-user: Reindent signal handling
> linux-user: Define TARGET_ERESTART* errno values
> linux-user: Renumber TARGET_QEMU_ESIGRETURN, make it not arch-specific
> linux-user: Support for restarting system calls for x86 targets
> linux-user: Support for restarting system calls for ARM targets
> linux-user: Support for restarting system calls for MIPS targets
> linux-user: Support for restarting system calls for PPC targets
> linux-user: Support for restarting system calls for SPARC targets
> linux-user: Support for restarting system calls for SH4 targets
> linux-user: Support for restarting system calls for Alpha targets
> linux-user: Support for restarting system calls for UniCore32 targets
> linux-user: Support for restarting system calls for OpenRISC targets
> linux-user: Support for restarting system calls for M68K targets
> linux-user: Support for restarting system calls for S390 targets
> linux-user: Support for restarting system calls for CRIS targets
> linux-user: Support for restarting system calls for Microblaze targets
> linux-user: Add debug code to exercise restarting system calls
> linux-user: Provide safe_syscall for fixing races between signals and
> syscalls
> linux-user: Use safe_syscall for read and write system calls
> linux-user: Use safe_syscall for open and openat system calls
> linux-user: Use safe_syscall for wait system calls
> linux-user: Use safe_syscall for execve syscall
>
> Makefile.target | 4 +-
> linux-user/Makefile.objs | 3 +-
> linux-user/alpha/target_signal.h | 1 +
> linux-user/arm/target_signal.h | 1 +
> linux-user/cris/target_signal.h | 1 +
> linux-user/errno_defs.h | 17 +
> linux-user/host/x86_64/hostdep.h | 38 +
> linux-user/host/x86_64/safe-syscall.inc.S | 81 ++
> linux-user/m68k/target_signal.h | 1 +
> linux-user/main.c | 225 ++--
> linux-user/microblaze/target_signal.h | 1 +
> linux-user/mips/target_signal.h | 1 +
> linux-user/mips/target_syscall.h | 4 -
> linux-user/mips64/target_signal.h | 1 +
> linux-user/mips64/target_syscall.h | 4 -
> linux-user/openrisc/target_signal.h | 1 +
> linux-user/ppc/target_signal.h | 1 +
> linux-user/ppc/target_syscall.h | 2 -
> linux-user/qemu.h | 127 ++-
> linux-user/s390x/target_signal.h | 1 +
> linux-user/safe-syscall.S | 30 +
> linux-user/sh4/target_signal.h | 1 +
> linux-user/signal.c | 1610
> +++++++++++++++--------------
> linux-user/sparc/target_signal.h | 1 +
> linux-user/sparc64/target_signal.h | 1 +
> linux-user/syscall.c | 188 +++-
> linux-user/tilegx/target_signal.h | 1 +
> 27 files changed, 1428 insertions(+), 919 deletions(-)
> create mode 100644 linux-user/host/x86_64/hostdep.h
> create mode 100644 linux-user/host/x86_64/safe-syscall.inc.S
> create mode 100644 linux-user/safe-syscall.S
>
> --
> 1.9.1
- [Qemu-devel] [PATCH v2 08/28] linux-user: Support for restarting system calls for MIPS targets, (continued)
- [Qemu-devel] [PATCH v2 10/28] linux-user: Support for restarting system calls for SPARC targets, Peter Maydell, 2016/05/12
- [Qemu-devel] [PATCH v2 26/28] linux-user: Use safe_syscall for execve syscall, Peter Maydell, 2016/05/12
- [Qemu-devel] [PATCH v2 28/28] linux-user: Use safe_syscall for futex syscall, Peter Maydell, 2016/05/12
- [Qemu-devel] [PATCH v2 21/28] linux-user: Add debug code to exercise restarting system calls, Peter Maydell, 2016/05/12
- Re: [Qemu-devel] [PATCH v2 00/28] linux-user: fix race between signals and syscalls,
Peter Maydell <=
- Re: [Qemu-devel] [PATCH v2 00/28] linux-user: fix race between signals and syscalls, Riku Voipio, 2016/05/24