Otherwise it will trip on the forms used in recent architecture.

Ideally, we should have different handlers for different architecture
levels but our current implementation of TLB flushing is dumb enough
that this will do for now.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

Not that anything remotely recent supports tlbia but ...
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

On ppc64 especially, we flush the tlb on any slbie or tlbie instruction.

However, those instructions often come in bursts of 3 or more (context
switch will favor a series of slbie's for example to an slbia if the
SLB has less than a certain number of entries in it, and tlbie's can
happen in a series, with PAPR, H_BULK_REMOVE can remove up to 4 entries
at a time.

Doing a tlb_flush() each time is a waste of time. We end up doing a memset
of the whole TLB, reloading it for the next instruction, memset'ing again,
etc...

Those instructions don't have to take effect immediately. For slbie, they
can wait for the next context synchronizing event. For tlbie, the next
tlbsync.

This implements batching by keeping a flag that indicates that we have a
TLB in need of flushing. We check it on interrupts, rfi's, isync's and
tlbsync and flush the TLB if needed.

This reduces the number of tlb_flush() on a boot to a ubuntu installer
first dialog screen from roughly 360K down to 36K.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
[clg: added a 'CPUPPCState *' variable in h_remove() and
      h_bulk_remove() ]
Signed-off-by: NCédric Le Goater <clg@kaod.org>
[dwg: removed spurious whitespace change, use 0/1 not true/false
      consistently, since tlb_need_flush has int type]
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

We rework the way the MMU indices are calculated, providing separate
indices for I and D side based on MSR:IR and MSR:DR respectively,
and thus no longer need to flush the TLB on context changes. This also
adds correct support for HV as a separate address space.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

We don't use the resulting accessors and this gets in the way of
the split I/D TLB work.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

linux-user pull request v2 for may 2016

# gpg: Signature made Fri 27 May 2016 12:51:10 BST using RSA key ID DE3C9BC0
# gpg: Good signature from "Riku Voipio <riku.voipio@iki.fi>"
# gpg:                 aka "Riku Voipio <riku.voipio@linaro.org>"

* remotes/riku/tags/pull-linux-user-20160527: (38 commits)
  linux-user,target-ppc: fix use of MSR_LE
  linux-user/signal.c: Use s390 target space address instead of host space
  linux-user/signal.c: Use target address instead of host address for microblaze restorer
  linux-user/signal.c: Generate opcode data for restorer in setup_rt_frame
  linux-user: arm: Remove ARM_cpsr and similar #defines
  linux-user: Use direct syscalls for setuid(), etc
  linux-user: x86_64: Don't use 16-bit UIDs
  linux-user: Use g_try_malloc() in do_msgrcv()
  linux-user: Handle msgrcv error case correctly
  linux-user: Handle negative values in timespec conversion
  linux-user: Use safe_syscall for futex syscall
  linux-user: Use safe_syscall for pselect, select syscalls
  linux-user: Use safe_syscall for execve syscall
  linux-user: Use safe_syscall for wait system calls
  linux-user: Use safe_syscall for open and openat system calls
  linux-user: Use safe_syscall for read and write system calls
  linux-user: Provide safe_syscall for fixing races between signals and syscalls
  linux-user: Add debug code to exercise restarting system calls
  linux-user: Support for restarting system calls for Microblaze targets
  linux-user: Set r14 on exit from microblaze syscall
  ...
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

setup_frame()/setup_rt_frame()/restore_user_regs() are using
MSR_LE as the similar kernel functions do: as a bitmask.

But in QEMU, MSR_LE is a bit position, so change this
accordingly.

The previous code was doing nothing as MSR_LE is 0,
and "env->msr &= ~MSR_LE" doesn't change the value of msr.

And yes, a user process can change its endianness,
see linux kernel commit:

    fab5db9 [PATCH] powerpc: Implement support for setting little-endian mode via prctl

and prctl(2): PR_SET_ENDIAN, PR_GET_ENDIAN
Reviewed-by: NThomas Huth <huth@tuxfamily.org>
Signed-off-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

The return address is in target space, so the restorer address needs to
be target space, too.
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>

The return address is in target space, so the restorer address needs to
be target space, too.
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Original implementation uses do_rt_sigreturn directly in host space,
when a guest program is in unwind procedure in guest space, it will get
an incorrect restore address, then causes unwind failure.

Also cleanup the original incorrect indentation.
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NChen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

The #defines of ARM_cpsr and friends in linux-user/arm/target-syscall.h
can clash with versions in the system headers if building on an
ARM or AArch64 build (though this seems to be dependent on the version
of the system headers). The QEMU defines are not very useful (it's
not clear that they're intended for use with the target_pt_regs struct
rather than (say) the CPUARMState structure) and we only use them in one
function in elfload.c anyway. So just remove the #defines and directly
access regs->uregs[].
Reported-by: NChristopher Covington <cov@codeaurora.org>
Tested-by: NChristopher Covington <cov@codeaurora.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

On Linux the setuid(), setgid(), etc system calls have different semantics
from the libc functions. The libc functions follow POSIX and update the
credentials for all threads in the process; the system calls update only
the thread which makes the call. (This impedance mismatch is worked around
in libc by signalling all threads to tell them to do a syscall, in a
byzantine and fragile way; see http://ewontfix.com/17/.)

Since in linux-user we are trying to emulate the system call semantics,
we must implement all these syscalls to directly call the underlying
host syscall, rather than calling the host libc function.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

The 64-bit x86 syscall ABI uses 32-bit UIDs; only define
USE_UID16 for 32-bit x86.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

In do_msgrcv() we want to allocate a message buffer, whose size
is passed to us by the guest. That means we could legitimately
fail, so use g_try_malloc() and handle the error case, in the same
way that do_msgsnd() does.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

The msgrcv ABI is a bit odd -- the msgsz argument is a size_t, which is
unsigned, but it must fail EINVAL if the value is negative when cast
to a long. We were incorrectly passing the value through an
"unsigned int", which meant that if the guest was 32-bit longs and
the host was 64-bit longs an input of 0xffffffff (which should trigger
EINVAL) would simply be passed to the host msgrcv() as 0xffffffff,
where it does not cause the host kernel to reject it.
Follow the same approach as do_msgsnd() in using a ssize_t and
doing the check for negative values by hand, so we correctly fail
in this corner case.

This fixes the msgrcv03 Linux Test Project test case, which otherwise
hangs.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

In a struct timespec, both fields are signed longs. Converting
them from guest to host with code like
    host_ts->tv_sec = tswapal(target_ts->tv_sec);
mishandles negative values if the guest has 32-bit longs and
the host has 64-bit longs because tswapal()'s return type is
abi_ulong: the assignment will zero-extend into the host long
type rather than sign-extending it.

Make the conversion routines use __get_user() and __set_user()
instead: this automatically picks up the signedness of the
field type and does the correct kind of sign or zero extension.
It also handles the possibility that the target struct is not
sufficiently aligned for the host's requirements.

In particular, this fixes a hang when running the Linux Test Project
mq_timedsend01 and mq_timedreceive01 tests: one of the test cases
sets the timeout to -1 and expects an EINVAL failure, but we were
setting a very long timeout instead.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Use the safe_syscall wrapper for the futex syscall.

In particular, this fixes hangs when using programs that link
against the Boehm garbage collector, including the Mono runtime.

(We don't change the sys_futex() call in the implementation of
the exit syscall, because as the FIXME comment there notes
that should be handled by disabling signals, since we can't
easily back out if the futex were to return ERESTARTSYS.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Use the safe_syscall wrapper for the pselect and select syscalls.
Since not every architecture has the select syscall, we now
have to implement select in terms of pselect, which means doing
timeval<->timespec conversion.

(Five years on from the initial patch that added pselect support
to QEMU and a decade after pselect6 went into the kernel, it seems
safe to not try to support hosts with header files which don't
define __NR_pselect6.)
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Wrap execve() in the safe-syscall handling. Although execve() is not
an interruptible syscall, it is a special case: if we allow a signal
to happen before we make the host$ syscall then we will 'lose' it,
because at the point of execve the process leaves QEMU's control.  So
we use the safe syscall wrapper to ensure that we either take the
signal as a guest signal, or else it does not happen before the
execve completes and makes it the other program's problem.

The practical upshot is that without this SIGTERM could fail to
terminate the process.
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-25-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: expanded commit message to explain in more detail why this is
 needed, and add comment about it too]
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Use safe_syscall for waitpid, waitid and wait4 syscalls. Note that this
change allows us to implement support for waitid's fifth (rusage) argument
in future; for the moment we ignore it as we have done up til now.
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-18-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: Adjust to new safe_syscall convention. Add fifth waitid syscall argument
 (which isn't present in the libc interface but is in the syscall ABI)]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Restart open() and openat() if signals occur before,
or during with SA_RESTART.
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-17-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: Adjusted to follow new -1-and-set-errno safe_syscall convention]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Restart read() and write() if signals occur before, or during with SA_RESTART
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-15-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: Update to new safe_syscall() convention of setting errno]
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

If a signal is delivered immediately before a blocking system call the
handler will only be called after the system call returns, which may be a
long time later or never.

This is fixed by using a function (safe_syscall) that checks if a guest
signal is pending prior to making a system call, and if so does not call the
system call and returns -TARGET_ERESTARTSYS. If a signal is received between
the check and the system call host_signal_handler() rewinds execution to
before the check. This rewinding has the effect of closing the race window
so that safe_syscall will reliably either (a) go into the host syscall
with no unprocessed guest signals pending or or (b) return
-TARGET_ERESTARTSYS so that the caller can deal with the signals.
Implementing this requires a per-host-architecture assembly language
fragment.

This will also resolve the mishandling of the SA_RESTART flag where
we would restart a host system call and not call the guest signal handler
until the syscall finally completed -- syscall restarting now always
happens at the guest syscall level so the guest signal handler will run.
(The host syscall will never be restarted because if the host kernel
rewinds the PC to point at the syscall insn for a restart then our
host_signal_handler() will see this and arrange the guest PC rewind.)

This commit contains the infrastructure for implementing safe_syscall
and the assembly language fragment for x86-64, but does not change any
syscalls to use it.
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-14-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM:
 * Avoid having an architecture if-ladder in configure by putting
   linux-user/host/$(ARCH) on the include path and including
   safe-syscall.inc.S from it
 * Avoid ifdef ladder in signal.c by creating new hostdep.h to hold
   host-architecture-specific things
 * Added copyright/license header to safe-syscall.inc.S
 * Rewrote commit message
 * Added comments to safe-syscall.inc.S
 * Changed calling convention of safe_syscall() to match syscall()
   (returns -1 and host error in errno on failure)
 * Added a long comment in qemu.h about how to use safe_syscall()
   to implement guest syscalls.
]
RV: squashed Peters "fixup! linux-user: compile on non-x86-64 hosts"
patch
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

If DEBUG_ERESTARTSYS is set restart all system calls once. This
is pure debug code for exercising the syscall restart code paths
in the per-architecture cpu main loops.
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-10-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: Add comment and a commented-out #define next to the commented-out
 generic DEBUG #define; remove the check on TARGET_USE_ERESTARTSYS;
 tweak comment message]
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the Microblaze main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code on sigreturn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state

Note that this in passing fixes a bug where we were corrupting
the guest r[3] on sigreturn with the guest's r[10] because
do_sigreturn() was returning env->regs[10] but the register for
syscall return values is env->regs[3].
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-11-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: Commit message tweaks; drop TARGET_USE_ERESTARTSYS define;
 drop whitespace changes]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

All syscall exits on microblaze result in r14 being equal to the
PC we return to, because the kernel syscall exit instruction "rtbd"
does this. (This is true even for sigreturn(); note that r14 is
not a userspace-usable register as the kernel may clobber it at
any point.)

Emulate the setting of r14 on exit; this isn't really a guest
visible change for valid guest code because r14 isn't reliably
observable anyway. However having the code and the comment helps
to explain why it's ok for the ERESTARTSYS handling not to undo
the changes to r14 that happen on syscall entry.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the tilegx main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * return -TARGET_QEMU_ESIGRETURN from sigreturn rather than current R_RE
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state

Note that this fixes a bug where a sigreturn which happened to have
an errno value in TILEGX_R_RE would incorrectly cause TILEGX_R_ERR
to get set.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the CRIS main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code on sigreturn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-34-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the S390 main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code on sigreturn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-33-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; remove stray double semicolon; drop
 TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the M68K main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code on sigreturn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-32-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the OpenRISC main loop code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state

(We don't implement sigreturn on this target so there is no
code there to update.)
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-31-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the UniCore32 main loop code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state

(We don't support signals on this target so there is no sigreturn code
to update.)
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-30-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the Alpha main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-13-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define;
 PC is env->pc, not env->ir[IR_PV]]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the SH4 main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code on sigreturn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-12-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the SPARC main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code on sigreturn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-9-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: Commit message tweaks; drop TARGET_USE_ERESTARTSYS define]
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the PPC main loop code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn

(We already handle TARGET_QEMU_ESIGRETURN.)
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-8-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the MIPS main loop code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn

(We already handle TARGET_QEMU_ESIGRETURN.)
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-7-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the 32-bit and 64-bit ARM main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code on sigreturn
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch any guest CPU state
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-6-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: tweak commit message; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Update the x86 main loop and sigreturn code:
 * on TARGET_ERESTARTSYS, wind guest PC backwards to repeat syscall insn
 * set all guest CPU state within signal.c code rather than passing it
   back out as the "return code" from do_sigreturn()
 * handle TARGET_QEMU_ESIGRETURN in the main loop as the indication
   that the main loop should not touch EAX
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-5-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
[PMM: Commit message tweaks; drop TARGET_USE_ERESTARTSYS define]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

Currently we define a QEMU-internal errno TARGET_QEMU_ESIGRETURN
only on the MIPS and PPC targets; move this to errno_defs.h
so it is available for all architectures, and renumber it to 513.
We pick 513 because this is safe from future use as a system call return
value: Linux uses it as ERESTART_NOINTR internally and never allows that
errno to escape to userspace.
Signed-off-by: NTimothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-4-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: TARGET_ERESTARTSYS split out into preceding patch, add comment]
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NLaurent Vivier <laurent@vivier.eu>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>