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[IA64] Liberate the signal layer from IA64 assembler
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Currently IA64 has a assembler implementation of sigrtprocmask.
Having a single architecture implement this in assembler language
is a serious maintenance problem that inhibits further evolution of the
signal subsystem.  Everyone who wants to do deep changes to signals
would need to learn that assembler language.

Whatever performance improvements IA64 gets from this it cannot be worth
the price in maintainability.

We have some locking problems in signal that need to be fixed,
but this roadblock needs to be removed first.

So just disable the special assembler IA64 implementation and fall back to a
normal syscall there.

Acked-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
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Andi Kleen authored and Tony Luck committed May 16, 2012
1 parent 98e4cff commit 4035c6d
Showing 1 changed file with 1 addition and 170 deletions.
171 changes: 1 addition & 170 deletions arch/ia64/kernel/fsys.S
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Original file line number Diff line number Diff line change
Expand Up @@ -371,175 +371,6 @@ ENTRY(fsys_clock_gettime)
br.many .gettime
END(fsys_clock_gettime)

/*
* long fsys_rt_sigprocmask (int how, sigset_t *set, sigset_t *oset, size_t sigsetsize).
*/
#if _NSIG_WORDS != 1
# error Sorry, fsys_rt_sigprocmask() needs to be updated for _NSIG_WORDS != 1.
#endif
ENTRY(fsys_rt_sigprocmask)
.prologue
.altrp b6
.body

add r2=IA64_TASK_BLOCKED_OFFSET,r16
add r9=TI_FLAGS+IA64_TASK_SIZE,r16
cmp4.ltu p6,p0=SIG_SETMASK,r32

cmp.ne p15,p0=r0,r34 // oset != NULL?
tnat.nz p8,p0=r34
add r31=IA64_TASK_SIGHAND_OFFSET,r16
;;
ld8 r3=[r2] // read/prefetch current->blocked
ld4 r9=[r9]
tnat.nz.or p6,p0=r35

cmp.ne.or p6,p0=_NSIG_WORDS*8,r35
tnat.nz.or p6,p0=r32
(p6) br.spnt.few .fail_einval // fail with EINVAL
;;
#ifdef CONFIG_SMP
ld8 r31=[r31] // r31 <- current->sighand
#endif
and r9=TIF_ALLWORK_MASK,r9
tnat.nz.or p8,p0=r33
;;
cmp.ne p7,p0=0,r9
cmp.eq p6,p0=r0,r33 // set == NULL?
add r31=IA64_SIGHAND_SIGLOCK_OFFSET,r31 // r31 <- current->sighand->siglock
(p8) br.spnt.few .fail_efault // fail with EFAULT
(p7) br.spnt.many fsys_fallback_syscall // got pending kernel work...
(p6) br.dpnt.many .store_mask // -> short-circuit to just reading the signal mask

/* Argh, we actually have to do some work and _update_ the signal mask: */

EX(.fail_efault, probe.r.fault r33, 3) // verify user has read-access to *set
EX(.fail_efault, ld8 r14=[r33]) // r14 <- *set
mov r17=(1 << (SIGKILL - 1)) | (1 << (SIGSTOP - 1))
;;

RSM_PSR_I(p0, r18, r19) // mask interrupt delivery
andcm r14=r14,r17 // filter out SIGKILL & SIGSTOP
mov r8=EINVAL // default to EINVAL

#ifdef CONFIG_SMP
// __ticket_spin_trylock(r31)
ld4 r17=[r31]
;;
mov.m ar.ccv=r17
extr.u r9=r17,17,15
adds r19=1,r17
extr.u r18=r17,0,15
;;
cmp.eq p6,p7=r9,r18
;;
(p6) cmpxchg4.acq r9=[r31],r19,ar.ccv
(p6) dep.z r20=r19,1,15 // next serving ticket for unlock
(p7) br.cond.spnt.many .lock_contention
;;
cmp4.eq p0,p7=r9,r17
adds r31=2,r31
(p7) br.cond.spnt.many .lock_contention
ld8 r3=[r2] // re-read current->blocked now that we hold the lock
;;
#else
ld8 r3=[r2] // re-read current->blocked now that we hold the lock
#endif
add r18=IA64_TASK_PENDING_OFFSET+IA64_SIGPENDING_SIGNAL_OFFSET,r16
add r19=IA64_TASK_SIGNAL_OFFSET,r16
cmp4.eq p6,p0=SIG_BLOCK,r32
;;
ld8 r19=[r19] // r19 <- current->signal
cmp4.eq p7,p0=SIG_UNBLOCK,r32
cmp4.eq p8,p0=SIG_SETMASK,r32
;;
ld8 r18=[r18] // r18 <- current->pending.signal
.pred.rel.mutex p6,p7,p8
(p6) or r14=r3,r14 // SIG_BLOCK
(p7) andcm r14=r3,r14 // SIG_UNBLOCK

(p8) mov r14=r14 // SIG_SETMASK
(p6) mov r8=0 // clear error code
// recalc_sigpending()
add r17=IA64_SIGNAL_GROUP_STOP_COUNT_OFFSET,r19

add r19=IA64_SIGNAL_SHARED_PENDING_OFFSET+IA64_SIGPENDING_SIGNAL_OFFSET,r19
;;
ld4 r17=[r17] // r17 <- current->signal->group_stop_count
(p7) mov r8=0 // clear error code

ld8 r19=[r19] // r19 <- current->signal->shared_pending
;;
cmp4.gt p6,p7=r17,r0 // p6/p7 <- (current->signal->group_stop_count > 0)?
(p8) mov r8=0 // clear error code

or r18=r18,r19 // r18 <- current->pending | current->signal->shared_pending
;;
// r18 <- (current->pending | current->signal->shared_pending) & ~current->blocked:
andcm r18=r18,r14
add r9=TI_FLAGS+IA64_TASK_SIZE,r16
;;

(p7) cmp.ne.or.andcm p6,p7=r18,r0 // p6/p7 <- signal pending
mov r19=0 // i must not leak kernel bits...
(p6) br.cond.dpnt.many .sig_pending
;;

1: ld4 r17=[r9] // r17 <- current->thread_info->flags
;;
mov ar.ccv=r17
and r18=~_TIF_SIGPENDING,r17 // r18 <- r17 & ~(1 << TIF_SIGPENDING)
;;

st8 [r2]=r14 // update current->blocked with new mask
cmpxchg4.acq r8=[r9],r18,ar.ccv // current->thread_info->flags <- r18
;;
cmp.ne p6,p0=r17,r8 // update failed?
(p6) br.cond.spnt.few 1b // yes -> retry

#ifdef CONFIG_SMP
// __ticket_spin_unlock(r31)
st2.rel [r31]=r20
mov r20=0 // i must not leak kernel bits...
#endif
SSM_PSR_I(p0, p9, r31)
;;

srlz.d // ensure psr.i is set again
mov r18=0 // i must not leak kernel bits...

.store_mask:
EX(.fail_efault, (p15) probe.w.fault r34, 3) // verify user has write-access to *oset
EX(.fail_efault, (p15) st8 [r34]=r3)
mov r2=0 // i must not leak kernel bits...
mov r3=0 // i must not leak kernel bits...
mov r8=0 // return 0
mov r9=0 // i must not leak kernel bits...
mov r14=0 // i must not leak kernel bits...
mov r17=0 // i must not leak kernel bits...
mov r31=0 // i must not leak kernel bits...
FSYS_RETURN

.sig_pending:
#ifdef CONFIG_SMP
// __ticket_spin_unlock(r31)
st2.rel [r31]=r20 // release the lock
#endif
SSM_PSR_I(p0, p9, r17)
;;
srlz.d
br.sptk.many fsys_fallback_syscall // with signal pending, do the heavy-weight syscall

#ifdef CONFIG_SMP
.lock_contention:
/* Rather than spinning here, fall back on doing a heavy-weight syscall. */
SSM_PSR_I(p0, p9, r17)
;;
srlz.d
br.sptk.many fsys_fallback_syscall
#endif
END(fsys_rt_sigprocmask)

/*
* fsys_getcpu doesn't use the third parameter in this implementation. It reads
* current_thread_info()->cpu and corresponding node in cpu_to_node_map.
Expand Down Expand Up @@ -920,7 +751,7 @@ paravirt_fsyscall_table:
data8 0 // sigaltstack
data8 0 // rt_sigaction
data8 0 // rt_sigpending
data8 fsys_rt_sigprocmask // rt_sigprocmask
data8 0 // rt_sigprocmask
data8 0 // rt_sigqueueinfo // 1180
data8 0 // rt_sigreturn
data8 0 // rt_sigsuspend
Expand Down

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