diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2008-05-07 09:22:52 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2008-05-07 09:23:00 +0200 |
| commit | 2688905e6a9b3647bf7b452cb0ff2bdb166bd8fe (patch) | |
| tree | 389b9c29eaaa7eb49a9e7d3bb601959fb9d27af8 /arch/s390/kernel/entry.S | |
| parent | c0a18111e571138747a98af18b3a2124df56a0d1 (diff) | |
[S390] s390: Optimize user and work TIF check
On return from syscall or interrupt, we have to check if we return to
userspace (likely) and if there is work todo (less likely) to decide
if we handle the work. We can optimize this check: we first check for
the less likely work case and then check for userspace.
This patch is also a preparation for an additional patch, that fixes a bug
in KVM dealing with cpu bound guests.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/entry.S')
| -rw-r--r-- | arch/s390/kernel/entry.S | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index bdbb3bcd78a5..708cf9cf9a35 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -279,8 +279,6 @@ sysc_do_restart: st %r2,SP_R2(%r15) # store return value (change R2 on stack) sysc_return: - tm SP_PSW+1(%r15),0x01 # returning to user ? - bno BASED(sysc_restore) tm __TI_flags+3(%r9),_TIF_WORK_SVC bnz BASED(sysc_work) # there is work to do (signals etc.) sysc_restore: @@ -312,6 +310,8 @@ sysc_work_loop: # One of the work bits is on. Find out which one. # sysc_work: + tm SP_PSW+1(%r15),0x01 # returning to user ? + bno BASED(sysc_restore) tm __TI_flags+3(%r9),_TIF_MCCK_PENDING bo BASED(sysc_mcck_pending) tm __TI_flags+3(%r9),_TIF_NEED_RESCHED @@ -602,12 +602,6 @@ io_no_vtime: la %r2,SP_PTREGS(%r15) # address of register-save area basr %r14,%r1 # branch to standard irq handler io_return: - tm SP_PSW+1(%r15),0x01 # returning to user ? -#ifdef CONFIG_PREEMPT - bno BASED(io_preempt) # no -> check for preemptive scheduling -#else - bno BASED(io_restore) # no-> skip resched & signal -#endif tm __TI_flags+3(%r9),_TIF_WORK_INT bnz BASED(io_work) # there is work to do (signals etc.) io_restore: @@ -629,10 +623,18 @@ io_restore_trace_psw: .long 0, io_restore_trace + 0x80000000 #endif -#ifdef CONFIG_PREEMPT -io_preempt: +# +# switch to kernel stack, then check the TIF bits +# +io_work: + tm SP_PSW+1(%r15),0x01 # returning to user ? +#ifndef CONFIG_PREEMPT + bno BASED(io_restore) # no-> skip resched & signal +#else + bnz BASED(io_work_user) # no -> check for preemptive scheduling + # check for preemptive scheduling icm %r0,15,__TI_precount(%r9) - bnz BASED(io_restore) + bnz BASED(io_restore) # preemption disabled l %r1,SP_R15(%r15) s %r1,BASED(.Lc_spsize) mvc SP_PTREGS(__PT_SIZE,%r1),SP_PTREGS(%r15) @@ -646,10 +648,7 @@ io_resume_loop: br %r1 # call schedule #endif -# -# switch to kernel stack, then check the TIF bits -# -io_work: +io_work_user: l %r1,__LC_KERNEL_STACK s %r1,BASED(.Lc_spsize) mvc SP_PTREGS(__PT_SIZE,%r1),SP_PTREGS(%r15) |