diff options
| author | David Mosberger-Tang <davidm@hpl.hp.com> | 2005-04-27 21:16:07 -0700 |
|---|---|---|
| committer | Tony Luck <tony.luck@intel.com> | 2005-04-27 21:16:07 -0700 |
| commit | 96e017495e6833adcbad84783e3c5eb685836bbf (patch) | |
| tree | 41504d1ba4f94282d109224936ae6829109c3e6d /arch/ia64/kernel/entry.S | |
| parent | 3c79c8b1d92a9ae3edf3cbcd2c43c553ee0f1d83 (diff) | |
[IA64] On return from syscall, hint b7 with __kernel_syscall_via_epc().
Why is this a good idea? Clearing b7 to 0 is guaranteed to do us no
good and writing it with __kernel_syscall_via_epc() yields a 6 cycle
improvement _if_ the application performs another EPC-based system-
call without overwriting b7, which is not all that uncommon. Well
worth the minimal cost of 1 bundle of code.
Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/kernel/entry.S')
| -rw-r--r-- | arch/ia64/kernel/entry.S | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S index 0c84bed1bda9..6359d7ffbb7c 100644 --- a/arch/ia64/kernel/entry.S +++ b/arch/ia64/kernel/entry.S @@ -692,7 +692,7 @@ ENTRY(ia64_leave_syscall) ;; (p6) ld4 r31=[r18] // load current_thread_info()->flags ld8 r19=[r2],PT(B6)-PT(LOADRS) // load ar.rsc value for "loadrs" - mov b7=r0 // clear b7 + nop.i 0 ;; ld8 r23=[r3],PT(R11)-PT(AR_BSPSTORE) // load ar.bspstore (may be garbage) ld8 r18=[r2],PT(R9)-PT(B6) // load b6 @@ -754,7 +754,14 @@ ENTRY(ia64_leave_syscall) (pUStk) ld4 r17=[r3] // r17 = cpu_data->phys_stacked_size_p8 mov.m ar.csd=r0 // M2 clear ar.csd mov f10=f0 // clear f10 + + nop.m 0 + movl r14=__kernel_syscall_via_epc // X ;; + nop.m 0 + nop.m 0 + mov b7=r14 // I0 clear b7 (hint with __kernel_syscall_via_epc) + mov r14=r0 // clear r14 mov f11=f0 // clear f11 (pKStk) br.cond.dpnt.many skip_rbs_switch |