From a359bb1190f213d282f4934fd461cf440d87dae0 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 22 Jun 2015 17:27:48 +0200 Subject: [PATCH] s390/kernel: squeeze a few more cycles out of the system call handler Reorder the instructions of UPDATE_VTIME to improve superscalar execution, remove duplicate checks for problem-state from the asynchronous interrupt handlers, and move the check for problem-state from the synchronous exit path to the program check path as it is only needed for program checks inside the kernel. Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/entry.S | 75 ++++++++++++++++++---------------------- 1 file changed, 34 insertions(+), 41 deletions(-) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 9406e7a62d2f..a721c39d014d 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -83,7 +83,7 @@ _PIF_WORK = (_PIF_PER_TRAP) #endif .endm - .macro SWITCH_ASYNC savearea,stack,shift + .macro SWITCH_ASYNC savearea,stack,shift,timer tmhh %r8,0x0001 # interrupting from user ? jnz 1f lgr %r14,%r9 @@ -97,23 +97,25 @@ _PIF_WORK = (_PIF_PER_TRAP) 0: lg %r14,\stack # are we already on the target stack? slgr %r14,%r15 srag %r14,%r14,\shift - jnz 1f + jnz 2f CHECK_STACK 1<<\shift,\savearea aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) - j 2f -1: lg %r15,\stack # load target stack -2: la %r11,STACK_FRAME_OVERHEAD(%r15) + j 3f +1: LAST_BREAK %r14 + UPDATE_VTIME %r14,%r15,\timer +2: lg %r15,\stack # load target stack +3: la %r11,STACK_FRAME_OVERHEAD(%r15) .endm - .macro UPDATE_VTIME scratch,enter_timer - lg \scratch,__LC_EXIT_TIMER - slg \scratch,\enter_timer - alg \scratch,__LC_USER_TIMER - stg \scratch,__LC_USER_TIMER - lg \scratch,__LC_LAST_UPDATE_TIMER - slg \scratch,__LC_EXIT_TIMER - alg \scratch,__LC_SYSTEM_TIMER - stg \scratch,__LC_SYSTEM_TIMER + .macro UPDATE_VTIME w1,w2,enter_timer + lg \w1,__LC_EXIT_TIMER + lg \w2,__LC_LAST_UPDATE_TIMER + slg \w1,\enter_timer + slg \w2,__LC_EXIT_TIMER + alg \w1,__LC_USER_TIMER + alg \w2,__LC_SYSTEM_TIMER + stg \w1,__LC_USER_TIMER + stg \w2,__LC_SYSTEM_TIMER mvc __LC_LAST_UPDATE_TIMER(8),\enter_timer .endm @@ -246,9 +248,9 @@ ENTRY(system_call) .Lsysc_per: lg %r15,__LC_KERNEL_STACK la %r11,STACK_FRAME_OVERHEAD(%r15) # pointer to pt_regs -.Lsysc_vtime: - UPDATE_VTIME %r13,__LC_SYNC_ENTER_TIMER LAST_BREAK %r13 +.Lsysc_vtime: + UPDATE_VTIME %r10,%r13,__LC_SYNC_ENTER_TIMER stmg %r0,%r7,__PT_R0(%r11) mvc __PT_R8(64,%r11),__LC_SAVE_AREA_SYNC mvc __PT_PSW(16,%r11),__LC_SVC_OLD_PSW @@ -278,8 +280,6 @@ ENTRY(system_call) .Lsysc_return: LOCKDEP_SYS_EXIT .Lsysc_tif: - tm __PT_PSW+1(%r11),0x01 # returning to user ? - jno .Lsysc_restore tm __PT_FLAGS+7(%r11),_PIF_WORK jnz .Lsysc_work tm __TI_flags+7(%r12),_TIF_WORK @@ -467,8 +467,8 @@ ENTRY(pgm_check_handler) 1: CHECK_STACK STACK_SIZE,__LC_SAVE_AREA_SYNC aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) j 3f -2: UPDATE_VTIME %r14,__LC_SYNC_ENTER_TIMER - LAST_BREAK %r14 +2: LAST_BREAK %r14 + UPDATE_VTIME %r14,%r15,__LC_SYNC_ENTER_TIMER lg %r15,__LC_KERNEL_STACK lg %r14,__TI_task(%r12) aghi %r14,__TASK_thread # pointer to thread_struct @@ -498,11 +498,15 @@ ENTRY(pgm_check_handler) llgh %r10,__PT_INT_CODE+2(%r11) nill %r10,0x007f sll %r10,2 - je .Lsysc_return + je .Lpgm_return lgf %r1,0(%r10,%r1) # load address of handler routine lgr %r2,%r11 # pass pointer to pt_regs basr %r14,%r1 # branch to interrupt-handler - j .Lsysc_return +.Lpgm_return: + LOCKDEP_SYS_EXIT + tm __PT_PSW+1(%r11),0x01 # returning to user ? + jno .Lsysc_restore + j .Lsysc_tif # # PER event in supervisor state, must be kprobes @@ -512,7 +516,7 @@ ENTRY(pgm_check_handler) xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) lgr %r2,%r11 # pass pointer to pt_regs brasl %r14,do_per_trap - j .Lsysc_return + j .Lpgm_return # # single stepped system call @@ -535,12 +539,8 @@ ENTRY(io_int_handler) lg %r12,__LC_THREAD_INFO larl %r13,cleanup_critical lmg %r8,%r9,__LC_IO_OLD_PSW - SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT - tmhh %r8,0x0001 # interrupting from user? - jz .Lio_skip - UPDATE_VTIME %r14,__LC_ASYNC_ENTER_TIMER - LAST_BREAK %r14 -.Lio_skip: + SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT,\ + __LC_ASYNC_ENTER_TIMER stmg %r0,%r7,__PT_R0(%r11) mvc __PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC stmg %r8,%r9,__PT_PSW(%r11) @@ -712,12 +712,8 @@ ENTRY(ext_int_handler) lg %r12,__LC_THREAD_INFO larl %r13,cleanup_critical lmg %r8,%r9,__LC_EXT_OLD_PSW - SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT - tmhh %r8,0x0001 # interrupting from user ? - jz .Lext_skip - UPDATE_VTIME %r14,__LC_ASYNC_ENTER_TIMER - LAST_BREAK %r14 -.Lext_skip: + SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_STACK,STACK_SHIFT,\ + __LC_ASYNC_ENTER_TIMER stmg %r0,%r7,__PT_R0(%r11) mvc __PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC stmg %r8,%r9,__PT_PSW(%r11) @@ -896,11 +892,8 @@ ENTRY(mcck_int_handler) mvc __LC_MCCK_ENTER_TIMER(8),0(%r14) 3: tm __LC_MCCK_CODE+2,0x09 # mwp + ia of old psw valid? jno .Lmcck_panic # no -> skip cleanup critical - SWITCH_ASYNC __LC_GPREGS_SAVE_AREA+64,__LC_PANIC_STACK,PAGE_SHIFT - tm %r8,0x0001 # interrupting from user ? - jz .Lmcck_skip - UPDATE_VTIME %r14,__LC_MCCK_ENTER_TIMER - LAST_BREAK %r14 + SWITCH_ASYNC __LC_GPREGS_SAVE_AREA+64,__LC_PANIC_STACK,PAGE_SHIFT,\ + __LC_MCCK_ENTER_TIMER .Lmcck_skip: lghi %r14,__LC_GPREGS_SAVE_AREA+64 stmg %r0,%r7,__PT_R0(%r11) @@ -1125,7 +1118,7 @@ cleanup_critical: .quad system_call .quad .Lsysc_stmg .quad .Lsysc_per - .quad .Lsysc_vtime+18 + .quad .Lsysc_vtime+36 .quad .Lsysc_vtime+42 .Lcleanup_sysc_tif: -- 2.39.2