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s390: run user space and KVM guests with modified branch prediction
Define TIF_ISOLATE_BP and TIF_ISOLATE_BP_GUEST and add the necessary plumbing in entry.S to be able to run user space and KVM guests with limited branch prediction. To switch a user space process to limited branch prediction the s390_isolate_bp() function has to be call, and to run a vCPU of a KVM guest associated with the current task with limited branch prediction call s390_isolate_bp_guest(). Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
parent
d768bd892f
commit
6b73044b2b
@ -378,6 +378,9 @@ extern void memcpy_absolute(void *, void *, size_t);
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memcpy_absolute(&(dest), &__tmp, sizeof(__tmp)); \
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} while (0)
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extern int s390_isolate_bp(void);
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extern int s390_isolate_bp_guest(void);
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_S390_PROCESSOR_H */
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@ -58,6 +58,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
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#define TIF_GUARDED_STORAGE 4 /* load guarded storage control block */
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#define TIF_PATCH_PENDING 5 /* pending live patching update */
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#define TIF_PGSTE 6 /* New mm's will use 4K page tables */
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#define TIF_ISOLATE_BP 8 /* Run process with isolated BP */
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#define TIF_ISOLATE_BP_GUEST 9 /* Run KVM guests with isolated BP */
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#define TIF_31BIT 16 /* 32bit process */
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#define TIF_MEMDIE 17 /* is terminating due to OOM killer */
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@ -78,6 +80,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
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#define _TIF_UPROBE _BITUL(TIF_UPROBE)
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#define _TIF_GUARDED_STORAGE _BITUL(TIF_GUARDED_STORAGE)
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#define _TIF_PATCH_PENDING _BITUL(TIF_PATCH_PENDING)
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#define _TIF_ISOLATE_BP _BITUL(TIF_ISOLATE_BP)
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#define _TIF_ISOLATE_BP_GUEST _BITUL(TIF_ISOLATE_BP_GUEST)
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#define _TIF_31BIT _BITUL(TIF_31BIT)
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#define _TIF_SINGLE_STEP _BITUL(TIF_SINGLE_STEP)
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@ -107,6 +107,7 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART)
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aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
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j 3f
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1: UPDATE_VTIME %r14,%r15,\timer
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BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
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2: lg %r15,__LC_ASYNC_STACK # load async stack
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3: la %r11,STACK_FRAME_OVERHEAD(%r15)
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.endm
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@ -187,6 +188,40 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART)
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.popsection
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.endm
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.macro BPENTER tif_ptr,tif_mask
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.pushsection .altinstr_replacement, "ax"
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662: .word 0xc004, 0x0000, 0x0000 # 6 byte nop
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.word 0xc004, 0x0000, 0x0000 # 6 byte nop
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.popsection
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664: TSTMSK \tif_ptr,\tif_mask
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jz . + 8
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.long 0xb2e8d000
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.pushsection .altinstructions, "a"
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.long 664b - .
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.long 662b - .
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.word 82
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.byte 12
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.byte 12
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.popsection
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.endm
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.macro BPEXIT tif_ptr,tif_mask
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TSTMSK \tif_ptr,\tif_mask
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.pushsection .altinstr_replacement, "ax"
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662: jnz . + 8
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.long 0xb2e8d000
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.popsection
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664: jz . + 8
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.long 0xb2e8c000
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.pushsection .altinstructions, "a"
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.long 664b - .
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.long 662b - .
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.word 82
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.byte 8
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.byte 8
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.popsection
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.endm
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.section .kprobes.text, "ax"
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.Ldummy:
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/*
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@ -240,9 +275,11 @@ ENTRY(__switch_to)
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*/
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ENTRY(sie64a)
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stmg %r6,%r14,__SF_GPRS(%r15) # save kernel registers
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lg %r12,__LC_CURRENT
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stg %r2,__SF_EMPTY(%r15) # save control block pointer
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stg %r3,__SF_EMPTY+8(%r15) # save guest register save area
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xc __SF_EMPTY+16(8,%r15),__SF_EMPTY+16(%r15) # reason code = 0
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mvc __SF_EMPTY+24(8,%r15),__TI_flags(%r12) # copy thread flags
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TSTMSK __LC_CPU_FLAGS,_CIF_FPU # load guest fp/vx registers ?
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jno .Lsie_load_guest_gprs
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brasl %r14,load_fpu_regs # load guest fp/vx regs
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@ -259,11 +296,12 @@ ENTRY(sie64a)
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jnz .Lsie_skip
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TSTMSK __LC_CPU_FLAGS,_CIF_FPU
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jo .Lsie_skip # exit if fp/vx regs changed
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BPON
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BPEXIT __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
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.Lsie_entry:
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sie 0(%r14)
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.Lsie_exit:
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BPOFF
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BPENTER __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
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.Lsie_skip:
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ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE
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lctlg %c1,%c1,__LC_USER_ASCE # load primary asce
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@ -324,6 +362,7 @@ ENTRY(system_call)
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la %r11,STACK_FRAME_OVERHEAD(%r15) # pointer to pt_regs
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.Lsysc_vtime:
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UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER
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BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
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stmg %r0,%r7,__PT_R0(%r11)
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# clear user controlled register to prevent speculative use
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xgr %r0,%r0
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@ -362,7 +401,7 @@ ENTRY(system_call)
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jnz .Lsysc_work # check for work
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TSTMSK __LC_CPU_FLAGS,_CIF_WORK
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jnz .Lsysc_work
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BPON
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BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
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.Lsysc_restore:
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lg %r14,__LC_VDSO_PER_CPU
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lmg %r0,%r10,__PT_R0(%r11)
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@ -597,6 +636,7 @@ ENTRY(pgm_check_handler)
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aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
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j 4f
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2: UPDATE_VTIME %r14,%r15,__LC_SYNC_ENTER_TIMER
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BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
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lg %r15,__LC_KERNEL_STACK
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lgr %r14,%r12
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aghi %r14,__TASK_thread # pointer to thread_struct
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@ -729,7 +769,7 @@ ENTRY(io_int_handler)
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mvc __LC_RETURN_PSW(16),__PT_PSW(%r11)
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tm __PT_PSW+1(%r11),0x01 # returning to user ?
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jno .Lio_exit_kernel
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BPON
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BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
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.Lio_exit_timer:
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stpt __LC_EXIT_TIMER
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mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
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@ -1165,7 +1205,7 @@ ENTRY(mcck_int_handler)
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mvc __LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW
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tm __LC_RETURN_MCCK_PSW+1,0x01 # returning to user ?
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jno 0f
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BPON
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BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
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stpt __LC_EXIT_TIMER
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mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
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0: lmg %r11,%r15,__PT_R11(%r11)
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@ -1292,7 +1332,8 @@ cleanup_critical:
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clg %r9,BASED(.Lsie_crit_mcck_length)
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jh 1f
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oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST
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1: lg %r9,__SF_EMPTY(%r15) # get control block pointer
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1: BPENTER __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
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lg %r9,__SF_EMPTY(%r15) # get control block pointer
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ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE
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lctlg %c1,%c1,__LC_USER_ASCE # load primary asce
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larl %r9,sie_exit # skip forward to sie_exit
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@ -197,3 +197,21 @@ const struct seq_operations cpuinfo_op = {
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.stop = c_stop,
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.show = show_cpuinfo,
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};
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int s390_isolate_bp(void)
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{
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if (!test_facility(82))
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return -EOPNOTSUPP;
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set_thread_flag(TIF_ISOLATE_BP);
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return 0;
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}
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EXPORT_SYMBOL(s390_isolate_bp);
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int s390_isolate_bp_guest(void)
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{
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if (!test_facility(82))
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return -EOPNOTSUPP;
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set_thread_flag(TIF_ISOLATE_BP_GUEST);
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return 0;
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}
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EXPORT_SYMBOL(s390_isolate_bp_guest);
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