/* * PowerPC version * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) * Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP * Copyright (C) 1996 Cort Dougan * Adapted for Power Macintosh by Paul Mackerras. * Low-level exception handlers and MMU support * rewritten by Paul Mackerras. * Copyright (C) 1996 Paul Mackerras. * MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net). * * This file contains the system call entry code, context switch * code, and exception/interrupt return code for PowerPC. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * System calls. */ .section ".toc","aw" SYS_CALL_TABLE: .tc sys_call_table[TC],sys_call_table /* This value is used to mark exception frames on the stack. */ exception_marker: .tc ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER .section ".text" .align 7 .globl system_call_common system_call_common: #ifdef CONFIG_PPC_TRANSACTIONAL_MEM BEGIN_FTR_SECTION extrdi. r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */ bne tabort_syscall END_FTR_SECTION_IFSET(CPU_FTR_TM) #endif andi. r10,r12,MSR_PR mr r10,r1 addi r1,r1,-INT_FRAME_SIZE beq- 1f ld r1,PACAKSAVE(r13) 1: std r10,0(r1) std r11,_NIP(r1) std r12,_MSR(r1) std r0,GPR0(r1) std r10,GPR1(r1) beq 2f /* if from kernel mode */ ACCOUNT_CPU_USER_ENTRY(r13, r10, r11) 2: std r2,GPR2(r1) std r3,GPR3(r1) mfcr r2 std r4,GPR4(r1) std r5,GPR5(r1) std r6,GPR6(r1) std r7,GPR7(r1) std r8,GPR8(r1) li r11,0 std r11,GPR9(r1) std r11,GPR10(r1) std r11,GPR11(r1) std r11,GPR12(r1) std r11,_XER(r1) std r11,_CTR(r1) std r9,GPR13(r1) mflr r10 /* * This clears CR0.SO (bit 28), which is the error indication on * return from this system call. */ rldimi r2,r11,28,(63-28) li r11,0xc01 std r10,_LINK(r1) std r11,_TRAP(r1) std r3,ORIG_GPR3(r1) std r2,_CCR(r1) ld r2,PACATOC(r13) addi r9,r1,STACK_FRAME_OVERHEAD ld r11,exception_marker@toc(r2) std r11,-16(r9) /* "regshere" marker */ #if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) && defined(CONFIG_PPC_SPLPAR) BEGIN_FW_FTR_SECTION beq 33f /* if from user, see if there are any DTL entries to process */ ld r10,PACALPPACAPTR(r13) /* get ptr to VPA */ ld r11,PACA_DTL_RIDX(r13) /* get log read index */ addi r10,r10,LPPACA_DTLIDX LDX_BE r10,0,r10 /* get log write index */ cmpd cr1,r11,r10 beq+ cr1,33f bl accumulate_stolen_time REST_GPR(0,r1) REST_4GPRS(3,r1) REST_2GPRS(7,r1) addi r9,r1,STACK_FRAME_OVERHEAD 33: END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR) #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE && CONFIG_PPC_SPLPAR */ /* * A syscall should always be called with interrupts enabled * so we just unconditionally hard-enable here. When some kind * of irq tracing is used, we additionally check that condition * is correct */ #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_BUG) lbz r10,PACASOFTIRQEN(r13) xori r10,r10,1 1: tdnei r10,0 EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING #endif #ifdef CONFIG_PPC_BOOK3E wrteei 1 #else li r11,MSR_RI ori r11,r11,MSR_EE mtmsrd r11,1 #endif /* CONFIG_PPC_BOOK3E */ /* We do need to set SOFTE in the stack frame or the return * from interrupt will be painful */ li r10,1 std r10,SOFTE(r1) CURRENT_THREAD_INFO(r11, r1) ld r10,TI_FLAGS(r11) andi. r11,r10,_TIF_SYSCALL_DOTRACE bne syscall_dotrace /* does not return */ cmpldi 0,r0,NR_syscalls bge- syscall_enosys system_call: /* label this so stack traces look sane */ /* * Need to vector to 32 Bit or default sys_call_table here, * based on caller's run-mode / personality. */ ld r11,SYS_CALL_TABLE@toc(2) andi. r10,r10,_TIF_32BIT beq 15f addi r11,r11,8 /* use 32-bit syscall entries */ clrldi r3,r3,32 clrldi r4,r4,32 clrldi r5,r5,32 clrldi r6,r6,32 clrldi r7,r7,32 clrldi r8,r8,32 15: slwi r0,r0,4 ldx r12,r11,r0 /* Fetch system call handler [ptr] */ mtctr r12 bctrl /* Call handler */ .Lsyscall_exit: std r3,RESULT(r1) CURRENT_THREAD_INFO(r12, r1) ld r8,_MSR(r1) #ifdef CONFIG_PPC_BOOK3S /* No MSR:RI on BookE */ andi. r10,r8,MSR_RI beq- unrecov_restore #endif /* * Disable interrupts so current_thread_info()->flags can't change, * and so that we don't get interrupted after loading SRR0/1. */ #ifdef CONFIG_PPC_BOOK3E wrteei 0 #else /* * For performance reasons we clear RI the same time that we * clear EE. We only need to clear RI just before we restore r13 * below, but batching it with EE saves us one expensive mtmsrd call. * We have to be careful to restore RI if we branch anywhere from * here (eg syscall_exit_work). */ li r11,0 mtmsrd r11,1 #endif /* CONFIG_PPC_BOOK3E */ ld r9,TI_FLAGS(r12) li r11,-MAX_ERRNO andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) bne- syscall_exit_work /* If MSR_FP and MSR_VEC are set in user msr, then no need to restore */ li r7,MSR_FP #ifdef CONFIG_ALTIVEC oris r7,r7,MSR_VEC@h #endif and r0,r8,r7 cmpd r0,r7 bne syscall_restore_math .Lsyscall_restore_math_cont: cmpld r3,r11 ld r5,_CCR(r1) bge- syscall_error .Lsyscall_error_cont: ld r7,_NIP(r1) BEGIN_FTR_SECTION stdcx. r0,0,r1 /* to clear the reservation */ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) andi. r6,r8,MSR_PR ld r4,_LINK(r1) beq- 1f ACCOUNT_CPU_USER_EXIT(r13, r11, r12) BEGIN_FTR_SECTION HMT_MEDIUM_LOW END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) ld r13,GPR13(r1) /* only restore r13 if returning to usermode */ 1: ld r2,GPR2(r1) ld r1,GPR1(r1) mtlr r4 mtcr r5 mtspr SPRN_SRR0,r7 mtspr SPRN_SRR1,r8 RFI b . /* prevent speculative execution */ syscall_error: oris r5,r5,0x1000 /* Set SO bit in CR */ neg r3,r3 std r5,_CCR(r1) b .Lsyscall_error_cont syscall_restore_math: /* * Some initial tests from restore_math to avoid the heavyweight * C code entry and MSR manipulations. */ LOAD_REG_IMMEDIATE(r0, MSR_TS_MASK) and. r0,r0,r8 bne 1f ld r7,PACACURRENT(r13) lbz r0,THREAD+THREAD_LOAD_FP(r7) #ifdef CONFIG_ALTIVEC lbz r6,THREAD+THREAD_LOAD_VEC(r7) add r0,r0,r6 #endif cmpdi r0,0 beq .Lsyscall_restore_math_cont 1: addi r3,r1,STACK_FRAME_OVERHEAD #ifdef CONFIG_PPC_BOOK3S li r10,MSR_RI mtmsrd r10,1 /* Restore RI */ #endif bl restore_math #ifdef CONFIG_PPC_BOOK3S li r11,0 mtmsrd r11,1 #endif /* Restore volatiles, reload MSR from updated one */ ld r8,_MSR(r1) ld r3,RESULT(r1) li r11,-MAX_ERRNO b .Lsyscall_restore_math_cont /* Traced system call support */ syscall_dotrace: bl save_nvgprs addi r3,r1,STACK_FRAME_OVERHEAD bl do_syscall_trace_enter /* * We use the return value of do_syscall_trace_enter() as the syscall * number. If the syscall was rejected for any reason do_syscall_trace_enter() * returns an invalid syscall number and the test below against * NR_syscalls will fail. */ mr r0,r3 /* Restore argument registers just clobbered and/or possibly changed. */ ld r3,GPR3(r1) ld r4,GPR4(r1) ld r5,GPR5(r1) ld r6,GPR6(r1) ld r7,GPR7(r1) ld r8,GPR8(r1) /* Repopulate r9 and r10 for the system_call path */ addi r9,r1,STACK_FRAME_OVERHEAD CURRENT_THREAD_INFO(r10, r1) ld r10,TI_FLAGS(r10) cmpldi r0,NR_syscalls blt+ system_call /* Return code is already in r3 thanks to do_syscall_trace_enter() */ b .Lsyscall_exit syscall_enosys: li r3,-ENOSYS b .Lsyscall_exit syscall_exit_work: #ifdef CONFIG_PPC_BOOK3S li r10,MSR_RI mtmsrd r10,1 /* Restore RI */ #endif /* If TIF_RESTOREALL is set, don't scribble on either r3 or ccr. If TIF_NOERROR is set, just save r3 as it is. */ andi. r0,r9,_TIF_RESTOREALL beq+ 0f REST_NVGPRS(r1) b 2f 0: cmpld r3,r11 /* r11 is -MAX_ERRNO */ blt+ 1f andi. r0,r9,_TIF_NOERROR bne- 1f ld r5,_CCR(r1) neg r3,r3 oris r5,r5,0x1000 /* Set SO bit in CR */ std r5,_CCR(r1) 1: std r3,GPR3(r1) 2: andi. r0,r9,(_TIF_PERSYSCALL_MASK) beq 4f /* Clear per-syscall TIF flags if any are set. */ li r11,_TIF_PERSYSCALL_MASK addi r12,r12,TI_FLAGS 3: ldarx r10,0,r12 andc r10,r10,r11 stdcx. r10,0,r12 bne- 3b subi r12,r12,TI_FLAGS 4: /* Anything else left to do? */ BEGIN_FTR_SECTION lis r3,INIT_PPR@highest /* Set thread.ppr = 3 */ ld r10,PACACURRENT(r13) sldi r3,r3,32 /* bits 11-13 are used for ppr */ std r3,TASKTHREADPPR(r10) END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP) beq ret_from_except_lite /* Re-enable interrupts */ #ifdef CONFIG_PPC_BOOK3E wrteei 1 #else li r10,MSR_RI ori r10,r10,MSR_EE mtmsrd r10,1 #endif /* CONFIG_PPC_BOOK3E */ bl save_nvgprs addi r3,r1,STACK_FRAME_OVERHEAD bl do_syscall_trace_leave b ret_from_except #ifdef CONFIG_PPC_TRANSACTIONAL_MEM tabort_syscall: /* Firstly we need to enable TM in the kernel */ mfmsr r10 li r9, 1 rldimi r10, r9, MSR_TM_LG, 63-MSR_TM_LG mtmsrd r10, 0 /* tabort, this dooms the transaction, nothing else */ li r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT) TABORT(R9) /* * Return directly to userspace. We have corrupted user register state, * but userspace will never see that register state. Execution will * resume after the tbegin of the aborted transaction with the * checkpointed register state. */ li r9, MSR_RI andc r10, r10, r9 mtmsrd r10, 1 mtspr SPRN_SRR0, r11 mtspr SPRN_SRR1, r12 rfid b . /* prevent speculative execution */ #endif /* Save non-volatile GPRs, if not already saved. */ _GLOBAL(save_nvgprs) ld r11,_TRAP(r1) andi. r0,r11,1 beqlr- SAVE_NVGPRS(r1) clrrdi r0,r11,1 std r0,_TRAP(r1) blr /* * The sigsuspend and rt_sigsuspend system calls can call do_signal * and thus put the process into the stopped state where we might * want to examine its user state with ptrace. Therefore we need * to save all the nonvolatile registers (r14 - r31) before calling * the C code. Similarly, fork, vfork and clone need the full * register state on the stack so that it can be copied to the child. */ _GLOBAL(ppc_fork) bl save_nvgprs bl sys_fork b .Lsyscall_exit _GLOBAL(ppc_vfork) bl save_nvgprs bl sys_vfork b .Lsyscall_exit _GLOBAL(ppc_clone) bl save_nvgprs bl sys_clone b .Lsyscall_exit _GLOBAL(ppc32_swapcontext) bl save_nvgprs bl compat_sys_swapcontext b .Lsyscall_exit _GLOBAL(ppc64_swapcontext) bl save_nvgprs bl sys_swapcontext b .Lsyscall_exit _GLOBAL(ppc_switch_endian) bl save_nvgprs bl sys_switch_endian b .Lsyscall_exit _GLOBAL(ret_from_fork) bl schedule_tail REST_NVGPRS(r1) li r3,0 b .Lsyscall_exit _GLOBAL(ret_from_kernel_thread) bl schedule_tail REST_NVGPRS(r1) mtlr r14 mr r3,r15 #ifdef PPC64_ELF_ABI_v2 mr r12,r14 #endif blrl li r3,0 b .Lsyscall_exit /* * This routine switches between two different tasks. The process * state of one is saved on its kernel stack. Then the state * of the other is restored from its kernel stack. The memory * management hardware is updated to the second process's state. * Finally, we can return to the second process, via ret_from_except. * On entry, r3 points to the THREAD for the current task, r4 * points to the THREAD for the new task. * * Note: there are two ways to get to the "going out" portion * of this code; either by coming in via the entry (_switch) * or via "fork" which must set up an environment equivalent * to the "_switch" path. If you change this you'll have to change * the fork code also. * * The code which creates the new task context is in 'copy_thread' * in arch/powerpc/kernel/process.c */ .align 7 _GLOBAL(_switch) mflr r0 std r0,16(r1) stdu r1,-SWITCH_FRAME_SIZE(r1) /* r3-r13 are caller saved -- Cort */ SAVE_8GPRS(14, r1) SAVE_10GPRS(22, r1) std r0,_NIP(r1) /* Return to switch caller */ mfcr r23 std r23,_CCR(r1) std r1,KSP(r3) /* Set old stack pointer */ #ifdef CONFIG_SMP /* We need a sync somewhere here to make sure that if the * previous task gets rescheduled on another CPU, it sees all * stores it has performed on this one. */ sync #endif /* CONFIG_SMP */ /* * The kernel context switch path must contain a spin_lock, * which contains larx/stcx, which will clear any reservation * of the task being switched. */ BEGIN_FTR_SECTION /* * A cp_abort (copy paste abort) here ensures that when context switching, a * copy from one process can't leak into the paste of another. */ PPC_CP_ABORT END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) #ifdef CONFIG_PPC_BOOK3S /* Cancel all explict user streams as they will have no use after context * switch and will stop the HW from creating streams itself */ DCBT_STOP_ALL_STREAM_IDS(r6) #endif addi r6,r4,-THREAD /* Convert THREAD to 'current' */ std r6,PACACURRENT(r13) /* Set new 'current' */ ld r8,KSP(r4) /* new stack pointer */ #ifdef CONFIG_PPC_STD_MMU_64 BEGIN_MMU_FTR_SECTION b 2f END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX) BEGIN_FTR_SECTION clrrdi r6,r8,28 /* get its ESID */ clrrdi r9,r1,28 /* get current sp ESID */ FTR_SECTION_ELSE clrrdi r6,r8,40 /* get its 1T ESID */ clrrdi r9,r1,40 /* get current sp 1T ESID */ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_1T_SEGMENT) clrldi. r0,r6,2 /* is new ESID c00000000? */ cmpd cr1,r6,r9 /* or is new ESID the same as current ESID? */ cror eq,4*cr1+eq,eq beq 2f /* if yes, don't slbie it */ /* Bolt in the new stack SLB entry */ ld r7,KSP_VSID(r4) /* Get new stack's VSID */ oris r0,r6,(SLB_ESID_V)@h ori r0,r0,(SLB_NUM_BOLTED-1)@l BEGIN_FTR_SECTION li r9,MMU_SEGSIZE_1T /* insert B field */ oris r6,r6,(MMU_SEGSIZE_1T << SLBIE_SSIZE_SHIFT)@h rldimi r7,r9,SLB_VSID_SSIZE_SHIFT,0 END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT) /* Update the last bolted SLB. No write barriers are needed * here, provided we only update the current CPU's SLB shadow * buffer. */ ld r9,PACA_SLBSHADOWPTR(r13) li r12,0 std r12,SLBSHADOW_STACKESID(r9) /* Clear ESID */ li r12,SLBSHADOW_STACKVSID STDX_BE r7,r12,r9 /* Save VSID */ li r12,SLBSHADOW_STACKESID STDX_BE r0,r12,r9 /* Save ESID */ /* No need to check for MMU_FTR_NO_SLBIE_B here, since when * we have 1TB segments, the only CPUs known to have the errata * only support less than 1TB of system memory and we'll never * actually hit this code path. */ slbie r6 slbie r6 /* Workaround POWER5 < DD2.1 issue */ slbmte r7,r0 isync 2: #endif /* CONFIG_PPC_STD_MMU_64 */ CURRENT_THREAD_INFO(r7, r8) /* base of new stack */ /* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE because we don't need to leave the 288-byte ABI gap at the top of the kernel stack. */ addi r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE /* * PMU interrupts in radix may come in here. They will use r1, not * PACAKSAVE, so this stack switch will not cause a problem. They * will store to the process stack, which may then be migrated to * another CPU. However the rq lock release on this CPU paired with * the rq lock acquire on the new CPU before the stack becomes * active on the new CPU, will order those stores. */ mr r1,r8 /* start using new stack pointer */ std r7,PACAKSAVE(r13) ld r6,_CCR(r1) mtcrf 0xFF,r6 /* r3-r13 are destroyed -- Cort */ REST_8GPRS(14, r1) REST_10GPRS(22, r1) /* convert old thread to its task_struct for return value */ addi r3,r3,-THREAD ld r7,_NIP(r1) /* Return to _switch caller in new task */ mtlr r7 addi r1,r1,SWITCH_FRAME_SIZE blr .align 7 _GLOBAL(ret_from_except) ld r11,_TRAP(r1) andi. r0,r11,1 bne ret_from_except_lite REST_NVGPRS(r1) _GLOBAL(ret_from_except_lite) /* * Disable interrupts so that current_thread_info()->flags * can't change between when we test it and when we return * from the interrupt. */ #ifdef CONFIG_PPC_BOOK3E wrteei 0 #else li r10,MSR_RI mtmsrd r10,1 /* Update machine state */ #endif /* CONFIG_PPC_BOOK3E */ CURRENT_THREAD_INFO(r9, r1) ld r3,_MSR(r1) #ifdef CONFIG_PPC_BOOK3E ld r10,PACACURRENT(r13) #endif /* CONFIG_PPC_BOOK3E */ ld r4,TI_FLAGS(r9) andi. r3,r3,MSR_PR beq resume_kernel #ifdef CONFIG_PPC_BOOK3E lwz r3,(THREAD+THREAD_DBCR0)(r10) #endif /* CONFIG_PPC_BOOK3E */ /* Check current_thread_info()->flags */ andi. r0,r4,_TIF_USER_WORK_MASK bne 1f #ifdef CONFIG_PPC_BOOK3E /* * Check to see if the dbcr0 register is set up to debug. * Use the internal debug mode bit to do this. */ andis. r0,r3,DBCR0_IDM@h beq restore mfmsr r0 rlwinm r0,r0,0,~MSR_DE /* Clear MSR.DE */ mtmsr r0 mtspr SPRN_DBCR0,r3 li r10, -1 mtspr SPRN_DBSR,r10 b restore #else addi r3,r1,STACK_FRAME_OVERHEAD bl restore_math b restore #endif 1: andi. r0,r4,_TIF_NEED_RESCHED beq 2f bl restore_interrupts SCHEDULE_USER b ret_from_except_lite 2: #ifdef CONFIG_PPC_TRANSACTIONAL_MEM andi. r0,r4,_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM bne 3f /* only restore TM if nothing else to do */ addi r3,r1,STACK_FRAME_OVERHEAD bl restore_tm_state b restore 3: #endif bl save_nvgprs /* * Use a non volatile GPR to save and restore our thread_info flags * across the call to restore_interrupts. */ mr r30,r4 bl restore_interrupts mr r4,r30 addi r3,r1,STACK_FRAME_OVERHEAD bl do_notify_resume b ret_from_except resume_kernel: /* check current_thread_info, _TIF_EMULATE_STACK_STORE */ andis. r8,r4,_TIF_EMULATE_STACK_STORE@h beq+ 1f addi r8,r1,INT_FRAME_SIZE /* Get the kprobed function entry */ ld r3,GPR1(r1) subi r3,r3,INT_FRAME_SIZE /* dst: Allocate a trampoline exception frame */ mr r4,r1 /* src: current exception frame */ mr r1,r3 /* Reroute the trampoline frame to r1 */ /* Copy from the original to the trampoline. */ li r5,INT_FRAME_SIZE/8 /* size: INT_FRAME_SIZE */ li r6,0 /* start offset: 0 */ mtctr r5 2: ldx r0,r6,r4 stdx r0,r6,r3 addi r6,r6,8 bdnz 2b /* Do real store operation to complete stdu */ ld r5,GPR1(r1) std r8,0(r5) /* Clear _TIF_EMULATE_STACK_STORE flag */ lis r11,_TIF_EMULATE_STACK_STORE@h addi r5,r9,TI_FLAGS 0: ldarx r4,0,r5 andc r4,r4,r11 stdcx. r4,0,r5 bne- 0b 1: #ifdef CONFIG_PREEMPT /* Check if we need to preempt */ andi. r0,r4,_TIF_NEED_RESCHED beq+ restore /* Check that preempt_count() == 0 and interrupts are enabled */ lwz r8,TI_PREEMPT(r9) cmpwi cr1,r8,0 ld r0,SOFTE(r1) cmpdi r0,0 crandc eq,cr1*4+eq,eq bne restore /* * Here we are preempting the current task. We want to make * sure we are soft-disabled first and reconcile irq state. */ RECONCILE_IRQ_STATE(r3,r4) 1: bl preempt_schedule_irq /* Re-test flags and eventually loop */ CURRENT_THREAD_INFO(r9, r1) ld r4,TI_FLAGS(r9) andi. r0,r4,_TIF_NEED_RESCHED bne 1b /* * arch_local_irq_restore() from preempt_schedule_irq above may * enable hard interrupt but we really should disable interrupts * when we return from the interrupt, and so that we don't get * interrupted after loading SRR0/1. */ #ifdef CONFIG_PPC_BOOK3E wrteei 0 #else li r10,MSR_RI mtmsrd r10,1 /* Update machine state */ #endif /* CONFIG_PPC_BOOK3E */ #endif /* CONFIG_PREEMPT */ .globl fast_exc_return_irq fast_exc_return_irq: restore: /* * This is the main kernel exit path. First we check if we * are about to re-enable interrupts */ ld r5,SOFTE(r1) lbz r6,PACASOFTIRQEN(r13) cmpwi cr0,r5,0 beq restore_irq_off /* We are enabling, were we already enabled ? Yes, just return */ cmpwi cr0,r6,1 beq cr0,do_restore /* * We are about to soft-enable interrupts (we are hard disabled * at this point). We check if there's anything that needs to * be replayed first. */ lbz r0,PACAIRQHAPPENED(r13) cmpwi cr0,r0,0 bne- restore_check_irq_replay /* * Get here when nothing happened while soft-disabled, just * soft-enable and move-on. We will hard-enable as a side * effect of rfi */ restore_no_replay: TRACE_ENABLE_INTS li r0,1 stb r0,PACASOFTIRQEN(r13); /* * Final return path. BookE is handled in a different file */ do_restore: #ifdef CONFIG_PPC_BOOK3E b exception_return_book3e #else /* * Clear the reservation. If we know the CPU tracks the address of * the reservation then we can potentially save some cycles and use * a larx. On POWER6 and POWER7 this is significantly faster. */ BEGIN_FTR_SECTION stdcx. r0,0,r1 /* to clear the reservation */ FTR_SECTION_ELSE ldarx r4,0,r1 ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) /* * Some code path such as load_up_fpu or altivec return directly * here. They run entirely hard disabled and do not alter the * interrupt state. They also don't use lwarx/stwcx. and thus * are known not to leave dangling reservations. */ .globl fast_exception_return fast_exception_return: ld r3,_MSR(r1) ld r4,_CTR(r1) ld r0,_LINK(r1) mtctr r4 mtlr r0 ld r4,_XER(r1) mtspr SPRN_XER,r4 REST_8GPRS(5, r1) andi. r0,r3,MSR_RI beq- unrecov_restore /* Load PPR from thread struct before we clear MSR:RI */ BEGIN_FTR_SECTION ld r2,PACACURRENT(r13) ld r2,TASKTHREADPPR(r2) END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) /* * Clear RI before restoring r13. If we are returning to * userspace and we take an exception after restoring r13, * we end up corrupting the userspace r13 value. */ li r4,0 mtmsrd r4,1 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM /* TM debug */ std r3, PACATMSCRATCH(r13) /* Stash returned-to MSR */ #endif /* * r13 is our per cpu area, only restore it if we are returning to * userspace the value stored in the stack frame may belong to * another CPU. */ andi. r0,r3,MSR_PR beq 1f BEGIN_FTR_SECTION mtspr SPRN_PPR,r2 /* Restore PPR */ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) ACCOUNT_CPU_USER_EXIT(r13, r2, r4) REST_GPR(13, r1) 1: mtspr SPRN_SRR1,r3 ld r2,_CCR(r1) mtcrf 0xFF,r2 ld r2,_NIP(r1) mtspr SPRN_SRR0,r2 ld r0,GPR0(r1) ld r2,GPR2(r1) ld r3,GPR3(r1) ld r4,GPR4(r1) ld r1,GPR1(r1) rfid b . /* prevent speculative execution */ #endif /* CONFIG_PPC_BOOK3E */ /* * We are returning to a context with interrupts soft disabled. * * However, we may also about to hard enable, so we need to * make sure that in this case, we also clear PACA_IRQ_HARD_DIS * or that bit can get out of sync and bad things will happen */ restore_irq_off: ld r3,_MSR(r1) lbz r7,PACAIRQHAPPENED(r13) andi. r0,r3,MSR_EE beq 1f rlwinm r7,r7,0,~PACA_IRQ_HARD_DIS stb r7,PACAIRQHAPPENED(r13) 1: li r0,0 stb r0,PACASOFTIRQEN(r13); TRACE_DISABLE_INTS b do_restore /* * Something did happen, check if a re-emit is needed * (this also clears paca->irq_happened) */ restore_check_irq_replay: /* XXX: We could implement a fast path here where we check * for irq_happened being just 0x01, in which case we can * clear it and return. That means that we would potentially * miss a decrementer having wrapped all the way around. * * Still, this might be useful for things like hash_page */ bl __check_irq_replay cmpwi cr0,r3,0 beq restore_no_replay /* * We need to re-emit an interrupt. We do so by re-using our * existing exception frame. We first change the trap value, * but we need to ensure we preserve the low nibble of it */ ld r4,_TRAP(r1) clrldi r4,r4,60 or r4,r4,r3 std r4,_TRAP(r1) /* * Then find the right handler and call it. Interrupts are * still soft-disabled and we keep them that way. */ cmpwi cr0,r3,0x500 bne 1f addi r3,r1,STACK_FRAME_OVERHEAD; bl do_IRQ b ret_from_except 1: cmpwi cr0,r3,0xe60 bne 1f addi r3,r1,STACK_FRAME_OVERHEAD; bl handle_hmi_exception b ret_from_except 1: cmpwi cr0,r3,0x900 bne 1f addi r3,r1,STACK_FRAME_OVERHEAD; bl timer_interrupt b ret_from_except #ifdef CONFIG_PPC_DOORBELL 1: #ifdef CONFIG_PPC_BOOK3E cmpwi cr0,r3,0x280 #else BEGIN_FTR_SECTION cmpwi cr0,r3,0xe80 FTR_SECTION_ELSE cmpwi cr0,r3,0xa00 ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE) #endif /* CONFIG_PPC_BOOK3E */ bne 1f addi r3,r1,STACK_FRAME_OVERHEAD; bl doorbell_exception b ret_from_except #endif /* CONFIG_PPC_DOORBELL */ 1: b ret_from_except /* What else to do here ? */ unrecov_restore: addi r3,r1,STACK_FRAME_OVERHEAD bl unrecoverable_exception b unrecov_restore #ifdef CONFIG_PPC_RTAS /* * On CHRP, the Run-Time Abstraction Services (RTAS) have to be * called with the MMU off. * * In addition, we need to be in 32b mode, at least for now. * * Note: r3 is an input parameter to rtas, so don't trash it... */ _GLOBAL(enter_rtas) mflr r0 std r0,16(r1) stdu r1,-RTAS_FRAME_SIZE(r1) /* Save SP and create stack space. */ /* Because RTAS is running in 32b mode, it clobbers the high order half * of all registers that it saves. We therefore save those registers * RTAS might touch to the stack. (r0, r3-r13 are caller saved) */ SAVE_GPR(2, r1) /* Save the TOC */ SAVE_GPR(13, r1) /* Save paca */ SAVE_8GPRS(14, r1) /* Save the non-volatiles */ SAVE_10GPRS(22, r1) /* ditto */ mfcr r4 std r4,_CCR(r1) mfctr r5 std r5,_CTR(r1) mfspr r6,SPRN_XER std r6,_XER(r1) mfdar r7 std r7,_DAR(r1) mfdsisr r8 std r8,_DSISR(r1) /* Temporary workaround to clear CR until RTAS can be modified to * ignore all bits. */ li r0,0 mtcr r0 #ifdef CONFIG_BUG /* There is no way it is acceptable to get here with interrupts enabled, * check it with the asm equivalent of WARN_ON */ lbz r0,PACASOFTIRQEN(r13) 1: tdnei r0,0 EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING #endif /* Hard-disable interrupts */ mfmsr r6 rldicl r7,r6,48,1 rotldi r7,r7,16 mtmsrd r7,1 /* Unfortunately, the stack pointer and the MSR are also clobbered, * so they are saved in the PACA which allows us to restore * our original state after RTAS returns. */ std r1,PACAR1(r13) std r6,PACASAVEDMSR(r13) /* Setup our real return addr */ LOAD_REG_ADDR(r4,rtas_return_loc) clrldi r4,r4,2 /* convert to realmode address */ mtlr r4 li r0,0 ori r0,r0,MSR_EE|MSR_SE|MSR_BE|MSR_RI andc r0,r6,r0 li r9,1 rldicr r9,r9,MSR_SF_LG,(63-MSR_SF_LG) ori r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI|MSR_LE andc r6,r0,r9 sync /* disable interrupts so SRR0/1 */ mtmsrd r0 /* don't get trashed */ LOAD_REG_ADDR(r4, rtas) ld r5,RTASENTRY(r4) /* get the rtas->entry value */ ld r4,RTASBASE(r4) /* get the rtas->base value */ mtspr SPRN_SRR0,r5 mtspr SPRN_SRR1,r6 rfid b . /* prevent speculative execution */ rtas_return_loc: FIXUP_ENDIAN /* relocation is off at this point */ GET_PACA(r4) clrldi r4,r4,2 /* convert to realmode address */ bcl 20,31,$+4 0: mflr r3 ld r3,(1f-0b)(r3) /* get &rtas_restore_regs */ mfmsr r6 li r0,MSR_RI andc r6,r6,r0 sync mtmsrd r6 ld r1,PACAR1(r4) /* Restore our SP */ ld r4,PACASAVEDMSR(r4) /* Restore our MSR */ mtspr SPRN_SRR0,r3 mtspr SPRN_SRR1,r4 rfid b . /* prevent speculative execution */ .align 3 1: .llong rtas_restore_regs rtas_restore_regs: /* relocation is on at this point */ REST_GPR(2, r1) /* Restore the TOC */ REST_GPR(13, r1) /* Restore paca */ REST_8GPRS(14, r1) /* Restore the non-volatiles */ REST_10GPRS(22, r1) /* ditto */ GET_PACA(r13) ld r4,_CCR(r1) mtcr r4 ld r5,_CTR(r1) mtctr r5 ld r6,_XER(r1) mtspr SPRN_XER,r6 ld r7,_DAR(r1) mtdar r7 ld r8,_DSISR(r1) mtdsisr r8 addi r1,r1,RTAS_FRAME_SIZE /* Unstack our frame */ ld r0,16(r1) /* get return address */ mtlr r0 blr /* return to caller */ #endif /* CONFIG_PPC_RTAS */ _GLOBAL(enter_prom) mflr r0 std r0,16(r1) stdu r1,-PROM_FRAME_SIZE(r1) /* Save SP and create stack space */ /* Because PROM is running in 32b mode, it clobbers the high order half * of all registers that it saves. We therefore save those registers * PROM might touch to the stack. (r0, r3-r13 are caller saved) */ SAVE_GPR(2, r1) SAVE_GPR(13, r1) SAVE_8GPRS(14, r1) SAVE_10GPRS(22, r1) mfcr r10 mfmsr r11 std r10,_CCR(r1) std r11,_MSR(r1) /* Put PROM address in SRR0 */ mtsrr0 r4 /* Setup our trampoline return addr in LR */ bcl 20,31,$+4 0: mflr r4 addi r4,r4,(1f - 0b) mtlr r4 /* Prepare a 32-bit mode big endian MSR */ #ifdef CONFIG_PPC_BOOK3E rlwinm r11,r11,0,1,31 mtsrr1 r11 rfi #else /* CONFIG_PPC_BOOK3E */ LOAD_REG_IMMEDIATE(r12, MSR_SF | MSR_ISF | MSR_LE) andc r11,r11,r12 mtsrr1 r11 rfid #endif /* CONFIG_PPC_BOOK3E */ 1: /* Return from OF */ FIXUP_ENDIAN /* Just make sure that r1 top 32 bits didn't get * corrupt by OF */ rldicl r1,r1,0,32 /* Restore the MSR (back to 64 bits) */ ld r0,_MSR(r1) MTMSRD(r0) isync /* Restore other registers */ REST_GPR(2, r1) REST_GPR(13, r1) REST_8GPRS(14, r1) REST_10GPRS(22, r1) ld r4,_CCR(r1) mtcr r4 addi r1,r1,PROM_FRAME_SIZE ld r0,16(r1) mtlr r0 blr