/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * 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. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_PPC_BOOK3S #include #else #include #endif #include #include /* * System calls. */ .section ".text" #ifdef CONFIG_PPC_BOOK3S_64 #define FLUSH_COUNT_CACHE \ 1: nop; \ patch_site 1b, patch__call_flush_branch_caches1; \ 1: nop; \ patch_site 1b, patch__call_flush_branch_caches2; \ 1: nop; \ patch_site 1b, patch__call_flush_branch_caches3 .macro nops number .rept \number nop .endr .endm .balign 32 .global flush_branch_caches flush_branch_caches: /* Save LR into r9 */ mflr r9 // Flush the link stack .rept 64 bl .+4 .endr b 1f nops 6 .balign 32 /* Restore LR */ 1: mtlr r9 // If we're just flushing the link stack, return here 3: nop patch_site 3b patch__flush_link_stack_return li r9,0x7fff mtctr r9 PPC_BCCTR_FLUSH 2: nop patch_site 2b patch__flush_count_cache_return nops 3 .rept 278 .balign 32 PPC_BCCTR_FLUSH nops 7 .endr blr #else #define FLUSH_COUNT_CACHE #endif /* CONFIG_PPC_BOOK3S_64 */ /* * 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 interrupt_return. * 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_NVGPRS(r1) std r0,_NIP(r1) /* Return to switch caller */ mfcr r23 std r23,_CCR(r1) std r1,KSP(r3) /* Set old stack pointer */ kuap_check_amr r9, r10 FLUSH_COUNT_CACHE /* Clobbers r9, ctr */ /* * On SMP kernels, care must be taken because a task may be * scheduled off CPUx and on to CPUy. Memory ordering must be * considered. * * Cacheable stores on CPUx will be visible when the task is * scheduled on CPUy by virtue of the core scheduler barriers * (see "Notes on Program-Order guarantees on SMP systems." in * kernel/sched/core.c). * * Uncacheable stores in the case of involuntary preemption must * be taken care of. The smp_mb__after_spinlock() in __schedule() * is implemented as hwsync on powerpc, which orders MMIO too. So * long as there is an hwsync in the context switch path, it will * be executed on the source CPU after the task has performed * all MMIO ops on that CPU, and on the destination CPU before the * task performs any MMIO ops there. */ /* * The kernel context switch path must contain a spin_lock, * which contains larx/stcx, which will clear any reservation * of the task being switched. */ #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_BOOK3S_STOP_ALL_STREAM_IDS(r6) #endif addi r6,r4,-THREAD /* Convert THREAD to 'current' */ std r6,PACACURRENT(r13) /* Set new 'current' */ #if defined(CONFIG_STACKPROTECTOR) ld r6, TASK_CANARY(r6) std r6, PACA_CANARY(r13) #endif ld r8,KSP(r4) /* new stack pointer */ #ifdef CONFIG_PPC_64S_HASH_MMU 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. */ isync slbie r6 BEGIN_FTR_SECTION slbie r6 /* Workaround POWER5 < DD2.1 issue */ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S) slbmte r7,r0 isync 2: #endif /* CONFIG_PPC_64S_HASH_MMU */ clrrdi r7, r8, THREAD_SHIFT /* 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_NVGPRS(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 #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,-SWITCH_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_NVGPRS(r1) /* Save the non-volatiles */ 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,PACAIRQSOFTMASK(r13) 1: tdeqi r0,IRQS_ENABLED EMIT_WARN_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 __enter_rtas: LOAD_REG_ADDR(r4, rtas) ld r5,RTASENTRY(r4) /* get the rtas->entry value */ ld r4,RTASBASE(r4) /* get the rtas->base value */ /* * RTAS runs in 32-bit big endian real mode, but leave MSR[RI] on as we * may hit NMI (SRESET or MCE) while in RTAS. RTAS should disable RI in * its critical regions (as specified in PAPR+ section 7.2.1). MSR[S] * is not impacted by RFI_TO_KERNEL (only urfid can unset it). So if * MSR[S] is set, it will remain when entering RTAS. */ LOAD_REG_IMMEDIATE(r6, MSR_ME | MSR_RI) li r0,0 mtmsrd r0,1 /* disable RI before using SRR0/1 */ mtspr SPRN_SRR0,r5 mtspr SPRN_SRR1,r6 RFI_TO_KERNEL b . /* prevent speculative execution */ rtas_return_loc: FIXUP_ENDIAN /* * Clear RI and set SF before anything. */ mfmsr r6 li r0,MSR_RI andc r6,r6,r0 sldi r0,r0,(MSR_SF_LG - MSR_RI_LG) or r6,r6,r0 sync mtmsrd r6 /* relocation is off at this point */ GET_PACA(r4) clrldi r4,r4,2 /* convert to realmode address */ bcl 20,31,$+4 0: mflr r3 ld r3,(1f-0b)(r3) /* get &rtas_restore_regs */ ld r1,PACAR1(r4) /* Restore our SP */ ld r4,PACASAVEDMSR(r4) /* Restore our MSR */ mtspr SPRN_SRR0,r3 mtspr SPRN_SRR1,r4 RFI_TO_KERNEL b . /* prevent speculative execution */ _ASM_NOKPROBE_SYMBOL(__enter_rtas) _ASM_NOKPROBE_SYMBOL(rtas_return_loc) .align 3 1: .8byte rtas_restore_regs rtas_restore_regs: /* relocation is on at this point */ REST_GPR(2, r1) /* Restore the TOC */ REST_GPR(13, r1) /* Restore paca */ REST_NVGPRS(r1) /* Restore the non-volatiles */ GET_PACA(r13) ld r4,_CCR(r1) mtcr r4 ld r5,_CTR(r1) mtctr r5 ld r6,_XER(r1) mtspr SPRN_XER,r6 ld r7,_DAR(r1) mtdar r7 ld r8,_DSISR(r1) mtdsisr r8 addi r1,r1,SWITCH_FRAME_SIZE /* Unstack our frame */ ld r0,16(r1) /* get return address */ mtlr r0 blr /* return to caller */ #endif /* CONFIG_PPC_RTAS */ _GLOBAL(enter_prom) mflr r0 std r0,16(r1) stdu r1,-SWITCH_FRAME_SIZE(r1) /* Save SP and create stack space */ /* Because PROM is running in 32b mode, it clobbers the high order half * of all registers that it saves. We therefore save those registers * PROM might touch to the stack. (r0, r3-r13 are caller saved) */ SAVE_GPR(2, r1) SAVE_GPR(13, r1) SAVE_NVGPRS(r1) mfcr r10 mfmsr r11 std r10,_CCR(r1) std r11,_MSR(r1) /* Put PROM address in SRR0 */ mtsrr0 r4 /* Setup our trampoline return addr in LR */ bcl 20,31,$+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_LE) andc r11,r11,r12 mtsrr1 r11 RFI_TO_KERNEL #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_NVGPRS(r1) ld r4,_CCR(r1) mtcr r4 addi r1,r1,SWITCH_FRAME_SIZE ld r0,16(r1) mtlr r0 blr