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Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S new file mode 100644 index 000000000..3e2e37e6e --- /dev/null +++ b/arch/powerpc/kernel/entry_64.S @@ -0,0 +1,329 @@ +/* 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 <cort@cs.nmt.edu> + * 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 <linux/errno.h> +#include <linux/err.h> +#include <asm/cache.h> +#include <asm/unistd.h> +#include <asm/processor.h> +#include <asm/page.h> +#include <asm/mmu.h> +#include <asm/thread_info.h> +#include <asm/code-patching-asm.h> +#include <asm/ppc_asm.h> +#include <asm/asm-offsets.h> +#include <asm/cputable.h> +#include <asm/firmware.h> +#include <asm/bug.h> +#include <asm/ptrace.h> +#include <asm/irqflags.h> +#include <asm/hw_irq.h> +#include <asm/context_tracking.h> +#include <asm/ppc-opcode.h> +#include <asm/barrier.h> +#include <asm/export.h> +#include <asm/asm-compat.h> +#ifdef CONFIG_PPC_BOOK3S +#include <asm/exception-64s.h> +#else +#include <asm/exception-64e.h> +#endif +#include <asm/feature-fixups.h> +#include <asm/kup.h> + +/* + * 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 + +_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_64 + rlwinm r11,r11,0,1,31 + mtsrr1 r11 + rfi +#else /* CONFIG_PPC_BOOK3E_64 */ + LOAD_REG_IMMEDIATE(r12, MSR_SF | MSR_LE) + andc r11,r11,r12 + mtsrr1 r11 + RFI_TO_KERNEL +#endif /* CONFIG_PPC_BOOK3E_64 */ + +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 |