1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Low-level SPU handling
4 *
5 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
6 *
7 * Author: Arnd Bergmann <arndb@de.ibm.com>
8 */
9#include <linux/sched/signal.h>
10#include <linux/mm.h>
11
12#include <asm/spu.h>
13#include <asm/spu_csa.h>
14
15#include "spufs.h"
16
17/**
18 * Handle an SPE event, depending on context SPU_CREATE_EVENTS_ENABLED flag.
19 *
20 * If the context was created with events, we just set the return event.
21 * Otherwise, send an appropriate signal to the process.
22 */
23static void spufs_handle_event(struct spu_context *ctx,
24 unsigned long ea, int type)
25{
26 if (ctx->flags & SPU_CREATE_EVENTS_ENABLED) {
27 ctx->event_return |= type;
28 wake_up_all(&ctx->stop_wq);
29 return;
30 }
31
32 switch (type) {
33 case SPE_EVENT_INVALID_DMA:
34 force_sig_fault(SIGBUS, BUS_OBJERR, NULL);
35 break;
36 case SPE_EVENT_SPE_DATA_STORAGE:
37 ctx->ops->restart_dma(ctx);
38 force_sig_fault(SIGSEGV, SEGV_ACCERR, addr: (void __user *)ea);
39 break;
40 case SPE_EVENT_DMA_ALIGNMENT:
41 /* DAR isn't set for an alignment fault :( */
42 force_sig_fault(SIGBUS, BUS_ADRALN, NULL);
43 break;
44 case SPE_EVENT_SPE_ERROR:
45 force_sig_fault(
46 SIGILL, ILL_ILLOPC,
47 addr: (void __user *)(unsigned long)
48 ctx->ops->npc_read(ctx) - 4);
49 break;
50 }
51}
52
53int spufs_handle_class0(struct spu_context *ctx)
54{
55 unsigned long stat = ctx->csa.class_0_pending & CLASS0_INTR_MASK;
56
57 if (likely(!stat))
58 return 0;
59
60 if (stat & CLASS0_DMA_ALIGNMENT_INTR)
61 spufs_handle_event(ctx, ea: ctx->csa.class_0_dar,
62 type: SPE_EVENT_DMA_ALIGNMENT);
63
64 if (stat & CLASS0_INVALID_DMA_COMMAND_INTR)
65 spufs_handle_event(ctx, ea: ctx->csa.class_0_dar,
66 type: SPE_EVENT_INVALID_DMA);
67
68 if (stat & CLASS0_SPU_ERROR_INTR)
69 spufs_handle_event(ctx, ea: ctx->csa.class_0_dar,
70 type: SPE_EVENT_SPE_ERROR);
71
72 ctx->csa.class_0_pending = 0;
73
74 return -EIO;
75}
76
77/*
78 * bottom half handler for page faults, we can't do this from
79 * interrupt context, since we might need to sleep.
80 * we also need to give up the mutex so we can get scheduled
81 * out while waiting for the backing store.
82 *
83 * TODO: try calling hash_page from the interrupt handler first
84 * in order to speed up the easy case.
85 */
86int spufs_handle_class1(struct spu_context *ctx)
87{
88 u64 ea, dsisr, access;
89 unsigned long flags;
90 vm_fault_t flt = 0;
91 int ret;
92
93 /*
94 * dar and dsisr get passed from the registers
95 * to the spu_context, to this function, but not
96 * back to the spu if it gets scheduled again.
97 *
98 * if we don't handle the fault for a saved context
99 * in time, we can still expect to get the same fault
100 * the immediately after the context restore.
101 */
102 ea = ctx->csa.class_1_dar;
103 dsisr = ctx->csa.class_1_dsisr;
104
105 if (!(dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED)))
106 return 0;
107
108 spuctx_switch_state(ctx, new_state: SPU_UTIL_IOWAIT);
109
110 pr_debug("ctx %p: ea %016llx, dsisr %016llx state %d\n", ctx, ea,
111 dsisr, ctx->state);
112
113 ctx->stats.hash_flt++;
114 if (ctx->state == SPU_STATE_RUNNABLE)
115 ctx->spu->stats.hash_flt++;
116
117 /* we must not hold the lock when entering copro_handle_mm_fault */
118 spu_release(ctx);
119
120 access = (_PAGE_PRESENT | _PAGE_READ);
121 access |= (dsisr & MFC_DSISR_ACCESS_PUT) ? _PAGE_WRITE : 0UL;
122 local_irq_save(flags);
123 ret = hash_page(ea, access, 0x300, dsisr);
124 local_irq_restore(flags);
125
126 /* hashing failed, so try the actual fault handler */
127 if (ret)
128 ret = copro_handle_mm_fault(current->mm, ea, dsisr, &flt);
129
130 /*
131 * This is nasty: we need the state_mutex for all the bookkeeping even
132 * if the syscall was interrupted by a signal. ewww.
133 */
134 mutex_lock(&ctx->state_mutex);
135
136 /*
137 * Clear dsisr under ctxt lock after handling the fault, so that
138 * time slicing will not preempt the context while the page fault
139 * handler is running. Context switch code removes mappings.
140 */
141 ctx->csa.class_1_dar = ctx->csa.class_1_dsisr = 0;
142
143 /*
144 * If we handled the fault successfully and are in runnable
145 * state, restart the DMA.
146 * In case of unhandled error report the problem to user space.
147 */
148 if (!ret) {
149 if (flt & VM_FAULT_MAJOR)
150 ctx->stats.maj_flt++;
151 else
152 ctx->stats.min_flt++;
153 if (ctx->state == SPU_STATE_RUNNABLE) {
154 if (flt & VM_FAULT_MAJOR)
155 ctx->spu->stats.maj_flt++;
156 else
157 ctx->spu->stats.min_flt++;
158 }
159
160 if (ctx->spu)
161 ctx->ops->restart_dma(ctx);
162 } else
163 spufs_handle_event(ctx, ea, type: SPE_EVENT_SPE_DATA_STORAGE);
164
165 spuctx_switch_state(ctx, new_state: SPU_UTIL_SYSTEM);
166 return ret;
167}
168

source code of linux/arch/powerpc/platforms/cell/spufs/fault.c