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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * arch/sh/kernel/process.c
4 *
5 * This file handles the architecture-dependent parts of process handling..
6 *
7 * Copyright (C) 1995 Linus Torvalds
8 *
9 * SuperH version: Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
10 * Copyright (C) 2006 Lineo Solutions Inc. support SH4A UBC
11 * Copyright (C) 2002 - 2008 Paul Mundt
12 */
13#include <linux/module.h>
14#include <linux/mm.h>
15#include <linux/sched/debug.h>
16#include <linux/sched/task.h>
17#include <linux/sched/task_stack.h>
18#include <linux/slab.h>
19#include <linux/elfcore.h>
20#include <linux/fs.h>
21#include <linux/ftrace.h>
22#include <linux/hw_breakpoint.h>
23#include <linux/prefetch.h>
24#include <linux/stackprotector.h>
25#include <linux/uaccess.h>
26#include <asm/mmu_context.h>
27#include <asm/fpu.h>
28#include <asm/syscalls.h>
29#include <asm/switch_to.h>
30
31void show_regs(struct pt_regs * regs)
32{
33 pr_info("\n");
34 show_regs_print_info(KERN_DEFAULT);
35
36 pr_info("PC is at %pS\n", (void *)instruction_pointer(regs));
37 pr_info("PR is at %pS\n", (void *)regs->pr);
38
39 pr_info("PC : %08lx SP : %08lx SR : %08lx ", regs->pc,
40 regs->regs[15], regs->sr);
41#ifdef CONFIG_MMU
42 pr_cont("TEA : %08x\n", __raw_readl(MMU_TEA));
43#else
44 pr_cont("\n");
45#endif
46
47 pr_info("R0 : %08lx R1 : %08lx R2 : %08lx R3 : %08lx\n",
48 regs->regs[0], regs->regs[1], regs->regs[2], regs->regs[3]);
49 pr_info("R4 : %08lx R5 : %08lx R6 : %08lx R7 : %08lx\n",
50 regs->regs[4], regs->regs[5], regs->regs[6], regs->regs[7]);
51 pr_info("R8 : %08lx R9 : %08lx R10 : %08lx R11 : %08lx\n",
52 regs->regs[8], regs->regs[9], regs->regs[10], regs->regs[11]);
53 pr_info("R12 : %08lx R13 : %08lx R14 : %08lx\n",
54 regs->regs[12], regs->regs[13], regs->regs[14]);
55 pr_info("MACH: %08lx MACL: %08lx GBR : %08lx PR : %08lx\n",
56 regs->mach, regs->macl, regs->gbr, regs->pr);
57
58 show_trace(NULL, (unsigned long *)regs->regs[15], regs, KERN_DEFAULT);
59 show_code(regs);
60}
61
62void start_thread(struct pt_regs *regs, unsigned long new_pc,
63 unsigned long new_sp)
64{
65 regs->pr = 0;
66 regs->sr = SR_FD;
67 regs->pc = new_pc;
68 regs->regs[15] = new_sp;
69
70 free_thread_xstate(current);
71}
72EXPORT_SYMBOL(start_thread);
73
74void flush_thread(void)
75{
76 struct task_struct *tsk = current;
77
78 flush_ptrace_hw_breakpoint(tsk);
79
80#if defined(CONFIG_SH_FPU)
81 /* Forget lazy FPU state */
82 clear_fpu(tsk, task_pt_regs(tsk));
83 clear_used_math();
84#endif
85}
86
87asmlinkage void ret_from_fork(void);
88asmlinkage void ret_from_kernel_thread(void);
89
90int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
91{
92 u64 clone_flags = args->flags;
93 unsigned long usp = args->stack;
94 unsigned long tls = args->tls;
95 struct thread_info *ti = task_thread_info(p);
96 struct pt_regs *childregs;
97
98#if defined(CONFIG_SH_DSP)
99 struct task_struct *tsk = current;
100
101 if (is_dsp_enabled(tsk)) {
102 /* We can use the __save_dsp or just copy the struct:
103 * __save_dsp(p);
104 * p->thread.dsp_status.status |= SR_DSP
105 */
106 p->thread.dsp_status = tsk->thread.dsp_status;
107 }
108#endif
109
110 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
111
112 childregs = task_pt_regs(p);
113 p->thread.sp = (unsigned long) childregs;
114 if (unlikely(args->fn)) {
115 memset(childregs, 0, sizeof(struct pt_regs));
116 p->thread.pc = (unsigned long) ret_from_kernel_thread;
117 childregs->regs[4] = (unsigned long) args->fn_arg;
118 childregs->regs[5] = (unsigned long) args->fn;
119 childregs->sr = SR_MD;
120#if defined(CONFIG_SH_FPU)
121 childregs->sr |= SR_FD;
122#endif
123 ti->status &= ~TS_USEDFPU;
124 p->thread.fpu_counter = 0;
125 return 0;
126 }
127 *childregs = *current_pt_regs();
128
129 if (usp)
130 childregs->regs[15] = usp;
131
132 if (clone_flags & CLONE_SETTLS)
133 childregs->gbr = tls;
134
135 childregs->regs[0] = 0; /* Set return value for child */
136 p->thread.pc = (unsigned long) ret_from_fork;
137 return 0;
138}
139
140/*
141 * switch_to(x,y) should switch tasks from x to y.
142 *
143 */
144__notrace_funcgraph struct task_struct *
145__switch_to(struct task_struct *prev, struct task_struct *next)
146{
147 struct thread_struct *next_t = &next->thread;
148
149#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)
150 __stack_chk_guard = next->stack_canary;
151#endif
152
153 unlazy_fpu(prev, task_pt_regs(prev));
154
155 /* we're going to use this soon, after a few expensive things */
156 if (next->thread.fpu_counter > 5)
157 prefetch(next_t->xstate);
158
159#ifdef CONFIG_MMU
160 /*
161 * Restore the kernel mode register
162 * k7 (r7_bank1)
163 */
164 asm volatile("ldc %0, r7_bank"
165 : /* no output */
166 : "r" (task_thread_info(next)));
167#endif
168
169 /*
170 * If the task has used fpu the last 5 timeslices, just do a full
171 * restore of the math state immediately to avoid the trap; the
172 * chances of needing FPU soon are obviously high now
173 */
174 if (next->thread.fpu_counter > 5)
175 __fpu_state_restore();
176
177 return prev;
178}
179
180unsigned long __get_wchan(struct task_struct *p)
181{
182 unsigned long pc;
183
184 /*
185 * The same comment as on the Alpha applies here, too ...
186 */
187 pc = thread_saved_pc(p);
188
189#ifdef CONFIG_FRAME_POINTER
190 if (in_sched_functions(pc)) {
191 unsigned long schedule_frame = (unsigned long)p->thread.sp;
192 return ((unsigned long *)schedule_frame)[21];
193 }
194#endif
195
196 return pc;
197}