1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
  4 *  Chen Liqin <liqin.chen@sunplusct.com>
  5 *  Lennox Wu <lennox.wu@sunplusct.com>
  6 * Copyright (C) 2012 Regents of the University of California
  7 * Copyright (C) 2017 SiFive
  8 */
  9
 10#include <linux/cpu.h>
 11#include <linux/kernel.h>
 12#include <linux/sched.h>
 13#include <linux/sched/debug.h>
 14#include <linux/sched/task_stack.h>
 15#include <linux/tick.h>
 16#include <linux/ptrace.h>
 17#include <linux/uaccess.h>
 18
 19#include <asm/unistd.h>
 20#include <asm/processor.h>
 21#include <asm/csr.h>
 22#include <asm/stacktrace.h>
 23#include <asm/string.h>
 24#include <asm/switch_to.h>
 25#include <asm/thread_info.h>
 26#include <asm/cpuidle.h>
 27
 28register unsigned long gp_in_global __asm__("gp");
 29
 30#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
 31#include <linux/stackprotector.h>
 32unsigned long __stack_chk_guard __read_mostly;
 33EXPORT_SYMBOL(__stack_chk_guard);
 34#endif
 35
 36extern asmlinkage void ret_from_fork(void);
 37extern asmlinkage void ret_from_kernel_thread(void);
 38
 39void arch_cpu_idle(void)
 40{
 41	cpu_do_idle();
 42	raw_local_irq_enable();
 43}
 44
 45void __show_regs(struct pt_regs *regs)
 46{
 47	show_regs_print_info(KERN_DEFAULT);
 48
 49	if (!user_mode(regs)) {
 50		pr_cont("epc : %pS\n", (void *)regs->epc);
 51		pr_cont(" ra : %pS\n", (void *)regs->ra);
 52	}
 53
 54	pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
 55		regs->epc, regs->ra, regs->sp);
 56	pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
 57		regs->gp, regs->tp, regs->t0);
 58	pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
 59		regs->t1, regs->t2, regs->s0);
 60	pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
 61		regs->s1, regs->a0, regs->a1);
 62	pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
 63		regs->a2, regs->a3, regs->a4);
 64	pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
 65		regs->a5, regs->a6, regs->a7);
 66	pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
 67		regs->s2, regs->s3, regs->s4);
 68	pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
 69		regs->s5, regs->s6, regs->s7);
 70	pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
 71		regs->s8, regs->s9, regs->s10);
 72	pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
 73		regs->s11, regs->t3, regs->t4);
 74	pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
 75		regs->t5, regs->t6);
 76
 77	pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
 78		regs->status, regs->badaddr, regs->cause);
 79}
 80void show_regs(struct pt_regs *regs)
 81{
 82	__show_regs(regs);
 83	if (!user_mode(regs))
 84		dump_backtrace(regs, NULL, KERN_DEFAULT);
 85}
 86
 87#ifdef CONFIG_COMPAT
 88static bool compat_mode_supported __read_mostly;
 89
 90bool compat_elf_check_arch(Elf32_Ehdr *hdr)
 91{
 92	return compat_mode_supported &&
 93	       hdr->e_machine == EM_RISCV &&
 94	       hdr->e_ident[EI_CLASS] == ELFCLASS32;
 95}
 96
 97static int __init compat_mode_detect(void)
 98{
 99	unsigned long tmp = csr_read(CSR_STATUS);
100
101	csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
102	compat_mode_supported =
103			(csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;
104
105	csr_write(CSR_STATUS, tmp);
106
107	pr_info("riscv: ELF compat mode %s",
108			compat_mode_supported ? "supported" : "unsupported");
109
110	return 0;
111}
112early_initcall(compat_mode_detect);
113#endif
114
115void start_thread(struct pt_regs *regs, unsigned long pc,
116	unsigned long sp)
117{
118	regs->status = SR_PIE;
119	if (has_fpu()) {
120		regs->status |= SR_FS_INITIAL;
121		/*
122		 * Restore the initial value to the FP register
123		 * before starting the user program.
124		 */
125		fstate_restore(current, regs);
126	}
127	regs->epc = pc;
128	regs->sp = sp;
129
130#ifdef CONFIG_64BIT
131	regs->status &= ~SR_UXL;
132
133	if (is_compat_task())
134		regs->status |= SR_UXL_32;
135	else
136		regs->status |= SR_UXL_64;
137#endif
138}
139
140void flush_thread(void)
141{
142#ifdef CONFIG_FPU
143	/*
144	 * Reset FPU state and context
145	 *	frm: round to nearest, ties to even (IEEE default)
146	 *	fflags: accrued exceptions cleared
147	 */
148	fstate_off(current, task_pt_regs(current));
149	memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
150#endif
151}
152
153int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
154{
155	fstate_save(src, task_pt_regs(src));
156	*dst = *src;
157	return 0;
158}
159
160int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
161{
162	unsigned long clone_flags = args->flags;
163	unsigned long usp = args->stack;
164	unsigned long tls = args->tls;
165	struct pt_regs *childregs = task_pt_regs(p);
166
167	memset(&p->thread.s, 0, sizeof(p->thread.s));
168
169	/* p->thread holds context to be restored by __switch_to() */
170	if (unlikely(args->fn)) {
171		/* Kernel thread */
172		memset(childregs, 0, sizeof(struct pt_regs));
173		childregs->gp = gp_in_global;
174		/* Supervisor/Machine, irqs on: */
175		childregs->status = SR_PP | SR_PIE;
176
177		p->thread.ra = (unsigned long)ret_from_kernel_thread;
178		p->thread.s[0] = (unsigned long)args->fn;
179		p->thread.s[1] = (unsigned long)args->fn_arg;
180	} else {
181		*childregs = *(current_pt_regs());
182		if (usp) /* User fork */
183			childregs->sp = usp;
184		if (clone_flags & CLONE_SETTLS)
185			childregs->tp = tls;
186		childregs->a0 = 0; /* Return value of fork() */
187		p->thread.ra = (unsigned long)ret_from_fork;
188	}
189	p->thread.sp = (unsigned long)childregs; /* kernel sp */
190	return 0;
191}