arch/loongarch/kernel/process.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Author: Huacai Chen <chenhuacai@loongson.cn>
  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
  *
  * Derived from MIPS:
  * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
  * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
  * Copyright (C) 2004 Thiemo Seufer
  * Copyright (C) 2013  Imagination Technologies Ltd.
  */
 #include <linux/cpu.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task.h>
 #include <linux/sched/task_stack.h>
 #include <linux/mm.h>
 #include <linux/stddef.h>
 #include <linux/unistd.h>
 #include <linux/export.h>
 #include <linux/ptrace.h>
 #include <linux/mman.h>
 #include <linux/personality.h>
 #include <linux/sys.h>
 #include <linux/completion.h>
 #include <linux/kallsyms.h>
 #include <linux/random.h>
 #include <linux/prctl.h>
 #include <linux/nmi.h>

 #include <asm/asm.h>
 #include <asm/bootinfo.h>
 #include <asm/cpu.h>
 #include <asm/elf.h>
 #include <asm/fpu.h>
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
 #include <asm/loongarch.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/reg.h>
 #include <asm/unwind.h>
 #include <asm/vdso.h>

 /*
  * Idle related variables and functions
  */

 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
 EXPORT_SYMBOL(boot_option_idle_override);

 #ifdef CONFIG_HOTPLUG_CPU
 void arch_cpu_idle_dead(void)
 {
 	play_dead();
 }
 #endif

 asmlinkage void ret_from_fork(void);
 asmlinkage void ret_from_kernel_thread(void);

 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
 {
 	unsigned long crmd;
 	unsigned long prmd;
 	unsigned long euen;

 	/* New thread loses kernel privileges. */
 	crmd = regs->csr_crmd & ~(PLV_MASK);
 	crmd |= PLV_USER;
 	regs->csr_crmd = crmd;

 	prmd = regs->csr_prmd & ~(PLV_MASK);
 	prmd |= PLV_USER;
 	regs->csr_prmd = prmd;

 	euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
 	regs->csr_euen = euen;
 	lose_fpu(0);

 	clear_thread_flag(TIF_LSX_CTX_LIVE);
 	clear_thread_flag(TIF_LASX_CTX_LIVE);
 	clear_used_math();
 	regs->csr_era = pc;
 	regs->regs[3] = sp;
 }

 void exit_thread(struct task_struct *tsk)
 {
 }

 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
 	/*
 	 * Save any process state which is live in hardware registers to the
 	 * parent context prior to duplication. This prevents the new child
 	 * state becoming stale if the parent is preempted before copy_thread()
 	 * gets a chance to save the parent's live hardware registers to the
 	 * child context.
 	 */
 	preempt_disable();

 	if (is_fpu_owner())
 		save_fp(current);

 	preempt_enable();

 	if (used_math())
 		memcpy(dst, src, sizeof(struct task_struct));
 	else
 		memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));

 	return 0;
 }

 /*
  * Copy architecture-specific thread state
  */
 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 {
 	unsigned long childksp;
 	unsigned long tls = args->tls;
 	unsigned long usp = args->stack;
 	unsigned long clone_flags = args->flags;
 	struct pt_regs *childregs, *regs = current_pt_regs();

 	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

 	/* set up new TSS. */
 	childregs = (struct pt_regs *) childksp - 1;
 	/*  Put the stack after the struct pt_regs.  */
 	childksp = (unsigned long) childregs;
 	p->thread.sched_cfa = 0;
 	p->thread.csr_euen = 0;
 	p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
 	p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
 	p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
 	if (unlikely(args->fn)) {
 		/* kernel thread */
 		p->thread.reg03 = childksp;
 		p->thread.reg23 = (unsigned long)args->fn;
 		p->thread.reg24 = (unsigned long)args->fn_arg;
 		p->thread.reg01 = (unsigned long)ret_from_kernel_thread;
 		p->thread.sched_ra = (unsigned long)ret_from_kernel_thread;
 		memset(childregs, 0, sizeof(struct pt_regs));
 		childregs->csr_euen = p->thread.csr_euen;
 		childregs->csr_crmd = p->thread.csr_crmd;
 		childregs->csr_prmd = p->thread.csr_prmd;
 		childregs->csr_ecfg = p->thread.csr_ecfg;
 		goto out;
 	}

 	/* user thread */
 	*childregs = *regs;
 	childregs->regs[4] = 0; /* Child gets zero as return value */
 	if (usp)
 		childregs->regs[3] = usp;

 	p->thread.reg03 = (unsigned long) childregs;
 	p->thread.reg01 = (unsigned long) ret_from_fork;
 	p->thread.sched_ra = (unsigned long) ret_from_fork;

 	/*
 	 * New tasks lose permission to use the fpu. This accelerates context
 	 * switching for most programs since they don't use the fpu.
 	 */
 	childregs->csr_euen = 0;

 	if (clone_flags & CLONE_SETTLS)
 		childregs->regs[2] = tls;

 out:
 	clear_tsk_thread_flag(p, TIF_USEDFPU);
 	clear_tsk_thread_flag(p, TIF_USEDSIMD);
 	clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
 	clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);

 	return 0;
 }

 unsigned long __get_wchan(struct task_struct *task)
 {
 	unsigned long pc = 0;
 	struct unwind_state state;

 	if (!try_get_task_stack(task))
 		return 0;

 	for (unwind_start(&state, task, NULL);
 	     !unwind_done(&state); unwind_next_frame(&state)) {
 		pc = unwind_get_return_address(&state);
 		if (!pc)
 			break;
 		if (in_sched_functions(pc))
 			continue;
 		break;
 	}

 	put_task_stack(task);

 	return pc;
 }

 bool in_irq_stack(unsigned long stack, struct stack_info *info)
 {
 	unsigned long nextsp;
 	unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
 	unsigned long end = begin + IRQ_STACK_START;

 	if (stack < begin || stack >= end)
 		return false;

 	nextsp = *(unsigned long *)end;
 	if (nextsp & (SZREG - 1))
 		return false;

 	info->begin = begin;
 	info->end = end;
 	info->next_sp = nextsp;
 	info->type = STACK_TYPE_IRQ;

 	return true;
 }

 bool in_task_stack(unsigned long stack, struct task_struct *task,
 			struct stack_info *info)
 {
 	unsigned long begin = (unsigned long)task_stack_page(task);
 	unsigned long end = begin + THREAD_SIZE;

 	if (stack < begin || stack >= end)
 		return false;

 	info->begin = begin;
 	info->end = end;
 	info->next_sp = 0;
 	info->type = STACK_TYPE_TASK;

 	return true;
 }

 int get_stack_info(unsigned long stack, struct task_struct *task,
 		   struct stack_info *info)
 {
 	task = task ? : current;

 	if (!stack || stack & (SZREG - 1))
 		goto unknown;

 	if (in_task_stack(stack, task, info))
 		return 0;

 	if (task != current)
 		goto unknown;

 	if (in_irq_stack(stack, info))
 		return 0;

 unknown:
 	info->type = STACK_TYPE_UNKNOWN;
 	return -EINVAL;
 }

 unsigned long stack_top(void)
 {
 	unsigned long top = TASK_SIZE & PAGE_MASK;

 	/* Space for the VDSO & data page */
 	top -= PAGE_ALIGN(current->thread.vdso->size);
 	top -= PAGE_SIZE;

 	/* Space to randomize the VDSO base */
 	if (current->flags & PF_RANDOMIZE)
 		top -= VDSO_RANDOMIZE_SIZE;

 	return top;
 }

 /*
  * Don't forget that the stack pointer must be aligned on a 8 bytes
  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
  */
 unsigned long arch_align_stack(unsigned long sp)
 {
 	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 		sp -= prandom_u32_max(PAGE_SIZE);

 	return sp & STACK_ALIGN;
 }

 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
 static struct cpumask backtrace_csd_busy;

 static void handle_backtrace(void *info)
 {
 	nmi_cpu_backtrace(get_irq_regs());
 	cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
 }

 static void raise_backtrace(cpumask_t *mask)
 {
 	call_single_data_t *csd;
 	int cpu;

 	for_each_cpu(cpu, mask) {
 		/*
 		 * If we previously sent an IPI to the target CPU & it hasn't
 		 * cleared its bit in the busy cpumask then it didn't handle
 		 * our previous IPI & it's not safe for us to reuse the
 		 * call_single_data_t.
 		 */
 		if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
 			pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
 				cpu);
 			continue;
 		}

 		csd = &per_cpu(backtrace_csd, cpu);
 		csd->func = handle_backtrace;
 		smp_call_function_single_async(cpu, csd);
 	}
 }

 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 {
 	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
 }

 #ifdef CONFIG_64BIT
 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
 {
 	unsigned int i;

 	for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
 		uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
 	}

 	uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
 	uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
 	uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
 	uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
 	uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
 	uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
 	uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
 	uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
 }
 #endif /* CONFIG_64BIT */
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Author: Huacai Chen <chenhuacai@loongson.cn>
	* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
	*
	* Derived from MIPS:
	* Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
	* Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
	* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
	* Copyright (C) 2004 Thiemo Seufer
	* Copyright (C) 2013 Imagination Technologies Ltd.
	*/
	#include <linux/cpu.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/sched.h>
	#include <linux/sched/debug.h>
	#include <linux/sched/task.h>
	#include <linux/sched/task_stack.h>
	#include <linux/mm.h>
	#include <linux/stddef.h>
	#include <linux/unistd.h>
	#include <linux/export.h>
	#include <linux/ptrace.h>
	#include <linux/mman.h>
	#include <linux/personality.h>
	#include <linux/sys.h>
	#include <linux/completion.h>
	#include <linux/kallsyms.h>
	#include <linux/random.h>
	#include <linux/prctl.h>
	#include <linux/nmi.h>

	#include <asm/asm.h>
	#include <asm/bootinfo.h>
	#include <asm/cpu.h>
	#include <asm/elf.h>
	#include <asm/fpu.h>
	#include <asm/io.h>
	#include <asm/irq.h>
	#include <asm/irq_regs.h>
	#include <asm/loongarch.h>
	#include <asm/pgtable.h>
	#include <asm/processor.h>
	#include <asm/reg.h>
	#include <asm/unwind.h>
	#include <asm/vdso.h>

	/*
	* Idle related variables and functions
	*/

	unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
	EXPORT_SYMBOL(boot_option_idle_override);

	#ifdef CONFIG_HOTPLUG_CPU
	void arch_cpu_idle_dead(void)
	{
	play_dead();
	}
	#endif

	asmlinkage void ret_from_fork(void);
	asmlinkage void ret_from_kernel_thread(void);

	void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
	{
	unsigned long crmd;
	unsigned long prmd;
	unsigned long euen;

	/* New thread loses kernel privileges. */
	crmd = regs->csr_crmd & ~(PLV_MASK);
	crmd \|= PLV_USER;
	regs->csr_crmd = crmd;

	prmd = regs->csr_prmd & ~(PLV_MASK);
	prmd \|= PLV_USER;
	regs->csr_prmd = prmd;

	euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
	regs->csr_euen = euen;
	lose_fpu(0);

	clear_thread_flag(TIF_LSX_CTX_LIVE);
	clear_thread_flag(TIF_LASX_CTX_LIVE);
	clear_used_math();
	regs->csr_era = pc;
	regs->regs[3] = sp;
	}

	void exit_thread(struct task_struct *tsk)
	{
	}

	int arch_dup_task_struct(struct task_struct dst, struct task_struct src)
	{
	/*
	* Save any process state which is live in hardware registers to the
	* parent context prior to duplication. This prevents the new child
	* state becoming stale if the parent is preempted before copy_thread()
	* gets a chance to save the parent's live hardware registers to the
	* child context.
	*/
	preempt_disable();

	if (is_fpu_owner())
	save_fp(current);

	preempt_enable();

	if (used_math())
	memcpy(dst, src, sizeof(struct task_struct));
	else
	memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));

	return 0;
	}

	/*
	* Copy architecture-specific thread state
	*/
	int copy_thread(struct task_struct p, const struct kernel_clone_args args)
	{
	unsigned long childksp;
	unsigned long tls = args->tls;
	unsigned long usp = args->stack;
	unsigned long clone_flags = args->flags;
	struct pt_regs childregs, regs = current_pt_regs();

	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

	/* set up new TSS. */
	childregs = (struct pt_regs *) childksp - 1;
	/* Put the stack after the struct pt_regs. */
	childksp = (unsigned long) childregs;
	p->thread.sched_cfa = 0;
	p->thread.csr_euen = 0;
	p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
	p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
	p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
	if (unlikely(args->fn)) {
	/* kernel thread */
	p->thread.reg03 = childksp;
	p->thread.reg23 = (unsigned long)args->fn;
	p->thread.reg24 = (unsigned long)args->fn_arg;
	p->thread.reg01 = (unsigned long)ret_from_kernel_thread;
	p->thread.sched_ra = (unsigned long)ret_from_kernel_thread;
	memset(childregs, 0, sizeof(struct pt_regs));
	childregs->csr_euen = p->thread.csr_euen;
	childregs->csr_crmd = p->thread.csr_crmd;
	childregs->csr_prmd = p->thread.csr_prmd;
	childregs->csr_ecfg = p->thread.csr_ecfg;
	goto out;
	}

	/* user thread */
	childregs = regs;
	childregs->regs[4] = 0; /* Child gets zero as return value */
	if (usp)
	childregs->regs[3] = usp;

	p->thread.reg03 = (unsigned long) childregs;
	p->thread.reg01 = (unsigned long) ret_from_fork;
	p->thread.sched_ra = (unsigned long) ret_from_fork;

	/*
	* New tasks lose permission to use the fpu. This accelerates context
	* switching for most programs since they don't use the fpu.
	*/
	childregs->csr_euen = 0;

	if (clone_flags & CLONE_SETTLS)
	childregs->regs[2] = tls;

	out:
	clear_tsk_thread_flag(p, TIF_USEDFPU);
	clear_tsk_thread_flag(p, TIF_USEDSIMD);
	clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
	clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);

	return 0;
	}

	unsigned long __get_wchan(struct task_struct *task)
	{
	unsigned long pc = 0;
	struct unwind_state state;

	if (!try_get_task_stack(task))
	return 0;

	for (unwind_start(&state, task, NULL);
	!unwind_done(&state); unwind_next_frame(&state)) {
	pc = unwind_get_return_address(&state);
	if (!pc)
	break;
	if (in_sched_functions(pc))
	continue;
	break;
	}

	put_task_stack(task);

	return pc;
	}

	bool in_irq_stack(unsigned long stack, struct stack_info *info)
	{
	unsigned long nextsp;
	unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
	unsigned long end = begin + IRQ_STACK_START;

	if (stack < begin \|\| stack >= end)
	return false;

	nextsp = (unsigned long )end;
	if (nextsp & (SZREG - 1))
	return false;

	info->begin = begin;
	info->end = end;
	info->next_sp = nextsp;
	info->type = STACK_TYPE_IRQ;

	return true;
	}

	bool in_task_stack(unsigned long stack, struct task_struct *task,
	struct stack_info *info)
	{
	unsigned long begin = (unsigned long)task_stack_page(task);
	unsigned long end = begin + THREAD_SIZE;

	if (stack < begin \|\| stack >= end)
	return false;

	info->begin = begin;
	info->end = end;
	info->next_sp = 0;
	info->type = STACK_TYPE_TASK;

	return true;
	}

	int get_stack_info(unsigned long stack, struct task_struct *task,
	struct stack_info *info)
	{
	task = task ? : current;

	if (!stack \|\| stack & (SZREG - 1))
	goto unknown;

	if (in_task_stack(stack, task, info))
	return 0;

	if (task != current)
	goto unknown;

	if (in_irq_stack(stack, info))
	return 0;

	unknown:
	info->type = STACK_TYPE_UNKNOWN;
	return -EINVAL;
	}

	unsigned long stack_top(void)
	{
	unsigned long top = TASK_SIZE & PAGE_MASK;

	/* Space for the VDSO & data page */
	top -= PAGE_ALIGN(current->thread.vdso->size);
	top -= PAGE_SIZE;

	/* Space to randomize the VDSO base */
	if (current->flags & PF_RANDOMIZE)
	top -= VDSO_RANDOMIZE_SIZE;

	return top;
	}

	/*
	* Don't forget that the stack pointer must be aligned on a 8 bytes
	* boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
	*/
	unsigned long arch_align_stack(unsigned long sp)
	{
	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
	sp -= prandom_u32_max(PAGE_SIZE);

	return sp & STACK_ALIGN;
	}

	static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
	static struct cpumask backtrace_csd_busy;

	static void handle_backtrace(void *info)
	{
	nmi_cpu_backtrace(get_irq_regs());
	cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
	}

	static void raise_backtrace(cpumask_t *mask)
	{
	call_single_data_t *csd;
	int cpu;

	for_each_cpu(cpu, mask) {
	/*
	* If we previously sent an IPI to the target CPU & it hasn't
	* cleared its bit in the busy cpumask then it didn't handle
	* our previous IPI & it's not safe for us to reuse the
	* call_single_data_t.
	*/
	if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
	pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
	cpu);
	continue;
	}

	csd = &per_cpu(backtrace_csd, cpu);
	csd->func = handle_backtrace;
	smp_call_function_single_async(cpu, csd);
	}
	}

	void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
	{
	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
	}

	#ifdef CONFIG_64BIT
	void loongarch_dump_regs64(u64 uregs, const struct pt_regs regs)
	{
	unsigned int i;

	for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
	uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
	}

	uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
	uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
	uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
	uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
	uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
	uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
	uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
	uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
	}
	#endif /* CONFIG_64BIT */