// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) * * Amit Bhor, Kanika Nema: Codito Technologies 2004 */ #include <linux/errno.h>#include <linux/module.h>#include <linux/sched.h>#include <linux/sched/task.h>#include <linux/sched/task_stack.h> #include <linux/mm.h>#include <linux/fs.h>#include <linux/unistd.h>#include <linux/ptrace.h>#include <linux/slab.h>#include <linux/syscalls.h>#include <linux/elf.h>#include <linux/tick.h> #include <asm/fpu.h> SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr){	task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;	return 0;} /* * We return the user space TLS data ptr as sys-call return code * Ideally it should be copy to user. * However we can cheat by the fact that some sys-calls do return * absurdly high values * Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx * it won't be considered a sys-call error * and it will be loads better than copy-to-user, which is a definite * D-TLB Miss */SYSCALL_DEFINE0(arc_gettls){	return task_thread_info(current)->thr_ptr;} SYSCALL_DEFINE3(arc_usr_cmpxchg, int __user *, uaddr, int, expected, int, new){	struct pt_regs *regs = current_pt_regs();	u32 uval;	int ret; 	/*	 * This is only for old cores lacking LLOCK/SCOND, which by definition	 * can't possibly be SMP. Thus doesn't need to be SMP safe.	 * And this also helps reduce the overhead for serializing in	 * the UP case	 */	WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP)); 	/* Z indicates to userspace if operation succeeded */	regs->status32 &= ~STATUS_Z_MASK; 	ret = access_ok(uaddr, sizeof(*uaddr));	if (!ret)		 goto fail; again:	preempt_disable(); 	ret = __get_user(uval, uaddr);	if (ret)		 goto fault; 	if (uval != expected)		 goto out; 	ret = __put_user(new, uaddr);	if (ret)		 goto fault; 	regs->status32 |= STATUS_Z_MASK; out:	preempt_enable();	return uval; fault:	preempt_enable(); 	if (unlikely(ret != -EFAULT))		 goto fail; 	mmap_read_lock(current->mm);	ret = fixup_user_fault(current->mm, (unsigned long) uaddr,			       FAULT_FLAG_WRITE, NULL);	mmap_read_unlock(current->mm); 	if (likely(!ret))		 goto again; fail:	force_sig(SIGSEGV);	return ret;} #ifdef CONFIG_ISA_ARCV2 void arch_cpu_idle(void){	/* Re-enable interrupts <= default irq priority before committing SLEEP */	const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO; 	__asm__ __volatile__(		"sleep %0	\n"		:		:"I"(arg)); /* can't be "r" has to be embedded const */ 	raw_local_irq_disable();} #else	/* ARC700 */ void arch_cpu_idle(void){	/* sleep, but enable both set E1/E2 (levels of interrupts) before committing */	__asm__ __volatile__("sleep 0x3	\n");	raw_local_irq_disable();} #endif asmlinkage void ret_from_fork(void); /* * Copy architecture-specific thread state * * Layout of Child kernel mode stack as setup at the end of this function is * * |     ...        | * |     ...        | * |    unused      | * |                | * ------------------ * |     r25        |   <==== top of Stack (thread_info.ksp) * ~                ~ * |    --to--      |   (CALLEE Regs of kernel mode) * |     r13        | * ------------------ * |     fp         | * |    blink       |   @ret_from_fork * ------------------ * |                | * ~                ~ * ~                ~ * |                | * ------------------ * |     r12        | * ~                ~ * |    --to--      |   (scratch Regs of user mode) * |     r0         | * ------------------ * |      SP        | * |    orig_r0     | * |    event/ECR   | * ------------------  <===== END of PAGE */int copy_thread(struct task_struct *p, const struct kernel_clone_args *args){	unsigned long clone_flags = args->flags;	unsigned long usp = args->stack;	unsigned long tls = args->tls;	struct pt_regs *c_regs;        /* child's pt_regs */	unsigned long *childksp;       /* to unwind out of __switch_to() */	struct callee_regs *c_callee;  /* child's callee regs */	struct callee_regs *parent_callee;  /* paren't callee */	struct pt_regs *regs = current_pt_regs(); 	/* Mark the specific anchors to begin with (see pic above) */	c_regs = task_pt_regs(p);	childksp = (unsigned long *)c_regs - 2;  /* 2 words for FP/BLINK */	c_callee = ((struct callee_regs *)childksp) - 1; 	/*	 * __switch_to() uses thread_info.ksp to start unwinding stack	 * For kernel threads we don't need to create callee regs, the	 * stack layout nevertheless needs to remain the same.	 * Also, since __switch_to anyways unwinds callee regs, we use	 * this to populate kernel thread entry-pt/args into callee regs,	 * so that ret_from_kernel_thread() becomes simpler.	 */	task_thread_info(p)->ksp = (unsigned long)c_callee;	/* THREAD_INFO_KSP */ 	/* __switch_to expects FP(0), BLINK(return addr) at top */	childksp[0] = 0;			/* fp */	childksp[1] = (unsigned long)ret_from_fork; /* blink */ 	if (unlikely(args->fn)) {		memset(c_regs, 0, sizeof(struct pt_regs)); 		c_callee->r13 = (unsigned long)args->fn_arg;		c_callee->r14 = (unsigned long)args->fn; 		return 0;	} 	/*--------- User Task Only --------------*/ 	/* __switch_to expects FP(0), BLINK(return addr) at top of stack */	childksp[0] = 0;				/* for POP fp */	childksp[1] = (unsigned long)ret_from_fork;	/* for POP blink */ 	/* Copy parents pt regs on child's kernel mode stack */	*c_regs = *regs; 	if (usp)		c_regs->sp = usp; 	c_regs->r0 = 0;		/* fork returns 0 in child */ 	parent_callee = ((struct callee_regs *)regs) - 1;	*c_callee = *parent_callee; 	if (unlikely(clone_flags & CLONE_SETTLS)) {		/*		 * set task's userland tls data ptr from 4th arg		 * clone C-lib call is difft from clone sys-call		 */		task_thread_info(p)->thr_ptr = tls;	} else {		/* Normal fork case: set parent's TLS ptr in child */		task_thread_info(p)->thr_ptr =		task_thread_info(current)->thr_ptr;	}  	/*	 * setup usermode thread pointer #1:	 * when child is picked by scheduler, __switch_to() uses @c_callee to	 * populate usermode callee regs: this works (despite being in a kernel	 * function) since special return path for child @ret_from_fork()	 * ensures those regs are not clobbered all the way to RTIE to usermode	 */	c_callee->r25 = task_thread_info(p)->thr_ptr; 	return 0;} /* * Do necessary setup to start up a new user task */void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp){	regs->sp = usp;	regs->ret = pc; 	/*	 * [U]ser Mode bit set	 * [L] ZOL loop inhibited to begin with - cleared by a LP insn	 * Interrupts enabled	 */	regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; 	fpu_init_task(regs); 	/* bogus seed values for debugging */	regs->lp_start = 0x10;	regs->lp_end = 0x80;} /* * Some archs flush debug and FPU info here */void flush_thread(void){} int elf_check_arch(const struct elf32_hdr *x){	unsigned int eflags; 	if (x->e_machine != EM_ARC_INUSE) {		pr_err("ELF not built for %s ISA\n",			is_isa_arcompact() ? "ARCompact":"ARCv2");		return 0;	} 	eflags = x->e_flags;	if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) {		pr_err("ABI mismatch - you need newer toolchain\n");		force_fatal_sig(SIGSEGV);		return 0;	} 	return 1;}EXPORT_SYMBOL(elf_check_arch);