1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5 * Amit Bhor, Kanika Nema: Codito Technologies 2004
8 #include <linux/errno.h>
9 #include <linux/module.h>
10 #include <linux/sched.h>
11 #include <linux/sched/task.h>
12 #include <linux/sched/task_stack.h>
16 #include <linux/unistd.h>
17 #include <linux/ptrace.h>
18 #include <linux/slab.h>
19 #include <linux/syscalls.h>
20 #include <linux/elf.h>
21 #include <linux/tick.h>
25 SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
27 task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
32 * We return the user space TLS data ptr as sys-call return code
33 * Ideally it should be copy to user.
34 * However we can cheat by the fact that some sys-calls do return
35 * absurdly high values
36 * Since the tls dat aptr is not going to be in range of 0xFFFF_xxxx
37 * it won't be considered a sys-call error
38 * and it will be loads better than copy-to-user, which is a definite
41 SYSCALL_DEFINE0(arc_gettls)
43 return task_thread_info(current)->thr_ptr;
46 SYSCALL_DEFINE3(arc_usr_cmpxchg, int __user *, uaddr, int, expected, int, new)
48 struct pt_regs *regs = current_pt_regs();
53 * This is only for old cores lacking LLOCK/SCOND, which by definition
54 * can't possibly be SMP. Thus doesn't need to be SMP safe.
55 * And this also helps reduce the overhead for serializing in
58 WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP));
60 /* Z indicates to userspace if operation succeeded */
61 regs->status32 &= ~STATUS_Z_MASK;
63 ret = access_ok(uaddr, sizeof(*uaddr));
70 ret = __get_user(uval, uaddr);
77 ret = __put_user(new, uaddr);
81 regs->status32 |= STATUS_Z_MASK;
90 if (unlikely(ret != -EFAULT))
93 mmap_read_lock(current->mm);
94 ret = fixup_user_fault(current->mm, (unsigned long) uaddr,
95 FAULT_FLAG_WRITE, NULL);
96 mmap_read_unlock(current->mm);
106 #ifdef CONFIG_ISA_ARCV2
108 void arch_cpu_idle(void)
110 /* Re-enable interrupts <= default irq priority before committing SLEEP */
111 const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO;
113 __asm__ __volatile__(
116 :"I"(arg)); /* can't be "r" has to be embedded const */
118 raw_local_irq_disable();
123 void arch_cpu_idle(void)
125 /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */
126 __asm__ __volatile__("sleep 0x3 \n");
127 raw_local_irq_disable();
132 asmlinkage void ret_from_fork(void);
135 * Copy architecture-specific thread state
137 * Layout of Child kernel mode stack as setup at the end of this function is
144 * | r25 | <==== top of Stack (thread.ksp)
146 * | --to-- | (CALLEE Regs of kernel mode)
150 * | blink | @ret_from_fork
159 * | --to-- | (scratch Regs of user mode)
166 * ------------------ <===== END of PAGE
168 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
170 unsigned long clone_flags = args->flags;
171 unsigned long usp = args->stack;
172 unsigned long tls = args->tls;
173 struct pt_regs *c_regs; /* child's pt_regs */
174 unsigned long *childksp; /* to unwind out of __switch_to() */
175 struct callee_regs *c_callee; /* child's callee regs */
176 struct callee_regs *parent_callee; /* paren't callee */
177 struct pt_regs *regs = current_pt_regs();
179 /* Mark the specific anchors to begin with (see pic above) */
180 c_regs = task_pt_regs(p);
181 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */
182 c_callee = ((struct callee_regs *)childksp) - 1;
185 * __switch_to() uses thread.ksp to start unwinding stack
186 * For kernel threads we don't need to create callee regs, the
187 * stack layout nevertheless needs to remain the same.
188 * Also, since __switch_to anyways unwinds callee regs, we use
189 * this to populate kernel thread entry-pt/args into callee regs,
190 * so that ret_from_kernel_thread() becomes simpler.
192 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */
194 /* __switch_to expects FP(0), BLINK(return addr) at top */
195 childksp[0] = 0; /* fp */
196 childksp[1] = (unsigned long)ret_from_fork; /* blink */
198 if (unlikely(args->fn)) {
199 memset(c_regs, 0, sizeof(struct pt_regs));
201 c_callee->r13 = (unsigned long)args->fn_arg;
202 c_callee->r14 = (unsigned long)args->fn;
207 /*--------- User Task Only --------------*/
209 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */
210 childksp[0] = 0; /* for POP fp */
211 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */
213 /* Copy parents pt regs on child's kernel mode stack */
219 c_regs->r0 = 0; /* fork returns 0 in child */
221 parent_callee = ((struct callee_regs *)regs) - 1;
222 *c_callee = *parent_callee;
224 if (unlikely(clone_flags & CLONE_SETTLS)) {
226 * set task's userland tls data ptr from 4th arg
227 * clone C-lib call is difft from clone sys-call
229 task_thread_info(p)->thr_ptr = tls;
231 /* Normal fork case: set parent's TLS ptr in child */
232 task_thread_info(p)->thr_ptr =
233 task_thread_info(current)->thr_ptr;
238 * setup usermode thread pointer #1:
239 * when child is picked by scheduler, __switch_to() uses @c_callee to
240 * populate usermode callee regs: this works (despite being in a kernel
241 * function) since special return path for child @ret_from_fork()
242 * ensures those regs are not clobbered all the way to RTIE to usermode
244 c_callee->r25 = task_thread_info(p)->thr_ptr;
246 #ifdef CONFIG_ARC_CURR_IN_REG
248 * setup usermode thread pointer #2:
249 * however for this special use of r25 in kernel, __switch_to() sets
250 * r25 for kernel needs and only in the final return path is usermode
251 * r25 setup, from pt_regs->user_r25. So set that up as well
253 c_regs->user_r25 = c_callee->r25;
260 * Do necessary setup to start up a new user task
262 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
268 * [U]ser Mode bit set
269 * [L] ZOL loop inhibited to begin with - cleared by a LP insn
272 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS;
276 /* bogus seed values for debugging */
277 regs->lp_start = 0x10;
282 * Some archs flush debug and FPU info here
284 void flush_thread(void)
288 int elf_check_arch(const struct elf32_hdr *x)
292 if (x->e_machine != EM_ARC_INUSE) {
293 pr_err("ELF not built for %s ISA\n",
294 is_isa_arcompact() ? "ARCompact":"ARCv2");
299 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) {
300 pr_err("ABI mismatch - you need newer toolchain\n");
301 force_fatal_sig(SIGSEGV);
307 EXPORT_SYMBOL(elf_check_arch);