1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 *
5 * Amit Bhor, Kanika Nema: Codito Technologies 2004
6 */
7
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>
13
14 #include <linux/mm.h>
15 #include <linux/fs.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>
22
23 #include <asm/fpu.h>
24
SYSCALL_DEFINE1(arc_settls,void *,user_tls_data_ptr)25 SYSCALL_DEFINE1(arc_settls, void *, user_tls_data_ptr)
26 {
27 task_thread_info(current)->thr_ptr = (unsigned int)user_tls_data_ptr;
28 return 0;
29 }
30
31 /*
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
39 * D-TLB Miss
40 */
SYSCALL_DEFINE0(arc_gettls)41 SYSCALL_DEFINE0(arc_gettls)
42 {
43 return task_thread_info(current)->thr_ptr;
44 }
45
SYSCALL_DEFINE3(arc_usr_cmpxchg,int __user *,uaddr,int,expected,int,new)46 SYSCALL_DEFINE3(arc_usr_cmpxchg, int __user *, uaddr, int, expected, int, new)
47 {
48 struct pt_regs *regs = current_pt_regs();
49 u32 uval;
50 int ret;
51
52 /*
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
56 * the UP case
57 */
58 WARN_ON_ONCE(IS_ENABLED(CONFIG_SMP));
59
60 /* Z indicates to userspace if operation succeeded */
61 regs->status32 &= ~STATUS_Z_MASK;
62
63 ret = access_ok(uaddr, sizeof(*uaddr));
64 if (!ret)
65 goto fail;
66
67 again:
68 preempt_disable();
69
70 ret = __get_user(uval, uaddr);
71 if (ret)
72 goto fault;
73
74 if (uval != expected)
75 goto out;
76
77 ret = __put_user(new, uaddr);
78 if (ret)
79 goto fault;
80
81 regs->status32 |= STATUS_Z_MASK;
82
83 out:
84 preempt_enable();
85 return uval;
86
87 fault:
88 preempt_enable();
89
90 if (unlikely(ret != -EFAULT))
91 goto fail;
92
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);
97
98 if (likely(!ret))
99 goto again;
100
101 fail:
102 force_sig(SIGSEGV);
103 return ret;
104 }
105
106 #ifdef CONFIG_ISA_ARCV2
107
arch_cpu_idle(void)108 void arch_cpu_idle(void)
109 {
110 /* Re-enable interrupts <= default irq priority before committing SLEEP */
111 const unsigned int arg = 0x10 | ARCV2_IRQ_DEF_PRIO;
112
113 __asm__ __volatile__(
114 "sleep %0 \n"
115 :
116 :"I"(arg)); /* can't be "r" has to be embedded const */
117 }
118
119 #else /* ARC700 */
120
arch_cpu_idle(void)121 void arch_cpu_idle(void)
122 {
123 /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */
124 __asm__ __volatile__("sleep 0x3 \n");
125 }
126
127 #endif
128
129 asmlinkage void ret_from_fork(void);
130
131 /*
132 * Copy architecture-specific thread state
133 *
134 * Layout of Child kernel mode stack as setup at the end of this function is
135 *
136 * | ... |
137 * | ... |
138 * | unused |
139 * | |
140 * ------------------
141 * | r25 | <==== top of Stack (thread.ksp)
142 * ~ ~
143 * | --to-- | (CALLEE Regs of kernel mode)
144 * | r13 |
145 * ------------------
146 * | fp |
147 * | blink | @ret_from_fork
148 * ------------------
149 * | |
150 * ~ ~
151 * ~ ~
152 * | |
153 * ------------------
154 * | r12 |
155 * ~ ~
156 * | --to-- | (scratch Regs of user mode)
157 * | r0 |
158 * ------------------
159 * | SP |
160 * | orig_r0 |
161 * | event/ECR |
162 * | user_r25 |
163 * ------------------ <===== END of PAGE
164 */
copy_thread(unsigned long clone_flags,unsigned long usp,unsigned long kthread_arg,struct task_struct * p,unsigned long tls)165 int copy_thread(unsigned long clone_flags, unsigned long usp,
166 unsigned long kthread_arg, struct task_struct *p,
167 unsigned long tls)
168 {
169 struct pt_regs *c_regs; /* child's pt_regs */
170 unsigned long *childksp; /* to unwind out of __switch_to() */
171 struct callee_regs *c_callee; /* child's callee regs */
172 struct callee_regs *parent_callee; /* paren't callee */
173 struct pt_regs *regs = current_pt_regs();
174
175 /* Mark the specific anchors to begin with (see pic above) */
176 c_regs = task_pt_regs(p);
177 childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */
178 c_callee = ((struct callee_regs *)childksp) - 1;
179
180 /*
181 * __switch_to() uses thread.ksp to start unwinding stack
182 * For kernel threads we don't need to create callee regs, the
183 * stack layout nevertheless needs to remain the same.
184 * Also, since __switch_to anyways unwinds callee regs, we use
185 * this to populate kernel thread entry-pt/args into callee regs,
186 * so that ret_from_kernel_thread() becomes simpler.
187 */
188 p->thread.ksp = (unsigned long)c_callee; /* THREAD_KSP */
189
190 /* __switch_to expects FP(0), BLINK(return addr) at top */
191 childksp[0] = 0; /* fp */
192 childksp[1] = (unsigned long)ret_from_fork; /* blink */
193
194 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
195 memset(c_regs, 0, sizeof(struct pt_regs));
196
197 c_callee->r13 = kthread_arg;
198 c_callee->r14 = usp; /* function */
199
200 return 0;
201 }
202
203 /*--------- User Task Only --------------*/
204
205 /* __switch_to expects FP(0), BLINK(return addr) at top of stack */
206 childksp[0] = 0; /* for POP fp */
207 childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */
208
209 /* Copy parents pt regs on child's kernel mode stack */
210 *c_regs = *regs;
211
212 if (usp)
213 c_regs->sp = usp;
214
215 c_regs->r0 = 0; /* fork returns 0 in child */
216
217 parent_callee = ((struct callee_regs *)regs) - 1;
218 *c_callee = *parent_callee;
219
220 if (unlikely(clone_flags & CLONE_SETTLS)) {
221 /*
222 * set task's userland tls data ptr from 4th arg
223 * clone C-lib call is difft from clone sys-call
224 */
225 task_thread_info(p)->thr_ptr = tls;
226 } else {
227 /* Normal fork case: set parent's TLS ptr in child */
228 task_thread_info(p)->thr_ptr =
229 task_thread_info(current)->thr_ptr;
230 }
231
232
233 /*
234 * setup usermode thread pointer #1:
235 * when child is picked by scheduler, __switch_to() uses @c_callee to
236 * populate usermode callee regs: this works (despite being in a kernel
237 * function) since special return path for child @ret_from_fork()
238 * ensures those regs are not clobbered all the way to RTIE to usermode
239 */
240 c_callee->r25 = task_thread_info(p)->thr_ptr;
241
242 #ifdef CONFIG_ARC_CURR_IN_REG
243 /*
244 * setup usermode thread pointer #2:
245 * however for this special use of r25 in kernel, __switch_to() sets
246 * r25 for kernel needs and only in the final return path is usermode
247 * r25 setup, from pt_regs->user_r25. So set that up as well
248 */
249 c_regs->user_r25 = c_callee->r25;
250 #endif
251
252 return 0;
253 }
254
255 /*
256 * Do necessary setup to start up a new user task
257 */
start_thread(struct pt_regs * regs,unsigned long pc,unsigned long usp)258 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
259 {
260 regs->sp = usp;
261 regs->ret = pc;
262
263 /*
264 * [U]ser Mode bit set
265 * [L] ZOL loop inhibited to begin with - cleared by a LP insn
266 * Interrupts enabled
267 */
268 regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS;
269
270 fpu_init_task(regs);
271
272 /* bogus seed values for debugging */
273 regs->lp_start = 0x10;
274 regs->lp_end = 0x80;
275 }
276
277 /*
278 * Some archs flush debug and FPU info here
279 */
flush_thread(void)280 void flush_thread(void)
281 {
282 }
283
elf_check_arch(const struct elf32_hdr * x)284 int elf_check_arch(const struct elf32_hdr *x)
285 {
286 unsigned int eflags;
287
288 if (x->e_machine != EM_ARC_INUSE) {
289 pr_err("ELF not built for %s ISA\n",
290 is_isa_arcompact() ? "ARCompact":"ARCv2");
291 return 0;
292 }
293
294 eflags = x->e_flags;
295 if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) {
296 pr_err("ABI mismatch - you need newer toolchain\n");
297 force_fatal_sig(SIGSEGV);
298 return 0;
299 }
300
301 return 1;
302 }
303 EXPORT_SYMBOL(elf_check_arch);
304