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 | |
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 | */ |
41 | SYSCALL_DEFINE0(arc_gettls) |
42 | { |
43 | return task_thread_info(current)->thr_ptr; |
44 | } |
45 | |
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, address: (unsigned long) uaddr, |
95 | fault_flags: 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 | |
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 | raw_local_irq_disable(); |
119 | } |
120 | |
121 | #else /* ARC700 */ |
122 | |
123 | void arch_cpu_idle(void) |
124 | { |
125 | /* sleep, but enable both set E1/E2 (levels of interrupts) before committing */ |
126 | __asm__ __volatile__("sleep 0x3 \n" ); |
127 | raw_local_irq_disable(); |
128 | } |
129 | |
130 | #endif |
131 | |
132 | asmlinkage void ret_from_fork(void); |
133 | |
134 | /* |
135 | * Copy architecture-specific thread state |
136 | * |
137 | * Layout of Child kernel mode stack as setup at the end of this function is |
138 | * |
139 | * | ... | |
140 | * | ... | |
141 | * | unused | |
142 | * | | |
143 | * ------------------ |
144 | * | r25 | <==== top of Stack (thread_info.ksp) |
145 | * ~ ~ |
146 | * | --to-- | (CALLEE Regs of kernel mode) |
147 | * | r13 | |
148 | * ------------------ |
149 | * | fp | |
150 | * | blink | @ret_from_fork |
151 | * ------------------ |
152 | * | | |
153 | * ~ ~ |
154 | * ~ ~ |
155 | * | | |
156 | * ------------------ |
157 | * | r12 | |
158 | * ~ ~ |
159 | * | --to-- | (scratch Regs of user mode) |
160 | * | r0 | |
161 | * ------------------ |
162 | * | SP | |
163 | * | orig_r0 | |
164 | * | event/ECR | |
165 | * ------------------ <===== END of PAGE |
166 | */ |
167 | int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) |
168 | { |
169 | unsigned long clone_flags = args->flags; |
170 | unsigned long usp = args->stack; |
171 | unsigned long tls = args->tls; |
172 | struct pt_regs *c_regs; /* child's pt_regs */ |
173 | unsigned long *childksp; /* to unwind out of __switch_to() */ |
174 | struct callee_regs *c_callee; /* child's callee regs */ |
175 | struct callee_regs *parent_callee; /* paren't callee */ |
176 | struct pt_regs *regs = current_pt_regs(); |
177 | |
178 | /* Mark the specific anchors to begin with (see pic above) */ |
179 | c_regs = task_pt_regs(p); |
180 | childksp = (unsigned long *)c_regs - 2; /* 2 words for FP/BLINK */ |
181 | c_callee = ((struct callee_regs *)childksp) - 1; |
182 | |
183 | /* |
184 | * __switch_to() uses thread_info.ksp to start unwinding stack |
185 | * For kernel threads we don't need to create callee regs, the |
186 | * stack layout nevertheless needs to remain the same. |
187 | * Also, since __switch_to anyways unwinds callee regs, we use |
188 | * this to populate kernel thread entry-pt/args into callee regs, |
189 | * so that ret_from_kernel_thread() becomes simpler. |
190 | */ |
191 | task_thread_info(p)->ksp = (unsigned long)c_callee; /* THREAD_INFO_KSP */ |
192 | |
193 | /* __switch_to expects FP(0), BLINK(return addr) at top */ |
194 | childksp[0] = 0; /* fp */ |
195 | childksp[1] = (unsigned long)ret_from_fork; /* blink */ |
196 | |
197 | if (unlikely(args->fn)) { |
198 | memset(c_regs, 0, sizeof(struct pt_regs)); |
199 | |
200 | c_callee->r13 = (unsigned long)args->fn_arg; |
201 | c_callee->r14 = (unsigned long)args->fn; |
202 | |
203 | return 0; |
204 | } |
205 | |
206 | /*--------- User Task Only --------------*/ |
207 | |
208 | /* __switch_to expects FP(0), BLINK(return addr) at top of stack */ |
209 | childksp[0] = 0; /* for POP fp */ |
210 | childksp[1] = (unsigned long)ret_from_fork; /* for POP blink */ |
211 | |
212 | /* Copy parents pt regs on child's kernel mode stack */ |
213 | *c_regs = *regs; |
214 | |
215 | if (usp) |
216 | c_regs->sp = usp; |
217 | |
218 | c_regs->r0 = 0; /* fork returns 0 in child */ |
219 | |
220 | parent_callee = ((struct callee_regs *)regs) - 1; |
221 | *c_callee = *parent_callee; |
222 | |
223 | if (unlikely(clone_flags & CLONE_SETTLS)) { |
224 | /* |
225 | * set task's userland tls data ptr from 4th arg |
226 | * clone C-lib call is difft from clone sys-call |
227 | */ |
228 | task_thread_info(p)->thr_ptr = tls; |
229 | } else { |
230 | /* Normal fork case: set parent's TLS ptr in child */ |
231 | task_thread_info(p)->thr_ptr = |
232 | task_thread_info(current)->thr_ptr; |
233 | } |
234 | |
235 | |
236 | /* |
237 | * setup usermode thread pointer #1: |
238 | * when child is picked by scheduler, __switch_to() uses @c_callee to |
239 | * populate usermode callee regs: this works (despite being in a kernel |
240 | * function) since special return path for child @ret_from_fork() |
241 | * ensures those regs are not clobbered all the way to RTIE to usermode |
242 | */ |
243 | c_callee->r25 = task_thread_info(p)->thr_ptr; |
244 | |
245 | return 0; |
246 | } |
247 | |
248 | /* |
249 | * Do necessary setup to start up a new user task |
250 | */ |
251 | void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp) |
252 | { |
253 | regs->sp = usp; |
254 | regs->ret = pc; |
255 | |
256 | /* |
257 | * [U]ser Mode bit set |
258 | * [L] ZOL loop inhibited to begin with - cleared by a LP insn |
259 | * Interrupts enabled |
260 | */ |
261 | regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS; |
262 | |
263 | fpu_init_task(regs); |
264 | |
265 | /* bogus seed values for debugging */ |
266 | regs->lp_start = 0x10; |
267 | regs->lp_end = 0x80; |
268 | } |
269 | |
270 | /* |
271 | * Some archs flush debug and FPU info here |
272 | */ |
273 | void flush_thread(void) |
274 | { |
275 | } |
276 | |
277 | int elf_check_arch(const struct elf32_hdr *x) |
278 | { |
279 | unsigned int eflags; |
280 | |
281 | if (x->e_machine != EM_ARC_INUSE) { |
282 | pr_err("ELF not built for %s ISA\n" , |
283 | is_isa_arcompact() ? "ARCompact" :"ARCv2" ); |
284 | return 0; |
285 | } |
286 | |
287 | eflags = x->e_flags; |
288 | if ((eflags & EF_ARC_OSABI_MSK) != EF_ARC_OSABI_CURRENT) { |
289 | pr_err("ABI mismatch - you need newer toolchain\n" ); |
290 | force_fatal_sig(SIGSEGV); |
291 | return 0; |
292 | } |
293 | |
294 | return 1; |
295 | } |
296 | EXPORT_SYMBOL(elf_check_arch); |
297 | |