2 * arch/xtensa/kernel/process.c
4 * Xtensa Processor version.
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
10 * Copyright (C) 2001 - 2005 Tensilica Inc.
12 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
13 * Chris Zankel <chris@zankel.net>
14 * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
18 #include <linux/errno.h>
19 #include <linux/sched.h>
20 #include <linux/sched/debug.h>
21 #include <linux/sched/task.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/kernel.h>
25 #include <linux/smp.h>
26 #include <linux/stddef.h>
27 #include <linux/unistd.h>
28 #include <linux/ptrace.h>
29 #include <linux/elf.h>
30 #include <linux/hw_breakpoint.h>
31 #include <linux/init.h>
32 #include <linux/prctl.h>
33 #include <linux/init_task.h>
34 #include <linux/module.h>
35 #include <linux/mqueue.h>
37 #include <linux/slab.h>
38 #include <linux/rcupdate.h>
40 #include <linux/uaccess.h>
42 #include <asm/processor.h>
43 #include <asm/platform.h>
46 #include <linux/atomic.h>
47 #include <asm/asm-offsets.h>
49 #include <asm/hw_breakpoint.h>
50 #include <asm/traps.h>
52 extern void ret_from_fork(void);
53 extern void ret_from_kernel_thread(void);
55 void (*pm_power_off)(void) = NULL;
56 EXPORT_SYMBOL(pm_power_off);
59 #ifdef CONFIG_STACKPROTECTOR
60 #include <linux/stackprotector.h>
61 unsigned long __stack_chk_guard __read_mostly;
62 EXPORT_SYMBOL(__stack_chk_guard);
65 #if XTENSA_HAVE_COPROCESSORS
67 void local_coprocessors_flush_release_all(void)
69 struct thread_info **coprocessor_owner;
70 struct thread_info *unique_owner[XCHAL_CP_MAX];
74 coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
75 xtensa_set_sr(XCHAL_CP_MASK, cpenable);
77 for (i = 0; i < XCHAL_CP_MAX; i++) {
78 struct thread_info *ti = coprocessor_owner[i];
81 coprocessor_flush(ti, i);
83 for (j = 0; j < n; j++)
84 if (unique_owner[j] == ti)
87 unique_owner[n++] = ti;
89 coprocessor_owner[i] = NULL;
92 for (i = 0; i < n; i++) {
93 /* pairs with memw (1) in fast_coprocessor and memw in switch_to */
95 unique_owner[i]->cpenable = 0;
97 xtensa_set_sr(0, cpenable);
100 static void local_coprocessor_release_all(void *info)
102 struct thread_info *ti = info;
103 struct thread_info **coprocessor_owner;
106 coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
108 /* Walk through all cp owners and release it for the requested one. */
110 for (i = 0; i < XCHAL_CP_MAX; i++) {
111 if (coprocessor_owner[i] == ti)
112 coprocessor_owner[i] = NULL;
114 /* pairs with memw (1) in fast_coprocessor and memw in switch_to */
117 if (ti == current_thread_info())
118 xtensa_set_sr(0, cpenable);
121 void coprocessor_release_all(struct thread_info *ti)
124 /* pairs with memw (2) in fast_coprocessor */
126 smp_call_function_single(ti->cp_owner_cpu,
127 local_coprocessor_release_all,
132 static void local_coprocessor_flush_all(void *info)
134 struct thread_info *ti = info;
135 struct thread_info **coprocessor_owner;
136 unsigned long old_cpenable;
139 coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
140 old_cpenable = xtensa_xsr(ti->cpenable, cpenable);
142 for (i = 0; i < XCHAL_CP_MAX; i++) {
143 if (coprocessor_owner[i] == ti)
144 coprocessor_flush(ti, i);
146 xtensa_set_sr(old_cpenable, cpenable);
149 void coprocessor_flush_all(struct thread_info *ti)
152 /* pairs with memw (2) in fast_coprocessor */
154 smp_call_function_single(ti->cp_owner_cpu,
155 local_coprocessor_flush_all,
160 static void local_coprocessor_flush_release_all(void *info)
162 local_coprocessor_flush_all(info);
163 local_coprocessor_release_all(info);
166 void coprocessor_flush_release_all(struct thread_info *ti)
169 /* pairs with memw (2) in fast_coprocessor */
171 smp_call_function_single(ti->cp_owner_cpu,
172 local_coprocessor_flush_release_all,
181 * Powermanagement idle function, if any is provided by the platform.
183 void arch_cpu_idle(void)
189 * This is called when the thread calls exit().
191 void exit_thread(struct task_struct *tsk)
193 #if XTENSA_HAVE_COPROCESSORS
194 coprocessor_release_all(task_thread_info(tsk));
199 * Flush thread state. This is called when a thread does an execve()
200 * Note that we flush coprocessor registers for the case execve fails.
202 void flush_thread(void)
204 #if XTENSA_HAVE_COPROCESSORS
205 struct thread_info *ti = current_thread_info();
206 coprocessor_flush_release_all(ti);
208 flush_ptrace_hw_breakpoint(current);
212 * this gets called so that we can store coprocessor state into memory and
213 * copy the current task into the new thread.
215 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
217 #if XTENSA_HAVE_COPROCESSORS
218 coprocessor_flush_all(task_thread_info(src));
227 * There are two modes in which this function is called:
228 * 1) Userspace thread creation,
229 * regs != NULL, usp_thread_fn is userspace stack pointer.
230 * It is expected to copy parent regs (in case CLONE_VM is not set
231 * in the clone_flags) and set up passed usp in the childregs.
232 * 2) Kernel thread creation,
233 * regs == NULL, usp_thread_fn is the function to run in the new thread
234 * and thread_fn_arg is its parameter.
235 * childregs are not used for the kernel threads.
237 * The stack layout for the new thread looks like this:
239 * +------------------------+
241 * +------------------------+ <- thread.sp = sp in dummy-frame
242 * | dummy-frame | (saved in dummy-frame spill-area)
243 * +------------------------+
245 * We create a dummy frame to return to either ret_from_fork or
246 * ret_from_kernel_thread:
247 * a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
248 * sp points to itself (thread.sp)
249 * a2, a3 are unused for userspace threads,
250 * a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
252 * Note: This is a pristine frame, so we don't need any spill region on top of
255 * The fun part: if we're keeping the same VM (i.e. cloning a thread,
256 * not an entire process), we're normally given a new usp, and we CANNOT share
257 * any live address register windows. If we just copy those live frames over,
258 * the two threads (parent and child) will overflow the same frames onto the
259 * parent stack at different times, likely corrupting the parent stack (esp.
260 * if the parent returns from functions that called clone() and calls new
261 * ones, before the child overflows its now old copies of its parent windows).
262 * One solution is to spill windows to the parent stack, but that's fairly
263 * involved. Much simpler to just not copy those live frames across.
266 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
268 unsigned long clone_flags = args->flags;
269 unsigned long usp_thread_fn = args->stack;
270 unsigned long tls = args->tls;
271 struct pt_regs *childregs = task_pt_regs(p);
273 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
274 struct thread_info *ti;
277 #if defined(__XTENSA_WINDOWED_ABI__)
278 /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
279 SPILL_SLOT(childregs, 1) = (unsigned long)childregs;
280 SPILL_SLOT(childregs, 0) = 0;
282 p->thread.sp = (unsigned long)childregs;
283 #elif defined(__XTENSA_CALL0_ABI__)
284 /* Reserve 16 bytes for the _switch_to stack frame. */
285 p->thread.sp = (unsigned long)childregs - 16;
287 #error Unsupported Xtensa ABI
291 struct pt_regs *regs = current_pt_regs();
292 unsigned long usp = usp_thread_fn ?
293 usp_thread_fn : regs->areg[1];
295 p->thread.ra = MAKE_RA_FOR_CALL(
296 (unsigned long)ret_from_fork, 0x1);
299 childregs->areg[1] = usp;
300 childregs->areg[2] = 0;
302 /* When sharing memory with the parent thread, the child
303 usually starts on a pristine stack, so we have to reset
304 windowbase, windowstart and wmask.
305 (Note that such a new thread is required to always create
306 an initial call4 frame)
307 The exception is vfork, where the new thread continues to
308 run on the parent's stack until it calls execve. This could
309 be a call8 or call12, which requires a legal stack frame
310 of the previous caller for the overflow handlers to work.
311 (Note that it's always legal to overflow live registers).
312 In this case, ensure to spill at least the stack pointer
315 if (clone_flags & CLONE_VM) {
316 /* check that caller window is live and same stack */
317 int len = childregs->wmask & ~0xf;
318 if (regs->areg[1] == usp && len != 0) {
319 int callinc = (regs->areg[0] >> 30) & 3;
320 int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
321 put_user(regs->areg[caller_ars+1],
322 (unsigned __user*)(usp - 12));
324 childregs->wmask = 1;
325 childregs->windowstart = 1;
326 childregs->windowbase = 0;
329 if (clone_flags & CLONE_SETTLS)
330 childregs->threadptr = tls;
332 p->thread.ra = MAKE_RA_FOR_CALL(
333 (unsigned long)ret_from_kernel_thread, 1);
335 /* pass parameters to ret_from_kernel_thread: */
336 #if defined(__XTENSA_WINDOWED_ABI__)
338 * a2 = thread_fn, a3 = thread_fn arg.
339 * Window underflow will load registers from the
340 * spill slots on the stack on return from _switch_to.
342 SPILL_SLOT(childregs, 2) = (unsigned long)args->fn;
343 SPILL_SLOT(childregs, 3) = (unsigned long)args->fn_arg;
344 #elif defined(__XTENSA_CALL0_ABI__)
346 * a12 = thread_fn, a13 = thread_fn arg.
347 * _switch_to epilogue will load registers from the stack.
349 ((unsigned long *)p->thread.sp)[0] = (unsigned long)args->fn;
350 ((unsigned long *)p->thread.sp)[1] = (unsigned long)args->fn_arg;
352 #error Unsupported Xtensa ABI
355 /* Childregs are only used when we're going to userspace
356 * in which case start_thread will set them up.
360 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
361 ti = task_thread_info(p);
365 clear_ptrace_hw_breakpoint(p);
372 * These bracket the sleeping functions..
375 unsigned long __get_wchan(struct task_struct *p)
377 unsigned long sp, pc;
378 unsigned long stack_page = (unsigned long) task_stack_page(p);
382 pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
385 if (sp < stack_page + sizeof(struct task_struct) ||
386 sp >= (stack_page + THREAD_SIZE) ||
389 if (!in_sched_functions(pc))
392 /* Stack layout: sp-4: ra, sp-3: sp' */
394 pc = MAKE_PC_FROM_RA(SPILL_SLOT(sp, 0), sp);
395 sp = SPILL_SLOT(sp, 1);
396 } while (count++ < 16);