~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/xtensa/kernel/process.c

Version: ~ [ linux-5.3 ] ~ [ linux-5.2.14 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.72 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.143 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.192 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.192 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.73 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  * arch/xtensa/kernel/process.c
  3  *
  4  * Xtensa Processor version.
  5  *
  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
  8  * for more details.
  9  *
 10  * Copyright (C) 2001 - 2005 Tensilica Inc.
 11  *
 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>
 15  * Kevin Chea
 16  */
 17 
 18 #include <linux/errno.h>
 19 #include <linux/sched.h>
 20 #include <linux/kernel.h>
 21 #include <linux/mm.h>
 22 #include <linux/smp.h>
 23 #include <linux/stddef.h>
 24 #include <linux/unistd.h>
 25 #include <linux/ptrace.h>
 26 #include <linux/elf.h>
 27 #include <linux/hw_breakpoint.h>
 28 #include <linux/init.h>
 29 #include <linux/prctl.h>
 30 #include <linux/init_task.h>
 31 #include <linux/module.h>
 32 #include <linux/mqueue.h>
 33 #include <linux/fs.h>
 34 #include <linux/slab.h>
 35 #include <linux/rcupdate.h>
 36 
 37 #include <asm/pgtable.h>
 38 #include <linux/uaccess.h>
 39 #include <asm/io.h>
 40 #include <asm/processor.h>
 41 #include <asm/platform.h>
 42 #include <asm/mmu.h>
 43 #include <asm/irq.h>
 44 #include <linux/atomic.h>
 45 #include <asm/asm-offsets.h>
 46 #include <asm/regs.h>
 47 #include <asm/hw_breakpoint.h>
 48 
 49 extern void ret_from_fork(void);
 50 extern void ret_from_kernel_thread(void);
 51 
 52 struct task_struct *current_set[NR_CPUS] = {&init_task, };
 53 
 54 void (*pm_power_off)(void) = NULL;
 55 EXPORT_SYMBOL(pm_power_off);
 56 
 57 
 58 #if XTENSA_HAVE_COPROCESSORS
 59 
 60 void coprocessor_release_all(struct thread_info *ti)
 61 {
 62         unsigned long cpenable;
 63         int i;
 64 
 65         /* Make sure we don't switch tasks during this operation. */
 66 
 67         preempt_disable();
 68 
 69         /* Walk through all cp owners and release it for the requested one. */
 70 
 71         cpenable = ti->cpenable;
 72 
 73         for (i = 0; i < XCHAL_CP_MAX; i++) {
 74                 if (coprocessor_owner[i] == ti) {
 75                         coprocessor_owner[i] = 0;
 76                         cpenable &= ~(1 << i);
 77                 }
 78         }
 79 
 80         ti->cpenable = cpenable;
 81         coprocessor_clear_cpenable();
 82 
 83         preempt_enable();
 84 }
 85 
 86 void coprocessor_flush_all(struct thread_info *ti)
 87 {
 88         unsigned long cpenable;
 89         int i;
 90 
 91         preempt_disable();
 92 
 93         cpenable = ti->cpenable;
 94 
 95         for (i = 0; i < XCHAL_CP_MAX; i++) {
 96                 if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
 97                         coprocessor_flush(ti, i);
 98                 cpenable >>= 1;
 99         }
100 
101         preempt_enable();
102 }
103 
104 #endif
105 
106 
107 /*
108  * Powermanagement idle function, if any is provided by the platform.
109  */
110 void arch_cpu_idle(void)
111 {
112         platform_idle();
113 }
114 
115 /*
116  * This is called when the thread calls exit().
117  */
118 void exit_thread(struct task_struct *tsk)
119 {
120 #if XTENSA_HAVE_COPROCESSORS
121         coprocessor_release_all(task_thread_info(tsk));
122 #endif
123 }
124 
125 /*
126  * Flush thread state. This is called when a thread does an execve()
127  * Note that we flush coprocessor registers for the case execve fails.
128  */
129 void flush_thread(void)
130 {
131 #if XTENSA_HAVE_COPROCESSORS
132         struct thread_info *ti = current_thread_info();
133         coprocessor_flush_all(ti);
134         coprocessor_release_all(ti);
135 #endif
136         flush_ptrace_hw_breakpoint(current);
137 }
138 
139 /*
140  * this gets called so that we can store coprocessor state into memory and
141  * copy the current task into the new thread.
142  */
143 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
144 {
145 #if XTENSA_HAVE_COPROCESSORS
146         coprocessor_flush_all(task_thread_info(src));
147 #endif
148         *dst = *src;
149         return 0;
150 }
151 
152 /*
153  * Copy thread.
154  *
155  * There are two modes in which this function is called:
156  * 1) Userspace thread creation,
157  *    regs != NULL, usp_thread_fn is userspace stack pointer.
158  *    It is expected to copy parent regs (in case CLONE_VM is not set
159  *    in the clone_flags) and set up passed usp in the childregs.
160  * 2) Kernel thread creation,
161  *    regs == NULL, usp_thread_fn is the function to run in the new thread
162  *    and thread_fn_arg is its parameter.
163  *    childregs are not used for the kernel threads.
164  *
165  * The stack layout for the new thread looks like this:
166  *
167  *      +------------------------+
168  *      |       childregs        |
169  *      +------------------------+ <- thread.sp = sp in dummy-frame
170  *      |      dummy-frame       |    (saved in dummy-frame spill-area)
171  *      +------------------------+
172  *
173  * We create a dummy frame to return to either ret_from_fork or
174  *   ret_from_kernel_thread:
175  *   a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
176  *   sp points to itself (thread.sp)
177  *   a2, a3 are unused for userspace threads,
178  *   a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
179  *
180  * Note: This is a pristine frame, so we don't need any spill region on top of
181  *       childregs.
182  *
183  * The fun part:  if we're keeping the same VM (i.e. cloning a thread,
184  * not an entire process), we're normally given a new usp, and we CANNOT share
185  * any live address register windows.  If we just copy those live frames over,
186  * the two threads (parent and child) will overflow the same frames onto the
187  * parent stack at different times, likely corrupting the parent stack (esp.
188  * if the parent returns from functions that called clone() and calls new
189  * ones, before the child overflows its now old copies of its parent windows).
190  * One solution is to spill windows to the parent stack, but that's fairly
191  * involved.  Much simpler to just not copy those live frames across.
192  */
193 
194 int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
195                 unsigned long thread_fn_arg, struct task_struct *p)
196 {
197         struct pt_regs *childregs = task_pt_regs(p);
198 
199 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
200         struct thread_info *ti;
201 #endif
202 
203         /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
204         *((int*)childregs - 3) = (unsigned long)childregs;
205         *((int*)childregs - 4) = 0;
206 
207         p->thread.sp = (unsigned long)childregs;
208 
209         if (!(p->flags & PF_KTHREAD)) {
210                 struct pt_regs *regs = current_pt_regs();
211                 unsigned long usp = usp_thread_fn ?
212                         usp_thread_fn : regs->areg[1];
213 
214                 p->thread.ra = MAKE_RA_FOR_CALL(
215                                 (unsigned long)ret_from_fork, 0x1);
216 
217                 /* This does not copy all the regs.
218                  * In a bout of brilliance or madness,
219                  * ARs beyond a0-a15 exist past the end of the struct.
220                  */
221                 *childregs = *regs;
222                 childregs->areg[1] = usp;
223                 childregs->areg[2] = 0;
224 
225                 /* When sharing memory with the parent thread, the child
226                    usually starts on a pristine stack, so we have to reset
227                    windowbase, windowstart and wmask.
228                    (Note that such a new thread is required to always create
229                    an initial call4 frame)
230                    The exception is vfork, where the new thread continues to
231                    run on the parent's stack until it calls execve. This could
232                    be a call8 or call12, which requires a legal stack frame
233                    of the previous caller for the overflow handlers to work.
234                    (Note that it's always legal to overflow live registers).
235                    In this case, ensure to spill at least the stack pointer
236                    of that frame. */
237 
238                 if (clone_flags & CLONE_VM) {
239                         /* check that caller window is live and same stack */
240                         int len = childregs->wmask & ~0xf;
241                         if (regs->areg[1] == usp && len != 0) {
242                                 int callinc = (regs->areg[0] >> 30) & 3;
243                                 int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
244                                 put_user(regs->areg[caller_ars+1],
245                                          (unsigned __user*)(usp - 12));
246                         }
247                         childregs->wmask = 1;
248                         childregs->windowstart = 1;
249                         childregs->windowbase = 0;
250                 } else {
251                         int len = childregs->wmask & ~0xf;
252                         memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
253                                &regs->areg[XCHAL_NUM_AREGS - len/4], len);
254                 }
255 
256                 /* The thread pointer is passed in the '4th argument' (= a5) */
257                 if (clone_flags & CLONE_SETTLS)
258                         childregs->threadptr = childregs->areg[5];
259         } else {
260                 p->thread.ra = MAKE_RA_FOR_CALL(
261                                 (unsigned long)ret_from_kernel_thread, 1);
262 
263                 /* pass parameters to ret_from_kernel_thread:
264                  * a2 = thread_fn, a3 = thread_fn arg
265                  */
266                 *((int *)childregs - 1) = thread_fn_arg;
267                 *((int *)childregs - 2) = usp_thread_fn;
268 
269                 /* Childregs are only used when we're going to userspace
270                  * in which case start_thread will set them up.
271                  */
272         }
273 
274 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
275         ti = task_thread_info(p);
276         ti->cpenable = 0;
277 #endif
278 
279         clear_ptrace_hw_breakpoint(p);
280 
281         return 0;
282 }
283 
284 
285 /*
286  * These bracket the sleeping functions..
287  */
288 
289 unsigned long get_wchan(struct task_struct *p)
290 {
291         unsigned long sp, pc;
292         unsigned long stack_page = (unsigned long) task_stack_page(p);
293         int count = 0;
294 
295         if (!p || p == current || p->state == TASK_RUNNING)
296                 return 0;
297 
298         sp = p->thread.sp;
299         pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
300 
301         do {
302                 if (sp < stack_page + sizeof(struct task_struct) ||
303                     sp >= (stack_page + THREAD_SIZE) ||
304                     pc == 0)
305                         return 0;
306                 if (!in_sched_functions(pc))
307                         return pc;
308 
309                 /* Stack layout: sp-4: ra, sp-3: sp' */
310 
311                 pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
312                 sp = *(unsigned long *)sp - 3;
313         } while (count++ < 16);
314         return 0;
315 }
316 
317 /*
318  * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
319  * of processor registers.  Besides different ordering,
320  * xtensa_gregset_t contains non-live register information that
321  * 'struct pt_regs' does not.  Exception handling (primarily) uses
322  * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
323  *
324  */
325 
326 void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
327 {
328         unsigned long wb, ws, wm;
329         int live, last;
330 
331         wb = regs->windowbase;
332         ws = regs->windowstart;
333         wm = regs->wmask;
334         ws = ((ws >> wb) | (ws << (WSBITS - wb))) & ((1 << WSBITS) - 1);
335 
336         /* Don't leak any random bits. */
337 
338         memset(elfregs, 0, sizeof(*elfregs));
339 
340         /* Note:  PS.EXCM is not set while user task is running; its
341          * being set in regs->ps is for exception handling convenience.
342          */
343 
344         elfregs->pc             = regs->pc;
345         elfregs->ps             = (regs->ps & ~(1 << PS_EXCM_BIT));
346         elfregs->lbeg           = regs->lbeg;
347         elfregs->lend           = regs->lend;
348         elfregs->lcount         = regs->lcount;
349         elfregs->sar            = regs->sar;
350         elfregs->windowstart    = ws;
351 
352         live = (wm & 2) ? 4 : (wm & 4) ? 8 : (wm & 8) ? 12 : 16;
353         last = XCHAL_NUM_AREGS - (wm >> 4) * 4;
354         memcpy(elfregs->a, regs->areg, live * 4);
355         memcpy(elfregs->a + last, regs->areg + last, (wm >> 4) * 16);
356 }
357 
358 int dump_fpu(void)
359 {
360         return 0;
361 }
362 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp