1 // SPDX-License-Identifier: GPL-2.0+
3 * Author: Hanlu Li <lihanlu@loongson.cn>
4 * Huacai Chen <chenhuacai@loongson.cn>
5 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
8 * Copyright (C) 1991, 1992 Linus Torvalds
9 * Copyright (C) 1994 - 2000 Ralf Baechle
10 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
11 * Copyright (C) 2014, Imagination Technologies Ltd.
13 #include <linux/audit.h>
14 #include <linux/cache.h>
15 #include <linux/context_tracking.h>
16 #include <linux/irqflags.h>
17 #include <linux/sched.h>
19 #include <linux/personality.h>
20 #include <linux/smp.h>
21 #include <linux/kernel.h>
22 #include <linux/signal.h>
23 #include <linux/errno.h>
24 #include <linux/wait.h>
25 #include <linux/ptrace.h>
26 #include <linux/unistd.h>
27 #include <linux/compiler.h>
28 #include <linux/syscalls.h>
29 #include <linux/uaccess.h>
32 #include <asm/cacheflush.h>
33 #include <asm/cpu-features.h>
35 #include <asm/ucontext.h>
39 # define DEBUGP(fmt, args...) printk("%s: " fmt, __func__, ##args)
41 # define DEBUGP(fmt, args...)
44 /* Make sure we will not lose FPU ownership */
45 #define lock_fpu_owner() ({ preempt_disable(); pagefault_disable(); })
46 #define unlock_fpu_owner() ({ pagefault_enable(); preempt_enable(); })
48 /* Assembly functions to move context to/from the FPU */
50 _save_fp_context(void __user *fpregs, void __user *fcc, void __user *csr);
52 _restore_fp_context(void __user *fpregs, void __user *fcc, void __user *csr);
55 struct siginfo rs_info;
56 struct ucontext rs_uctx;
60 struct sctx_info *addr;
64 struct extctx_layout {
67 struct _ctx_layout fpu;
68 struct _ctx_layout end;
71 static void __user *get_ctx_through_ctxinfo(struct sctx_info *info)
73 return (void __user *)((char *)info + sizeof(struct sctx_info));
77 * Thread saved context copy to/from a signal context presumed to be on the
78 * user stack, and therefore accessed with appropriate macros from uaccess.h.
80 static int copy_fpu_to_sigcontext(struct fpu_context __user *ctx)
84 uint64_t __user *regs = (uint64_t *)&ctx->regs;
85 uint64_t __user *fcc = &ctx->fcc;
86 uint32_t __user *fcsr = &ctx->fcsr;
88 for (i = 0; i < NUM_FPU_REGS; i++) {
90 __put_user(get_fpr64(¤t->thread.fpu.fpr[i], 0),
93 err |= __put_user(current->thread.fpu.fcc, fcc);
94 err |= __put_user(current->thread.fpu.fcsr, fcsr);
99 static int copy_fpu_from_sigcontext(struct fpu_context __user *ctx)
104 uint64_t __user *regs = (uint64_t *)&ctx->regs;
105 uint64_t __user *fcc = &ctx->fcc;
106 uint32_t __user *fcsr = &ctx->fcsr;
108 for (i = 0; i < NUM_FPU_REGS; i++) {
109 err |= __get_user(fpr_val, ®s[i]);
110 set_fpr64(¤t->thread.fpu.fpr[i], 0, fpr_val);
112 err |= __get_user(current->thread.fpu.fcc, fcc);
113 err |= __get_user(current->thread.fpu.fcsr, fcsr);
119 * Wrappers for the assembly _{save,restore}_fp_context functions.
121 static int save_hw_fpu_context(struct fpu_context __user *ctx)
123 uint64_t __user *regs = (uint64_t *)&ctx->regs;
124 uint64_t __user *fcc = &ctx->fcc;
125 uint32_t __user *fcsr = &ctx->fcsr;
127 return _save_fp_context(regs, fcc, fcsr);
130 static int restore_hw_fpu_context(struct fpu_context __user *ctx)
132 uint64_t __user *regs = (uint64_t *)&ctx->regs;
133 uint64_t __user *fcc = &ctx->fcc;
134 uint32_t __user *fcsr = &ctx->fcsr;
136 return _restore_fp_context(regs, fcc, fcsr);
139 static int fcsr_pending(unsigned int __user *fcsr)
142 unsigned int csr, enabled;
144 err = __get_user(csr, fcsr);
145 enabled = ((csr & FPU_CSR_ALL_E) << 24);
147 * If the signal handler set some FPU exceptions, clear it and
152 err |= __put_user(csr, fcsr);
161 static int protected_save_fpu_context(struct extctx_layout *extctx)
164 struct sctx_info __user *info = extctx->fpu.addr;
165 struct fpu_context __user *fpu_ctx = (struct fpu_context *)get_ctx_through_ctxinfo(info);
166 uint64_t __user *regs = (uint64_t *)&fpu_ctx->regs;
167 uint64_t __user *fcc = &fpu_ctx->fcc;
168 uint32_t __user *fcsr = &fpu_ctx->fcsr;
173 err = save_hw_fpu_context(fpu_ctx);
175 err = copy_fpu_to_sigcontext(fpu_ctx);
178 err |= __put_user(FPU_CTX_MAGIC, &info->magic);
179 err |= __put_user(extctx->fpu.size, &info->size);
183 /* Touch the FPU context and try again */
184 err = __put_user(0, ®s[0]) |
185 __put_user(0, ®s[31]) |
189 return err; /* really bad sigcontext */
195 static int protected_restore_fpu_context(struct extctx_layout *extctx)
197 int err = 0, sig = 0, tmp __maybe_unused;
198 struct sctx_info __user *info = extctx->fpu.addr;
199 struct fpu_context __user *fpu_ctx = (struct fpu_context *)get_ctx_through_ctxinfo(info);
200 uint64_t __user *regs = (uint64_t *)&fpu_ctx->regs;
201 uint64_t __user *fcc = &fpu_ctx->fcc;
202 uint32_t __user *fcsr = &fpu_ctx->fcsr;
204 err = sig = fcsr_pending(fcsr);
211 err = restore_hw_fpu_context(fpu_ctx);
213 err = copy_fpu_from_sigcontext(fpu_ctx);
218 /* Touch the FPU context and try again */
219 err = __get_user(tmp, ®s[0]) |
220 __get_user(tmp, ®s[31]) |
221 __get_user(tmp, fcc) |
222 __get_user(tmp, fcsr);
224 break; /* really bad sigcontext */
230 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
231 struct extctx_layout *extctx)
234 struct sctx_info __user *info;
236 err |= __put_user(regs->csr_era, &sc->sc_pc);
237 err |= __put_user(extctx->flags, &sc->sc_flags);
239 err |= __put_user(0, &sc->sc_regs[0]);
240 for (i = 1; i < 32; i++)
241 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
243 if (extctx->fpu.addr)
244 err |= protected_save_fpu_context(extctx);
246 /* Set the "end" magic */
247 info = (struct sctx_info *)extctx->end.addr;
248 err |= __put_user(0, &info->magic);
249 err |= __put_user(0, &info->size);
254 static int parse_extcontext(struct sigcontext __user *sc, struct extctx_layout *extctx)
257 unsigned int magic, size;
258 struct sctx_info __user *info = (struct sctx_info __user *)&sc->sc_extcontext;
261 err |= __get_user(magic, &info->magic);
262 err |= __get_user(size, &info->size);
271 if (size < (sizeof(struct sctx_info) +
272 sizeof(struct fpu_context)))
274 extctx->fpu.addr = info;
281 info = (struct sctx_info *)((char *)info + size);
291 static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
294 struct extctx_layout extctx;
296 memset(&extctx, 0, sizeof(struct extctx_layout));
298 err = __get_user(extctx.flags, &sc->sc_flags);
302 err = parse_extcontext(sc, &extctx);
306 conditional_used_math(extctx.flags & SC_USED_FP);
309 * The signal handler may have used FPU; give it up if the program
310 * doesn't want it following sigreturn.
312 if (!(extctx.flags & SC_USED_FP))
315 /* Always make any pending restarted system calls return -EINTR */
316 current->restart_block.fn = do_no_restart_syscall;
318 err |= __get_user(regs->csr_era, &sc->sc_pc);
319 for (i = 1; i < 32; i++)
320 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
323 err |= protected_restore_fpu_context(&extctx);
329 static unsigned int handle_flags(void)
331 unsigned int flags = 0;
333 flags = used_math() ? SC_USED_FP : 0;
335 switch (current->thread.error_code) {
337 flags |= SC_ADDRERR_RD;
340 flags |= SC_ADDRERR_WR;
347 static unsigned long extframe_alloc(struct extctx_layout *extctx,
348 struct _ctx_layout *layout,
349 size_t size, unsigned int align, unsigned long base)
351 unsigned long new_base = base - size;
353 new_base = round_down(new_base, (align < 16 ? 16 : align));
354 new_base -= sizeof(struct sctx_info);
356 layout->addr = (void *)new_base;
357 layout->size = (unsigned int)(base - new_base);
358 extctx->size += layout->size;
363 static unsigned long setup_extcontext(struct extctx_layout *extctx, unsigned long sp)
365 unsigned long new_sp = sp;
367 memset(extctx, 0, sizeof(struct extctx_layout));
369 extctx->flags = handle_flags();
371 /* Grow down, alloc "end" context info first. */
372 new_sp -= sizeof(struct sctx_info);
373 extctx->end.addr = (void *)new_sp;
374 extctx->end.size = (unsigned int)sizeof(struct sctx_info);
375 extctx->size += extctx->end.size;
377 if (extctx->flags & SC_USED_FP) {
379 new_sp = extframe_alloc(extctx, &extctx->fpu,
380 sizeof(struct fpu_context), FPU_CTX_ALIGN, new_sp);
386 void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
387 struct extctx_layout *extctx)
391 /* Default to using normal stack */
395 * If we are on the alternate signal stack and would overflow it, don't.
396 * Return an always-bogus address instead so we will die with SIGSEGV.
398 if (on_sig_stack(sp) &&
399 !likely(on_sig_stack(sp - sizeof(struct rt_sigframe))))
400 return (void __user __force *)(-1UL);
402 sp = sigsp(sp, ksig);
403 sp = round_down(sp, 16);
404 sp = setup_extcontext(extctx, sp);
405 sp -= sizeof(struct rt_sigframe);
407 if (!IS_ALIGNED(sp, 16))
410 return (void __user *)sp;
414 * Atomically swap in the new signal mask, and wait for a signal.
417 asmlinkage long sys_rt_sigreturn(void)
421 struct pt_regs *regs;
422 struct rt_sigframe __user *frame;
424 regs = current_pt_regs();
425 frame = (struct rt_sigframe __user *)regs->regs[3];
426 if (!access_ok(frame, sizeof(*frame)))
428 if (__copy_from_user(&set, &frame->rs_uctx.uc_sigmask, sizeof(set)))
431 set_current_blocked(&set);
433 sig = restore_sigcontext(regs, &frame->rs_uctx.uc_mcontext);
439 regs->regs[0] = 0; /* No syscall restarting */
440 if (restore_altstack(&frame->rs_uctx.uc_stack))
443 return regs->regs[4];
450 static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
451 struct pt_regs *regs, sigset_t *set)
454 struct extctx_layout extctx;
455 struct rt_sigframe __user *frame;
457 frame = get_sigframe(ksig, regs, &extctx);
458 if (!access_ok(frame, sizeof(*frame) + extctx.size))
461 /* Create siginfo. */
462 err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);
464 /* Create the ucontext. */
465 err |= __put_user(0, &frame->rs_uctx.uc_flags);
466 err |= __put_user(NULL, &frame->rs_uctx.uc_link);
467 err |= __save_altstack(&frame->rs_uctx.uc_stack, regs->regs[3]);
468 err |= setup_sigcontext(regs, &frame->rs_uctx.uc_mcontext, &extctx);
469 err |= __copy_to_user(&frame->rs_uctx.uc_sigmask, set, sizeof(*set));
475 * Arguments to signal handler:
478 * a1 = pointer to siginfo
479 * a2 = pointer to ucontext
481 * c0_era point to the signal handler, $r3 (sp) points to
482 * the struct rt_sigframe.
484 regs->regs[4] = ksig->sig;
485 regs->regs[5] = (unsigned long) &frame->rs_info;
486 regs->regs[6] = (unsigned long) &frame->rs_uctx;
487 regs->regs[3] = (unsigned long) frame;
488 regs->regs[1] = (unsigned long) sig_return;
489 regs->csr_era = (unsigned long) ksig->ka.sa.sa_handler;
491 DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
492 current->comm, current->pid,
493 frame, regs->csr_era, regs->regs[1]);
498 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
501 sigset_t *oldset = sigmask_to_save();
502 void *vdso = current->mm->context.vdso;
504 /* Are we from a system call? */
506 switch (regs->regs[4]) {
507 case -ERESTART_RESTARTBLOCK:
508 case -ERESTARTNOHAND:
509 regs->regs[4] = -EINTR;
512 if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
513 regs->regs[4] = -EINTR;
517 case -ERESTARTNOINTR:
518 regs->regs[4] = regs->orig_a0;
522 regs->regs[0] = 0; /* Don't deal with this again. */
525 rseq_signal_deliver(ksig, regs);
527 ret = setup_rt_frame(vdso + current->thread.vdso->offset_sigreturn, ksig, regs, oldset);
529 signal_setup_done(ret, ksig, 0);
532 void arch_do_signal_or_restart(struct pt_regs *regs)
536 if (get_signal(&ksig)) {
537 /* Whee! Actually deliver the signal. */
538 handle_signal(&ksig, regs);
542 /* Are we from a system call? */
544 switch (regs->regs[4]) {
545 case -ERESTARTNOHAND:
547 case -ERESTARTNOINTR:
548 regs->regs[4] = regs->orig_a0;
552 case -ERESTART_RESTARTBLOCK:
553 regs->regs[4] = regs->orig_a0;
554 regs->regs[11] = __NR_restart_syscall;
558 regs->regs[0] = 0; /* Don't deal with this again. */
562 * If there's no signal to deliver, we just put the saved sigmask
565 restore_saved_sigmask();