1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#include <linux/sched.h>
 16#include <linux/mm.h>
 17#include <linux/smp.h>
 18#include <linux/kernel.h>
 19#include <linux/signal.h>
 20#include <linux/errno.h>
 21#include <linux/wait.h>
 22#include <linux/unistd.h>
 23#include <linux/stddef.h>
 24#include <linux/personality.h>
 25#include <linux/suspend.h>
 26#include <linux/ptrace.h>
 27#include <linux/elf.h>
 28#include <linux/compat.h>
 29#include <linux/syscalls.h>
 30#include <linux/uaccess.h>
 31#include <asm/processor.h>
 32#include <asm/ucontext.h>
 33#include <asm/sigframe.h>
 34#include <asm/syscalls.h>
 35#include <asm/vdso.h>
 36#include <arch/interrupts.h>
 37
 38struct compat_ucontext {
 39	compat_ulong_t	  uc_flags;
 40	compat_uptr_t     uc_link;
 41	struct compat_sigaltstack	  uc_stack;
 42	struct sigcontext uc_mcontext;
 43	sigset_t	  uc_sigmask;	/* mask last for extensibility */
 44};
 45
 46struct compat_rt_sigframe {
 47	unsigned char save_area[C_ABI_SAVE_AREA_SIZE]; /* caller save area */
 48	struct compat_siginfo info;
 49	struct compat_ucontext uc;
 50};
 51
 52int copy_siginfo_to_user32(struct compat_siginfo __user *to, const siginfo_t *from)
 53{
 54	int err;
 55
 56	if (!access_ok(VERIFY_WRITE, to, sizeof(struct compat_siginfo)))
 57		return -EFAULT;
 58
 59	/* If you change siginfo_t structure, please make sure that
 60	   this code is fixed accordingly.
 61	   It should never copy any pad contained in the structure
 62	   to avoid security leaks, but must copy the generic
 63	   3 ints plus the relevant union member.  */
 64	err = __put_user(from->si_signo, &to->si_signo);
 65	err |= __put_user(from->si_errno, &to->si_errno);
 66	err |= __put_user((short)from->si_code, &to->si_code);
 67
 68	if (from->si_code < 0) {
 69		err |= __put_user(from->si_pid, &to->si_pid);
 70		err |= __put_user(from->si_uid, &to->si_uid);
 71		err |= __put_user(from->si_int, &to->si_int);
 72	} else {
 73		/*
 74		 * First 32bits of unions are always present:
 75		 * si_pid === si_band === si_tid === si_addr(LS half)
 76		 */
 77		err |= __put_user(from->_sifields._pad[0],
 78				  &to->_sifields._pad[0]);
 79		switch (from->si_code >> 16) {
 80		case __SI_FAULT >> 16:
 81			break;
 82		case __SI_CHLD >> 16:
 83			err |= __put_user(from->si_utime, &to->si_utime);
 84			err |= __put_user(from->si_stime, &to->si_stime);
 85			err |= __put_user(from->si_status, &to->si_status);
 86			/* FALL THROUGH */
 87		default:
 88		case __SI_KILL >> 16:
 89			err |= __put_user(from->si_uid, &to->si_uid);
 90			break;
 91		case __SI_POLL >> 16:
 92			err |= __put_user(from->si_fd, &to->si_fd);
 93			break;
 94		case __SI_TIMER >> 16:
 95			err |= __put_user(from->si_overrun, &to->si_overrun);
 96			err |= __put_user(from->si_int, &to->si_int);
 97			break;
 98			 /* This is not generated by the kernel as of now.  */
 99		case __SI_RT >> 16:
100		case __SI_MESGQ >> 16:
101			err |= __put_user(from->si_uid, &to->si_uid);
102			err |= __put_user(from->si_int, &to->si_int);
103			break;
104		}
105	}
106	return err;
107}
108
109int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
110{
111	int err;
112
113	if (!access_ok(VERIFY_READ, from, sizeof(struct compat_siginfo)))
114		return -EFAULT;
115
116	err = __get_user(to->si_signo, &from->si_signo);
117	err |= __get_user(to->si_errno, &from->si_errno);
118	err |= __get_user(to->si_code, &from->si_code);
119
120	err |= __get_user(to->si_pid, &from->si_pid);
121	err |= __get_user(to->si_uid, &from->si_uid);
122	err |= __get_user(to->si_int, &from->si_int);
123
124	return err;
125}
126
127/* The assembly shim for this function arranges to ignore the return value. */
128long compat_sys_rt_sigreturn(void)
129{
130	struct pt_regs *regs = current_pt_regs();
131	struct compat_rt_sigframe __user *frame =
132		(struct compat_rt_sigframe __user *) compat_ptr(regs->sp);
133	sigset_t set;
134
135	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
136		goto badframe;
137	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
138		goto badframe;
139
140	set_current_blocked(&set);
141
142	if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
143		goto badframe;
144
145	if (compat_restore_altstack(&frame->uc.uc_stack))
146		goto badframe;
147
148	return 0;
149
150badframe:
151	signal_fault("bad sigreturn frame", regs, frame, 0);
152	return 0;
153}
154
155/*
156 * Determine which stack to use..
157 */
158static inline void __user *compat_get_sigframe(struct k_sigaction *ka,
159					       struct pt_regs *regs,
160					       size_t frame_size)
161{
162	unsigned long sp;
163
164	/* Default to using normal stack */
165	sp = (unsigned long)compat_ptr(regs->sp);
166
167	/*
168	 * If we are on the alternate signal stack and would overflow
169	 * it, don't.  Return an always-bogus address instead so we
170	 * will die with SIGSEGV.
171	 */
172	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
173		return (void __user __force *)-1UL;
174
175	/* This is the X/Open sanctioned signal stack switching.  */
176	if (ka->sa.sa_flags & SA_ONSTACK) {
177		if (sas_ss_flags(sp) == 0)
178			sp = current->sas_ss_sp + current->sas_ss_size;
179	}
180
181	sp -= frame_size;
182	/*
183	 * Align the stack pointer according to the TILE ABI,
184	 * i.e. so that on function entry (sp & 15) == 0.
185	 */
186	sp &= -16UL;
187	return (void __user *) sp;
188}
189
190int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
191			  struct pt_regs *regs)
192{
193	unsigned long restorer;
194	struct compat_rt_sigframe __user *frame;
195	int err = 0, sig = ksig->sig;
196
197	frame = compat_get_sigframe(&ksig->ka, regs, sizeof(*frame));
198
199	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
200		goto err;
201
202	/* Always write at least the signal number for the stack backtracer. */
203	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
204		/* At sigreturn time, restore the callee-save registers too. */
205		err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
206		regs->flags |= PT_FLAGS_RESTORE_REGS;
207	} else {
208		err |= __put_user(ksig->info.si_signo, &frame->info.si_signo);
209	}
210
211	/* Create the ucontext.  */
212	err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
213	err |= __put_user(0, &frame->uc.uc_flags);
214	err |= __put_user(0, &frame->uc.uc_link);
215	err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
216	err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
217	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
218	if (err)
219		goto err;
220
221	restorer = VDSO_SYM(&__vdso_rt_sigreturn);
222	if (ksig->ka.sa.sa_flags & SA_RESTORER)
223		restorer = ptr_to_compat_reg(ksig->ka.sa.sa_restorer);
224
225	/*
226	 * Set up registers for signal handler.
227	 * Registers that we don't modify keep the value they had from
228	 * user-space at the time we took the signal.
229	 * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
230	 * since some things rely on this (e.g. glibc's debug/segfault.c).
231	 */
232	regs->pc = ptr_to_compat_reg(ksig->ka.sa.sa_handler);
233	regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
234	regs->sp = ptr_to_compat_reg(frame);
235	regs->lr = restorer;
236	regs->regs[0] = (unsigned long) sig;
237	regs->regs[1] = ptr_to_compat_reg(&frame->info);
238	regs->regs[2] = ptr_to_compat_reg(&frame->uc);
239	regs->flags |= PT_FLAGS_CALLER_SAVES;
240	return 0;
241
242err:
243	trace_unhandled_signal("bad sigreturn frame", regs,
244			      (unsigned long)frame, SIGSEGV);
245	return -EFAULT;
246}