Initial import

1 files changed, 499 insertions, 0 deletions

diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c
new file mode 100644
index 000000000..e87adaa07
--- /dev/null
+++ b/arch/xtensa/kernel/signal.c
@@ -0,0 +1,499 @@
+/*
+ * arch/xtensa/kernel/signal.c
+ *
+ * Default platform functions.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2005, 2006 Tensilica Inc.
+ * Copyright (C) 1991, 1992  Linus Torvalds
+ * 1997-11-28  Modified for POSIX.1b signals by Richard Henderson
+ *
+ * Chris Zankel <chris@zankel.net>
+ * Joe Taylor <joe@tensilica.com>
+ */
+
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/ptrace.h>
+#include <linux/personality.h>
+#include <linux/tracehook.h>
+
+#include <asm/ucontext.h>
+#include <asm/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/coprocessor.h>
+#include <asm/unistd.h>
+
+#define DEBUG_SIG  0
+
+extern struct task_struct *coproc_owners[];
+
+struct rt_sigframe
+{
+	struct siginfo info;
+	struct ucontext uc;
+	struct {
+		xtregs_opt_t opt;
+		xtregs_user_t user;
+#if XTENSA_HAVE_COPROCESSORS
+		xtregs_coprocessor_t cp;
+#endif
+	} xtregs;
+	unsigned char retcode[6];
+	unsigned int window[4];
+};
+
+/* 
+ * Flush register windows stored in pt_regs to stack.
+ * Returns 1 for errors.
+ */
+
+int
+flush_window_regs_user(struct pt_regs *regs)
+{
+	const unsigned long ws = regs->windowstart;
+	const unsigned long wb = regs->windowbase;
+	unsigned long sp = 0;
+	unsigned long wm;
+	int err = 1;
+	int base;
+
+	/* Return if no other frames. */
+
+	if (regs->wmask == 1)
+		return 0;
+
+	/* Rotate windowmask and skip empty frames. */
+
+	wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
+	base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
+		
+	/* For call8 or call12 frames, we need the previous stack pointer. */
+
+	if ((regs->wmask & 2) == 0)
+		if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
+			goto errout;
+
+	/* Spill frames to stack. */
+
+	while (base < XCHAL_NUM_AREGS / 4) {
+
+		int m = (wm >> base);
+		int inc = 0;
+
+		/* Save registers a4..a7 (call8) or a4...a11 (call12) */
+
+		if (m & 2) {			/* call4 */
+			inc = 1;
+
+		} else if (m & 4) {		/* call8 */
+			if (copy_to_user((void*)(sp - 32),
+					   &regs->areg[(base + 1) * 4], 16))
+				goto errout;
+			inc = 2;
+
+		} else if (m & 8) {	/* call12 */
+			if (copy_to_user((void*)(sp - 48),
+					   &regs->areg[(base + 1) * 4], 32))
+				goto errout;
+			inc = 3;
+		}
+
+		/* Save current frame a0..a3 under next SP */
+
+		sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
+		if (copy_to_user((void*)(sp - 16), &regs->areg[base * 4], 16))
+			goto errout;
+
+		/* Get current stack pointer for next loop iteration. */
+
+		sp = regs->areg[base * 4 + 1];
+		base += inc;
+	}
+
+	regs->wmask = 1;
+	regs->windowstart = 1 << wb;
+
+	return 0;
+
+errout:
+	return err;
+}
+
+/*
+ * Note: We don't copy double exception 'regs', we have to finish double exc. 
+ * first before we return to signal handler! This dbl.exc.handler might cause 
+ * another double exception, but I think we are fine as the situation is the 
+ * same as if we had returned to the signal handerl and got an interrupt 
+ * immediately...
+ */
+
+static int
+setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
+{
+	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
+	struct thread_info *ti = current_thread_info();
+	int err = 0;
+
+#define COPY(x)	err |= __put_user(regs->x, &sc->sc_##x)
+	COPY(pc);
+	COPY(ps);
+	COPY(lbeg);
+	COPY(lend);
+	COPY(lcount);
+	COPY(sar);
+#undef COPY
+
+	err |= flush_window_regs_user(regs);
+	err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);
+	err |= __put_user(0, &sc->sc_xtregs);
+
+	if (err)
+		return err;
+
+#if XTENSA_HAVE_COPROCESSORS
+	coprocessor_flush_all(ti);
+	coprocessor_release_all(ti);
+	err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
+			      sizeof (frame->xtregs.cp));
+#endif
+	err |= __copy_to_user(&frame->xtregs.opt, &regs->xtregs_opt,
+			      sizeof (xtregs_opt_t));
+	err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user,
+			      sizeof (xtregs_user_t));
+
+	err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs);
+
+	return err;
+}
+
+static int
+restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame)
+{
+	struct sigcontext __user *sc = &frame->uc.uc_mcontext;
+	struct thread_info *ti = current_thread_info();
+	unsigned int err = 0;
+	unsigned long ps;
+
+#define COPY(x)	err |= __get_user(regs->x, &sc->sc_##x)
+	COPY(pc);
+	COPY(lbeg);
+	COPY(lend);
+	COPY(lcount);
+	COPY(sar);
+#undef COPY
+
+	/* All registers were flushed to stack. Start with a prestine frame. */
+
+	regs->wmask = 1;
+	regs->windowbase = 0;
+	regs->windowstart = 1;
+
+	regs->syscall = -1;		/* disable syscall checks */
+
+	/* For PS, restore only PS.CALLINC.
+	 * Assume that all other bits are either the same as for the signal
+	 * handler, or the user mode value doesn't matter (e.g. PS.OWB).
+	 */
+	err |= __get_user(ps, &sc->sc_ps);
+	regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);
+
+	/* Additional corruption checks */
+
+	if ((regs->lcount > 0)
+	    && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
+		err = 1;
+
+	err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);
+
+	if (err)
+		return err;
+
+	/* The signal handler may have used coprocessors in which
+	 * case they are still enabled.  We disable them to force a
+	 * reloading of the original task's CP state by the lazy
+	 * context-switching mechanisms of CP exception handling.
+	 * Also, we essentially discard any coprocessor state that the
+	 * signal handler created. */
+
+#if XTENSA_HAVE_COPROCESSORS
+	coprocessor_release_all(ti);
+	err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp,
+				sizeof (frame->xtregs.cp));
+#endif
+	err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user,
+				sizeof (xtregs_user_t));
+	err |= __copy_from_user(&regs->xtregs_opt, &frame->xtregs.opt,
+				sizeof (xtregs_opt_t));
+
+	return err;
+}
+
+
+/*
+ * Do a signal return; undo the signal stack.
+ */
+
+asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3,
+				    long a4, long a5, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+	sigset_t set;
+	int ret;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	if (regs->depc > 64)
+		panic("rt_sigreturn in double exception!\n");
+
+	frame = (struct rt_sigframe __user *) regs->areg[1];
+
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+
+	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
+		goto badframe;
+
+	set_current_blocked(&set);
+
+	if (restore_sigcontext(regs, frame))
+		goto badframe;
+
+	ret = regs->areg[2];
+
+	if (restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return ret;
+
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+
+
+/*
+ * Set up a signal frame.
+ */
+
+static int
+gen_return_code(unsigned char *codemem)
+{
+	int err = 0;
+
+	/*
+	 * The 12-bit immediate is really split up within the 24-bit MOVI
+	 * instruction.  As long as the above system call numbers fit within
+	 * 8-bits, the following code works fine. See the Xtensa ISA for
+	 * details.
+	 */
+
+#if __NR_rt_sigreturn > 255
+# error Generating the MOVI instruction below breaks!
+#endif
+
+#ifdef __XTENSA_EB__   /* Big Endian version */
+	/* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
+	err |= __put_user(0x22, &codemem[0]);
+	err |= __put_user(0x0a, &codemem[1]);
+	err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
+	/* Generate instruction:  SYSCALL */
+	err |= __put_user(0x00, &codemem[3]);
+	err |= __put_user(0x05, &codemem[4]);
+	err |= __put_user(0x00, &codemem[5]);
+
+#elif defined __XTENSA_EL__   /* Little Endian version */
+	/* Generate instruction:  MOVI a2, __NR_rt_sigreturn */
+	err |= __put_user(0x22, &codemem[0]);
+	err |= __put_user(0xa0, &codemem[1]);
+	err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
+	/* Generate instruction:  SYSCALL */
+	err |= __put_user(0x00, &codemem[3]);
+	err |= __put_user(0x50, &codemem[4]);
+	err |= __put_user(0x00, &codemem[5]);
+#else
+# error Must use compiler for Xtensa processors.
+#endif
+
+	/* Flush generated code out of the data cache */
+
+	if (err == 0) {
+		__invalidate_icache_range((unsigned long)codemem, 6UL);
+		__flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
+	}
+
+	return err;
+}
+
+
+static int setup_frame(struct ksignal *ksig, sigset_t *set,
+		       struct pt_regs *regs)
+{
+	struct rt_sigframe *frame;
+	int err = 0, sig = ksig->sig;
+	unsigned long sp, ra, tp;
+
+	sp = regs->areg[1];
+
+	if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) {
+		sp = current->sas_ss_sp + current->sas_ss_size;
+	}
+
+	frame = (void *)((sp - sizeof(*frame)) & -16ul);
+
+	if (regs->depc > 64)
+		panic ("Double exception sys_sigreturn\n");
+
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) {
+		return -EFAULT;
+	}
+
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+		err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+	}
+
+	/* Create the user context.  */
+
+	err |= __put_user(0, &frame->uc.uc_flags);
+	err |= __put_user(0, &frame->uc.uc_link);
+	err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]);
+	err |= setup_sigcontext(frame, regs);
+	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+		ra = (unsigned long)ksig->ka.sa.sa_restorer;
+	} else {
+
+		/* Create sys_rt_sigreturn syscall in stack frame */
+
+		err |= gen_return_code(frame->retcode);
+
+		if (err) {
+			return -EFAULT;
+		}
+		ra = (unsigned long) frame->retcode;
+	}
+
+	/* 
+	 * Create signal handler execution context.
+	 * Return context not modified until this point.
+	 */
+
+	/* Set up registers for signal handler; preserve the threadptr */
+	tp = regs->threadptr;
+	start_thread(regs, (unsigned long) ksig->ka.sa.sa_handler,
+		     (unsigned long) frame);
+
+	/* Set up a stack frame for a call4
+	 * Note: PS.CALLINC is set to one by start_thread
+	 */
+	regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
+	regs->areg[6] = (unsigned long) sig;
+	regs->areg[7] = (unsigned long) &frame->info;
+	regs->areg[8] = (unsigned long) &frame->uc;
+	regs->threadptr = tp;
+
+#if DEBUG_SIG
+	printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
+		current->comm, current->pid, sig, frame, regs->pc);
+#endif
+
+	return 0;
+}
+
+/*
+ * Note that 'init' is a special process: it doesn't get signals it doesn't
+ * want to handle. Thus you cannot kill init even with a SIGKILL even by
+ * mistake.
+ *
+ * Note that we go through the signals twice: once to check the signals that
+ * the kernel can handle, and then we build all the user-level signal handling
+ * stack-frames in one go after that.
+ */
+static void do_signal(struct pt_regs *regs)
+{
+	struct ksignal ksig;
+
+	task_pt_regs(current)->icountlevel = 0;
+
+	if (get_signal(&ksig)) {
+		int ret;
+
+		/* Are we from a system call? */
+
+		if ((signed)regs->syscall >= 0) {
+
+			/* If so, check system call restarting.. */
+
+			switch (regs->areg[2]) {
+				case -ERESTARTNOHAND:
+				case -ERESTART_RESTARTBLOCK:
+					regs->areg[2] = -EINTR;
+					break;
+
+				case -ERESTARTSYS:
+					if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
+						regs->areg[2] = -EINTR;
+						break;
+					}
+					/* fallthrough */
+				case -ERESTARTNOINTR:
+					regs->areg[2] = regs->syscall;
+					regs->pc -= 3;
+					break;
+
+				default:
+					/* nothing to do */
+					if (regs->areg[2] != 0)
+					break;
+			}
+		}
+
+		/* Whee!  Actually deliver the signal.  */
+		/* Set up the stack frame */
+		ret = setup_frame(&ksig, sigmask_to_save(), regs);
+		signal_setup_done(ret, &ksig, 0);
+		if (current->ptrace & PT_SINGLESTEP)
+			task_pt_regs(current)->icountlevel = 1;
+
+		return;
+	}
+
+	/* Did we come from a system call? */
+	if ((signed) regs->syscall >= 0) {
+		/* Restart the system call - no handlers present */
+		switch (regs->areg[2]) {
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+			regs->areg[2] = regs->syscall;
+			regs->pc -= 3;
+			break;
+		case -ERESTART_RESTARTBLOCK:
+			regs->areg[2] = __NR_restart_syscall;
+			regs->pc -= 3;
+			break;
+		}
+	}
+
+	/* If there's no signal to deliver, we just restore the saved mask.  */
+	restore_saved_sigmask();
+
+	if (current->ptrace & PT_SINGLESTEP)
+		task_pt_regs(current)->icountlevel = 1;
+	return;
+}
+
+void do_notify_resume(struct pt_regs *regs)
+{
+	if (test_thread_flag(TIF_SIGPENDING))
+		do_signal(regs);
+
+	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
+		tracehook_notify_resume(regs);
+}