unicore32 core architecture: signals handling

This patch implements signals.

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>

1 files changed, 494 insertions, 0 deletions

diff --git a/arch/unicore32/kernel/signal.c b/arch/unicore32/kernel/signal.c
new file mode 100644
index 000000000000..b163fca56789
--- /dev/null
+++ b/arch/unicore32/kernel/signal.c
@@ -0,0 +1,494 @@
+/*
+ * linux/arch/unicore32/kernel/signal.c
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <linux/personality.h>
+#include <linux/freezer.h>
+#include <linux/uaccess.h>
+#include <linux/tracehook.h>
+#include <linux/elf.h>
+#include <linux/unistd.h>
+
+#include <asm/cacheflush.h>
+#include <asm/ucontext.h>
+
+#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
+
+/*
+ * For UniCore syscalls, we encode the syscall number into the instruction.
+ */
+#define SWI_SYS_SIGRETURN	(0xff000000) /* error number for new abi */
+#define SWI_SYS_RT_SIGRETURN	(0xff000000 | (__NR_rt_sigreturn))
+#define SWI_SYS_RESTART		(0xff000000 | (__NR_restart_syscall))
+
+#define KERN_SIGRETURN_CODE	(KUSER_VECPAGE_BASE + 0x00000500)
+#define KERN_RESTART_CODE	(KERN_SIGRETURN_CODE + sizeof(sigreturn_codes))
+
+const unsigned long sigreturn_codes[3] = {
+	SWI_SYS_SIGRETURN, SWI_SYS_RT_SIGRETURN,
+};
+
+const unsigned long syscall_restart_code[2] = {
+	SWI_SYS_RESTART,	/* swi	__NR_restart_syscall */
+	0x69efc004,		/* ldr	pc, [sp], #4 */
+};
+
+/*
+ * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
+ */
+struct sigframe {
+	struct ucontext uc;
+	unsigned long retcode[2];
+};
+
+struct rt_sigframe {
+	struct siginfo info;
+	struct sigframe sig;
+};
+
+static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
+{
+	sigset_t set;
+	int err;
+
+	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+	if (err == 0) {
+		sigdelsetmask(&set, ~_BLOCKABLE);
+		spin_lock_irq(&current->sighand->siglock);
+		current->blocked = set;
+		recalc_sigpending();
+		spin_unlock_irq(&current->sighand->siglock);
+	}
+
+	err |= __get_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
+	err |= __get_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
+	err |= __get_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
+	err |= __get_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
+	err |= __get_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
+	err |= __get_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
+	err |= __get_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
+	err |= __get_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
+	err |= __get_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
+	err |= __get_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
+	err |= __get_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
+	err |= __get_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
+	err |= __get_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
+	err |= __get_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
+	err |= __get_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
+	err |= __get_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
+	err |= __get_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
+	err |= __get_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
+	err |= __get_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
+	err |= __get_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
+	err |= __get_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
+	err |= __get_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
+	err |= __get_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
+	err |= __get_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
+	err |= __get_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
+	err |= __get_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
+	err |= __get_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
+	err |= __get_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
+	err |= __get_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
+	err |= __get_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
+	err |= __get_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
+	err |= __get_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
+	err |= __get_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
+
+	err |= !valid_user_regs(regs);
+
+	return err;
+}
+
+asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+	/*
+	 * Since we stacked the signal on a 64-bit boundary,
+	 * then 'sp' should be word aligned here.  If it's
+	 * not, then the user is trying to mess with us.
+	 */
+	if (regs->UCreg_sp & 7)
+		goto badframe;
+
+	frame = (struct rt_sigframe __user *)regs->UCreg_sp;
+
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, &frame->sig))
+		goto badframe;
+
+	if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)
+			== -EFAULT)
+		goto badframe;
+
+	return regs->UCreg_00;
+
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs,
+		sigset_t *set)
+{
+	int err = 0;
+
+	err |= __put_user(regs->UCreg_00, &sf->uc.uc_mcontext.regs.UCreg_00);
+	err |= __put_user(regs->UCreg_01, &sf->uc.uc_mcontext.regs.UCreg_01);
+	err |= __put_user(regs->UCreg_02, &sf->uc.uc_mcontext.regs.UCreg_02);
+	err |= __put_user(regs->UCreg_03, &sf->uc.uc_mcontext.regs.UCreg_03);
+	err |= __put_user(regs->UCreg_04, &sf->uc.uc_mcontext.regs.UCreg_04);
+	err |= __put_user(regs->UCreg_05, &sf->uc.uc_mcontext.regs.UCreg_05);
+	err |= __put_user(regs->UCreg_06, &sf->uc.uc_mcontext.regs.UCreg_06);
+	err |= __put_user(regs->UCreg_07, &sf->uc.uc_mcontext.regs.UCreg_07);
+	err |= __put_user(regs->UCreg_08, &sf->uc.uc_mcontext.regs.UCreg_08);
+	err |= __put_user(regs->UCreg_09, &sf->uc.uc_mcontext.regs.UCreg_09);
+	err |= __put_user(regs->UCreg_10, &sf->uc.uc_mcontext.regs.UCreg_10);
+	err |= __put_user(regs->UCreg_11, &sf->uc.uc_mcontext.regs.UCreg_11);
+	err |= __put_user(regs->UCreg_12, &sf->uc.uc_mcontext.regs.UCreg_12);
+	err |= __put_user(regs->UCreg_13, &sf->uc.uc_mcontext.regs.UCreg_13);
+	err |= __put_user(regs->UCreg_14, &sf->uc.uc_mcontext.regs.UCreg_14);
+	err |= __put_user(regs->UCreg_15, &sf->uc.uc_mcontext.regs.UCreg_15);
+	err |= __put_user(regs->UCreg_16, &sf->uc.uc_mcontext.regs.UCreg_16);
+	err |= __put_user(regs->UCreg_17, &sf->uc.uc_mcontext.regs.UCreg_17);
+	err |= __put_user(regs->UCreg_18, &sf->uc.uc_mcontext.regs.UCreg_18);
+	err |= __put_user(regs->UCreg_19, &sf->uc.uc_mcontext.regs.UCreg_19);
+	err |= __put_user(regs->UCreg_20, &sf->uc.uc_mcontext.regs.UCreg_20);
+	err |= __put_user(regs->UCreg_21, &sf->uc.uc_mcontext.regs.UCreg_21);
+	err |= __put_user(regs->UCreg_22, &sf->uc.uc_mcontext.regs.UCreg_22);
+	err |= __put_user(regs->UCreg_23, &sf->uc.uc_mcontext.regs.UCreg_23);
+	err |= __put_user(regs->UCreg_24, &sf->uc.uc_mcontext.regs.UCreg_24);
+	err |= __put_user(regs->UCreg_25, &sf->uc.uc_mcontext.regs.UCreg_25);
+	err |= __put_user(regs->UCreg_26, &sf->uc.uc_mcontext.regs.UCreg_26);
+	err |= __put_user(regs->UCreg_fp, &sf->uc.uc_mcontext.regs.UCreg_fp);
+	err |= __put_user(regs->UCreg_ip, &sf->uc.uc_mcontext.regs.UCreg_ip);
+	err |= __put_user(regs->UCreg_sp, &sf->uc.uc_mcontext.regs.UCreg_sp);
+	err |= __put_user(regs->UCreg_lr, &sf->uc.uc_mcontext.regs.UCreg_lr);
+	err |= __put_user(regs->UCreg_pc, &sf->uc.uc_mcontext.regs.UCreg_pc);
+	err |= __put_user(regs->UCreg_asr, &sf->uc.uc_mcontext.regs.UCreg_asr);
+
+	err |= __put_user(current->thread.trap_no,
+			&sf->uc.uc_mcontext.trap_no);
+	err |= __put_user(current->thread.error_code,
+			&sf->uc.uc_mcontext.error_code);
+	err |= __put_user(current->thread.address,
+			&sf->uc.uc_mcontext.fault_address);
+	err |= __put_user(set->sig[0], &sf->uc.uc_mcontext.oldmask);
+
+	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
+
+	return err;
+}
+
+static inline void __user *get_sigframe(struct k_sigaction *ka,
+		struct pt_regs *regs, int framesize)
+{
+	unsigned long sp = regs->UCreg_sp;
+	void __user *frame;
+
+	/*
+	 * This is the X/Open sanctioned signal stack switching.
+	 */
+	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
+		sp = current->sas_ss_sp + current->sas_ss_size;
+
+	/*
+	 * ATPCS B01 mandates 8-byte alignment
+	 */
+	frame = (void __user *)((sp - framesize) & ~7);
+
+	/*
+	 * Check that we can actually write to the signal frame.
+	 */
+	if (!access_ok(VERIFY_WRITE, frame, framesize))
+		frame = NULL;
+
+	return frame;
+}
+
+static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
+	     unsigned long __user *rc, void __user *frame, int usig)
+{
+	unsigned long handler = (unsigned long)ka->sa.sa_handler;
+	unsigned long retcode;
+	unsigned long asr = regs->UCreg_asr & ~PSR_f;
+
+	unsigned int idx = 0;
+
+	if (ka->sa.sa_flags & SA_SIGINFO)
+		idx += 1;
+
+	if (__put_user(sigreturn_codes[idx],   rc) ||
+	    __put_user(sigreturn_codes[idx+1], rc+1))
+		return 1;
+
+	retcode = KERN_SIGRETURN_CODE + (idx << 2);
+
+	regs->UCreg_00 = usig;
+	regs->UCreg_sp = (unsigned long)frame;
+	regs->UCreg_lr = retcode;
+	regs->UCreg_pc = handler;
+	regs->UCreg_asr = asr;
+
+	return 0;
+}
+
+static int setup_frame(int usig, struct k_sigaction *ka,
+		sigset_t *set, struct pt_regs *regs)
+{
+	struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
+	int err = 0;
+
+	if (!frame)
+		return 1;
+
+	/*
+	 * Set uc.uc_flags to a value which sc.trap_no would never have.
+	 */
+	err |= __put_user(0x5ac3c35a, &frame->uc.uc_flags);
+
+	err |= setup_sigframe(frame, regs, set);
+	if (err == 0)
+		err |= setup_return(regs, ka, frame->retcode, frame, usig);
+
+	return err;
+}
+
+static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
+	       sigset_t *set, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame =
+			get_sigframe(ka, regs, sizeof(*frame));
+	stack_t stack;
+	int err = 0;
+
+	if (!frame)
+		return 1;
+
+	err |= copy_siginfo_to_user(&frame->info, info);
+
+	err |= __put_user(0, &frame->sig.uc.uc_flags);
+	err |= __put_user(NULL, &frame->sig.uc.uc_link);
+
+	memset(&stack, 0, sizeof(stack));
+	stack.ss_sp = (void __user *)current->sas_ss_sp;
+	stack.ss_flags = sas_ss_flags(regs->UCreg_sp);
+	stack.ss_size = current->sas_ss_size;
+	err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
+
+	err |= setup_sigframe(&frame->sig, regs, set);
+	if (err == 0)
+		err |= setup_return(regs, ka, frame->sig.retcode, frame, usig);
+
+	if (err == 0) {
+		/*
+		 * For realtime signals we must also set the second and third
+		 * arguments for the signal handler.
+		 */
+		regs->UCreg_01 = (unsigned long)&frame->info;
+		regs->UCreg_02 = (unsigned long)&frame->sig.uc;
+	}
+
+	return err;
+}
+
+static inline void setup_syscall_restart(struct pt_regs *regs)
+{
+	regs->UCreg_00 = regs->UCreg_ORIG_00;
+	regs->UCreg_pc -= 4;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static int handle_signal(unsigned long sig, struct k_sigaction *ka,
+	      siginfo_t *info, sigset_t *oldset,
+	      struct pt_regs *regs, int syscall)
+{
+	struct thread_info *thread = current_thread_info();
+	struct task_struct *tsk = current;
+	int usig = sig;
+	int ret;
+
+	/*
+	 * If we were from a system call, check for system call restarting...
+	 */
+	if (syscall) {
+		switch (regs->UCreg_00) {
+		case -ERESTART_RESTARTBLOCK:
+		case -ERESTARTNOHAND:
+			regs->UCreg_00 = -EINTR;
+			break;
+		case -ERESTARTSYS:
+			if (!(ka->sa.sa_flags & SA_RESTART)) {
+				regs->UCreg_00 = -EINTR;
+				break;
+			}
+			/* fallthrough */
+		case -ERESTARTNOINTR:
+			setup_syscall_restart(regs);
+		}
+	}
+
+	/*
+	 * translate the signal
+	 */
+	if (usig < 32 && thread->exec_domain
+			&& thread->exec_domain->signal_invmap)
+		usig = thread->exec_domain->signal_invmap[usig];
+
+	/*
+	 * Set up the stack frame
+	 */
+	if (ka->sa.sa_flags & SA_SIGINFO)
+		ret = setup_rt_frame(usig, ka, info, oldset, regs);
+	else
+		ret = setup_frame(usig, ka, oldset, regs);
+
+	/*
+	 * Check that the resulting registers are actually sane.
+	 */
+	ret |= !valid_user_regs(regs);
+
+	if (ret != 0) {
+		force_sigsegv(sig, tsk);
+		return ret;
+	}
+
+	/*
+	 * Block the signal if we were successful.
+	 */
+	spin_lock_irq(&tsk->sighand->siglock);
+	sigorsets(&tsk->blocked, &tsk->blocked,
+		  &ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
+		sigaddset(&tsk->blocked, sig);
+	recalc_sigpending();
+	spin_unlock_irq(&tsk->sighand->siglock);
+
+	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, int syscall)
+{
+	struct k_sigaction ka;
+	siginfo_t info;
+	int signr;
+
+	/*
+	 * We want the common case to go fast, which
+	 * is why we may in certain cases get here from
+	 * kernel mode. Just return without doing anything
+	 * if so.
+	 */
+	if (!user_mode(regs))
+		return;
+
+	if (try_to_freeze())
+		goto no_signal;
+
+	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+	if (signr > 0) {
+		sigset_t *oldset;
+
+		if (test_thread_flag(TIF_RESTORE_SIGMASK))
+			oldset = &current->saved_sigmask;
+		else
+			oldset = &current->blocked;
+		if (handle_signal(signr, &ka, &info, oldset, regs, syscall)
+				== 0) {
+			/*
+			 * A signal was successfully delivered; the saved
+			 * sigmask will have been stored in the signal frame,
+			 * and will be restored by sigreturn, so we can simply
+			 * clear the TIF_RESTORE_SIGMASK flag.
+			 */
+			if (test_thread_flag(TIF_RESTORE_SIGMASK))
+				clear_thread_flag(TIF_RESTORE_SIGMASK);
+		}
+		return;
+	}
+
+ no_signal:
+	/*
+	 * No signal to deliver to the process - restart the syscall.
+	 */
+	if (syscall) {
+		if (regs->UCreg_00 == -ERESTART_RESTARTBLOCK) {
+				u32 __user *usp;
+
+				regs->UCreg_sp -= 4;
+				usp = (u32 __user *)regs->UCreg_sp;
+
+				if (put_user(regs->UCreg_pc, usp) == 0) {
+					regs->UCreg_pc = KERN_RESTART_CODE;
+				} else {
+					regs->UCreg_sp += 4;
+					force_sigsegv(0, current);
+				}
+		}
+		if (regs->UCreg_00 == -ERESTARTNOHAND ||
+		    regs->UCreg_00 == -ERESTARTSYS ||
+		    regs->UCreg_00 == -ERESTARTNOINTR) {
+			setup_syscall_restart(regs);
+		}
+
+		/* If there's no signal to deliver, we just put the saved
+		 * sigmask back.
+		 */
+		if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
+			clear_thread_flag(TIF_RESTORE_SIGMASK);
+			sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
+		}
+	}
+}
+
+asmlinkage void do_notify_resume(struct pt_regs *regs,
+		unsigned int thread_flags, int syscall)
+{
+	if (thread_flags & _TIF_SIGPENDING)
+		do_signal(regs, syscall);
+
+	if (thread_flags & _TIF_NOTIFY_RESUME) {
+		clear_thread_flag(TIF_NOTIFY_RESUME);
+		tracehook_notify_resume(regs);
+		if (current->replacement_session_keyring)
+			key_replace_session_keyring();
+	}
+}
+
+/*
+ * Copy signal return handlers into the vector page, and
+ * set sigreturn to be a pointer to these.
+ */
+void __init early_signal_init(void)
+{
+	memcpy((void *)kuser_vecpage_to_vectors(KERN_SIGRETURN_CODE),
+			sigreturn_codes, sizeof(sigreturn_codes));
+	memcpy((void *)kuser_vecpage_to_vectors(KERN_RESTART_CODE),
+			syscall_restart_code, sizeof(syscall_restart_code));
+	/* Need not to flush icache, since early_trap_init will do it last. */
+}