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From:   Guo Ren <ren_guo@c-sky.com>
To:     linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
        tglx@linutronix.de, daniel.lezcano@linaro.org,
        jason@lakedaemon.net, arnd@arndb.de
Cc:     c-sky_gcc_upstream@c-sky.com, gnu-csky@mentor.com,
        thomas.petazzoni@bootlin.com, wbx@uclibc-ng.org,
        Guo Ren <ren_guo@c-sky.com>
Subject: [PATCH 10/19] csky: Signal handling
Date:   Mon, 19 Mar 2018 03:51:32 +0800
Message-Id: <f482eb9ffcebaf12595d5d6043953de221fda024.1521399976.git.ren_guo@c-sky.com>
In-Reply-To: <cover.1521399976.git.ren_guo@c-sky.com>
References: <cover.1521399976.git.ren_guo@c-sky.com>
In-Reply-To: <cover.1521399976.git.ren_guo@c-sky.com>
References: <cover.1521399976.git.ren_guo@c-sky.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
---
 arch/csky/include/uapi/asm/sigcontext.h |  33 +++
 arch/csky/include/uapi/asm/signal.h     | 164 ++++++++++++++
 arch/csky/kernel/signal.c               | 379 ++++++++++++++++++++++++++++++++
 3 files changed, 576 insertions(+)
 create mode 100644 arch/csky/include/uapi/asm/sigcontext.h
 create mode 100644 arch/csky/include/uapi/asm/signal.h
 create mode 100644 arch/csky/kernel/signal.c

diff --git a/arch/csky/include/uapi/asm/sigcontext.h b/arch/csky/include/uapi/asm/sigcontext.h
new file mode 100644
index 0000000..8ef0ce8
--- /dev/null
+++ b/arch/csky/include/uapi/asm/sigcontext.h
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+#ifndef _ASM_CSKY_SIGCONTEXT_H
+#define _ASM_CSKY_SIGCONTEXT_H
+
+struct sigcontext {
+	unsigned long   sc_mask;     /* old sigmask */
+        unsigned long   sc_usp;      /* old user stack pointer */
+        unsigned long   sc_a0;
+        unsigned long   sc_a1;
+        unsigned long   sc_a2;
+        unsigned long   sc_a3;
+	// ABIV2: r4 ~ r13; ABIV1: r6 ~ r14, r1.
+        unsigned long   sc_regs[10];
+        unsigned long   sc_r15;
+#if (__CSKY__ == 2)                     /* config CPU=cskyv2(ck800) */
+	// r16 ~ r31;
+        unsigned long   sc_exregs[16];
+        unsigned long   sc_rhi;
+        unsigned long   sc_rlo;
+#endif
+        unsigned long   sc_sr;
+        unsigned long   sc_pc;
+	/* fpu */
+        unsigned long   sc_fcr;
+        unsigned long   sc_fsr;		/* Nothing in CPU_CSKYV2 */
+        unsigned long   sc_fesr;
+        unsigned long   sc_feinst1;	/* Nothing in CPU_CSKYV2 */
+        unsigned long   sc_feinst2;	/* Nothing in CPU_CSKYV2 */
+        unsigned long   sc_fpregs[32];
+};
+
+#endif /* _ASM_CSKY_SIGCONTEXT_H */
diff --git a/arch/csky/include/uapi/asm/signal.h b/arch/csky/include/uapi/asm/signal.h
new file mode 100644
index 0000000..3bc0004
--- /dev/null
+++ b/arch/csky/include/uapi/asm/signal.h
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+#ifndef __ASM_CSKY_SIGNAL_H
+#define __ASM_CSKY_SIGNAL_H
+
+#define __ARCH_HAS_SA_RESTORER
+#include <linux/types.h>
+
+/* Avoid too many header ordering problems.  */
+struct siginfo;
+
+#ifdef __KERNEL__
+
+/* Most things should be clean enough to redefine this at will, if care
+   is taken to make libc match.  */
+
+#define _NSIG		64
+#define _NSIG_BPW	32
+#define _NSIG_WORDS	(_NSIG / _NSIG_BPW)
+
+typedef unsigned long old_sigset_t;		/* at least 32 bits */
+
+typedef struct {
+	unsigned long sig[_NSIG_WORDS];
+} sigset_t;
+
+#else
+
+/* Here we must cater to libcs that poke about in kernel headers.  */
+
+#define NSIG		32
+typedef unsigned long sigset_t;
+
+#endif /* __KERNEL__ */
+
+#define SIGHUP		 1
+#define SIGINT		 2
+#define SIGQUIT		 3
+#define SIGILL		 4
+#define SIGTRAP		 5
+#define SIGABRT		 6
+#define SIGIOT		 6
+#define SIGBUS		 7
+#define SIGFPE		 8
+#define SIGKILL		 9
+#define SIGUSR1		10
+#define SIGSEGV		11
+#define SIGUSR2		12
+#define SIGPIPE		13
+#define SIGALRM		14
+#define SIGTERM		15
+#define SIGSTKFLT	16
+#define SIGCHLD		17
+#define SIGCONT		18
+#define SIGSTOP		19
+#define SIGTSTP		20
+#define SIGTTIN		21
+#define SIGTTOU		22
+#define SIGURG		23
+#define SIGXCPU		24
+#define SIGXFSZ		25
+#define SIGVTALRM	26
+#define SIGPROF		27
+#define SIGWINCH	28
+#define SIGIO		29
+#define SIGPOLL		SIGIO
+/*
+#define SIGLOST		29
+*/
+#define SIGPWR		30
+#define SIGSYS		31
+#define	SIGUNUSED	31
+
+/* These should not be considered constants from userland.  */
+#define SIGRTMIN	32
+#define SIGRTMAX	(_NSIG-1)
+
+/*
+ * SA_FLAGS values:
+ *
+ * SA_ONSTACK indicates that a registered stack_t will be used.
+ * SA_INTERRUPT is a no-op, but left due to historical reasons. Use the
+ * SA_RESTART flag to get restarting signals (which were the default long ago)
+ * SA_NOCLDSTOP flag to turn off SIGCHLD when children stop.
+ * SA_RESETHAND clears the handler when the signal is delivered.
+ * SA_NOCLDWAIT flag on SIGCHLD to inhibit zombies.
+ * SA_NODEFER prevents the current signal from being masked in the handler.
+ *
+ * SA_ONESHOT and SA_NOMASK are the historical Linux names for the Single
+ * Unix names RESETHAND and NODEFER respectively.
+ */
+#define SA_NOCLDSTOP		0x00000001
+#define SA_NOCLDWAIT		0x00000002 /* not supported yet */
+#define SA_SIGINFO		0x00000004
+#define SA_ONSTACK		0x08000000
+#define SA_RESTART		0x10000000
+#define SA_NODEFER		0x40000000
+#define SA_RESETHAND		0x80000000
+
+#define SA_NOMASK		SA_NODEFER
+#define SA_ONESHOT		SA_RESETHAND
+#define SA_INTERRUPT		0x20000000 /* dummy -- ignored */
+
+/*
+ * sigaltstack controls
+ */
+#define SS_ONSTACK	1
+#define SS_DISABLE	2
+
+#define MINSIGSTKSZ	2048
+#define SIGSTKSZ	8192
+
+#include <asm-generic/signal-defs.h>
+
+#ifdef __KERNEL__
+
+/*
+ * These values of sa_flags are used only by the kernel as part of the
+ * irq handling routines.
+ *
+ * SA_INTERRUPT is also used by the irq handling routines.
+ * SA_SHIRQ is for shared interrupt support on PCI and EISA.
+ */
+#define SA_PROBE			SA_ONESHOT
+#define SA_SAMPLE_RANDOM		SA_RESTART
+#define SA_SHIRQ			0x04000000
+#endif
+
+#define SIG_BLOCK          0	/* for blocking signals */
+#define SIG_UNBLOCK        1	/* for unblocking signals */
+#define SIG_SETMASK        2	/* for setting the signal mask */
+
+#ifndef __KERNEL__
+
+/* Here we must cater to libcs that poke about in kernel headers.  */
+
+struct sigaction {
+	union {
+	  __sighandler_t _sa_handler;
+	  void (*_sa_sigaction)(int, struct siginfo *, void *);
+	} _u;
+	sigset_t sa_mask;
+	unsigned long sa_flags;
+	void (*sa_restorer)(void);
+};
+
+#define sa_handler	_u._sa_handler
+#define sa_sigaction	_u._sa_sigaction
+
+#endif /* __KERNEL__ */
+
+typedef struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+} stack_t;
+
+#ifdef __KERNEL__
+
+#include <asm/sigcontext.h>
+#define ptrace_signal_deliver()		do{}while(0)
+#endif /* __KERNEL__ */
+
+#endif
diff --git a/arch/csky/kernel/signal.c b/arch/csky/kernel/signal.c
new file mode 100644
index 0000000..ce27972
--- /dev/null
+++ b/arch/csky/kernel/signal.c
@@ -0,0 +1,379 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/syscalls.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/ptrace.h>
+#include <linux/unistd.h>
+#include <linux/stddef.h>
+#include <linux/highuid.h>
+#include <linux/personality.h>
+#include <linux/tty.h>
+#include <linux/binfmts.h>
+#include <linux/tracehook.h>
+#include <linux/freezer.h>
+#include <linux/uaccess.h>
+
+#include <asm/setup.h>
+#include <asm/pgtable.h>
+#include <asm/traps.h>
+#include <asm/ucontext.h>
+#include <asm/vdso.h>
+
+#include <abi/regdef.h>
+#ifdef CONFIG_CPU_HAS_FPU
+#include <abi/fpu.h>
+#endif
+
+#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
+
+struct rt_sigframe
+{
+	int sig;
+	struct siginfo *pinfo;
+	void *puc;
+	struct siginfo info;
+	struct ucontext uc;
+};
+
+static inline int
+restore_sigframe(struct pt_regs *regs, struct sigcontext *usc, int *pr2)
+{
+	int err = 0;
+	int i = 0;
+	unsigned long usp;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current_thread_info()->task->restart_block.fn = do_no_restart_syscall;
+
+	/* restore passed registers */
+	err |= __get_user(regs->a0, &usc->sc_a0);
+	err |= __get_user(regs->a1, &usc->sc_a1);
+	err |= __get_user(regs->a2, &usc->sc_a2);
+	err |= __get_user(regs->a3, &usc->sc_a3);
+	for(i = 0; i < 10; i++)
+		err |= __get_user(regs->regs[i], &usc->sc_regs[i]);
+
+	err |= __get_user(regs->r15, &usc->sc_r15);
+#if defined(__CSKYABIV2__)
+	for(i = 0; i < 16; i++)
+	{
+		err |= __get_user(regs->exregs[i], &usc->sc_exregs[i]);
+	}
+	err |= __get_user(regs->rhi, &usc->sc_rhi);
+	err |= __get_user(regs->rlo, &usc->sc_rlo);
+#endif
+	err |= __get_user(regs->sr, &usc->sc_sr);
+	err |= __get_user(regs->pc, &usc->sc_pc);
+	err |= __get_user(usp, &usc->sc_usp);
+	wrusp(usp);
+
+#ifdef CONFIG_CPU_HAS_FPU
+	err |= restore_fpu_state(usc);
+#endif
+	*pr2 = regs->a0;
+	return err;
+}
+
+asmlinkage int
+do_rt_sigreturn(void)
+{
+	unsigned long usp = rdusp();
+	struct rt_sigframe *frame = (struct rt_sigframe *)usp;
+	sigset_t set;
+	int a0;
+	struct pt_regs *regs = current_pt_regs();
+
+	if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
+		goto badframe;
+
+	sigdelsetmask(&set, ~_BLOCKABLE);
+	spin_lock_irq(&current->sighand->siglock);
+	current->blocked = set;
+	recalc_sigpending( );
+	spin_unlock_irq(&current->sighand->siglock);
+
+	if (restore_sigframe(regs, &frame->uc.uc_mcontext, &a0))
+		goto badframe;
+
+	return a0;
+
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+/*
+ * Set up a signal frame.
+ */
+
+static inline int setup_sigframe(struct sigcontext *sc, struct pt_regs *regs,
+		unsigned long mask)
+{
+	int err = 0;
+	int i = 0;
+
+	err |= __put_user(mask, &sc->sc_mask);
+	err |= __put_user(rdusp(), &sc->sc_usp);
+	err |= __put_user(regs->a0, &sc->sc_a0);
+	err |= __put_user(regs->a1, &sc->sc_a1);
+	err |= __put_user(regs->a2, &sc->sc_a2);
+	err |= __put_user(regs->a3, &sc->sc_a3);
+	for(i = 0; i < 10; i++)
+	{
+		err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
+	}
+	err |= __put_user(regs->r15, &sc->sc_r15);
+#if defined(__CSKYABIV2__)
+	for(i = 0; i < 16; i++)
+	{
+		err |= __put_user(regs->exregs[i], &sc->sc_exregs[i]);
+	}
+	err |= __put_user(regs->rhi, &sc->sc_rhi);
+	err |= __put_user(regs->rlo, &sc->sc_rlo);
+#endif
+	err |= __put_user(regs->sr, &sc->sc_sr);
+	err |= __put_user(regs->pc, &sc->sc_pc);
+
+#ifdef CONFIG_CPU_HAS_FPU
+	err |= save_fpu_state(sc, regs);
+#endif
+
+	return err;
+}
+
+static inline void *
+get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
+{
+	unsigned long usp;
+
+	/* Default to using normal stack.  */
+	usp = rdusp();
+
+	/* This is the X/Open sanctioned signal stack switching.  */
+	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(usp)) {
+		if (!on_sig_stack(usp))
+			usp = current->sas_ss_sp + current->sas_ss_size;
+	}
+	return (void *)((usp - frame_size) & -8UL);
+}
+
+static int setup_rt_frame (int sig, struct k_sigaction *ka, siginfo_t *info,
+		sigset_t *set, struct pt_regs *regs)
+{
+	struct rt_sigframe *frame;
+	int err = 0;
+
+	struct csky_vdso *vdso = current->mm->context.vdso;
+
+	frame = get_sigframe(ka, regs, sizeof(*frame));
+	if (!frame)
+		return 1;
+
+	err |= __put_user(sig, &frame->sig);
+	err |= __put_user(&frame->info, &frame->pinfo);
+	err |= __put_user(&frame->uc, &frame->puc);
+	err |= copy_siginfo_to_user(&frame->info, info);
+
+	/* Create the ucontext.  */
+	err |= __put_user(0, &frame->uc.uc_flags);
+	err |= __put_user(0, &frame->uc.uc_link);
+	err |= __put_user((void *)current->sas_ss_sp,
+			&frame->uc.uc_stack.ss_sp);
+	err |= __put_user(sas_ss_flags(rdusp()),
+			&frame->uc.uc_stack.ss_flags);
+	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+	err |= setup_sigframe(&frame->uc.uc_mcontext, regs, 0);
+	err |= copy_to_user (&frame->uc.uc_sigmask, set, sizeof(*set));
+
+	if (err)
+		goto give_sigsegv;
+
+	/* Set up registers for signal handler */
+	wrusp ((unsigned long) frame);
+	regs->pc = (unsigned long) ka->sa.sa_handler;
+	regs->r15 = (unsigned long)vdso->rt_signal_retcode;
+
+adjust_stack:
+	regs->a0 = sig; /* first arg is signo */
+	regs->a1 = (unsigned long)(&(frame->info)); /* second arg is (siginfo_t*) */
+	regs->a2 = (unsigned long)(&(frame->uc));/* third arg pointer to ucontext */
+	return err;
+
+give_sigsegv:
+	if (sig == SIGSEGV)
+		ka->sa.sa_handler = SIG_DFL;
+	force_sig(SIGSEGV, current);
+	goto adjust_stack;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static int
+handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
+		sigset_t *oldset, struct pt_regs *regs)
+{
+	struct task_struct *tsk = current;
+	int ret;
+
+	/* set up the stack frame, regardless of SA_SIGINFO, and pass info anyway. */
+	ret = setup_rt_frame(sig, ka, info, oldset, regs);
+
+	if (ret != 0) {
+		force_sigsegv(sig, tsk);
+		return ret;
+	}
+
+	/* Block the signal if we were successful. */
+	spin_lock_irq(&current->sighand->siglock);
+	sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
+	if (!(ka->sa.sa_flags & SA_NODEFER))
+		sigaddset(&current->blocked, sig);
+	recalc_sigpending();
+	spin_unlock_irq(&current->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)
+{
+	unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
+	struct ksignal ksig;
+
+	/*
+	 * 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;
+
+	current->thread.esp0 = (unsigned long)regs;
+
+	/*
+	 * If we were from a system call, check for system call restarting...
+	 */
+	if (syscall) {
+		continue_addr = regs->pc;
+#if defined(__CSKYABIV2__)
+		restart_addr = continue_addr - 4;
+#else
+		restart_addr = continue_addr - 2;
+#endif
+		retval = regs->a0;
+
+		/*
+		 * Prepare for system call restart.  We do this here so that a
+		 * debugger will see the already changed.
+		 */
+		switch (retval) {
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+			regs->a0 = regs->orig_a0;
+			regs->pc = restart_addr;
+			break;
+		case -ERESTART_RESTARTBLOCK:
+			regs->a0 = -EINTR;
+			break;
+		}
+	}
+
+	if (try_to_freeze())
+		goto no_signal;
+
+	/*
+	 * Get the signal to deliver.  When running under ptrace, at this
+	 * point the debugger may change all our registers ...
+	 */
+	if (get_signal(&ksig)) {
+		sigset_t *oldset;
+
+		/*
+		 * Depending on the signal settings we may need to revert the
+		 * decision to restart the system call.  But skip this if a
+		 * debugger has chosen to restart at a different PC.
+		 */
+		if (regs->pc == restart_addr) {
+			if (retval == -ERESTARTNOHAND
+					|| (retval == -ERESTARTSYS
+						&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
+				regs->a0 = -EINTR;
+				regs->pc = continue_addr;
+			}
+		}
+
+		if (test_thread_flag(TIF_RESTORE_SIGMASK))
+			oldset = &current->saved_sigmask;
+		else
+			oldset = &current->blocked;
+		/* Whee!  Actually deliver the signal.  */
+		if (handle_signal(ksig.sig, &ksig.ka, &ksig.info, oldset, regs) == 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:
+	if (syscall) {
+		/*
+		 * Handle restarting a different system call.  As above,
+		 * if a debugger has chosen to restart at a different PC,
+		 * ignore the restart.
+		 */
+		if (retval == -ERESTART_RESTARTBLOCK
+				&& regs->pc == continue_addr) {
+#if defined(__CSKYABIV2__)
+			regs->regs[3] = __NR_restart_syscall;
+			regs->pc -= 4;
+#else
+			regs->regs[9] = __NR_restart_syscall;
+			regs->pc -= 2;
+#endif
+		}
+
+		/* 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(unsigned int thread_flags, struct pt_regs *regs, 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);
+	}
+}
-- 
2.7.4