Fixed MTP to work with TWRP

arch/s390/kernel/signal.c

@@ -0,0 +1,579 @@
+/*
+ *    Copyright IBM Corp. 1999, 2006
+ *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
+ *
+ *    Based on Intel version
+ * 
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
+ */
+
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/ptrace.h>
+#include <linux/unistd.h>
+#include <linux/stddef.h>
+#include <linux/tty.h>
+#include <linux/personality.h>
+#include <linux/binfmts.h>
+#include <linux/tracehook.h>
+#include <linux/syscalls.h>
+#include <linux/compat.h>
+#include <asm/ucontext.h>
+#include <asm/uaccess.h>
+#include <asm/lowcore.h>
+#include <asm/switch_to.h>
+#include "entry.h"
+
+/*
+ * Layout of an old-style signal-frame:
+ *	-----------------------------------------
+ *	| save area (_SIGNAL_FRAMESIZE)		|
+ *	-----------------------------------------
+ *	| struct sigcontext			|
+ *	|	oldmask				|
+ *	|	_sigregs *			|
+ *	-----------------------------------------
+ *	| _sigregs with				|
+ *	|	_s390_regs_common		|
+ *	|	_s390_fp_regs			|
+ *	-----------------------------------------
+ *	| int signo				|
+ *	-----------------------------------------
+ *	| _sigregs_ext with			|
+ *	|	gprs_high 64 byte (opt)		|
+ *	|	vxrs_low 128 byte (opt)		|
+ *	|	vxrs_high 256 byte (opt)	|
+ *	|	reserved 128 byte (opt)		|
+ *	-----------------------------------------
+ *	| __u16 svc_insn			|
+ *	-----------------------------------------
+ * The svc_insn entry with the sigreturn system call opcode does not
+ * have a fixed position and moves if gprs_high or vxrs exist.
+ * Future extensions will be added to _sigregs_ext.
+ */
+struct sigframe
+{
+	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
+	struct sigcontext sc;
+	_sigregs sregs;
+	int signo;
+	_sigregs_ext sregs_ext;
+	__u16 svc_insn;		/* Offset of svc_insn is NOT fixed! */
+};
+
+/*
+ * Layout of an rt signal-frame:
+ *	-----------------------------------------
+ *	| save area (_SIGNAL_FRAMESIZE)		|
+ *	-----------------------------------------
+ *	| svc __NR_rt_sigreturn 2 byte		|
+ *	-----------------------------------------
+ *	| struct siginfo			|
+ *	-----------------------------------------
+ *	| struct ucontext_extended with		|
+ *	|	unsigned long uc_flags		|
+ *	|	struct ucontext *uc_link	|
+ *	|	stack_t uc_stack		|
+ *	|	_sigregs uc_mcontext with	|
+ *	|		_s390_regs_common	|
+ *	|		_s390_fp_regs		|
+ *	|	sigset_t uc_sigmask		|
+ *	|	_sigregs_ext uc_mcontext_ext	|
+ *	|		gprs_high 64 byte (opt)	|
+ *	|		vxrs_low 128 byte (opt)	|
+ *	|		vxrs_high 256 byte (opt)|
+ *	|		reserved 128 byte (opt)	|
+ *	-----------------------------------------
+ * Future extensions will be added to _sigregs_ext.
+ */
+struct rt_sigframe
+{
+	__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
+	__u16 svc_insn;
+	struct siginfo info;
+	struct ucontext_extended uc;
+};
+
+/* Store registers needed to create the signal frame */
+static void store_sigregs(void)
+{
+	save_access_regs(current->thread.acrs);
+	save_fp_ctl(&current->thread.fp_regs.fpc);
+#ifdef CONFIG_64BIT
+	if (current->thread.vxrs) {
+		int i;
+
+		save_vx_regs(current->thread.vxrs);
+		for (i = 0; i < __NUM_FPRS; i++)
+			current->thread.fp_regs.fprs[i] =
+				*(freg_t *)(current->thread.vxrs + i);
+	} else
+#endif
+		save_fp_regs(current->thread.fp_regs.fprs);
+}
+
+/* Load registers after signal return */
+static void load_sigregs(void)
+{
+	restore_access_regs(current->thread.acrs);
+	/* restore_fp_ctl is done in restore_sigregs */
+#ifdef CONFIG_64BIT
+	if (current->thread.vxrs) {
+		int i;
+
+		for (i = 0; i < __NUM_FPRS; i++)
+			*(freg_t *)(current->thread.vxrs + i) =
+				current->thread.fp_regs.fprs[i];
+		restore_vx_regs(current->thread.vxrs);
+	} else
+#endif
+		restore_fp_regs(current->thread.fp_regs.fprs);
+}
+
+/* Returns non-zero on fault. */
+static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
+{
+	_sigregs user_sregs;
+
+	/* Copy a 'clean' PSW mask to the user to avoid leaking
+	   information about whether PER is currently on.  */
+	user_sregs.regs.psw.mask = PSW_USER_BITS |
+		(regs->psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
+	user_sregs.regs.psw.addr = regs->psw.addr;
+	memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
+	memcpy(&user_sregs.regs.acrs, current->thread.acrs,
+	       sizeof(user_sregs.regs.acrs));
+	memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
+	       sizeof(user_sregs.fpregs));
+	if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs)))
+		return -EFAULT;
+	return 0;
+}
+
+static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
+{
+	_sigregs user_sregs;
+
+	/* Alwys make any pending restarted system call return -EINTR */
+	current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+	if (__copy_from_user(&user_sregs, sregs, sizeof(user_sregs)))
+		return -EFAULT;
+
+	if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW_MASK_RI))
+		return -EINVAL;
+
+	/* Loading the floating-point-control word can fail. Do that first. */
+	if (restore_fp_ctl(&user_sregs.fpregs.fpc))
+		return -EINVAL;
+
+	/* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
+	regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
+		(user_sregs.regs.psw.mask & (PSW_MASK_USER | PSW_MASK_RI));
+	/* Check for invalid user address space control. */
+	if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
+		regs->psw.mask = PSW_ASC_PRIMARY |
+			(regs->psw.mask & ~PSW_MASK_ASC);
+	/* Check for invalid amode */
+	if (regs->psw.mask & PSW_MASK_EA)
+		regs->psw.mask |= PSW_MASK_BA;
+	regs->psw.addr = user_sregs.regs.psw.addr;
+	memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
+	memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
+	       sizeof(current->thread.acrs));
+
+	memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
+	       sizeof(current->thread.fp_regs));
+
+	clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
+	return 0;
+}
+
+/* Returns non-zero on fault. */
+static int save_sigregs_ext(struct pt_regs *regs,
+			    _sigregs_ext __user *sregs_ext)
+{
+#ifdef CONFIG_64BIT
+	__u64 vxrs[__NUM_VXRS_LOW];
+	int i;
+
+	/* Save vector registers to signal stack */
+	if (current->thread.vxrs) {
+		for (i = 0; i < __NUM_VXRS_LOW; i++)
+			vxrs[i] = *((__u64 *)(current->thread.vxrs + i) + 1);
+		if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
+				   sizeof(sregs_ext->vxrs_low)) ||
+		    __copy_to_user(&sregs_ext->vxrs_high,
+				   current->thread.vxrs + __NUM_VXRS_LOW,
+				   sizeof(sregs_ext->vxrs_high)))
+			return -EFAULT;
+	}
+#endif
+	return 0;
+}
+
+static int restore_sigregs_ext(struct pt_regs *regs,
+			       _sigregs_ext __user *sregs_ext)
+{
+#ifdef CONFIG_64BIT
+	__u64 vxrs[__NUM_VXRS_LOW];
+	int i;
+
+	/* Restore vector registers from signal stack */
+	if (current->thread.vxrs) {
+		if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
+				     sizeof(sregs_ext->vxrs_low)) ||
+		    __copy_from_user(current->thread.vxrs + __NUM_VXRS_LOW,
+				     &sregs_ext->vxrs_high,
+				     sizeof(sregs_ext->vxrs_high)))
+			return -EFAULT;
+		for (i = 0; i < __NUM_VXRS_LOW; i++)
+			*((__u64 *)(current->thread.vxrs + i) + 1) = vxrs[i];
+	}
+#endif
+	return 0;
+}
+
+SYSCALL_DEFINE0(sigreturn)
+{
+	struct pt_regs *regs = task_pt_regs(current);
+	struct sigframe __user *frame =
+		(struct sigframe __user *) regs->gprs[15];
+	sigset_t set;
+
+	if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
+		goto badframe;
+	set_current_blocked(&set);
+	if (restore_sigregs(regs, &frame->sregs))
+		goto badframe;
+	if (restore_sigregs_ext(regs, &frame->sregs_ext))
+		goto badframe;
+	load_sigregs();
+	return regs->gprs[2];
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+SYSCALL_DEFINE0(rt_sigreturn)
+{
+	struct pt_regs *regs = task_pt_regs(current);
+	struct rt_sigframe __user *frame =
+		(struct rt_sigframe __user *)regs->gprs[15];
+	sigset_t set;
+
+	if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
+		goto badframe;
+	set_current_blocked(&set);
+	if (restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+	if (restore_sigregs(regs, &frame->uc.uc_mcontext))
+		goto badframe;
+	if (restore_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
+		goto badframe;
+	load_sigregs();
+	return regs->gprs[2];
+badframe:
+	force_sig(SIGSEGV, current);
+	return 0;
+}
+
+/*
+ * Determine which stack to use..
+ */
+static inline void __user *
+get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
+{
+	unsigned long sp;
+
+	/* Default to using normal stack */
+	sp = regs->gprs[15];
+
+	/* Overflow on alternate signal stack gives SIGSEGV. */
+	if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
+		return (void __user *) -1UL;
+
+	/* This is the X/Open sanctioned signal stack switching.  */
+	if (ka->sa.sa_flags & SA_ONSTACK) {
+		if (! sas_ss_flags(sp))
+			sp = current->sas_ss_sp + current->sas_ss_size;
+	}
+
+	return (void __user *)((sp - frame_size) & -8ul);
+}
+
+static inline int map_signal(int sig)
+{
+	if (current_thread_info()->exec_domain
+	    && current_thread_info()->exec_domain->signal_invmap
+	    && sig < 32)
+		return current_thread_info()->exec_domain->signal_invmap[sig];
+	else
+		return sig;
+}
+
+static int setup_frame(int sig, struct k_sigaction *ka,
+		       sigset_t *set, struct pt_regs * regs)
+{
+	struct sigframe __user *frame;
+	struct sigcontext sc;
+	unsigned long restorer;
+	size_t frame_size;
+
+	/*
+	 * gprs_high are only present for a 31-bit task running on
+	 * a 64-bit kernel (see compat_signal.c) but the space for
+	 * gprs_high need to be allocated if vector registers are
+	 * included in the signal frame on a 31-bit system.
+	 */
+	frame_size = sizeof(*frame) - sizeof(frame->sregs_ext);
+	if (MACHINE_HAS_VX)
+		frame_size += sizeof(frame->sregs_ext);
+	frame = get_sigframe(ka, regs, frame_size);
+	if (frame == (void __user *) -1UL)
+		return -EFAULT;
+
+	/* Set up backchain. */
+	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
+		return -EFAULT;
+
+	/* Create struct sigcontext on the signal stack */
+	memcpy(&sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE);
+	sc.sregs = (_sigregs __user __force *) &frame->sregs;
+	if (__copy_to_user(&frame->sc, &sc, sizeof(frame->sc)))
+		return -EFAULT;
+
+	/* Store registers needed to create the signal frame */
+	store_sigregs();
+
+	/* Create _sigregs on the signal stack */
+	if (save_sigregs(regs, &frame->sregs))
+		return -EFAULT;
+
+	/* Place signal number on stack to allow backtrace from handler.  */
+	if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
+		return -EFAULT;
+
+	/* Create _sigregs_ext on the signal stack */
+	if (save_sigregs_ext(regs, &frame->sregs_ext))
+		return -EFAULT;
+
+	/* Set up to return from userspace.  If provided, use a stub
+	   already in userspace.  */
+	if (ka->sa.sa_flags & SA_RESTORER) {
+		restorer = (unsigned long) ka->sa.sa_restorer | PSW_ADDR_AMODE;
+	} else {
+		/* Signal frame without vector registers are short ! */
+		__u16 __user *svc = (void *) frame + frame_size - 2;
+		if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
+			return -EFAULT;
+		restorer = (unsigned long) svc | PSW_ADDR_AMODE;
+	}
+
+	/* Set up registers for signal handler */
+	regs->gprs[14] = restorer;
+	regs->gprs[15] = (unsigned long) frame;
+	/* Force default amode and default user address space control. */
+	regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
+		(PSW_USER_BITS & PSW_MASK_ASC) |
+		(regs->psw.mask & ~PSW_MASK_ASC);
+	regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
+
+	regs->gprs[2] = map_signal(sig);
+	regs->gprs[3] = (unsigned long) &frame->sc;
+
+	/* We forgot to include these in the sigcontext.
+	   To avoid breaking binary compatibility, they are passed as args. */
+	if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
+	    sig == SIGTRAP || sig == SIGFPE) {
+		/* set extra registers only for synchronous signals */
+		regs->gprs[4] = regs->int_code & 127;
+		regs->gprs[5] = regs->int_parm_long;
+		regs->gprs[6] = task_thread_info(current)->last_break;
+	}
+	return 0;
+}
+
+static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
+			  struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+	unsigned long uc_flags, restorer;
+	size_t frame_size;
+
+	frame_size = sizeof(struct rt_sigframe) - sizeof(_sigregs_ext);
+	/*
+	 * gprs_high are only present for a 31-bit task running on
+	 * a 64-bit kernel (see compat_signal.c) but the space for
+	 * gprs_high need to be allocated if vector registers are
+	 * included in the signal frame on a 31-bit system.
+	 */
+	uc_flags = 0;
+#ifdef CONFIG_64BIT
+	if (MACHINE_HAS_VX) {
+		frame_size += sizeof(_sigregs_ext);
+		if (current->thread.vxrs)
+			uc_flags |= UC_VXRS;
+	}
+#endif
+	frame = get_sigframe(&ksig->ka, regs, frame_size);
+	if (frame == (void __user *) -1UL)
+		return -EFAULT;
+
+	/* Set up backchain. */
+	if (__put_user(regs->gprs[15], (addr_t __user *) frame))
+		return -EFAULT;
+
+	/* Set up to return from userspace.  If provided, use a stub
+	   already in userspace.  */
+	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+		restorer = (unsigned long)
+			ksig->ka.sa.sa_restorer | PSW_ADDR_AMODE;
+	} else {
+		__u16 __user *svc = &frame->svc_insn;
+		if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
+			return -EFAULT;
+		restorer = (unsigned long) svc | PSW_ADDR_AMODE;
+	}
+
+	/* Create siginfo on the signal stack */
+	if (copy_siginfo_to_user(&frame->info, &ksig->info))
+		return -EFAULT;
+
+	/* Store registers needed to create the signal frame */
+	store_sigregs();
+
+	/* Create ucontext on the signal stack. */
+	if (__put_user(uc_flags, &frame->uc.uc_flags) ||
+	    __put_user(NULL, &frame->uc.uc_link) ||
+	    __save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
+	    save_sigregs(regs, &frame->uc.uc_mcontext) ||
+	    __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)) ||
+	    save_sigregs_ext(regs, &frame->uc.uc_mcontext_ext))
+		return -EFAULT;
+
+	/* Set up registers for signal handler */
+	regs->gprs[14] = restorer;
+	regs->gprs[15] = (unsigned long) frame;
+	/* Force default amode and default user address space control. */
+	regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
+		(PSW_USER_BITS & PSW_MASK_ASC) |
+		(regs->psw.mask & ~PSW_MASK_ASC);
+	regs->psw.addr = (unsigned long) ksig->ka.sa.sa_handler | PSW_ADDR_AMODE;
+
+	regs->gprs[2] = map_signal(ksig->sig);
+	regs->gprs[3] = (unsigned long) &frame->info;
+	regs->gprs[4] = (unsigned long) &frame->uc;
+	regs->gprs[5] = task_thread_info(current)->last_break;
+	return 0;
+}
+
+static void handle_signal(struct ksignal *ksig, sigset_t *oldset,
+			  struct pt_regs *regs)
+{
+	int ret;
+
+	/* Set up the stack frame */
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+		ret = setup_rt_frame(ksig, oldset, regs);
+	else
+		ret = setup_frame(ksig->sig, &ksig->ka, oldset, regs);
+
+	signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
+}
+
+/*
+ * 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.
+ */
+void do_signal(struct pt_regs *regs)
+{
+	struct ksignal ksig;
+	sigset_t *oldset = sigmask_to_save();
+
+	/*
+	 * Get signal to deliver. When running under ptrace, at this point
+	 * the debugger may change all our registers, including the system
+	 * call information.
+	 */
+	current_thread_info()->system_call =
+		test_pt_regs_flag(regs, PIF_SYSCALL) ? regs->int_code : 0;
+
+	if (get_signal(&ksig)) {
+		/* Whee!  Actually deliver the signal.  */
+		if (current_thread_info()->system_call) {
+			regs->int_code = current_thread_info()->system_call;
+			/* Check for system call restarting. */
+			switch (regs->gprs[2]) {
+			case -ERESTART_RESTARTBLOCK:
+			case -ERESTARTNOHAND:
+				regs->gprs[2] = -EINTR;
+				break;
+			case -ERESTARTSYS:
+				if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
+					regs->gprs[2] = -EINTR;
+					break;
+				}
+			/* fallthrough */
+			case -ERESTARTNOINTR:
+				regs->gprs[2] = regs->orig_gpr2;
+				regs->psw.addr =
+					__rewind_psw(regs->psw,
+						     regs->int_code >> 16);
+				break;
+			}
+		}
+		/* No longer in a system call */
+		clear_pt_regs_flag(regs, PIF_SYSCALL);
+
+		if (is_compat_task())
+			handle_signal32(&ksig, oldset, regs);
+		else
+			handle_signal(&ksig, oldset, regs);
+		return;
+	}
+
+	/* No handlers present - check for system call restart */
+	clear_pt_regs_flag(regs, PIF_SYSCALL);
+	if (current_thread_info()->system_call) {
+		regs->int_code = current_thread_info()->system_call;
+		switch (regs->gprs[2]) {
+		case -ERESTART_RESTARTBLOCK:
+			/* Restart with sys_restart_syscall */
+			regs->int_code = __NR_restart_syscall;
+		/* fallthrough */
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+			/* Restart system call with magic TIF bit. */
+			regs->gprs[2] = regs->orig_gpr2;
+			set_pt_regs_flag(regs, PIF_SYSCALL);
+			if (test_thread_flag(TIF_SINGLE_STEP))
+				clear_pt_regs_flag(regs, PIF_PER_TRAP);
+			break;
+		}
+	}
+
+	/*
+	 * If there's no signal to deliver, we just put the saved sigmask back.
+	 */
+	restore_saved_sigmask();
+}
+
+void do_notify_resume(struct pt_regs *regs)
+{
+	clear_thread_flag(TIF_NOTIFY_RESUME);
+	tracehook_notify_resume(regs);
+}