Fixed MTP to work with TWRP

arch/powerpc/kernel/signal.c

@@ -0,0 +1,197 @@
+/*
+ * Common signal handling code for both 32 and 64 bits
+ *
+ *    Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
+ *    Extracted from signal_32.c and signal_64.c
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License.  See the file README.legal in the main directory of
+ * this archive for more details.
+ */
+
+#include <linux/tracehook.h>
+#include <linux/signal.h>
+#include <linux/uprobes.h>
+#include <linux/key.h>
+#include <linux/context_tracking.h>
+#include <asm/hw_breakpoint.h>
+#include <asm/uaccess.h>
+#include <asm/unistd.h>
+#include <asm/debug.h>
+#include <asm/tm.h>
+
+#include "signal.h"
+
+/* Log an error when sending an unhandled signal to a process. Controlled
+ * through debug.exception-trace sysctl.
+ */
+
+int show_unhandled_signals = 1;
+
+/*
+ * Allocate space for the signal frame
+ */
+void __user *get_sigframe(struct ksignal *ksig, unsigned long sp,
+			   size_t frame_size, int is_32)
+{
+        unsigned long oldsp, newsp;
+
+        /* Default to using normal stack */
+        oldsp = get_clean_sp(sp, is_32);
+	oldsp = sigsp(oldsp, ksig);
+	newsp = (oldsp - frame_size) & ~0xFUL;
+
+	/* Check access */
+	if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
+		return NULL;
+
+        return (void __user *)newsp;
+}
+
+static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
+				  int has_handler)
+{
+	unsigned long ret = regs->gpr[3];
+	int restart = 1;
+
+	/* syscall ? */
+	if (TRAP(regs) != 0x0C00)
+		return;
+
+	/* error signalled ? */
+	if (!(regs->ccr & 0x10000000))
+		return;
+
+	switch (ret) {
+	case ERESTART_RESTARTBLOCK:
+	case ERESTARTNOHAND:
+		/* ERESTARTNOHAND means that the syscall should only be
+		 * restarted if there was no handler for the signal, and since
+		 * we only get here if there is a handler, we dont restart.
+		 */
+		restart = !has_handler;
+		break;
+	case ERESTARTSYS:
+		/* ERESTARTSYS means to restart the syscall if there is no
+		 * handler or the handler was registered with SA_RESTART
+		 */
+		restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
+		break;
+	case ERESTARTNOINTR:
+		/* ERESTARTNOINTR means that the syscall should be
+		 * called again after the signal handler returns.
+		 */
+		break;
+	default:
+		return;
+	}
+	if (restart) {
+		if (ret == ERESTART_RESTARTBLOCK)
+			regs->gpr[0] = __NR_restart_syscall;
+		else
+			regs->gpr[3] = regs->orig_gpr3;
+		regs->nip -= 4;
+		regs->result = 0;
+	} else {
+		regs->result = -EINTR;
+		regs->gpr[3] = EINTR;
+		regs->ccr |= 0x10000000;
+	}
+}
+
+static void do_signal(struct pt_regs *regs)
+{
+	sigset_t *oldset = sigmask_to_save();
+	struct ksignal ksig;
+	int ret;
+	int is32 = is_32bit_task();
+
+	get_signal(&ksig);
+
+	/* Is there any syscall restart business here ? */
+	check_syscall_restart(regs, &ksig.ka, ksig.sig > 0);
+
+	if (ksig.sig <= 0) {
+		/* No signal to deliver -- put the saved sigmask back */
+		restore_saved_sigmask();
+		regs->trap = 0;
+		return;               /* no signals delivered */
+	}
+
+#ifndef CONFIG_PPC_ADV_DEBUG_REGS
+        /*
+	 * Reenable the DABR before delivering the signal to
+	 * user space. The DABR will have been cleared if it
+	 * triggered inside the kernel.
+	 */
+	if (current->thread.hw_brk.address &&
+		current->thread.hw_brk.type)
+		__set_breakpoint(&current->thread.hw_brk);
+#endif
+	/* Re-enable the breakpoints for the signal stack */
+	thread_change_pc(current, regs);
+
+	if (is32) {
+        	if (ksig.ka.sa.sa_flags & SA_SIGINFO)
+			ret = handle_rt_signal32(&ksig, oldset, regs);
+		else
+			ret = handle_signal32(&ksig, oldset, regs);
+	} else {
+		ret = handle_rt_signal64(&ksig, oldset, regs);
+	}
+
+	regs->trap = 0;
+	signal_setup_done(ret, &ksig, test_thread_flag(TIF_SINGLESTEP));
+}
+
+void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
+{
+	user_exit();
+
+	if (thread_info_flags & _TIF_UPROBE)
+		uprobe_notify_resume(regs);
+
+	if (thread_info_flags & _TIF_SIGPENDING)
+		do_signal(regs);
+
+	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+		clear_thread_flag(TIF_NOTIFY_RESUME);
+		tracehook_notify_resume(regs);
+	}
+
+	user_enter();
+}
+
+unsigned long get_tm_stackpointer(struct pt_regs *regs)
+{
+	/* When in an active transaction that takes a signal, we need to be
+	 * careful with the stack.  It's possible that the stack has moved back
+	 * up after the tbegin.  The obvious case here is when the tbegin is
+	 * called inside a function that returns before a tend.  In this case,
+	 * the stack is part of the checkpointed transactional memory state.
+	 * If we write over this non transactionally or in suspend, we are in
+	 * trouble because if we get a tm abort, the program counter and stack
+	 * pointer will be back at the tbegin but our in memory stack won't be
+	 * valid anymore.
+	 *
+	 * To avoid this, when taking a signal in an active transaction, we
+	 * need to use the stack pointer from the checkpointed state, rather
+	 * than the speculated state.  This ensures that the signal context
+	 * (written tm suspended) will be written below the stack required for
+	 * the rollback.  The transaction is aborted becuase of the treclaim,
+	 * so any memory written between the tbegin and the signal will be
+	 * rolled back anyway.
+	 *
+	 * For signals taken in non-TM or suspended mode, we use the
+	 * normal/non-checkpointed stack pointer.
+	 */
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	if (MSR_TM_ACTIVE(regs->msr)) {
+		tm_reclaim_current(TM_CAUSE_SIGNAL);
+		if (MSR_TM_TRANSACTIONAL(regs->msr))
+			return current->thread.ckpt_regs.gpr[1];
+	}
+#endif
+	return regs->gpr[1];
+}