[PATCH 1/3] powerpc: Consolidate *probe definitions

@@ -29,21 +29,16 @@
 #include <linux/types.h>
 #include <linux/ptrace.h>
 #include <linux/percpu.h>
+#include <asm/probes.h>
 
 #define  __ARCH_WANT_KPROBES_INSN_SLOT
 
 struct pt_regs;
 struct kprobe;
 
-typedef unsigned int kprobe_opcode_t;
-#define BREAKPOINT_INSTRUCTION	0x7fe00008	/* trap */
+typedef opcode_t kprobe_opcode_t;
 #define MAX_INSN_SIZE 1
 
-#define IS_TW(instr)		(((instr) & 0xfc0007fe) == 0x7c000008)
-#define IS_TD(instr)		(((instr) & 0xfc0007fe) == 0x7c000088)
-#define IS_TDI(instr)		(((instr) & 0xfc000000) == 0x08000000)
-#define IS_TWI(instr)		(((instr) & 0xfc000000) == 0x0c000000)
-
 #ifdef CONFIG_PPC64
 /*
  * 64bit powerpc uses function descriptors.

@@ -72,12 +67,6 @@ typedef unsigned int kprobe_opcode_t;
 		addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name); \
 	}								\
 }
-
-#define is_trap(instr)	(IS_TW(instr) || IS_TD(instr) || \
-			IS_TWI(instr) || IS_TDI(instr))
-#else
-/* Use stock kprobe_lookup_name since ppc32 doesn't use function descriptors */
-#define is_trap(instr)	(IS_TW(instr) || IS_TWI(instr))
 #endif
 
 #define flush_insn_slot(p)	do { } while (0)

@@ -0,0 +1,42 @@
+#ifndef _ASM_POWERPC_PROBES_H
+#define _ASM_POWERPC_PROBES_H
+#ifdef __KERNEL__
+/*
+ * Definitions common to probes files
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright IBM Corporation, 2012
+ */
+#include <linux/types.h>
+
+typedef u32 opcode_t;
+#define BREAKPOINT_INSTRUCTION	0x7fe00008	/* trap */
+
+/* Trap definitions per ISA */
+#define IS_TW(instr)		(((instr) & 0xfc0007fe) == 0x7c000008)
+#define IS_TD(instr)		(((instr) & 0xfc0007fe) == 0x7c000088)
+#define IS_TDI(instr)		(((instr) & 0xfc000000) == 0x08000000)
+#define IS_TWI(instr)		(((instr) & 0xfc000000) == 0x0c000000)
+
+#ifdef CONFIG_PPC64
+#define is_trap(instr)		(IS_TW(instr) || IS_TD(instr) || \
+				IS_TWI(instr) || IS_TDI(instr))
+#else
+#define is_trap(instr)		(IS_TW(instr) || IS_TWI(instr))
+#endif /* CONFIG_PPC64 */
+
+#endif /* __KERNEL__ */
+#endif	/* _ASM_POWERPC_PROBES_H */

@@ -219,6 +219,7 @@ struct thread_struct {
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 #endif
 	unsigned long	dabr;		/* Data address breakpoint register */
+	unsigned long	trap_nr;	/* last trap # on this thread */
 #ifdef CONFIG_ALTIVEC
 	/* Complete AltiVec register set */
 	vector128	vr[32] __attribute__((aligned(16)));

@@ -258,6 +258,7 @@ void do_send_trap(struct pt_regs *regs, 
 {
 	siginfo_t info;
 
+	current->thread.trap_nr = signal_code;
 	if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
 			11, SIGSEGV) == NOTIFY_STOP)
 		return;

@@ -275,6 +276,7 @@ void do_dabr(struct pt_regs *regs, unsig
 {
 	siginfo_t info;
 
+	current->thread.trap_nr = TRAP_HWBKPT;
 	if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
 			11, SIGSEGV) == NOTIFY_STOP)
 		return;

@@ -251,6 +251,7 @@ void _exception(int signr, struct pt_reg
 	if (arch_irqs_disabled() && !arch_irq_disabled_regs(regs))
 		local_irq_enable();
 
+	current->thread.trap_nr = code;
 	memset(&info, 0, sizeof(info));
 	info.si_signo = signr;
 	info.si_code = code;

@@ -133,6 +133,7 @@ static int do_sigbus(struct pt_regs *reg
 	up_read(&current->mm->mmap_sem);
 
 	if (user_mode(regs)) {
+		current->thread.trap_nr = BUS_ADRERR;
 		info.si_signo = SIGBUS;
 		info.si_errno = 0;
 		info.si_code = BUS_ADRERR;

@@ -102,6 +102,7 @@ static inline struct thread_info *curren
 #define TIF_RESTOREALL		11	/* Restore all regs (implies NOERROR) */
 #define TIF_NOERROR		12	/* Force successful syscall return */
 #define TIF_NOTIFY_RESUME	13	/* callback before returning to user */
+#define TIF_UPROBE		14	/* breakpointed or single-stepping */
 #define TIF_SYSCALL_TRACEPOINT	15	/* syscall tracepoint instrumentation */
 
 /* as above, but as bit values */

@@ -118,12 +119,13 @@ static inline struct thread_info *curren
 #define _TIF_RESTOREALL		(1<<TIF_RESTOREALL)
 #define _TIF_NOERROR		(1<<TIF_NOERROR)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
+#define _TIF_UPROBE		(1<<TIF_UPROBE)
 #define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)
 #define _TIF_SYSCALL_T_OR_A	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)
 
 #define _TIF_USER_WORK_MASK	(_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
-				 _TIF_NOTIFY_RESUME)
+				 _TIF_NOTIFY_RESUME | _TIF_UPROBE)
 #define _TIF_PERSYSCALL_MASK	(_TIF_RESTOREALL|_TIF_NOERROR)
 
 /* Bits in local_flags */

@@ -0,0 +1,55 @@
+#ifndef _ASM_UPROBES_H
+#define _ASM_UPROBES_H
+/*
+ * User-space Probes (UProbes) for powerpc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright IBM Corporation, 2007-2012
+ *
+ * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@in.ibm.com>
+ */
+
+#include <linux/notifier.h>
+#include <asm/probes.h>
+
+typedef opcode_t uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES		4
+#define UPROBE_XOL_SLOT_BYTES	(MAX_UINSN_BYTES)
+
+/* The following alias is needed for reference from arch-agnostic code */
+#define UPROBE_SWBP_INSN	BREAKPOINT_INSTRUCTION
+#define UPROBE_SWBP_INSN_SIZE	4 /* swbp insn size in bytes */
+
+struct arch_uprobe {
+	union {
+		u8	insn[MAX_UINSN_BYTES];
+		u32	ainsn;
+	};
+};
+
+struct arch_uprobe_task {
+	unsigned long	saved_trap_nr;
+};
+
+extern int  arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
+extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
+extern int  arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
+extern int  arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
+extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
+extern int  arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
+extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
+#endif	/* _ASM_UPROBES_H */

@@ -96,6 +96,7 @@ obj-$(CONFIG_MODULES)		+= ppc_ksyms.o
 obj-$(CONFIG_BOOTX_TEXT)	+= btext.o
 obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
+obj-$(CONFIG_UPROBES)		+= uprobes.o
 obj-$(CONFIG_PPC_UDBG_16550)	+= legacy_serial.o udbg_16550.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_SWIOTLB)		+= dma-swiotlb.o

@@ -11,6 +11,7 @@
 
 #include <linux/tracehook.h>
 #include <linux/signal.h>
+#include <linux/uprobes.h>
 #include <linux/key.h>
 #include <asm/hw_breakpoint.h>
 #include <asm/uaccess.h>

@@ -157,6 +158,11 @@ static int do_signal(struct pt_regs *reg
 
 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 {
+	if (thread_info_flags & _TIF_UPROBE) {
+		clear_thread_flag(TIF_UPROBE);
+		uprobe_notify_resume(regs);
+	}
+
 	if (thread_info_flags & _TIF_SIGPENDING)
 		do_signal(regs);
 

@@ -0,0 +1,184 @@
+/*
+ * User-space Probes (UProbes) for powerpc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright IBM Corporation, 2007-2012
+ *
+ * Adapted from the x86 port by Ananth N Mavinakayanahalli <ananth@in.ibm.com>
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <linux/uprobes.h>
+#include <linux/uaccess.h>
+#include <linux/kdebug.h>
+
+#include <asm/sstep.h>
+
+#define UPROBE_TRAP_NR	UINT_MAX
+
+/**
+ * arch_uprobe_analyze_insn
+ * @mm: the probed address space.
+ * @arch_uprobe: the probepoint information.
+ * @addr: vaddr to probe.
+ * Return 0 on success or a -ve number on error.
+ */
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
+		struct mm_struct *mm, unsigned long addr)
+{
+	if (addr & 0x03)
+		return -EINVAL;
+
+	/*
+	 * We currently don't support a uprobe on an already
+	 * existing breakpoint instruction underneath
+	 */
+	if (is_trap(auprobe->ainsn))
+		return -ENOTSUPP;
+	return 0;
+}
+
+/*
+ * arch_uprobe_pre_xol - prepare to execute out of line.
+ * @auprobe: the probepoint information.
+ * @regs: reflects the saved user state of current task.
+ */
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+	struct arch_uprobe_task *autask = &current->utask->autask;
+
+	autask->saved_trap_nr = current->thread.trap_nr;
+	current->thread.trap_nr = UPROBE_TRAP_NR;
+	regs->nip = current->utask->xol_vaddr;
+	return 0;
+}
+
+/**
+ * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
+ * @regs: Reflects the saved state of the task after it has hit a breakpoint
+ * instruction.
+ * Return the address of the breakpoint instruction.
+ */
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+	return instruction_pointer(regs);
+}
+
+/*
+ * If xol insn itself traps and generates a signal (SIGILL/SIGSEGV/etc),
+ * then detect the case where a singlestepped instruction jumps back to its
+ * own address. It is assumed that anything like do_page_fault/do_trap/etc
+ * sets thread.trap_nr != UINT_MAX.
+ *
+ * arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr,
+ * arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to
+ * UPROBE_TRAP_NR == UINT_MAX set by arch_uprobe_pre_xol().
+ */
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+	if (t->thread.trap_nr != UPROBE_TRAP_NR)
+		return true;
+
+	return false;
+}
+
+/*
+ * Called after single-stepping. To avoid the SMP problems that can
+ * occur when we temporarily put back the original opcode to
+ * single-step, we single-stepped a copy of the instruction.
+ *
+ * This function prepares to resume execution after the single-step.
+ */
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+	struct uprobe_task *utask = current->utask;
+
+	WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
+
+	current->thread.trap_nr = utask->autask.saved_trap_nr;
+
+	/*
+	 * On powerpc, except for loads and stores, most instructions
+	 * including ones that alter code flow (branches, calls, returns)
+	 * are emulated in the kernel. We get here only if the emulation
+	 * support doesn't exist and have to fix-up the next instruction
+	 * to be executed.
+	 */
+	regs->nip = utask->vaddr + MAX_UINSN_BYTES;
+	return 0;
+}
+
+/* callback routine for handling exceptions. */
+int arch_uprobe_exception_notify(struct notifier_block *self,
+				unsigned long val, void *data)
+{
+	struct die_args *args = data;
+	struct pt_regs *regs = args->regs;
+
+	/* regs == NULL is a kernel bug */
+	if (WARN_ON(!regs))
+		return NOTIFY_DONE;
+
+	/* We are only interested in userspace traps */
+	if (!user_mode(regs))
+		return NOTIFY_DONE;
+
+	switch (val) {
+	case DIE_BPT:
+		if (uprobe_pre_sstep_notifier(regs))
+			return NOTIFY_STOP;
+		break;
+	case DIE_SSTEP:
+		if (uprobe_post_sstep_notifier(regs))
+			return NOTIFY_STOP;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+/*
+ * This function gets called when XOL instruction either gets trapped or
+ * the thread has a fatal signal, so reset the instruction pointer to its
+ * probed address.
+ */
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+	struct uprobe_task *utask = current->utask;
+
+	current->thread.trap_nr = utask->autask.saved_trap_nr;
+	instruction_pointer_set(regs, utask->vaddr);
+}
+
+/*
+ * See if the instruction can be emulated.
+ * Returns true if instruction was emulated, false otherwise.
+ */
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+	int ret;
+
+	/*
+	 * emulate_step() returns 1 if the insn was successfully emulated.
+	 * For all other cases, we need to single-step in hardware.
+	 */
+	ret = emulate_step(regs, auprobe->ainsn);
+	if (ret > 0)
+		return true;
+
+	return false;
+}

@@ -239,6 +239,9 @@ config PPC_OF_PLATFORM_PCI
 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	def_bool y
 
+config ARCH_SUPPORTS_UPROBES
+	def_bool y
+
 config PPC_ADV_DEBUG_REGS
 	bool
 	depends on 40x || BOOKE