tile: support kprobes on tilegx

This change includes support for Kprobes, Jprobes and Return Probes. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Tony Lu <zlu@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

tile: support kprobes on tilegx
This change includes support for Kprobes, Jprobes and Return Probes. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Tony Lu <zlu@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Tony Lu · Chris Metcalf
1 parent a61fd5e366
Showing 14 changed files with 718 additions and 5 deletions Side-by-side Diff
arch/tile/Kconfig
arch/tile/include/asm/Kbuild
arch/tile/include/asm/kdebug.h
arch/tile/include/asm/kprobes.h
arch/tile/include/asm/ptrace.h
arch/tile/include/uapi/arch/opcode_tilegx.h
arch/tile/include/uapi/arch/opcode_tilepro.h
arch/tile/kernel/Makefile
arch/tile/kernel/kprobes.c
arch/tile/kernel/smp.c
arch/tile/kernel/traps.c
arch/tile/kernel/vmlinux.lds.S
arch/tile/mm/fault.c
samples/kprobes/kprobe_example.c
@@ -125,6 +125,8 @@
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_KPROBES
+	select HAVE_KRETPROBES
  
 config TILEPRO
 	def_bool !TILEGX
@@ -15,7 +15,6 @@
 generic-y += ioctls.h
 generic-y += ipcbuf.h
 generic-y += irq_regs.h
-generic-y += kdebug.h
 generic-y += local.h
 generic-y += msgbuf.h
 generic-y += mutex.h
+/*
+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
+ *
+ *   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, version 2.
+ *
+ *   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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#ifndef _ASM_TILE_KDEBUG_H
+#define _ASM_TILE_KDEBUG_H
+
+#include <linux/notifier.h>
+
+enum die_val {
+	DIE_OOPS = 1,
+	DIE_BREAK,
+	DIE_SSTEPBP,
+	DIE_PAGE_FAULT,
+	DIE_COMPILED_BPT
+};
+
+#endif /* _ASM_TILE_KDEBUG_H */
+/*
+ * arch/tile/include/asm/kprobes.h
+ *
+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
+ *
+ *   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, version 2.
+ *
+ *   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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#ifndef _ASM_TILE_KPROBES_H
+#define _ASM_TILE_KPROBES_H
+
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/percpu.h>
+
+#include <arch/opcode.h>
+
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+#define MAX_INSN_SIZE			2
+
+#define kretprobe_blacklist_size 0
+
+typedef tile_bundle_bits kprobe_opcode_t;
+
+#define flush_insn_slot(p)						\
+	flush_icache_range((unsigned long)p->addr,			\
+			   (unsigned long)p->addr +			\
+			   (MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
+
+struct kprobe;
+
+/* Architecture specific copy of original instruction. */
+struct arch_specific_insn {
+	kprobe_opcode_t *insn;
+};
+
+struct prev_kprobe {
+	struct kprobe *kp;
+	unsigned long status;
+	unsigned long saved_pc;
+};
+
+#define MAX_JPROBES_STACK_SIZE 128
+#define MAX_JPROBES_STACK_ADDR \
+	(((unsigned long)current_thread_info()) + THREAD_SIZE - 32 \
+		- sizeof(struct pt_regs))
+
+#define MIN_JPROBES_STACK_SIZE(ADDR)					\
+	((((ADDR) + MAX_JPROBES_STACK_SIZE) > MAX_JPROBES_STACK_ADDR)	\
+		? MAX_JPROBES_STACK_ADDR - (ADDR)			\
+		: MAX_JPROBES_STACK_SIZE)
+
+/* per-cpu kprobe control block. */
+struct kprobe_ctlblk {
+	unsigned long kprobe_status;
+	unsigned long kprobe_saved_pc;
+	unsigned long jprobe_saved_sp;
+	struct prev_kprobe prev_kprobe;
+	struct pt_regs jprobe_saved_regs;
+	char jprobes_stack[MAX_JPROBES_STACK_SIZE];
+};
+
+extern tile_bundle_bits breakpoint2_insn;
+extern tile_bundle_bits breakpoint_insn;
+
+void arch_remove_kprobe(struct kprobe *);
+
+extern int kprobe_exceptions_notify(struct notifier_block *self,
+			     unsigned long val, void *data);
+
+#endif /* _ASM_TILE_KPROBES_H */
@@ -33,6 +33,7 @@
  
 #ifndef __ASSEMBLY__
  
+#define regs_return_value(regs) ((regs)->regs[0])
 #define instruction_pointer(regs) ((regs)->pc)
 #define profile_pc(regs) instruction_pointer(regs)
 #define user_stack_pointer(regs) ((regs)->sp)
@@ -61,6 +61,7 @@
 #define TILE_BUNDLE_ALIGNMENT_IN_BYTES TILEGX_BUNDLE_ALIGNMENT_IN_BYTES
 #define TILE_LOG2_BUNDLE_ALIGNMENT_IN_BYTES \
   TILEGX_LOG2_BUNDLE_ALIGNMENT_IN_BYTES
+#define TILE_BPT_BUNDLE TILEGX_BPT_BUNDLE
  
 /* 64-bit pattern for a { bpt ; nop } bundle. */
 #define TILEGX_BPT_BUNDLE 0x286a44ae51485000ULL
@@ -71,6 +71,7 @@
 #define TILE_BUNDLE_ALIGNMENT_IN_BYTES TILEPRO_BUNDLE_ALIGNMENT_IN_BYTES
 #define TILE_LOG2_BUNDLE_ALIGNMENT_IN_BYTES \
   TILEPRO_LOG2_BUNDLE_ALIGNMENT_IN_BYTES
+#define TILE_BPT_BUNDLE TILEPRO_BPT_BUNDLE
  
 /* 64-bit pattern for a { bpt ; nop } bundle. */
 #define TILEPRO_BPT_BUNDLE 0x400b3cae70166000ULL
@@ -28,6 +28,7 @@
 obj-$(CONFIG_TILE_USB)		+= usb.o
 obj-$(CONFIG_TILE_HVGLUE_TRACE)	+= hvglue_trace.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o mcount_64.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
  
 obj-y				+= vdso/
+/*
+ * arch/tile/kernel/kprobes.c
+ * Kprobes on TILE-Gx
+ *
+ * Some portions copied from the MIPS version.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ * Copyright 2006 Sony Corp.
+ * Copyright 2010 Cavium Networks
+ *
+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
+ *
+ *   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, version 2.
+ *
+ *   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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+
+#include <arch/opcode.h>
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
+tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
+
+/*
+ * Check whether instruction is branch or jump, or if executing it
+ * has different results depending on where it is executed (e.g. lnk).
+ */
+static int __kprobes insn_has_control(kprobe_opcode_t insn)
+{
+	if (get_Mode(insn) != 0) {   /* Y-format bundle */
+		if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 ||
+		    get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1)
+			return 0;
+
+		switch (get_UnaryOpcodeExtension_Y1(insn)) {
+		case JALRP_UNARY_OPCODE_Y1:
+		case JALR_UNARY_OPCODE_Y1:
+		case JRP_UNARY_OPCODE_Y1:
+		case JR_UNARY_OPCODE_Y1:
+		case LNK_UNARY_OPCODE_Y1:
+			return 1;
+		default:
+			return 0;
+		}
+	}
+
+	switch (get_Opcode_X1(insn)) {
+	case BRANCH_OPCODE_X1:	/* branch instructions */
+	case JUMP_OPCODE_X1:	/* jump instructions: j and jal */
+		return 1;
+
+	case RRR_0_OPCODE_X1:   /* other jump instructions */
+		if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1)
+			return 0;
+		switch (get_UnaryOpcodeExtension_X1(insn)) {
+		case JALRP_UNARY_OPCODE_X1:
+		case JALR_UNARY_OPCODE_X1:
+		case JRP_UNARY_OPCODE_X1:
+		case JR_UNARY_OPCODE_X1:
+		case LNK_UNARY_OPCODE_X1:
+			return 1;
+		default:
+			return 0;
+		}
+	default:
+		return 0;
+	}
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+	unsigned long addr = (unsigned long)p->addr;
+
+	if (addr & (sizeof(kprobe_opcode_t) - 1))
+		return -EINVAL;
+
+	if (insn_has_control(*p->addr)) {
+		pr_notice("Kprobes for control instructions are not "
+			  "supported\n");
+		return -EINVAL;
+	}
+
+	/* insn: must be on special executable page on tile. */
+	p->ainsn.insn = get_insn_slot();
+	if (!p->ainsn.insn)
+		return -ENOMEM;
+
+	/*
+	 * In the kprobe->ainsn.insn[] array we store the original
+	 * instruction at index zero and a break trap instruction at
+	 * index one.
+	 */
+	memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
+	p->ainsn.insn[1] = breakpoint2_insn;
+	p->opcode = *p->addr;
+
+	return 0;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+	unsigned long addr_wr;
+
+	/* Operate on writable kernel text mapping. */
+	addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
+
+	if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
+		sizeof(breakpoint_insn)))
+		pr_err("%s: failed to enable kprobe\n", __func__);
+
+	smp_wmb();
+	flush_insn_slot(p);
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *kp)
+{
+	unsigned long addr_wr;
+
+	/* Operate on writable kernel text mapping. */
+	addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
+
+	if (probe_kernel_write((void *)addr_wr, &kp->opcode,
+		sizeof(kp->opcode)))
+		pr_err("%s: failed to enable kprobe\n", __func__);
+
+	smp_wmb();
+	flush_insn_slot(kp);
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+	if (p->ainsn.insn) {
+		free_insn_slot(p->ainsn.insn, 0);
+		p->ainsn.insn = NULL;
+	}
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+	kcb->prev_kprobe.kp = kprobe_running();
+	kcb->prev_kprobe.status = kcb->kprobe_status;
+	kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+	__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
+	kcb->kprobe_status = kcb->prev_kprobe.status;
+	kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+			struct kprobe_ctlblk *kcb)
+{
+	__this_cpu_write(current_kprobe, p);
+	kcb->kprobe_saved_pc = regs->pc;
+}
+
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+	/* Single step inline if the instruction is a break. */
+	if (p->opcode == breakpoint_insn ||
+	    p->opcode == breakpoint2_insn)
+		regs->pc = (unsigned long)p->addr;
+	else
+		regs->pc = (unsigned long)&p->ainsn.insn[0];
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *p;
+	int ret = 0;
+	kprobe_opcode_t *addr;
+	struct kprobe_ctlblk *kcb;
+
+	addr = (kprobe_opcode_t *)regs->pc;
+
+	/*
+	 * We don't want to be preempted for the entire
+	 * duration of kprobe processing.
+	 */
+	preempt_disable();
+	kcb = get_kprobe_ctlblk();
+
+	/* Check we're not actually recursing. */
+	if (kprobe_running()) {
+		p = get_kprobe(addr);
+		if (p) {
+			if (kcb->kprobe_status == KPROBE_HIT_SS &&
+			    p->ainsn.insn[0] == breakpoint_insn) {
+				goto no_kprobe;
+			}
+			/*
+			 * We have reentered the kprobe_handler(), since
+			 * another probe was hit while within the handler.
+			 * We here save the original kprobes variables and
+			 * just single step on the instruction of the new probe
+			 * without calling any user handlers.
+			 */
+			save_previous_kprobe(kcb);
+			set_current_kprobe(p, regs, kcb);
+			kprobes_inc_nmissed_count(p);
+			prepare_singlestep(p, regs);
+			kcb->kprobe_status = KPROBE_REENTER;
+			return 1;
+		} else {
+			if (*addr != breakpoint_insn) {
+				/*
+				 * The breakpoint instruction was removed by
+				 * another cpu right after we hit, no further
+				 * handling of this interrupt is appropriate.
+				 */
+				ret = 1;
+				goto no_kprobe;
+			}
+			p = __this_cpu_read(current_kprobe);
+			if (p->break_handler && p->break_handler(p, regs))
+				goto ss_probe;
+		}
+		goto no_kprobe;
+	}
+
+	p = get_kprobe(addr);
+	if (!p) {
+		if (*addr != breakpoint_insn) {
+			/*
+			 * The breakpoint instruction was removed right
+			 * after we hit it.  Another cpu has removed
+			 * either a probepoint or a debugger breakpoint
+			 * at this address.  In either case, no further
+			 * handling of this interrupt is appropriate.
+			 */
+			ret = 1;
+		}
+		/* Not one of ours: let kernel handle it. */
+		goto no_kprobe;
+	}
+
+	set_current_kprobe(p, regs, kcb);
+	kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+	if (p->pre_handler && p->pre_handler(p, regs)) {
+		/* Handler has already set things up, so skip ss setup. */
+		return 1;
+	}
+
+ss_probe:
+	prepare_singlestep(p, regs);
+	kcb->kprobe_status = KPROBE_HIT_SS;
+	return 1;
+
+no_kprobe:
+	preempt_enable_no_resched();
+	return ret;
+}
+
+/*
+ * Called after single-stepping.  p->addr is the address of the
+ * instruction that has been replaced by the breakpoint. 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.  The address of this copy is p->ainsn.insn.
+ *
+ * This function prepares to return from the post-single-step
+ * breakpoint trap.
+ */
+static void __kprobes resume_execution(struct kprobe *p,
+				       struct pt_regs *regs,
+				       struct kprobe_ctlblk *kcb)
+{
+	unsigned long orig_pc = kcb->kprobe_saved_pc;
+	regs->pc = orig_pc + 8;
+}
+
+static inline int post_kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (!cur)
+		return 0;
+
+	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+		kcb->kprobe_status = KPROBE_HIT_SSDONE;
+		cur->post_handler(cur, regs, 0);
+	}
+
+	resume_execution(cur, regs, kcb);
+
+	/* Restore back the original saved kprobes variables and continue. */
+	if (kcb->kprobe_status == KPROBE_REENTER) {
+		restore_previous_kprobe(kcb);
+		goto out;
+	}
+	reset_current_kprobe();
+out:
+	preempt_enable_no_resched();
+
+	return 1;
+}
+
+static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+		return 1;
+
+	if (kcb->kprobe_status & KPROBE_HIT_SS) {
+		/*
+		 * We are here because the instruction being single
+		 * stepped caused a page fault. We reset the current
+		 * kprobe and the ip points back to the probe address
+		 * and allow the page fault handler to continue as a
+		 * normal page fault.
+		 */
+		resume_execution(cur, regs, kcb);
+		reset_current_kprobe();
+		preempt_enable_no_resched();
+	}
+	return 0;
+}
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+				       unsigned long val, void *data)
+{
+	struct die_args *args = (struct die_args *)data;
+	int ret = NOTIFY_DONE;
+
+	switch (val) {
+	case DIE_BREAK:
+		if (kprobe_handler(args->regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_SSTEPBP:
+		if (post_kprobe_handler(args->regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_PAGE_FAULT:
+		/* kprobe_running() needs smp_processor_id(). */
+		preempt_disable();
+
+		if (kprobe_running()
+		    && kprobe_fault_handler(args->regs, args->trapnr))
+			ret = NOTIFY_STOP;
+		preempt_enable();
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct jprobe *jp = container_of(p, struct jprobe, kp);
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	kcb->jprobe_saved_regs = *regs;
+	kcb->jprobe_saved_sp = regs->sp;
+
+	memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
+	       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
+
+	regs->pc = (unsigned long)(jp->entry);
+
+	return 1;
+}
+
+/* Defined in the inline asm below. */
+void jprobe_return_end(void);
+
+void __kprobes jprobe_return(void)
+{
+	asm volatile(
+		"bpt\n\t"
+		".globl jprobe_return_end\n"
+		"jprobe_return_end:\n");
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (regs->pc >= (unsigned long)jprobe_return &&
+	    regs->pc <= (unsigned long)jprobe_return_end) {
+		*regs = kcb->jprobe_saved_regs;
+		memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
+		       MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
+		preempt_enable_no_resched();
+
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * Function return probe trampoline:
+ * - init_kprobes() establishes a probepoint here
+ * - When the probed function returns, this probe causes the
+ *   handlers to fire
+ */
+static void __used kretprobe_trampoline_holder(void)
+{
+	asm volatile(
+		"nop\n\t"
+		".global kretprobe_trampoline\n"
+		"kretprobe_trampoline:\n\t"
+		"nop\n\t"
+		: : : "memory");
+}
+
+void kretprobe_trampoline(void);
+
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+				      struct pt_regs *regs)
+{
+	ri->ret_addr = (kprobe_opcode_t *) regs->lr;
+
+	/* Replace the return addr with trampoline addr */
+	regs->lr = (unsigned long)kretprobe_trampoline;
+}
+
+/*
+ * Called when the probe at kretprobe trampoline is hit.
+ */
+static int __kprobes trampoline_probe_handler(struct kprobe *p,
+						struct pt_regs *regs)
+{
+	struct kretprobe_instance *ri = NULL;
+	struct hlist_head *head, empty_rp;
+	struct hlist_node *tmp;
+	unsigned long flags, orig_ret_address = 0;
+	unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;
+
+	INIT_HLIST_HEAD(&empty_rp);
+	kretprobe_hash_lock(current, &head, &flags);
+
+	/*
+	 * It is possible to have multiple instances associated with a given
+	 * task either because multiple functions in the call path have
+	 * a return probe installed on them, and/or more than one return
+	 * return probe was registered for a target function.
+	 *
+	 * We can handle this because:
+	 *     - instances are always inserted at the head of the list
+	 *     - when multiple return probes are registered for the same
+	 *       function, the first instance's ret_addr will point to the
+	 *       real return address, and all the rest will point to
+	 *       kretprobe_trampoline
+	 */
+	hlist_for_each_entry_safe(ri, tmp, head, hlist) {
+		if (ri->task != current)
+			/* another task is sharing our hash bucket */
+			continue;
+
+		if (ri->rp && ri->rp->handler)
+			ri->rp->handler(ri, regs);
+
+		orig_ret_address = (unsigned long)ri->ret_addr;
+		recycle_rp_inst(ri, &empty_rp);
+
+		if (orig_ret_address != trampoline_address) {
+			/*
+			 * This is the real return address. Any other
+			 * instances associated with this task are for
+			 * other calls deeper on the call stack
+			 */
+			break;
+		}
+	}
+
+	kretprobe_assert(ri, orig_ret_address, trampoline_address);
+	instruction_pointer(regs) = orig_ret_address;
+
+	reset_current_kprobe();
+	kretprobe_hash_unlock(current, &flags);
+	preempt_enable_no_resched();
+
+	hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
+	/*
+	 * By returning a non-zero value, we are telling
+	 * kprobe_handler() that we don't want the post_handler
+	 * to run (and have re-enabled preemption)
+	 */
+	return 1;
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+	if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
+		return 1;
+
+	return 0;
+}
+
+static struct kprobe trampoline_p = {
+	.addr = (kprobe_opcode_t *)kretprobe_trampoline,
+	.pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+	register_kprobe(&trampoline_p);
+	return 0;
+}
@@ -20,6 +20,7 @@
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <asm/cacheflush.h>
+#include <asm/homecache.h>
  
 HV_Topology smp_topology __write_once;
 EXPORT_SYMBOL(smp_topology);
@@ -167,9 +168,16 @@
 void flush_icache_range(unsigned long start, unsigned long end)
 {
 	struct ipi_flush flush = { start, end };
-	preempt_disable();
-	on_each_cpu(ipi_flush_icache_range, &flush, 1);
-	preempt_enable();
+
+	/* If invoked with irqs disabled, we can not issue IPIs. */
+	if (irqs_disabled())
+		flush_remote(0, HV_FLUSH_EVICT_L1I, NULL, 0, 0, 0,
+			NULL, NULL, 0);
+	else {
+		preempt_disable();
+		on_each_cpu(ipi_flush_icache_range, &flush, 1);
+		preempt_enable();
+	}
 }
  
  
@@ -15,6 +15,7 @@
 #include <linux/sched.h>
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
+#include <linux/kdebug.h>
 #include <linux/module.h>
 #include <linux/reboot.h>
 #include <linux/uaccess.h>
@@ -214,6 +215,43 @@
 #endif
 };
  
+static int do_bpt(struct pt_regs *regs)
+{
+	unsigned long bundle, bcode, bpt;
+
+	bundle = *(unsigned long *)instruction_pointer(regs);
+
+	/*
+	 * bpt shoule be { bpt; nop }, which is 0x286a44ae51485000ULL.
+	 * we encode the unused least significant bits for other purpose.
+	 */
+	bpt = bundle & ~((1ULL << 12) - 1);
+	if (bpt != TILE_BPT_BUNDLE)
+		return 0;
+
+	bcode = bundle & ((1ULL << 12) - 1);
+	/*
+	 * notify the kprobe handlers, if instruction is likely to
+	 * pertain to them.
+	 */
+	switch (bcode) {
+	/* breakpoint_insn */
+	case 0:
+		notify_die(DIE_BREAK, "debug", regs, bundle,
+			INT_ILL, SIGTRAP);
+		break;
+	/* breakpoint2_insn */
+	case DIE_SSTEPBP:
+		notify_die(DIE_SSTEPBP, "single_step", regs, bundle,
+			INT_ILL, SIGTRAP);
+		break;
+	default:
+		return 0;
+	}
+
+	return 1;
+}
+
 void __kprobes do_trap(struct pt_regs *regs, int fault_num,
 		       unsigned long reason)
 {
  
@@ -221,7 +259,12 @@
 	int signo, code;
 	unsigned long address = 0;
 	bundle_bits instr;
+	int is_kernel = !user_mode(regs);
  
+	/* Handle breakpoints, etc. */
+	if (is_kernel && fault_num == INT_ILL && do_bpt(regs))
+		return;
+
 	/* Re-enable interrupts, if they were previously enabled. */
 	if (!(regs->flags & PT_FLAGS_DISABLE_IRQ))
 		local_irq_enable();
@@ -230,7 +273,7 @@
 	 * If it hits in kernel mode and we can't fix it up, just exit the
 	 * current process and hope for the best.
 	 */
-	if (!user_mode(regs)) {
+	if (is_kernel) {
 		const char *name;
 		char buf[100];
 		if (fixup_exception(regs))  /* ILL_TRANS or UNALIGN_DATA */
@@ -43,6 +43,7 @@
     HEAD_TEXT
     SCHED_TEXT
     LOCK_TEXT
+    KPROBES_TEXT
     IRQENTRY_TEXT
     __fix_text_end = .;   /* tile-cpack won't rearrange before this */
     TEXT_TEXT
@@ -34,6 +34,7 @@
 #include <linux/hugetlb.h>
 #include <linux/syscalls.h>
 #include <linux/uaccess.h>
+#include <linux/kdebug.h>
  
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
@@ -720,6 +721,17 @@
 		   unsigned long address, unsigned long write)
 {
 	int is_page_fault;
+
+#ifdef CONFIG_KPROBES
+	/*
+	 * This is to notify the fault handler of the kprobes.  The
+	 * exception code is redundant as it is also carried in REGS,
+	 * but we pass it anyhow.
+	 */
+	if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
+		       regs->faultnum, SIGSEGV) == NOTIFY_STOP)
+		return;
+#endif
  
 #ifdef __tilegx__
 	/*
@@ -37,6 +37,11 @@
 			" status = 0x%lx\n",
 		p->addr, regs->cp0_epc, regs->cp0_status);
 #endif
+#ifdef CONFIG_TILEGX
+	printk(KERN_INFO "pre_handler: p->addr = 0x%p, pc = 0x%lx,"
+			" ex1 = 0x%lx\n",
+		p->addr, regs->pc, regs->ex1);
+#endif
  
 	/* A dump_stack() here will give a stack backtrace */
 	return 0;
@@ -57,6 +62,10 @@
 #ifdef CONFIG_MIPS
 	printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n",
 		p->addr, regs->cp0_status);
+#endif
+#ifdef CONFIG_TILEGX
+	printk(KERN_INFO "post_handler: p->addr = 0x%p, ex1 = 0x%lx\n",
+		p->addr, regs->ex1);
 #endif
 }
...	...	@@ -125,6 +125,8 @@
125	125	select HAVE_FUNCTION_GRAPH_TRACER
126	126	select HAVE_DYNAMIC_FTRACE
127	127	select HAVE_FTRACE_MCOUNT_RECORD
	128	+ select HAVE_KPROBES
	129	+ select HAVE_KRETPROBES
128	130
129	131	config TILEPRO
130	132	def_bool !TILEGX
...	...	@@ -15,7 +15,6 @@
15	15	generic-y += ioctls.h
16	16	generic-y += ipcbuf.h
17	17	generic-y += irq_regs.h
18		-generic-y += kdebug.h
19	18	generic-y += local.h
20	19	generic-y += msgbuf.h
21	20	generic-y += mutex.h
	1	+/*
	2	+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
	3	+ *
	4	+ * This program is free software; you can redistribute it and/or
	5	+ * modify it under the terms of the GNU General Public License
	6	+ * as published by the Free Software Foundation, version 2.
	7	+ *
	8	+ * This program is distributed in the hope that it will be useful, but
	9	+ * WITHOUT ANY WARRANTY; without even the implied warranty of
	10	+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	11	+ * NON INFRINGEMENT. See the GNU General Public License for
	12	+ * more details.
	13	+ */
	14	+
	15	+#ifndef _ASM_TILE_KDEBUG_H
	16	+#define _ASM_TILE_KDEBUG_H
	17	+
	18	+#include <linux/notifier.h>
	19	+
	20	+enum die_val {
	21	+ DIE_OOPS = 1,
	22	+ DIE_BREAK,
	23	+ DIE_SSTEPBP,
	24	+ DIE_PAGE_FAULT,
	25	+ DIE_COMPILED_BPT
	26	+};
	27	+
	28	+#endif /* _ASM_TILE_KDEBUG_H */
	1	+/*
	2	+ * arch/tile/include/asm/kprobes.h
	3	+ *
	4	+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
	5	+ *
	6	+ * This program is free software; you can redistribute it and/or
	7	+ * modify it under the terms of the GNU General Public License
	8	+ * as published by the Free Software Foundation, version 2.
	9	+ *
	10	+ * This program is distributed in the hope that it will be useful, but
	11	+ * WITHOUT ANY WARRANTY; without even the implied warranty of
	12	+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	13	+ * NON INFRINGEMENT. See the GNU General Public License for
	14	+ * more details.
	15	+ */
	16	+
	17	+#ifndef _ASM_TILE_KPROBES_H
	18	+#define _ASM_TILE_KPROBES_H
	19	+
	20	+#include <linux/types.h>
	21	+#include <linux/ptrace.h>
	22	+#include <linux/percpu.h>
	23	+
	24	+#include <arch/opcode.h>
	25	+
	26	+#define __ARCH_WANT_KPROBES_INSN_SLOT
	27	+#define MAX_INSN_SIZE 2
	28	+
	29	+#define kretprobe_blacklist_size 0
	30	+
	31	+typedef tile_bundle_bits kprobe_opcode_t;
	32	+
	33	+#define flush_insn_slot(p) \
	34	+ flush_icache_range((unsigned long)p->addr, \
	35	+ (unsigned long)p->addr + \
	36	+ (MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
	37	+
	38	+struct kprobe;
	39	+
	40	+/* Architecture specific copy of original instruction. */
	41	+struct arch_specific_insn {
	42	+ kprobe_opcode_t *insn;
	43	+};
	44	+
	45	+struct prev_kprobe {
	46	+ struct kprobe *kp;
	47	+ unsigned long status;
	48	+ unsigned long saved_pc;
	49	+};
	50	+
	51	+#define MAX_JPROBES_STACK_SIZE 128
	52	+#define MAX_JPROBES_STACK_ADDR \
	53	+ (((unsigned long)current_thread_info()) + THREAD_SIZE - 32 \
	54	+ - sizeof(struct pt_regs))
	55	+
	56	+#define MIN_JPROBES_STACK_SIZE(ADDR) \
	57	+ ((((ADDR) + MAX_JPROBES_STACK_SIZE) > MAX_JPROBES_STACK_ADDR) \
	58	+ ? MAX_JPROBES_STACK_ADDR - (ADDR) \
	59	+ : MAX_JPROBES_STACK_SIZE)
	60	+
	61	+/* per-cpu kprobe control block. */
	62	+struct kprobe_ctlblk {
	63	+ unsigned long kprobe_status;
	64	+ unsigned long kprobe_saved_pc;
	65	+ unsigned long jprobe_saved_sp;
	66	+ struct prev_kprobe prev_kprobe;
	67	+ struct pt_regs jprobe_saved_regs;
	68	+ char jprobes_stack[MAX_JPROBES_STACK_SIZE];
	69	+};
	70	+
	71	+extern tile_bundle_bits breakpoint2_insn;
	72	+extern tile_bundle_bits breakpoint_insn;
	73	+
	74	+void arch_remove_kprobe(struct kprobe *);
	75	+
	76	+extern int kprobe_exceptions_notify(struct notifier_block *self,
	77	+ unsigned long val, void *data);
	78	+
	79	+#endif /* _ASM_TILE_KPROBES_H */
...	...	@@ -33,6 +33,7 @@
33	33
34	34	#ifndef __ASSEMBLY__
35	35
	36	+#define regs_return_value(regs) ((regs)->regs[0])
36	37	#define instruction_pointer(regs) ((regs)->pc)
37	38	#define profile_pc(regs) instruction_pointer(regs)
38	39	#define user_stack_pointer(regs) ((regs)->sp)
...	...	@@ -61,6 +61,7 @@
61	61	#define TILE_BUNDLE_ALIGNMENT_IN_BYTES TILEGX_BUNDLE_ALIGNMENT_IN_BYTES
62	62	#define TILE_LOG2_BUNDLE_ALIGNMENT_IN_BYTES \
63	63	TILEGX_LOG2_BUNDLE_ALIGNMENT_IN_BYTES
	64	+#define TILE_BPT_BUNDLE TILEGX_BPT_BUNDLE
64	65
65	66	/* 64-bit pattern for a { bpt ; nop } bundle. */
66	67	#define TILEGX_BPT_BUNDLE 0x286a44ae51485000ULL
...	...	@@ -71,6 +71,7 @@
71	71	#define TILE_BUNDLE_ALIGNMENT_IN_BYTES TILEPRO_BUNDLE_ALIGNMENT_IN_BYTES
72	72	#define TILE_LOG2_BUNDLE_ALIGNMENT_IN_BYTES \
73	73	TILEPRO_LOG2_BUNDLE_ALIGNMENT_IN_BYTES
	74	+#define TILE_BPT_BUNDLE TILEPRO_BPT_BUNDLE
74	75
75	76	/* 64-bit pattern for a { bpt ; nop } bundle. */
76	77	#define TILEPRO_BPT_BUNDLE 0x400b3cae70166000ULL
...	...	@@ -28,6 +28,7 @@
28	28	obj-$(CONFIG_TILE_USB) += usb.o
29	29	obj-$(CONFIG_TILE_HVGLUE_TRACE) += hvglue_trace.o
30	30	obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o mcount_64.o
	31	+obj-$(CONFIG_KPROBES) += kprobes.o
31	32
32	33	obj-y += vdso/
	1	+/*
	2	+ * arch/tile/kernel/kprobes.c
	3	+ * Kprobes on TILE-Gx
	4	+ *
	5	+ * Some portions copied from the MIPS version.
	6	+ *
	7	+ * Copyright (C) IBM Corporation, 2002, 2004
	8	+ * Copyright 2006 Sony Corp.
	9	+ * Copyright 2010 Cavium Networks
	10	+ *
	11	+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
	12	+ *
	13	+ * This program is free software; you can redistribute it and/or
	14	+ * modify it under the terms of the GNU General Public License
	15	+ * as published by the Free Software Foundation, version 2.
	16	+ *
	17	+ * This program is distributed in the hope that it will be useful, but
	18	+ * WITHOUT ANY WARRANTY; without even the implied warranty of
	19	+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	20	+ * NON INFRINGEMENT. See the GNU General Public License for
	21	+ * more details.
	22	+ */
	23	+
	24	+#include <linux/kprobes.h>
	25	+#include <linux/kdebug.h>
	26	+#include <linux/module.h>
	27	+#include <linux/slab.h>
	28	+#include <linux/uaccess.h>
	29	+#include <asm/cacheflush.h>
	30	+
	31	+#include <arch/opcode.h>
	32	+
	33	+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
	34	+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
	35	+
	36	+tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
	37	+tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE \| DIE_SSTEPBP;
	38	+
	39	+/*
	40	+ * Check whether instruction is branch or jump, or if executing it
	41	+ * has different results depending on where it is executed (e.g. lnk).
	42	+ */
	43	+static int __kprobes insn_has_control(kprobe_opcode_t insn)
	44	+{
	45	+ if (get_Mode(insn) != 0) { /* Y-format bundle */
	46	+ if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 \|\|
	47	+ get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1)
	48	+ return 0;
	49	+
	50	+ switch (get_UnaryOpcodeExtension_Y1(insn)) {
	51	+ case JALRP_UNARY_OPCODE_Y1:
	52	+ case JALR_UNARY_OPCODE_Y1:
	53	+ case JRP_UNARY_OPCODE_Y1:
	54	+ case JR_UNARY_OPCODE_Y1:
	55	+ case LNK_UNARY_OPCODE_Y1:
	56	+ return 1;
	57	+ default:
	58	+ return 0;
	59	+ }
	60	+ }
	61	+
	62	+ switch (get_Opcode_X1(insn)) {
	63	+ case BRANCH_OPCODE_X1: /* branch instructions */
	64	+ case JUMP_OPCODE_X1: /* jump instructions: j and jal */
	65	+ return 1;
	66	+
	67	+ case RRR_0_OPCODE_X1: /* other jump instructions */
	68	+ if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1)
	69	+ return 0;
	70	+ switch (get_UnaryOpcodeExtension_X1(insn)) {
	71	+ case JALRP_UNARY_OPCODE_X1:
	72	+ case JALR_UNARY_OPCODE_X1:
	73	+ case JRP_UNARY_OPCODE_X1:
	74	+ case JR_UNARY_OPCODE_X1:
	75	+ case LNK_UNARY_OPCODE_X1:
	76	+ return 1;
	77	+ default:
	78	+ return 0;
	79	+ }
	80	+ default:
	81	+ return 0;
	82	+ }
	83	+}
	84	+
	85	+int __kprobes arch_prepare_kprobe(struct kprobe *p)
	86	+{
	87	+ unsigned long addr = (unsigned long)p->addr;
	88	+
	89	+ if (addr & (sizeof(kprobe_opcode_t) - 1))
	90	+ return -EINVAL;
	91	+
	92	+ if (insn_has_control(*p->addr)) {
	93	+ pr_notice("Kprobes for control instructions are not "
	94	+ "supported\n");
	95	+ return -EINVAL;
	96	+ }
	97	+
	98	+ /* insn: must be on special executable page on tile. */
	99	+ p->ainsn.insn = get_insn_slot();
	100	+ if (!p->ainsn.insn)
	101	+ return -ENOMEM;
	102	+
	103	+ /*
	104	+ * In the kprobe->ainsn.insn[] array we store the original
	105	+ * instruction at index zero and a break trap instruction at
	106	+ * index one.
	107	+ */
	108	+ memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
	109	+ p->ainsn.insn[1] = breakpoint2_insn;
	110	+ p->opcode = *p->addr;
	111	+
	112	+ return 0;
	113	+}
	114	+
	115	+void __kprobes arch_arm_kprobe(struct kprobe *p)
	116	+{
	117	+ unsigned long addr_wr;
	118	+
	119	+ /* Operate on writable kernel text mapping. */
	120	+ addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
	121	+
	122	+ if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
	123	+ sizeof(breakpoint_insn)))
	124	+ pr_err("%s: failed to enable kprobe\n", __func__);
	125	+
	126	+ smp_wmb();
	127	+ flush_insn_slot(p);
	128	+}
	129	+
	130	+void __kprobes arch_disarm_kprobe(struct kprobe *kp)
	131	+{
	132	+ unsigned long addr_wr;
	133	+
	134	+ /* Operate on writable kernel text mapping. */
	135	+ addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
	136	+
	137	+ if (probe_kernel_write((void *)addr_wr, &kp->opcode,
	138	+ sizeof(kp->opcode)))
	139	+ pr_err("%s: failed to enable kprobe\n", __func__);
	140	+
	141	+ smp_wmb();
	142	+ flush_insn_slot(kp);
	143	+}
	144	+
	145	+void __kprobes arch_remove_kprobe(struct kprobe *p)
	146	+{
	147	+ if (p->ainsn.insn) {
	148	+ free_insn_slot(p->ainsn.insn, 0);
	149	+ p->ainsn.insn = NULL;
	150	+ }
	151	+}
	152	+
	153	+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
	154	+{
	155	+ kcb->prev_kprobe.kp = kprobe_running();
	156	+ kcb->prev_kprobe.status = kcb->kprobe_status;
	157	+ kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
	158	+}
	159	+
	160	+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
	161	+{
	162	+ __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
	163	+ kcb->kprobe_status = kcb->prev_kprobe.status;
	164	+ kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
	165	+}
	166	+
	167	+static void __kprobes set_current_kprobe(struct kprobe p, struct pt_regs regs,
	168	+ struct kprobe_ctlblk *kcb)
	169	+{
	170	+ __this_cpu_write(current_kprobe, p);
	171	+ kcb->kprobe_saved_pc = regs->pc;
	172	+}
	173	+
	174	+static void __kprobes prepare_singlestep(struct kprobe p, struct pt_regs regs)
	175	+{
	176	+ /* Single step inline if the instruction is a break. */
	177	+ if (p->opcode == breakpoint_insn \|\|
	178	+ p->opcode == breakpoint2_insn)
	179	+ regs->pc = (unsigned long)p->addr;
	180	+ else
	181	+ regs->pc = (unsigned long)&p->ainsn.insn[0];
	182	+}
	183	+
	184	+static int __kprobes kprobe_handler(struct pt_regs *regs)
	185	+{
	186	+ struct kprobe *p;
	187	+ int ret = 0;
	188	+ kprobe_opcode_t *addr;
	189	+ struct kprobe_ctlblk *kcb;
	190	+
	191	+ addr = (kprobe_opcode_t *)regs->pc;
	192	+
	193	+ /*
	194	+ * We don't want to be preempted for the entire
	195	+ * duration of kprobe processing.
	196	+ */
	197	+ preempt_disable();
	198	+ kcb = get_kprobe_ctlblk();
	199	+
	200	+ /* Check we're not actually recursing. */
	201	+ if (kprobe_running()) {
	202	+ p = get_kprobe(addr);
	203	+ if (p) {
	204	+ if (kcb->kprobe_status == KPROBE_HIT_SS &&
	205	+ p->ainsn.insn[0] == breakpoint_insn) {
	206	+ goto no_kprobe;
	207	+ }
	208	+ /*
	209	+ * We have reentered the kprobe_handler(), since
	210	+ * another probe was hit while within the handler.
	211	+ * We here save the original kprobes variables and
	212	+ * just single step on the instruction of the new probe
	213	+ * without calling any user handlers.
	214	+ */
	215	+ save_previous_kprobe(kcb);
	216	+ set_current_kprobe(p, regs, kcb);
	217	+ kprobes_inc_nmissed_count(p);
	218	+ prepare_singlestep(p, regs);
	219	+ kcb->kprobe_status = KPROBE_REENTER;
	220	+ return 1;
	221	+ } else {
	222	+ if (*addr != breakpoint_insn) {
	223	+ /*
	224	+ * The breakpoint instruction was removed by
	225	+ * another cpu right after we hit, no further
	226	+ * handling of this interrupt is appropriate.
	227	+ */
	228	+ ret = 1;
	229	+ goto no_kprobe;
	230	+ }
	231	+ p = __this_cpu_read(current_kprobe);
	232	+ if (p->break_handler && p->break_handler(p, regs))
	233	+ goto ss_probe;
	234	+ }
	235	+ goto no_kprobe;
	236	+ }
	237	+
	238	+ p = get_kprobe(addr);
	239	+ if (!p) {
	240	+ if (*addr != breakpoint_insn) {
	241	+ /*
	242	+ * The breakpoint instruction was removed right
	243	+ * after we hit it. Another cpu has removed
	244	+ * either a probepoint or a debugger breakpoint
	245	+ * at this address. In either case, no further
	246	+ * handling of this interrupt is appropriate.
	247	+ */
	248	+ ret = 1;
	249	+ }
	250	+ /* Not one of ours: let kernel handle it. */
	251	+ goto no_kprobe;
	252	+ }
	253	+
	254	+ set_current_kprobe(p, regs, kcb);
	255	+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
	256	+
	257	+ if (p->pre_handler && p->pre_handler(p, regs)) {
	258	+ /* Handler has already set things up, so skip ss setup. */
	259	+ return 1;
	260	+ }
	261	+
	262	+ss_probe:
	263	+ prepare_singlestep(p, regs);
	264	+ kcb->kprobe_status = KPROBE_HIT_SS;
	265	+ return 1;
	266	+
	267	+no_kprobe:
	268	+ preempt_enable_no_resched();
	269	+ return ret;
	270	+}
	271	+
	272	+/*
	273	+ * Called after single-stepping. p->addr is the address of the
	274	+ * instruction that has been replaced by the breakpoint. To avoid the
	275	+ * SMP problems that can occur when we temporarily put back the
	276	+ * original opcode to single-step, we single-stepped a copy of the
	277	+ * instruction. The address of this copy is p->ainsn.insn.
	278	+ *
	279	+ * This function prepares to return from the post-single-step
	280	+ * breakpoint trap.
	281	+ */
	282	+static void __kprobes resume_execution(struct kprobe *p,
	283	+ struct pt_regs *regs,
	284	+ struct kprobe_ctlblk *kcb)
	285	+{
	286	+ unsigned long orig_pc = kcb->kprobe_saved_pc;
	287	+ regs->pc = orig_pc + 8;
	288	+}
	289	+
	290	+static inline int post_kprobe_handler(struct pt_regs *regs)
	291	+{
	292	+ struct kprobe *cur = kprobe_running();
	293	+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	294	+
	295	+ if (!cur)
	296	+ return 0;
	297	+
	298	+ if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
	299	+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
	300	+ cur->post_handler(cur, regs, 0);
	301	+ }
	302	+
	303	+ resume_execution(cur, regs, kcb);
	304	+
	305	+ /* Restore back the original saved kprobes variables and continue. */
	306	+ if (kcb->kprobe_status == KPROBE_REENTER) {
	307	+ restore_previous_kprobe(kcb);
	308	+ goto out;
	309	+ }
	310	+ reset_current_kprobe();
	311	+out:
	312	+ preempt_enable_no_resched();
	313	+
	314	+ return 1;
	315	+}
	316	+
	317	+static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
	318	+{
	319	+ struct kprobe *cur = kprobe_running();
	320	+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	321	+
	322	+ if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
	323	+ return 1;
	324	+
	325	+ if (kcb->kprobe_status & KPROBE_HIT_SS) {
	326	+ /*
	327	+ * We are here because the instruction being single
	328	+ * stepped caused a page fault. We reset the current
	329	+ * kprobe and the ip points back to the probe address
	330	+ * and allow the page fault handler to continue as a
	331	+ * normal page fault.
	332	+ */
	333	+ resume_execution(cur, regs, kcb);
	334	+ reset_current_kprobe();
	335	+ preempt_enable_no_resched();
	336	+ }
	337	+ return 0;
	338	+}
	339	+
	340	+/*
	341	+ * Wrapper routine for handling exceptions.
	342	+ */
	343	+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
	344	+ unsigned long val, void *data)
	345	+{
	346	+ struct die_args args = (struct die_args )data;
	347	+ int ret = NOTIFY_DONE;
	348	+
	349	+ switch (val) {
	350	+ case DIE_BREAK:
	351	+ if (kprobe_handler(args->regs))
	352	+ ret = NOTIFY_STOP;
	353	+ break;
	354	+ case DIE_SSTEPBP:
	355	+ if (post_kprobe_handler(args->regs))
	356	+ ret = NOTIFY_STOP;
	357	+ break;
	358	+ case DIE_PAGE_FAULT:
	359	+ /* kprobe_running() needs smp_processor_id(). */
	360	+ preempt_disable();
	361	+
	362	+ if (kprobe_running()
	363	+ && kprobe_fault_handler(args->regs, args->trapnr))
	364	+ ret = NOTIFY_STOP;
	365	+ preempt_enable();
	366	+ break;
	367	+ default:
	368	+ break;
	369	+ }
	370	+ return ret;
	371	+}
	372	+
	373	+int __kprobes setjmp_pre_handler(struct kprobe p, struct pt_regs regs)
	374	+{
	375	+ struct jprobe *jp = container_of(p, struct jprobe, kp);
	376	+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	377	+
	378	+ kcb->jprobe_saved_regs = *regs;
	379	+ kcb->jprobe_saved_sp = regs->sp;
	380	+
	381	+ memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
	382	+ MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
	383	+
	384	+ regs->pc = (unsigned long)(jp->entry);
	385	+
	386	+ return 1;
	387	+}
	388	+
	389	+/* Defined in the inline asm below. */
	390	+void jprobe_return_end(void);
	391	+
	392	+void __kprobes jprobe_return(void)
	393	+{
	394	+ asm volatile(
	395	+ "bpt\n\t"
	396	+ ".globl jprobe_return_end\n"
	397	+ "jprobe_return_end:\n");
	398	+}
	399	+
	400	+int __kprobes longjmp_break_handler(struct kprobe p, struct pt_regs regs)
	401	+{
	402	+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
	403	+
	404	+ if (regs->pc >= (unsigned long)jprobe_return &&
	405	+ regs->pc <= (unsigned long)jprobe_return_end) {
	406	+ *regs = kcb->jprobe_saved_regs;
	407	+ memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
	408	+ MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
	409	+ preempt_enable_no_resched();
	410	+
	411	+ return 1;
	412	+ }
	413	+ return 0;
	414	+}
	415	+
	416	+/*
	417	+ * Function return probe trampoline:
	418	+ * - init_kprobes() establishes a probepoint here
	419	+ * - When the probed function returns, this probe causes the
	420	+ * handlers to fire
	421	+ */
	422	+static void __used kretprobe_trampoline_holder(void)
	423	+{
	424	+ asm volatile(
	425	+ "nop\n\t"
	426	+ ".global kretprobe_trampoline\n"
	427	+ "kretprobe_trampoline:\n\t"
	428	+ "nop\n\t"
	429	+ : : : "memory");
	430	+}
	431	+
	432	+void kretprobe_trampoline(void);
	433	+
	434	+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
	435	+ struct pt_regs *regs)
	436	+{
	437	+ ri->ret_addr = (kprobe_opcode_t *) regs->lr;
	438	+
	439	+ /* Replace the return addr with trampoline addr */
	440	+ regs->lr = (unsigned long)kretprobe_trampoline;
	441	+}
	442	+
	443	+/*
	444	+ * Called when the probe at kretprobe trampoline is hit.
	445	+ */
	446	+static int __kprobes trampoline_probe_handler(struct kprobe *p,
	447	+ struct pt_regs *regs)
	448	+{
	449	+ struct kretprobe_instance *ri = NULL;
	450	+ struct hlist_head *head, empty_rp;
	451	+ struct hlist_node *tmp;
	452	+ unsigned long flags, orig_ret_address = 0;
	453	+ unsigned long trampoline_address = (unsigned long)kretprobe_trampoline;
	454	+
	455	+ INIT_HLIST_HEAD(&empty_rp);
	456	+ kretprobe_hash_lock(current, &head, &flags);
	457	+
	458	+ /*
	459	+ * It is possible to have multiple instances associated with a given
	460	+ * task either because multiple functions in the call path have
	461	+ * a return probe installed on them, and/or more than one return
	462	+ * return probe was registered for a target function.
	463	+ *
	464	+ * We can handle this because:
	465	+ * - instances are always inserted at the head of the list
	466	+ * - when multiple return probes are registered for the same
	467	+ * function, the first instance's ret_addr will point to the
	468	+ * real return address, and all the rest will point to
	469	+ * kretprobe_trampoline
	470	+ */
	471	+ hlist_for_each_entry_safe(ri, tmp, head, hlist) {
	472	+ if (ri->task != current)
	473	+ /* another task is sharing our hash bucket */
	474	+ continue;
	475	+
	476	+ if (ri->rp && ri->rp->handler)
	477	+ ri->rp->handler(ri, regs);
	478	+
	479	+ orig_ret_address = (unsigned long)ri->ret_addr;
	480	+ recycle_rp_inst(ri, &empty_rp);
	481	+
	482	+ if (orig_ret_address != trampoline_address) {
	483	+ /*
	484	+ * This is the real return address. Any other
	485	+ * instances associated with this task are for
	486	+ * other calls deeper on the call stack
	487	+ */
	488	+ break;
	489	+ }
	490	+ }
	491	+
	492	+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
	493	+ instruction_pointer(regs) = orig_ret_address;
	494	+
	495	+ reset_current_kprobe();
	496	+ kretprobe_hash_unlock(current, &flags);
	497	+ preempt_enable_no_resched();
	498	+
	499	+ hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
	500	+ hlist_del(&ri->hlist);
	501	+ kfree(ri);
	502	+ }
	503	+ /*
	504	+ * By returning a non-zero value, we are telling
	505	+ * kprobe_handler() that we don't want the post_handler
	506	+ * to run (and have re-enabled preemption)
	507	+ */
	508	+ return 1;
	509	+}
	510	+
	511	+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
	512	+{
	513	+ if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
	514	+ return 1;
	515	+
	516	+ return 0;
	517	+}
	518	+
	519	+static struct kprobe trampoline_p = {
	520	+ .addr = (kprobe_opcode_t *)kretprobe_trampoline,
	521	+ .pre_handler = trampoline_probe_handler
	522	+};
	523	+
	524	+int __init arch_init_kprobes(void)
	525	+{
	526	+ register_kprobe(&trampoline_p);
	527	+ return 0;
	528	+}
...	...	@@ -20,6 +20,7 @@
20	20	#include <linux/irq.h>
21	21	#include <linux/module.h>
22	22	#include <asm/cacheflush.h>
	23	+#include <asm/homecache.h>
23	24
24	25	HV_Topology smp_topology __write_once;
25	26	EXPORT_SYMBOL(smp_topology);
...	...	@@ -167,9 +168,16 @@
167	168	void flush_icache_range(unsigned long start, unsigned long end)
168	169	{
169	170	struct ipi_flush flush = { start, end };
170		- preempt_disable();
171		- on_each_cpu(ipi_flush_icache_range, &flush, 1);
172		- preempt_enable();
	171	+
	172	+ /* If invoked with irqs disabled, we can not issue IPIs. */
	173	+ if (irqs_disabled())
	174	+ flush_remote(0, HV_FLUSH_EVICT_L1I, NULL, 0, 0, 0,
	175	+ NULL, NULL, 0);
	176	+ else {
	177	+ preempt_disable();
	178	+ on_each_cpu(ipi_flush_icache_range, &flush, 1);
	179	+ preempt_enable();
	180	+ }
173	181	}
174	182
175	183