Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf changes from Ingo Molnar:
 "There are lots of improvements, the biggest changes are:

  Main kernel side changes:

   - Improve uprobes performance by adding 'pre-filtering' support, by
     Oleg Nesterov.

   - Make some POWER7 events available in sysfs, equivalent to what was
     done on x86, from Sukadev Bhattiprolu.

   - tracing updates by Steve Rostedt - mostly misc fixes and smaller
     improvements.

   - Use perf/event tracing to report PCI Express advanced errors, by
     Tony Luck.

   - Enable northbridge performance counters on AMD family 15h, by Jacob
     Shin.

   - This tracing commit:

        tracing: Remove the extra 4 bytes of padding in events

     changes the ABI.  All involved parties (PowerTop in particular)
     seem to agree that it's safe to do now with the introduction of
     libtraceevent, but the devil is in the details ...

  Main tooling side changes:

   - Add 'event group view', from Namyung Kim:

     To use it, 'perf record' should group events when recording.  And
     then perf report parses the saved group relation from file header
     and prints them together if --group option is provided.  You can
     use the 'perf evlist' command to see event group information:

        $ perf record -e '{ref-cycles,cycles}' noploop 1
        [ perf record: Woken up 2 times to write data ]
        [ perf record: Captured and wrote 0.385 MB perf.data (~16807 samples) ]

        $ perf evlist --group
        {ref-cycles,cycles}

     With this example, default perf report will show you each event
     separately.

     You can use --group option to enable event group view:

        $ perf report --group
        ...
        # group: {ref-cycles,cycles}
        # ========
        # Samples: 7K of event 'anon group { ref-cycles, cycles }'
        # Event count (approx.): 6876107743
        #
        #         Overhead  Command      Shared Object                      Symbol
        # ................  .......  .................  ..........................
            99.84%  99.76%  noploop  noploop            [.] main
             0.07%   0.00%  noploop  ld-2.15.so         [.] strcmp
             0.03%   0.00%  noploop  [kernel.kallsyms]  [k] timerqueue_del
             0.03%   0.03%  noploop  [kernel.kallsyms]  [k] sched_clock_cpu
             0.02%   0.00%  noploop  [kernel.kallsyms]  [k] account_user_time
             0.01%   0.00%  noploop  [kernel.kallsyms]  [k] __alloc_pages_nodemask
             0.00%   0.00%  noploop  [kernel.kallsyms]  [k] native_write_msr_safe
             0.00%   0.11%  noploop  [kernel.kallsyms]  [k] _raw_spin_lock
             0.00%   0.06%  noploop  [kernel.kallsyms]  [k] find_get_page
             0.00%   0.02%  noploop  [kernel.kallsyms]  [k] rcu_check_callbacks
             0.00%   0.02%  noploop  [kernel.kallsyms]  [k] __current_kernel_time

     As you can see the Overhead column now contains both of ref-cycles
     and cycles and header line shows group information also - 'anon
     group { ref-cycles, cycles }'.  The output is sorted by period of
     group leader first.

   - Initial GTK+ annotate browser, from Namhyung Kim.

   - Add option for runtime switching perf data file in perf report,
     just press 's' and a menu with the valid files found in the current
     directory will be presented, from Feng Tang.

   - Add support to display whole group data for raw columns, from Jiri
     Olsa.

   - Add per processor socket count aggregation in perf stat, from
     Stephane Eranian.

   - Add interval printing in 'perf stat', from Stephane Eranian.

   - 'perf test' improvements

   - Add support for wildcards in tracepoint system name, from Jiri
     Olsa.

   - Add anonymous huge page recognition, from Joshua Zhu.

   - perf build-id cache now can show DSOs present in a perf.data file
     that are not in the cache, to integrate with build-id servers being
     put in place by organizations such as Fedora.

   - perf top now shares more of the evsel config/creation routines with
     'record', paving the way for further integration like 'top'
     snapshots, etc.

   - perf top now supports DWARF callchains.

   - Fix mmap limitations on 32-bit, fix from David Miller.

   - 'perf bench numa mem' NUMA performance measurement suite

   - ... and lots of fixes, performance improvements, cleanups and other
     improvements I failed to list - see the shortlog and git log for
     details."

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (270 commits)
  perf/x86/amd: Enable northbridge performance counters on AMD family 15h
  perf/hwbp: Fix cleanup in case of kzalloc failure
  perf tools: Fix build with bison 2.3 and older.
  perf tools: Limit unwind support to x86 archs
  perf annotate: Make it to be able to skip unannotatable symbols
  perf gtk/annotate: Fail early if it can't annotate
  perf gtk/annotate: Show source lines with gray color
  perf gtk/annotate: Support multiple event annotation
  perf ui/gtk: Implement basic GTK2 annotation browser
  perf annotate: Fix warning message on a missing vmlinux
  perf buildid-cache: Add --update option
  uprobes/perf: Avoid uprobe_apply() whenever possible
  uprobes/perf: Teach trace_uprobe/perf code to use UPROBE_HANDLER_REMOVE
  uprobes/perf: Teach trace_uprobe/perf code to pre-filter
  uprobes/perf: Teach trace_uprobe/perf code to track the active perf_event's
  uprobes: Introduce uprobe_apply()
  perf: Introduce hw_perf_event->tp_target and ->tp_list
  uprobes/perf: Always increment trace_uprobe->nhit
  uprobes/tracing: Kill uprobe_trace_consumer, embed uprobe_consumer into trace_uprobe
  uprobes/tracing: Introduce is_trace_uprobe_enabled()
  ...

1 files changed, 1064 insertions, 0 deletions

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
new file mode 100644
index 000000000000..e124554598ee
--- /dev/null
+++ b/arch/x86/kernel/kprobes/core.c
@@ -0,0 +1,1064 @@
+/*
+ *  Kernel Probes (KProbes)
+ *
+ * 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 (C) IBM Corporation, 2002, 2004
+ *
+ * 2002-Oct	Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
+ *		Probes initial implementation ( includes contributions from
+ *		Rusty Russell).
+ * 2004-July	Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
+ *		interface to access function arguments.
+ * 2004-Oct	Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
+ *		<prasanna@in.ibm.com> adapted for x86_64 from i386.
+ * 2005-Mar	Roland McGrath <roland@redhat.com>
+ *		Fixed to handle %rip-relative addressing mode correctly.
+ * 2005-May	Hien Nguyen <hien@us.ibm.com>, Jim Keniston
+ *		<jkenisto@us.ibm.com> and Prasanna S Panchamukhi
+ *		<prasanna@in.ibm.com> added function-return probes.
+ * 2005-May	Rusty Lynch <rusty.lynch@intel.com>
+ *		Added function return probes functionality
+ * 2006-Feb	Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added
+ *		kprobe-booster and kretprobe-booster for i386.
+ * 2007-Dec	Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster
+ *		and kretprobe-booster for x86-64
+ * 2007-Dec	Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven
+ *		<arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
+ *		unified x86 kprobes code.
+ */
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/hardirq.h>
+#include <linux/preempt.h>
+#include <linux/module.h>
+#include <linux/kdebug.h>
+#include <linux/kallsyms.h>
+#include <linux/ftrace.h>
+
+#include <asm/cacheflush.h>
+#include <asm/desc.h>
+#include <asm/pgtable.h>
+#include <asm/uaccess.h>
+#include <asm/alternative.h>
+#include <asm/insn.h>
+#include <asm/debugreg.h>
+
+#include "common.h"
+
+void jprobe_return_end(void);
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))
+
+#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
+	(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \
+	  (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) |   \
+	  (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) |   \
+	  (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf))    \
+	 << (row % 32))
+	/*
+	 * Undefined/reserved opcodes, conditional jump, Opcode Extension
+	 * Groups, and some special opcodes can not boost.
+	 * This is non-const and volatile to keep gcc from statically
+	 * optimizing it out, as variable_test_bit makes gcc think only
+	 * *(unsigned long*) is used.
+	 */
+static volatile u32 twobyte_is_boostable[256 / 32] = {
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f          */
+	/*      ----------------------------------------------          */
+	W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */
+	W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */
+	W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */
+	W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
+	W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
+	W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */
+	W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */
+	W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */
+	W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */
+	W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+	W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */
+	W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */
+	W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */
+	W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */
+	W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */
+	W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0)   /* f0 */
+	/*      -----------------------------------------------         */
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f          */
+};
+#undef W
+
+struct kretprobe_blackpoint kretprobe_blacklist[] = {
+	{"__switch_to", }, /* This function switches only current task, but
+			      doesn't switch kernel stack.*/
+	{NULL, NULL}	/* Terminator */
+};
+
+const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
+
+static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op)
+{
+	struct __arch_relative_insn {
+		u8 op;
+		s32 raddr;
+	} __packed *insn;
+
+	insn = (struct __arch_relative_insn *)from;
+	insn->raddr = (s32)((long)(to) - ((long)(from) + 5));
+	insn->op = op;
+}
+
+/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
+void __kprobes synthesize_reljump(void *from, void *to)
+{
+	__synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE);
+}
+
+/* Insert a call instruction at address 'from', which calls address 'to'.*/
+void __kprobes synthesize_relcall(void *from, void *to)
+{
+	__synthesize_relative_insn(from, to, RELATIVECALL_OPCODE);
+}
+
+/*
+ * Skip the prefixes of the instruction.
+ */
+static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn)
+{
+	insn_attr_t attr;
+
+	attr = inat_get_opcode_attribute((insn_byte_t)*insn);
+	while (inat_is_legacy_prefix(attr)) {
+		insn++;
+		attr = inat_get_opcode_attribute((insn_byte_t)*insn);
+	}
+#ifdef CONFIG_X86_64
+	if (inat_is_rex_prefix(attr))
+		insn++;
+#endif
+	return insn;
+}
+
+/*
+ * Returns non-zero if opcode is boostable.
+ * RIP relative instructions are adjusted at copying time in 64 bits mode
+ */
+int __kprobes can_boost(kprobe_opcode_t *opcodes)
+{
+	kprobe_opcode_t opcode;
+	kprobe_opcode_t *orig_opcodes = opcodes;
+
+	if (search_exception_tables((unsigned long)opcodes))
+		return 0;	/* Page fault may occur on this address. */
+
+retry:
+	if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
+		return 0;
+	opcode = *(opcodes++);
+
+	/* 2nd-byte opcode */
+	if (opcode == 0x0f) {
+		if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
+			return 0;
+		return test_bit(*opcodes,
+				(unsigned long *)twobyte_is_boostable);
+	}
+
+	switch (opcode & 0xf0) {
+#ifdef CONFIG_X86_64
+	case 0x40:
+		goto retry; /* REX prefix is boostable */
+#endif
+	case 0x60:
+		if (0x63 < opcode && opcode < 0x67)
+			goto retry; /* prefixes */
+		/* can't boost Address-size override and bound */
+		return (opcode != 0x62 && opcode != 0x67);
+	case 0x70:
+		return 0; /* can't boost conditional jump */
+	case 0xc0:
+		/* can't boost software-interruptions */
+		return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
+	case 0xd0:
+		/* can boost AA* and XLAT */
+		return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
+	case 0xe0:
+		/* can boost in/out and absolute jmps */
+		return ((opcode & 0x04) || opcode == 0xea);
+	case 0xf0:
+		if ((opcode & 0x0c) == 0 && opcode != 0xf1)
+			goto retry; /* lock/rep(ne) prefix */
+		/* clear and set flags are boostable */
+		return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
+	default:
+		/* segment override prefixes are boostable */
+		if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
+			goto retry; /* prefixes */
+		/* CS override prefix and call are not boostable */
+		return (opcode != 0x2e && opcode != 0x9a);
+	}
+}
+
+static unsigned long
+__recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
+{
+	struct kprobe *kp;
+
+	kp = get_kprobe((void *)addr);
+	/* There is no probe, return original address */
+	if (!kp)
+		return addr;
+
+	/*
+	 *  Basically, kp->ainsn.insn has an original instruction.
+	 *  However, RIP-relative instruction can not do single-stepping
+	 *  at different place, __copy_instruction() tweaks the displacement of
+	 *  that instruction. In that case, we can't recover the instruction
+	 *  from the kp->ainsn.insn.
+	 *
+	 *  On the other hand, kp->opcode has a copy of the first byte of
+	 *  the probed instruction, which is overwritten by int3. And
+	 *  the instruction at kp->addr is not modified by kprobes except
+	 *  for the first byte, we can recover the original instruction
+	 *  from it and kp->opcode.
+	 */
+	memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+	buf[0] = kp->opcode;
+	return (unsigned long)buf;
+}
+
+/*
+ * Recover the probed instruction at addr for further analysis.
+ * Caller must lock kprobes by kprobe_mutex, or disable preemption
+ * for preventing to release referencing kprobes.
+ */
+unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
+{
+	unsigned long __addr;
+
+	__addr = __recover_optprobed_insn(buf, addr);
+	if (__addr != addr)
+		return __addr;
+
+	return __recover_probed_insn(buf, addr);
+}
+
+/* Check if paddr is at an instruction boundary */
+static int __kprobes can_probe(unsigned long paddr)
+{
+	unsigned long addr, __addr, offset = 0;
+	struct insn insn;
+	kprobe_opcode_t buf[MAX_INSN_SIZE];
+
+	if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))
+		return 0;
+
+	/* Decode instructions */
+	addr = paddr - offset;
+	while (addr < paddr) {
+		/*
+		 * Check if the instruction has been modified by another
+		 * kprobe, in which case we replace the breakpoint by the
+		 * original instruction in our buffer.
+		 * Also, jump optimization will change the breakpoint to
+		 * relative-jump. Since the relative-jump itself is
+		 * normally used, we just go through if there is no kprobe.
+		 */
+		__addr = recover_probed_instruction(buf, addr);
+		kernel_insn_init(&insn, (void *)__addr);
+		insn_get_length(&insn);
+
+		/*
+		 * Another debugging subsystem might insert this breakpoint.
+		 * In that case, we can't recover it.
+		 */
+		if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
+			return 0;
+		addr += insn.length;
+	}
+
+	return (addr == paddr);
+}
+
+/*
+ * Returns non-zero if opcode modifies the interrupt flag.
+ */
+static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
+{
+	/* Skip prefixes */
+	insn = skip_prefixes(insn);
+
+	switch (*insn) {
+	case 0xfa:		/* cli */
+	case 0xfb:		/* sti */
+	case 0xcf:		/* iret/iretd */
+	case 0x9d:		/* popf/popfd */
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * Copy an instruction and adjust the displacement if the instruction
+ * uses the %rip-relative addressing mode.
+ * If it does, Return the address of the 32-bit displacement word.
+ * If not, return null.
+ * Only applicable to 64-bit x86.
+ */
+int __kprobes __copy_instruction(u8 *dest, u8 *src)
+{
+	struct insn insn;
+	kprobe_opcode_t buf[MAX_INSN_SIZE];
+
+	kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, (unsigned long)src));
+	insn_get_length(&insn);
+	/* Another subsystem puts a breakpoint, failed to recover */
+	if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
+		return 0;
+	memcpy(dest, insn.kaddr, insn.length);
+
+#ifdef CONFIG_X86_64
+	if (insn_rip_relative(&insn)) {
+		s64 newdisp;
+		u8 *disp;
+		kernel_insn_init(&insn, dest);
+		insn_get_displacement(&insn);
+		/*
+		 * The copied instruction uses the %rip-relative addressing
+		 * mode.  Adjust the displacement for the difference between
+		 * the original location of this instruction and the location
+		 * of the copy that will actually be run.  The tricky bit here
+		 * is making sure that the sign extension happens correctly in
+		 * this calculation, since we need a signed 32-bit result to
+		 * be sign-extended to 64 bits when it's added to the %rip
+		 * value and yield the same 64-bit result that the sign-
+		 * extension of the original signed 32-bit displacement would
+		 * have given.
+		 */
+		newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest;
+		BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check.  */
+		disp = (u8 *) dest + insn_offset_displacement(&insn);
+		*(s32 *) disp = (s32) newdisp;
+	}
+#endif
+	return insn.length;
+}
+
+static void __kprobes arch_copy_kprobe(struct kprobe *p)
+{
+	/* Copy an instruction with recovering if other optprobe modifies it.*/
+	__copy_instruction(p->ainsn.insn, p->addr);
+
+	/*
+	 * __copy_instruction can modify the displacement of the instruction,
+	 * but it doesn't affect boostable check.
+	 */
+	if (can_boost(p->ainsn.insn))
+		p->ainsn.boostable = 0;
+	else
+		p->ainsn.boostable = -1;
+
+	/* Also, displacement change doesn't affect the first byte */
+	p->opcode = p->ainsn.insn[0];
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+	if (alternatives_text_reserved(p->addr, p->addr))
+		return -EINVAL;
+
+	if (!can_probe((unsigned long)p->addr))
+		return -EILSEQ;
+	/* insn: must be on special executable page on x86. */
+	p->ainsn.insn = get_insn_slot();
+	if (!p->ainsn.insn)
+		return -ENOMEM;
+	arch_copy_kprobe(p);
+	return 0;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+	text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+	text_poke(p->addr, &p->opcode, 1);
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+	if (p->ainsn.insn) {
+		free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
+		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.old_flags = kcb->kprobe_old_flags;
+	kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags;
+}
+
+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_old_flags = kcb->prev_kprobe.old_flags;
+	kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags;
+}
+
+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_flags = kcb->kprobe_old_flags
+		= (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF));
+	if (is_IF_modifier(p->ainsn.insn))
+		kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF;
+}
+
+static void __kprobes clear_btf(void)
+{
+	if (test_thread_flag(TIF_BLOCKSTEP)) {
+		unsigned long debugctl = get_debugctlmsr();
+
+		debugctl &= ~DEBUGCTLMSR_BTF;
+		update_debugctlmsr(debugctl);
+	}
+}
+
+static void __kprobes restore_btf(void)
+{
+	if (test_thread_flag(TIF_BLOCKSTEP)) {
+		unsigned long debugctl = get_debugctlmsr();
+
+		debugctl |= DEBUGCTLMSR_BTF;
+		update_debugctlmsr(debugctl);
+	}
+}
+
+void __kprobes
+arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
+{
+	unsigned long *sara = stack_addr(regs);
+
+	ri->ret_addr = (kprobe_opcode_t *) *sara;
+
+	/* Replace the return addr with trampoline addr */
+	*sara = (unsigned long) &kretprobe_trampoline;
+}
+
+static void __kprobes
+setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb, int reenter)
+{
+	if (setup_detour_execution(p, regs, reenter))
+		return;
+
+#if !defined(CONFIG_PREEMPT)
+	if (p->ainsn.boostable == 1 && !p->post_handler) {
+		/* Boost up -- we can execute copied instructions directly */
+		if (!reenter)
+			reset_current_kprobe();
+		/*
+		 * Reentering boosted probe doesn't reset current_kprobe,
+		 * nor set current_kprobe, because it doesn't use single
+		 * stepping.
+		 */
+		regs->ip = (unsigned long)p->ainsn.insn;
+		preempt_enable_no_resched();
+		return;
+	}
+#endif
+	if (reenter) {
+		save_previous_kprobe(kcb);
+		set_current_kprobe(p, regs, kcb);
+		kcb->kprobe_status = KPROBE_REENTER;
+	} else
+		kcb->kprobe_status = KPROBE_HIT_SS;
+	/* Prepare real single stepping */
+	clear_btf();
+	regs->flags |= X86_EFLAGS_TF;
+	regs->flags &= ~X86_EFLAGS_IF;
+	/* single step inline if the instruction is an int3 */
+	if (p->opcode == BREAKPOINT_INSTRUCTION)
+		regs->ip = (unsigned long)p->addr;
+	else
+		regs->ip = (unsigned long)p->ainsn.insn;
+}
+
+/*
+ * We have reentered the kprobe_handler(), since another probe was hit while
+ * within the handler. We save the original kprobes variables and just single
+ * step on the instruction of the new probe without calling any user handlers.
+ */
+static int __kprobes
+reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
+{
+	switch (kcb->kprobe_status) {
+	case KPROBE_HIT_SSDONE:
+	case KPROBE_HIT_ACTIVE:
+		kprobes_inc_nmissed_count(p);
+		setup_singlestep(p, regs, kcb, 1);
+		break;
+	case KPROBE_HIT_SS:
+		/* A probe has been hit in the codepath leading up to, or just
+		 * after, single-stepping of a probed instruction. This entire
+		 * codepath should strictly reside in .kprobes.text section.
+		 * Raise a BUG or we'll continue in an endless reentering loop
+		 * and eventually a stack overflow.
+		 */
+		printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n",
+		       p->addr);
+		dump_kprobe(p);
+		BUG();
+	default:
+		/* impossible cases */
+		WARN_ON(1);
+		return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * Interrupts are disabled on entry as trap3 is an interrupt gate and they
+ * remain disabled throughout this function.
+ */
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+	kprobe_opcode_t *addr;
+	struct kprobe *p;
+	struct kprobe_ctlblk *kcb;
+
+	addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
+	/*
+	 * We don't want to be preempted for the entire
+	 * duration of kprobe processing. We conditionally
+	 * re-enable preemption at the end of this function,
+	 * and also in reenter_kprobe() and setup_singlestep().
+	 */
+	preempt_disable();
+
+	kcb = get_kprobe_ctlblk();
+	p = get_kprobe(addr);
+
+	if (p) {
+		if (kprobe_running()) {
+			if (reenter_kprobe(p, regs, kcb))
+				return 1;
+		} else {
+			set_current_kprobe(p, regs, kcb);
+			kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+			/*
+			 * If we have no pre-handler or it returned 0, we
+			 * continue with normal processing.  If we have a
+			 * pre-handler and it returned non-zero, it prepped
+			 * for calling the break_handler below on re-entry
+			 * for jprobe processing, so get out doing nothing
+			 * more here.
+			 */
+			if (!p->pre_handler || !p->pre_handler(p, regs))
+				setup_singlestep(p, regs, kcb, 0);
+			return 1;
+		}
+	} else if (*addr != BREAKPOINT_INSTRUCTION) {
+		/*
+		 * 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.
+		 * Back up over the (now missing) int3 and run
+		 * the original instruction.
+		 */
+		regs->ip = (unsigned long)addr;
+		preempt_enable_no_resched();
+		return 1;
+	} else if (kprobe_running()) {
+		p = __this_cpu_read(current_kprobe);
+		if (p->break_handler && p->break_handler(p, regs)) {
+			if (!skip_singlestep(p, regs, kcb))
+				setup_singlestep(p, regs, kcb, 0);
+			return 1;
+		}
+	} /* else: not a kprobe fault; let the kernel handle it */
+
+	preempt_enable_no_resched();
+	return 0;
+}
+
+/*
+ * When a retprobed function returns, this code saves registers and
+ * calls trampoline_handler() runs, which calls the kretprobe's handler.
+ */
+static void __used __kprobes kretprobe_trampoline_holder(void)
+{
+	asm volatile (
+			".global kretprobe_trampoline\n"
+			"kretprobe_trampoline: \n"
+#ifdef CONFIG_X86_64
+			/* We don't bother saving the ss register */
+			"	pushq %rsp\n"
+			"	pushfq\n"
+			SAVE_REGS_STRING
+			"	movq %rsp, %rdi\n"
+			"	call trampoline_handler\n"
+			/* Replace saved sp with true return address. */
+			"	movq %rax, 152(%rsp)\n"
+			RESTORE_REGS_STRING
+			"	popfq\n"
+#else
+			"	pushf\n"
+			SAVE_REGS_STRING
+			"	movl %esp, %eax\n"
+			"	call trampoline_handler\n"
+			/* Move flags to cs */
+			"	movl 56(%esp), %edx\n"
+			"	movl %edx, 52(%esp)\n"
+			/* Replace saved flags with true return address. */
+			"	movl %eax, 56(%esp)\n"
+			RESTORE_REGS_STRING
+			"	popf\n"
+#endif
+			"	ret\n");
+}
+
+/*
+ * Called from kretprobe_trampoline
+ */
+static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
+{
+	struct kretprobe_instance *ri = NULL;
+	struct hlist_head *head, empty_rp;
+	struct hlist_node *node, *tmp;
+	unsigned long flags, orig_ret_address = 0;
+	unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+	kprobe_opcode_t *correct_ret_addr = NULL;
+
+	INIT_HLIST_HEAD(&empty_rp);
+	kretprobe_hash_lock(current, &head, &flags);
+	/* fixup registers */
+#ifdef CONFIG_X86_64
+	regs->cs = __KERNEL_CS;
+#else
+	regs->cs = __KERNEL_CS | get_kernel_rpl();
+	regs->gs = 0;
+#endif
+	regs->ip = trampoline_address;
+	regs->orig_ax = ~0UL;
+
+	/*
+	 * It is possible to have multiple instances associated with a given
+	 * task either because multiple functions in the call path have
+	 * return probes installed on them, and/or more than one
+	 * return probe was registered for a target function.
+	 *
+	 * We can handle this because:
+	 *     - instances are always pushed into the head of the list
+	 *     - when multiple return probes are registered for the same
+	 *	 function, the (chronologically) first instance's ret_addr
+	 *	 will be the real return address, and all the rest will
+	 *	 point to kretprobe_trampoline.
+	 */
+	hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+		if (ri->task != current)
+			/* another task is sharing our hash bucket */
+			continue;
+
+		orig_ret_address = (unsigned long)ri->ret_addr;
+
+		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);
+
+	correct_ret_addr = ri->ret_addr;
+	hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+		if (ri->task != current)
+			/* another task is sharing our hash bucket */
+			continue;
+
+		orig_ret_address = (unsigned long)ri->ret_addr;
+		if (ri->rp && ri->rp->handler) {
+			__this_cpu_write(current_kprobe, &ri->rp->kp);
+			get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
+			ri->ret_addr = correct_ret_addr;
+			ri->rp->handler(ri, regs);
+			__this_cpu_write(current_kprobe, NULL);
+		}
+
+		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_hash_unlock(current, &flags);
+
+	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
+	return (void *)orig_ret_address;
+}
+
+/*
+ * Called after single-stepping.  p->addr is the address of the
+ * instruction whose first byte has been replaced by the "int 3"
+ * instruction.  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
+ * interrupt.  We have to fix up the stack as follows:
+ *
+ * 0) Except in the case of absolute or indirect jump or call instructions,
+ * the new ip is relative to the copied instruction.  We need to make
+ * it relative to the original instruction.
+ *
+ * 1) If the single-stepped instruction was pushfl, then the TF and IF
+ * flags are set in the just-pushed flags, and may need to be cleared.
+ *
+ * 2) If the single-stepped instruction was a call, the return address
+ * that is atop the stack is the address following the copied instruction.
+ * We need to make it the address following the original instruction.
+ *
+ * If this is the first time we've single-stepped the instruction at
+ * this probepoint, and the instruction is boostable, boost it: add a
+ * jump instruction after the copied instruction, that jumps to the next
+ * instruction after the probepoint.
+ */
+static void __kprobes
+resume_execution(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
+{
+	unsigned long *tos = stack_addr(regs);
+	unsigned long copy_ip = (unsigned long)p->ainsn.insn;
+	unsigned long orig_ip = (unsigned long)p->addr;
+	kprobe_opcode_t *insn = p->ainsn.insn;
+
+	/* Skip prefixes */
+	insn = skip_prefixes(insn);
+
+	regs->flags &= ~X86_EFLAGS_TF;
+	switch (*insn) {
+	case 0x9c:	/* pushfl */
+		*tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF);
+		*tos |= kcb->kprobe_old_flags;
+		break;
+	case 0xc2:	/* iret/ret/lret */
+	case 0xc3:
+	case 0xca:
+	case 0xcb:
+	case 0xcf:
+	case 0xea:	/* jmp absolute -- ip is correct */
+		/* ip is already adjusted, no more changes required */
+		p->ainsn.boostable = 1;
+		goto no_change;
+	case 0xe8:	/* call relative - Fix return addr */
+		*tos = orig_ip + (*tos - copy_ip);
+		break;
+#ifdef CONFIG_X86_32
+	case 0x9a:	/* call absolute -- same as call absolute, indirect */
+		*tos = orig_ip + (*tos - copy_ip);
+		goto no_change;
+#endif
+	case 0xff:
+		if ((insn[1] & 0x30) == 0x10) {
+			/*
+			 * call absolute, indirect
+			 * Fix return addr; ip is correct.
+			 * But this is not boostable
+			 */
+			*tos = orig_ip + (*tos - copy_ip);
+			goto no_change;
+		} else if (((insn[1] & 0x31) == 0x20) ||
+			   ((insn[1] & 0x31) == 0x21)) {
+			/*
+			 * jmp near and far, absolute indirect
+			 * ip is correct. And this is boostable
+			 */
+			p->ainsn.boostable = 1;
+			goto no_change;
+		}
+	default:
+		break;
+	}
+
+	if (p->ainsn.boostable == 0) {
+		if ((regs->ip > copy_ip) &&
+		    (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) {
+			/*
+			 * These instructions can be executed directly if it
+			 * jumps back to correct address.
+			 */
+			synthesize_reljump((void *)regs->ip,
+				(void *)orig_ip + (regs->ip - copy_ip));
+			p->ainsn.boostable = 1;
+		} else {
+			p->ainsn.boostable = -1;
+		}
+	}
+
+	regs->ip += orig_ip - copy_ip;
+
+no_change:
+	restore_btf();
+}
+
+/*
+ * Interrupts are disabled on entry as trap1 is an interrupt gate and they
+ * remain disabled throughout this function.
+ */
+static int __kprobes post_kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	if (!cur)
+		return 0;
+
+	resume_execution(cur, regs, kcb);
+	regs->flags |= kcb->kprobe_saved_flags;
+
+	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+		kcb->kprobe_status = KPROBE_HIT_SSDONE;
+		cur->post_handler(cur, regs, 0);
+	}
+
+	/* 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();
+
+	/*
+	 * if somebody else is singlestepping across a probe point, flags
+	 * will have TF set, in which case, continue the remaining processing
+	 * of do_debug, as if this is not a probe hit.
+	 */
+	if (regs->flags & X86_EFLAGS_TF)
+		return 0;
+
+	return 1;
+}
+
+int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+	struct kprobe *cur = kprobe_running();
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	switch (kcb->kprobe_status) {
+	case KPROBE_HIT_SS:
+	case KPROBE_REENTER:
+		/*
+		 * 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.
+		 */
+		regs->ip = (unsigned long)cur->addr;
+		regs->flags |= kcb->kprobe_old_flags;
+		if (kcb->kprobe_status == KPROBE_REENTER)
+			restore_previous_kprobe(kcb);
+		else
+			reset_current_kprobe();
+		preempt_enable_no_resched();
+		break;
+	case KPROBE_HIT_ACTIVE:
+	case KPROBE_HIT_SSDONE:
+		/*
+		 * We increment the nmissed count for accounting,
+		 * we can also use npre/npostfault count for accounting
+		 * these specific fault cases.
+		 */
+		kprobes_inc_nmissed_count(cur);
+
+		/*
+		 * We come here because instructions in the pre/post
+		 * handler caused the page_fault, this could happen
+		 * if handler tries to access user space by
+		 * copy_from_user(), get_user() etc. Let the
+		 * user-specified handler try to fix it first.
+		 */
+		if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+			return 1;
+
+		/*
+		 * In case the user-specified fault handler returned
+		 * zero, try to fix up.
+		 */
+		if (fixup_exception(regs))
+			return 1;
+
+		/*
+		 * fixup routine could not handle it,
+		 * Let do_page_fault() fix it.
+		 */
+		break;
+	default:
+		break;
+	}
+	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 = data;
+	int ret = NOTIFY_DONE;
+
+	if (args->regs && user_mode_vm(args->regs))
+		return ret;
+
+	switch (val) {
+	case DIE_INT3:
+		if (kprobe_handler(args->regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_DEBUG:
+		if (post_kprobe_handler(args->regs)) {
+			/*
+			 * Reset the BS bit in dr6 (pointed by args->err) to
+			 * denote completion of processing
+			 */
+			(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
+			ret = NOTIFY_STOP;
+		}
+		break;
+	case DIE_GPF:
+		/*
+		 * To be potentially processing a kprobe fault and to
+		 * trust the result from kprobe_running(), we have
+		 * be non-preemptible.
+		 */
+		if (!preemptible() && kprobe_running() &&
+		    kprobe_fault_handler(args->regs, args->trapnr))
+			ret = NOTIFY_STOP;
+		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);
+	unsigned long addr;
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	kcb->jprobe_saved_regs = *regs;
+	kcb->jprobe_saved_sp = stack_addr(regs);
+	addr = (unsigned long)(kcb->jprobe_saved_sp);
+
+	/*
+	 * As Linus pointed out, gcc assumes that the callee
+	 * owns the argument space and could overwrite it, e.g.
+	 * tailcall optimization. So, to be absolutely safe
+	 * we also save and restore enough stack bytes to cover
+	 * the argument area.
+	 */
+	memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
+	       MIN_STACK_SIZE(addr));
+	regs->flags &= ~X86_EFLAGS_IF;
+	trace_hardirqs_off();
+	regs->ip = (unsigned long)(jp->entry);
+	return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+	asm volatile (
+#ifdef CONFIG_X86_64
+			"       xchg   %%rbx,%%rsp	\n"
+#else
+			"       xchgl   %%ebx,%%esp	\n"
+#endif
+			"       int3			\n"
+			"       .globl jprobe_return_end\n"
+			"       jprobe_return_end:	\n"
+			"       nop			\n"::"b"
+			(kcb->jprobe_saved_sp):"memory");
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+	u8 *addr = (u8 *) (regs->ip - 1);
+	struct jprobe *jp = container_of(p, struct jprobe, kp);
+
+	if ((addr > (u8 *) jprobe_return) &&
+	    (addr < (u8 *) jprobe_return_end)) {
+		if (stack_addr(regs) != kcb->jprobe_saved_sp) {
+			struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
+			printk(KERN_ERR
+			       "current sp %p does not match saved sp %p\n",
+			       stack_addr(regs), kcb->jprobe_saved_sp);
+			printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
+			show_regs(saved_regs);
+			printk(KERN_ERR "Current registers\n");
+			show_regs(regs);
+			BUG();
+		}
+		*regs = kcb->jprobe_saved_regs;
+		memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
+		       kcb->jprobes_stack,
+		       MIN_STACK_SIZE(kcb->jprobe_saved_sp));
+		preempt_enable_no_resched();
+		return 1;
+	}
+	return 0;
+}
+
+int __init arch_init_kprobes(void)
+{
+	return arch_init_optprobes();
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+	return 0;
+}