v4.19.13 snapshot.
diff --git a/arch/x86/kernel/kprobes/Makefile b/arch/x86/kernel/kprobes/Makefile
new file mode 100644
index 0000000..0d33169
--- /dev/null
+++ b/arch/x86/kernel/kprobes/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for kernel probes
+#
+
+obj-$(CONFIG_KPROBES) += core.o
+obj-$(CONFIG_OPTPROBES) += opt.o
+obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o
diff --git a/arch/x86/kernel/kprobes/common.h b/arch/x86/kernel/kprobes/common.h
new file mode 100644
index 0000000..2b949f4
--- /dev/null
+++ b/arch/x86/kernel/kprobes/common.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __X86_KERNEL_KPROBES_COMMON_H
+#define __X86_KERNEL_KPROBES_COMMON_H
+
+/* Kprobes and Optprobes common header */
+
+#include <asm/asm.h>
+
+#ifdef CONFIG_FRAME_POINTER
+# define SAVE_RBP_STRING " push %" _ASM_BP "\n" \
+ " mov %" _ASM_SP ", %" _ASM_BP "\n"
+#else
+# define SAVE_RBP_STRING " push %" _ASM_BP "\n"
+#endif
+
+#ifdef CONFIG_X86_64
+#define SAVE_REGS_STRING \
+ /* Skip cs, ip, orig_ax. */ \
+ " subq $24, %rsp\n" \
+ " pushq %rdi\n" \
+ " pushq %rsi\n" \
+ " pushq %rdx\n" \
+ " pushq %rcx\n" \
+ " pushq %rax\n" \
+ " pushq %r8\n" \
+ " pushq %r9\n" \
+ " pushq %r10\n" \
+ " pushq %r11\n" \
+ " pushq %rbx\n" \
+ SAVE_RBP_STRING \
+ " pushq %r12\n" \
+ " pushq %r13\n" \
+ " pushq %r14\n" \
+ " pushq %r15\n"
+#define RESTORE_REGS_STRING \
+ " popq %r15\n" \
+ " popq %r14\n" \
+ " popq %r13\n" \
+ " popq %r12\n" \
+ " popq %rbp\n" \
+ " popq %rbx\n" \
+ " popq %r11\n" \
+ " popq %r10\n" \
+ " popq %r9\n" \
+ " popq %r8\n" \
+ " popq %rax\n" \
+ " popq %rcx\n" \
+ " popq %rdx\n" \
+ " popq %rsi\n" \
+ " popq %rdi\n" \
+ /* Skip orig_ax, ip, cs */ \
+ " addq $24, %rsp\n"
+#else
+#define SAVE_REGS_STRING \
+ /* Skip cs, ip, orig_ax and gs. */ \
+ " subl $16, %esp\n" \
+ " pushl %fs\n" \
+ " pushl %es\n" \
+ " pushl %ds\n" \
+ " pushl %eax\n" \
+ SAVE_RBP_STRING \
+ " pushl %edi\n" \
+ " pushl %esi\n" \
+ " pushl %edx\n" \
+ " pushl %ecx\n" \
+ " pushl %ebx\n"
+#define RESTORE_REGS_STRING \
+ " popl %ebx\n" \
+ " popl %ecx\n" \
+ " popl %edx\n" \
+ " popl %esi\n" \
+ " popl %edi\n" \
+ " popl %ebp\n" \
+ " popl %eax\n" \
+ /* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\
+ " addl $24, %esp\n"
+#endif
+
+/* Ensure if the instruction can be boostable */
+extern int can_boost(struct insn *insn, void *orig_addr);
+/* Recover instruction if given address is probed */
+extern unsigned long recover_probed_instruction(kprobe_opcode_t *buf,
+ unsigned long addr);
+/*
+ * Copy an instruction and adjust the displacement if the instruction
+ * uses the %rip-relative addressing mode.
+ */
+extern int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn);
+
+/* Generate a relative-jump/call instruction */
+extern void synthesize_reljump(void *dest, void *from, void *to);
+extern void synthesize_relcall(void *dest, void *from, void *to);
+
+#ifdef CONFIG_OPTPROBES
+extern int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter);
+extern unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr);
+#else /* !CONFIG_OPTPROBES */
+static inline int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter)
+{
+ return 0;
+}
+static inline unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
+{
+ return addr;
+}
+#endif
+
+#endif
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
new file mode 100644
index 0000000..b0d1e81
--- /dev/null
+++ b/arch/x86/kernel/kprobes/core.c
@@ -0,0 +1,1091 @@
+/*
+ * 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/sched/debug.h>
+#include <linux/extable.h>
+#include <linux/kdebug.h>
+#include <linux/kallsyms.h>
+#include <linux/ftrace.h>
+#include <linux/frame.h>
+#include <linux/kasan.h>
+#include <linux/moduleloader.h>
+
+#include <asm/text-patching.h>
+#include <asm/cacheflush.h>
+#include <asm/desc.h>
+#include <asm/pgtable.h>
+#include <linux/uaccess.h>
+#include <asm/alternative.h>
+#include <asm/insn.h>
+#include <asm/debugreg.h>
+#include <asm/set_memory.h>
+
+#include "common.h"
+
+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, 1) , /* 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 nokprobe_inline void
+__synthesize_relative_insn(void *dest, void *from, void *to, u8 op)
+{
+ struct __arch_relative_insn {
+ u8 op;
+ s32 raddr;
+ } __packed *insn;
+
+ insn = (struct __arch_relative_insn *)dest;
+ insn->raddr = (s32)((long)(to) - ((long)(from) + 5));
+ insn->op = op;
+}
+
+/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
+void synthesize_reljump(void *dest, void *from, void *to)
+{
+ __synthesize_relative_insn(dest, from, to, RELATIVEJUMP_OPCODE);
+}
+NOKPROBE_SYMBOL(synthesize_reljump);
+
+/* Insert a call instruction at address 'from', which calls address 'to'.*/
+void synthesize_relcall(void *dest, void *from, void *to)
+{
+ __synthesize_relative_insn(dest, from, to, RELATIVECALL_OPCODE);
+}
+NOKPROBE_SYMBOL(synthesize_relcall);
+
+/*
+ * Skip the prefixes of the instruction.
+ */
+static kprobe_opcode_t *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;
+}
+NOKPROBE_SYMBOL(skip_prefixes);
+
+/*
+ * Returns non-zero if INSN is boostable.
+ * RIP relative instructions are adjusted at copying time in 64 bits mode
+ */
+int can_boost(struct insn *insn, void *addr)
+{
+ kprobe_opcode_t opcode;
+
+ if (search_exception_tables((unsigned long)addr))
+ return 0; /* Page fault may occur on this address. */
+
+ /* 2nd-byte opcode */
+ if (insn->opcode.nbytes == 2)
+ return test_bit(insn->opcode.bytes[1],
+ (unsigned long *)twobyte_is_boostable);
+
+ if (insn->opcode.nbytes != 1)
+ return 0;
+
+ /* Can't boost Address-size override prefix */
+ if (unlikely(inat_is_address_size_prefix(insn->attr)))
+ return 0;
+
+ opcode = insn->opcode.bytes[0];
+
+ switch (opcode & 0xf0) {
+ case 0x60:
+ /* can't boost "bound" */
+ return (opcode != 0x62);
+ case 0x70:
+ return 0; /* can't boost conditional jump */
+ case 0x90:
+ return opcode != 0x9a; /* can't boost call far */
+ 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:
+ /* clear and set flags are boostable */
+ return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
+ default:
+ /* 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;
+ unsigned long faddr;
+
+ kp = get_kprobe((void *)addr);
+ faddr = ftrace_location(addr);
+ /*
+ * Addresses inside the ftrace location are refused by
+ * arch_check_ftrace_location(). Something went terribly wrong
+ * if such an address is checked here.
+ */
+ if (WARN_ON(faddr && faddr != addr))
+ return 0UL;
+ /*
+ * Use the current code if it is not modified by Kprobe
+ * and it cannot be modified by ftrace.
+ */
+ if (!kp && !faddr)
+ 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, in case on normal Kprobe, 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.
+ *
+ * In case of Kprobes using ftrace, we do not have a copy of
+ * the original instruction. In fact, the ftrace location might
+ * be modified at anytime and even could be in an inconsistent state.
+ * Fortunately, we know that the original code is the ideal 5-byte
+ * long NOP.
+ */
+ if (probe_kernel_read(buf, (void *)addr,
+ MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
+ return 0UL;
+
+ if (faddr)
+ memcpy(buf, ideal_nops[NOP_ATOMIC5], 5);
+ else
+ 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.
+ * Returns zero if the instruction can not get recovered (or access failed).
+ */
+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 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);
+ if (!__addr)
+ return 0;
+ kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE);
+ 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 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 with recovering modified instruction by kprobes
+ * and adjust the displacement if the instruction uses the %rip-relative
+ * addressing mode. Note that since @real will be the final place of copied
+ * instruction, displacement must be adjust by @real, not @dest.
+ * This returns the length of copied instruction, or 0 if it has an error.
+ */
+int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
+{
+ kprobe_opcode_t buf[MAX_INSN_SIZE];
+ unsigned long recovered_insn =
+ recover_probed_instruction(buf, (unsigned long)src);
+
+ if (!recovered_insn || !insn)
+ return 0;
+
+ /* This can access kernel text if given address is not recovered */
+ if (probe_kernel_read(dest, (void *)recovered_insn, MAX_INSN_SIZE))
+ return 0;
+
+ kernel_insn_init(insn, dest, MAX_INSN_SIZE);
+ insn_get_length(insn);
+
+ /* Another subsystem puts a breakpoint, failed to recover */
+ if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
+ return 0;
+
+ /* We should not singlestep on the exception masking instructions */
+ if (insn_masking_exception(insn))
+ return 0;
+
+#ifdef CONFIG_X86_64
+ /* Only x86_64 has RIP relative instructions */
+ if (insn_rip_relative(insn)) {
+ s64 newdisp;
+ u8 *disp;
+ /*
+ * 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 *) real;
+ if ((s64) (s32) newdisp != newdisp) {
+ pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp);
+ return 0;
+ }
+ disp = (u8 *) dest + insn_offset_displacement(insn);
+ *(s32 *) disp = (s32) newdisp;
+ }
+#endif
+ return insn->length;
+}
+
+/* Prepare reljump right after instruction to boost */
+static int prepare_boost(kprobe_opcode_t *buf, struct kprobe *p,
+ struct insn *insn)
+{
+ int len = insn->length;
+
+ if (can_boost(insn, p->addr) &&
+ MAX_INSN_SIZE - len >= RELATIVEJUMP_SIZE) {
+ /*
+ * These instructions can be executed directly if it
+ * jumps back to correct address.
+ */
+ synthesize_reljump(buf + len, p->ainsn.insn + len,
+ p->addr + insn->length);
+ len += RELATIVEJUMP_SIZE;
+ p->ainsn.boostable = true;
+ } else {
+ p->ainsn.boostable = false;
+ }
+
+ return len;
+}
+
+/* Make page to RO mode when allocate it */
+void *alloc_insn_page(void)
+{
+ void *page;
+
+ page = module_alloc(PAGE_SIZE);
+ if (page)
+ set_memory_ro((unsigned long)page & PAGE_MASK, 1);
+
+ return page;
+}
+
+/* Recover page to RW mode before releasing it */
+void free_insn_page(void *page)
+{
+ set_memory_nx((unsigned long)page & PAGE_MASK, 1);
+ set_memory_rw((unsigned long)page & PAGE_MASK, 1);
+ module_memfree(page);
+}
+
+static int arch_copy_kprobe(struct kprobe *p)
+{
+ struct insn insn;
+ kprobe_opcode_t buf[MAX_INSN_SIZE];
+ int len;
+
+ /* Copy an instruction with recovering if other optprobe modifies it.*/
+ len = __copy_instruction(buf, p->addr, p->ainsn.insn, &insn);
+ if (!len)
+ return -EINVAL;
+
+ /*
+ * __copy_instruction can modify the displacement of the instruction,
+ * but it doesn't affect boostable check.
+ */
+ len = prepare_boost(buf, p, &insn);
+
+ /* Check whether the instruction modifies Interrupt Flag or not */
+ p->ainsn.if_modifier = is_IF_modifier(buf);
+
+ /* Also, displacement change doesn't affect the first byte */
+ p->opcode = buf[0];
+
+ /* OK, write back the instruction(s) into ROX insn buffer */
+ text_poke(p->ainsn.insn, buf, len);
+
+ return 0;
+}
+
+int arch_prepare_kprobe(struct kprobe *p)
+{
+ int ret;
+
+ 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;
+
+ ret = arch_copy_kprobe(p);
+ if (ret) {
+ free_insn_slot(p->ainsn.insn, 0);
+ p->ainsn.insn = NULL;
+ }
+
+ return ret;
+}
+
+void arch_arm_kprobe(struct kprobe *p)
+{
+ text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+}
+
+void arch_disarm_kprobe(struct kprobe *p)
+{
+ text_poke(p->addr, &p->opcode, 1);
+}
+
+void arch_remove_kprobe(struct kprobe *p)
+{
+ if (p->ainsn.insn) {
+ free_insn_slot(p->ainsn.insn, p->ainsn.boostable);
+ p->ainsn.insn = NULL;
+ }
+}
+
+static nokprobe_inline void
+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 nokprobe_inline void
+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 nokprobe_inline void
+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 (p->ainsn.if_modifier)
+ kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF;
+}
+
+static nokprobe_inline void clear_btf(void)
+{
+ if (test_thread_flag(TIF_BLOCKSTEP)) {
+ unsigned long debugctl = get_debugctlmsr();
+
+ debugctl &= ~DEBUGCTLMSR_BTF;
+ update_debugctlmsr(debugctl);
+ }
+}
+
+static nokprobe_inline void restore_btf(void)
+{
+ if (test_thread_flag(TIF_BLOCKSTEP)) {
+ unsigned long debugctl = get_debugctlmsr();
+
+ debugctl |= DEBUGCTLMSR_BTF;
+ update_debugctlmsr(debugctl);
+ }
+}
+
+void 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;
+}
+NOKPROBE_SYMBOL(arch_prepare_kretprobe);
+
+static void 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 && !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;
+ 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;
+}
+NOKPROBE_SYMBOL(setup_singlestep);
+
+/*
+ * 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 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:
+ case KPROBE_HIT_SS:
+ kprobes_inc_nmissed_count(p);
+ setup_singlestep(p, regs, kcb, 1);
+ break;
+ case KPROBE_REENTER:
+ /* 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.
+ */
+ pr_err("Unrecoverable kprobe detected.\n");
+ dump_kprobe(p);
+ BUG();
+ default:
+ /* impossible cases */
+ WARN_ON(1);
+ return 0;
+ }
+
+ return 1;
+}
+NOKPROBE_SYMBOL(reenter_kprobe);
+
+/*
+ * Interrupts are disabled on entry as trap3 is an interrupt gate and they
+ * remain disabled throughout this function.
+ */
+int kprobe_int3_handler(struct pt_regs *regs)
+{
+ kprobe_opcode_t *addr;
+ struct kprobe *p;
+ struct kprobe_ctlblk *kcb;
+
+ if (user_mode(regs))
+ return 0;
+
+ addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
+ /*
+ * We don't want to be preempted for the entire duration of kprobe
+ * processing. Since int3 and debug trap disables irqs and we clear
+ * IF while singlestepping, it must be no preemptible.
+ */
+
+ 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, that means
+ * user handler setup registers to exit to another
+ * instruction, we must skip the single stepping.
+ */
+ if (!p->pre_handler || !p->pre_handler(p, regs))
+ setup_singlestep(p, regs, kcb, 0);
+ else
+ reset_current_kprobe();
+ 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;
+ return 1;
+ } /* else: not a kprobe fault; let the kernel handle it */
+
+ return 0;
+}
+NOKPROBE_SYMBOL(kprobe_int3_handler);
+
+/*
+ * When a retprobed function returns, this code saves registers and
+ * calls trampoline_handler() runs, which calls the kretprobe's handler.
+ */
+asm(
+ ".global kretprobe_trampoline\n"
+ ".type kretprobe_trampoline, @function\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"
+ ".size kretprobe_trampoline, .-kretprobe_trampoline\n"
+);
+NOKPROBE_SYMBOL(kretprobe_trampoline);
+STACK_FRAME_NON_STANDARD(kretprobe_trampoline);
+
+/*
+ * Called from kretprobe_trampoline
+ */
+__visible __used void *trampoline_handler(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;
+ 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(ri, 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, 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, tmp, &empty_rp, hlist) {
+ hlist_del(&ri->hlist);
+ kfree(ri);
+ }
+ return (void *)orig_ret_address;
+}
+NOKPROBE_SYMBOL(trampoline_handler);
+
+/*
+ * 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 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 = true;
+ 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 = true;
+ goto no_change;
+ }
+ default:
+ break;
+ }
+
+ regs->ip += orig_ip - copy_ip;
+
+no_change:
+ restore_btf();
+}
+NOKPROBE_SYMBOL(resume_execution);
+
+/*
+ * Interrupts are disabled on entry as trap1 is an interrupt gate and they
+ * remain disabled throughout this function.
+ */
+int kprobe_debug_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:
+ /*
+ * 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;
+}
+NOKPROBE_SYMBOL(kprobe_debug_handler);
+
+int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (unlikely(regs->ip == (unsigned long)cur->ainsn.insn)) {
+ /* This must happen on single-stepping */
+ WARN_ON(kcb->kprobe_status != KPROBE_HIT_SS &&
+ kcb->kprobe_status != 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;
+ /*
+ * Trap flag (TF) has been set here because this fault
+ * happened where the single stepping will be done.
+ * So clear it by resetting the current kprobe:
+ */
+ regs->flags &= ~X86_EFLAGS_TF;
+
+ /*
+ * If the TF flag was set before the kprobe hit,
+ * don't touch it:
+ */
+ regs->flags |= kcb->kprobe_old_flags;
+
+ if (kcb->kprobe_status == KPROBE_REENTER)
+ restore_previous_kprobe(kcb);
+ else
+ reset_current_kprobe();
+ } else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE ||
+ kcb->kprobe_status == 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, trapnr))
+ return 1;
+
+ /*
+ * fixup routine could not handle it,
+ * Let do_page_fault() fix it.
+ */
+ }
+
+ return 0;
+}
+NOKPROBE_SYMBOL(kprobe_fault_handler);
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int 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(args->regs))
+ return ret;
+
+ if (val == 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;
+ }
+ return ret;
+}
+NOKPROBE_SYMBOL(kprobe_exceptions_notify);
+
+bool arch_within_kprobe_blacklist(unsigned long addr)
+{
+ bool is_in_entry_trampoline_section = false;
+
+#ifdef CONFIG_X86_64
+ is_in_entry_trampoline_section =
+ (addr >= (unsigned long)__entry_trampoline_start &&
+ addr < (unsigned long)__entry_trampoline_end);
+#endif
+ return (addr >= (unsigned long)__kprobes_text_start &&
+ addr < (unsigned long)__kprobes_text_end) ||
+ (addr >= (unsigned long)__entry_text_start &&
+ addr < (unsigned long)__entry_text_end) ||
+ is_in_entry_trampoline_section;
+}
+
+int __init arch_init_kprobes(void)
+{
+ return 0;
+}
+
+int arch_trampoline_kprobe(struct kprobe *p)
+{
+ return 0;
+}
diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c
new file mode 100644
index 0000000..ef819e1
--- /dev/null
+++ b/arch/x86/kernel/kprobes/ftrace.c
@@ -0,0 +1,76 @@
+/*
+ * Dynamic Ftrace based Kprobes Optimization
+ *
+ * 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) Hitachi Ltd., 2012
+ */
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/hardirq.h>
+#include <linux/preempt.h>
+#include <linux/ftrace.h>
+
+#include "common.h"
+
+/* Ftrace callback handler for kprobes -- called under preepmt disabed */
+void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *ops, struct pt_regs *regs)
+{
+ struct kprobe *p;
+ struct kprobe_ctlblk *kcb;
+
+ /* Preempt is disabled by ftrace */
+ p = get_kprobe((kprobe_opcode_t *)ip);
+ if (unlikely(!p) || kprobe_disabled(p))
+ return;
+
+ kcb = get_kprobe_ctlblk();
+ if (kprobe_running()) {
+ kprobes_inc_nmissed_count(p);
+ } else {
+ unsigned long orig_ip = regs->ip;
+ /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
+ regs->ip = ip + sizeof(kprobe_opcode_t);
+
+ __this_cpu_write(current_kprobe, p);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ if (!p->pre_handler || !p->pre_handler(p, regs)) {
+ /*
+ * Emulate singlestep (and also recover regs->ip)
+ * as if there is a 5byte nop
+ */
+ regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
+ if (unlikely(p->post_handler)) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ p->post_handler(p, regs, 0);
+ }
+ regs->ip = orig_ip;
+ }
+ /*
+ * If pre_handler returns !0, it changes regs->ip. We have to
+ * skip emulating post_handler.
+ */
+ __this_cpu_write(current_kprobe, NULL);
+ }
+}
+NOKPROBE_SYMBOL(kprobe_ftrace_handler);
+
+int arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+ p->ainsn.insn = NULL;
+ p->ainsn.boostable = false;
+ return 0;
+}
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
new file mode 100644
index 0000000..6adf6e6
--- /dev/null
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -0,0 +1,498 @@
+/*
+ * Kernel Probes Jump Optimization (Optprobes)
+ *
+ * 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
+ * Copyright (C) Hitachi Ltd., 2012
+ */
+#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/extable.h>
+#include <linux/kdebug.h>
+#include <linux/kallsyms.h>
+#include <linux/ftrace.h>
+#include <linux/frame.h>
+
+#include <asm/text-patching.h>
+#include <asm/cacheflush.h>
+#include <asm/desc.h>
+#include <asm/pgtable.h>
+#include <linux/uaccess.h>
+#include <asm/alternative.h>
+#include <asm/insn.h>
+#include <asm/debugreg.h>
+#include <asm/set_memory.h>
+#include <asm/sections.h>
+#include <asm/nospec-branch.h>
+
+#include "common.h"
+
+unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
+{
+ struct optimized_kprobe *op;
+ struct kprobe *kp;
+ long offs;
+ int i;
+
+ for (i = 0; i < RELATIVEJUMP_SIZE; i++) {
+ kp = get_kprobe((void *)addr - i);
+ /* This function only handles jump-optimized kprobe */
+ if (kp && kprobe_optimized(kp)) {
+ op = container_of(kp, struct optimized_kprobe, kp);
+ /* If op->list is not empty, op is under optimizing */
+ if (list_empty(&op->list))
+ goto found;
+ }
+ }
+
+ return addr;
+found:
+ /*
+ * If the kprobe can be optimized, original bytes which can be
+ * overwritten by jump destination address. In this case, original
+ * bytes must be recovered from op->optinsn.copied_insn buffer.
+ */
+ if (probe_kernel_read(buf, (void *)addr,
+ MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
+ return 0UL;
+
+ if (addr == (unsigned long)kp->addr) {
+ buf[0] = kp->opcode;
+ memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+ } else {
+ offs = addr - (unsigned long)kp->addr - 1;
+ memcpy(buf, op->optinsn.copied_insn + offs, RELATIVE_ADDR_SIZE - offs);
+ }
+
+ return (unsigned long)buf;
+}
+
+/* Insert a move instruction which sets a pointer to eax/rdi (1st arg). */
+static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
+{
+#ifdef CONFIG_X86_64
+ *addr++ = 0x48;
+ *addr++ = 0xbf;
+#else
+ *addr++ = 0xb8;
+#endif
+ *(unsigned long *)addr = val;
+}
+
+asm (
+ "optprobe_template_func:\n"
+ ".global optprobe_template_entry\n"
+ "optprobe_template_entry:\n"
+#ifdef CONFIG_X86_64
+ /* We don't bother saving the ss register */
+ " pushq %rsp\n"
+ " pushfq\n"
+ SAVE_REGS_STRING
+ " movq %rsp, %rsi\n"
+ ".global optprobe_template_val\n"
+ "optprobe_template_val:\n"
+ ASM_NOP5
+ ASM_NOP5
+ ".global optprobe_template_call\n"
+ "optprobe_template_call:\n"
+ ASM_NOP5
+ /* Move flags to rsp */
+ " movq 144(%rsp), %rdx\n"
+ " movq %rdx, 152(%rsp)\n"
+ RESTORE_REGS_STRING
+ /* Skip flags entry */
+ " addq $8, %rsp\n"
+ " popfq\n"
+#else /* CONFIG_X86_32 */
+ " pushf\n"
+ SAVE_REGS_STRING
+ " movl %esp, %edx\n"
+ ".global optprobe_template_val\n"
+ "optprobe_template_val:\n"
+ ASM_NOP5
+ ".global optprobe_template_call\n"
+ "optprobe_template_call:\n"
+ ASM_NOP5
+ RESTORE_REGS_STRING
+ " addl $4, %esp\n" /* skip cs */
+ " popf\n"
+#endif
+ ".global optprobe_template_end\n"
+ "optprobe_template_end:\n"
+ ".type optprobe_template_func, @function\n"
+ ".size optprobe_template_func, .-optprobe_template_func\n");
+
+void optprobe_template_func(void);
+STACK_FRAME_NON_STANDARD(optprobe_template_func);
+
+#define TMPL_MOVE_IDX \
+ ((long)optprobe_template_val - (long)optprobe_template_entry)
+#define TMPL_CALL_IDX \
+ ((long)optprobe_template_call - (long)optprobe_template_entry)
+#define TMPL_END_IDX \
+ ((long)optprobe_template_end - (long)optprobe_template_entry)
+
+#define INT3_SIZE sizeof(kprobe_opcode_t)
+
+/* Optimized kprobe call back function: called from optinsn */
+static void
+optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
+{
+ /* This is possible if op is under delayed unoptimizing */
+ if (kprobe_disabled(&op->kp))
+ return;
+
+ preempt_disable();
+ if (kprobe_running()) {
+ kprobes_inc_nmissed_count(&op->kp);
+ } else {
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ /* Save skipped registers */
+#ifdef CONFIG_X86_64
+ regs->cs = __KERNEL_CS;
+#else
+ regs->cs = __KERNEL_CS | get_kernel_rpl();
+ regs->gs = 0;
+#endif
+ regs->ip = (unsigned long)op->kp.addr + INT3_SIZE;
+ regs->orig_ax = ~0UL;
+
+ __this_cpu_write(current_kprobe, &op->kp);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ opt_pre_handler(&op->kp, regs);
+ __this_cpu_write(current_kprobe, NULL);
+ }
+ preempt_enable();
+}
+NOKPROBE_SYMBOL(optimized_callback);
+
+static int copy_optimized_instructions(u8 *dest, u8 *src, u8 *real)
+{
+ struct insn insn;
+ int len = 0, ret;
+
+ while (len < RELATIVEJUMP_SIZE) {
+ ret = __copy_instruction(dest + len, src + len, real + len, &insn);
+ if (!ret || !can_boost(&insn, src + len))
+ return -EINVAL;
+ len += ret;
+ }
+ /* Check whether the address range is reserved */
+ if (ftrace_text_reserved(src, src + len - 1) ||
+ alternatives_text_reserved(src, src + len - 1) ||
+ jump_label_text_reserved(src, src + len - 1))
+ return -EBUSY;
+
+ return len;
+}
+
+/* Check whether insn is indirect jump */
+static int __insn_is_indirect_jump(struct insn *insn)
+{
+ return ((insn->opcode.bytes[0] == 0xff &&
+ (X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */
+ insn->opcode.bytes[0] == 0xea); /* Segment based jump */
+}
+
+/* Check whether insn jumps into specified address range */
+static int insn_jump_into_range(struct insn *insn, unsigned long start, int len)
+{
+ unsigned long target = 0;
+
+ switch (insn->opcode.bytes[0]) {
+ case 0xe0: /* loopne */
+ case 0xe1: /* loope */
+ case 0xe2: /* loop */
+ case 0xe3: /* jcxz */
+ case 0xe9: /* near relative jump */
+ case 0xeb: /* short relative jump */
+ break;
+ case 0x0f:
+ if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */
+ break;
+ return 0;
+ default:
+ if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */
+ break;
+ return 0;
+ }
+ target = (unsigned long)insn->next_byte + insn->immediate.value;
+
+ return (start <= target && target <= start + len);
+}
+
+static int insn_is_indirect_jump(struct insn *insn)
+{
+ int ret = __insn_is_indirect_jump(insn);
+
+#ifdef CONFIG_RETPOLINE
+ /*
+ * Jump to x86_indirect_thunk_* is treated as an indirect jump.
+ * Note that even with CONFIG_RETPOLINE=y, the kernel compiled with
+ * older gcc may use indirect jump. So we add this check instead of
+ * replace indirect-jump check.
+ */
+ if (!ret)
+ ret = insn_jump_into_range(insn,
+ (unsigned long)__indirect_thunk_start,
+ (unsigned long)__indirect_thunk_end -
+ (unsigned long)__indirect_thunk_start);
+#endif
+ return ret;
+}
+
+/* Decode whole function to ensure any instructions don't jump into target */
+static int can_optimize(unsigned long paddr)
+{
+ unsigned long addr, size = 0, offset = 0;
+ struct insn insn;
+ kprobe_opcode_t buf[MAX_INSN_SIZE];
+
+ /* Lookup symbol including addr */
+ if (!kallsyms_lookup_size_offset(paddr, &size, &offset))
+ return 0;
+
+ /*
+ * Do not optimize in the entry code due to the unstable
+ * stack handling and registers setup.
+ */
+ if (((paddr >= (unsigned long)__entry_text_start) &&
+ (paddr < (unsigned long)__entry_text_end)) ||
+ ((paddr >= (unsigned long)__irqentry_text_start) &&
+ (paddr < (unsigned long)__irqentry_text_end)))
+ return 0;
+
+ /* Check there is enough space for a relative jump. */
+ if (size - offset < RELATIVEJUMP_SIZE)
+ return 0;
+
+ /* Decode instructions */
+ addr = paddr - offset;
+ while (addr < paddr - offset + size) { /* Decode until function end */
+ unsigned long recovered_insn;
+ if (search_exception_tables(addr))
+ /*
+ * Since some fixup code will jumps into this function,
+ * we can't optimize kprobe in this function.
+ */
+ return 0;
+ recovered_insn = recover_probed_instruction(buf, addr);
+ if (!recovered_insn)
+ return 0;
+ kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
+ insn_get_length(&insn);
+ /* Another subsystem puts a breakpoint */
+ if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
+ return 0;
+ /* Recover address */
+ insn.kaddr = (void *)addr;
+ insn.next_byte = (void *)(addr + insn.length);
+ /* Check any instructions don't jump into target */
+ if (insn_is_indirect_jump(&insn) ||
+ insn_jump_into_range(&insn, paddr + INT3_SIZE,
+ RELATIVE_ADDR_SIZE))
+ return 0;
+ addr += insn.length;
+ }
+
+ return 1;
+}
+
+/* Check optimized_kprobe can actually be optimized. */
+int arch_check_optimized_kprobe(struct optimized_kprobe *op)
+{
+ int i;
+ struct kprobe *p;
+
+ for (i = 1; i < op->optinsn.size; i++) {
+ p = get_kprobe(op->kp.addr + i);
+ if (p && !kprobe_disabled(p))
+ return -EEXIST;
+ }
+
+ return 0;
+}
+
+/* Check the addr is within the optimized instructions. */
+int arch_within_optimized_kprobe(struct optimized_kprobe *op,
+ unsigned long addr)
+{
+ return ((unsigned long)op->kp.addr <= addr &&
+ (unsigned long)op->kp.addr + op->optinsn.size > addr);
+}
+
+/* Free optimized instruction slot */
+static
+void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty)
+{
+ if (op->optinsn.insn) {
+ free_optinsn_slot(op->optinsn.insn, dirty);
+ op->optinsn.insn = NULL;
+ op->optinsn.size = 0;
+ }
+}
+
+void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
+{
+ __arch_remove_optimized_kprobe(op, 1);
+}
+
+/*
+ * Copy replacing target instructions
+ * Target instructions MUST be relocatable (checked inside)
+ * This is called when new aggr(opt)probe is allocated or reused.
+ */
+int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
+ struct kprobe *__unused)
+{
+ u8 *buf = NULL, *slot;
+ int ret, len;
+ long rel;
+
+ if (!can_optimize((unsigned long)op->kp.addr))
+ return -EILSEQ;
+
+ buf = kzalloc(MAX_OPTINSN_SIZE, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ op->optinsn.insn = slot = get_optinsn_slot();
+ if (!slot) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ /*
+ * Verify if the address gap is in 2GB range, because this uses
+ * a relative jump.
+ */
+ rel = (long)slot - (long)op->kp.addr + RELATIVEJUMP_SIZE;
+ if (abs(rel) > 0x7fffffff) {
+ ret = -ERANGE;
+ goto err;
+ }
+
+ /* Copy arch-dep-instance from template */
+ memcpy(buf, optprobe_template_entry, TMPL_END_IDX);
+
+ /* Copy instructions into the out-of-line buffer */
+ ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr,
+ slot + TMPL_END_IDX);
+ if (ret < 0)
+ goto err;
+ op->optinsn.size = ret;
+ len = TMPL_END_IDX + op->optinsn.size;
+
+ /* Set probe information */
+ synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op);
+
+ /* Set probe function call */
+ synthesize_relcall(buf + TMPL_CALL_IDX,
+ slot + TMPL_CALL_IDX, optimized_callback);
+
+ /* Set returning jmp instruction at the tail of out-of-line buffer */
+ synthesize_reljump(buf + len, slot + len,
+ (u8 *)op->kp.addr + op->optinsn.size);
+ len += RELATIVEJUMP_SIZE;
+
+ /* We have to use text_poke for instuction buffer because it is RO */
+ text_poke(slot, buf, len);
+ ret = 0;
+out:
+ kfree(buf);
+ return ret;
+
+err:
+ __arch_remove_optimized_kprobe(op, 0);
+ goto out;
+}
+
+/*
+ * Replace breakpoints (int3) with relative jumps.
+ * Caller must call with locking kprobe_mutex and text_mutex.
+ */
+void arch_optimize_kprobes(struct list_head *oplist)
+{
+ struct optimized_kprobe *op, *tmp;
+ u8 insn_buf[RELATIVEJUMP_SIZE];
+
+ list_for_each_entry_safe(op, tmp, oplist, list) {
+ s32 rel = (s32)((long)op->optinsn.insn -
+ ((long)op->kp.addr + RELATIVEJUMP_SIZE));
+
+ WARN_ON(kprobe_disabled(&op->kp));
+
+ /* Backup instructions which will be replaced by jump address */
+ memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE,
+ RELATIVE_ADDR_SIZE);
+
+ insn_buf[0] = RELATIVEJUMP_OPCODE;
+ *(s32 *)(&insn_buf[1]) = rel;
+
+ text_poke_bp(op->kp.addr, insn_buf, RELATIVEJUMP_SIZE,
+ op->optinsn.insn);
+
+ list_del_init(&op->list);
+ }
+}
+
+/* Replace a relative jump with a breakpoint (int3). */
+void arch_unoptimize_kprobe(struct optimized_kprobe *op)
+{
+ u8 insn_buf[RELATIVEJUMP_SIZE];
+
+ /* Set int3 to first byte for kprobes */
+ insn_buf[0] = BREAKPOINT_INSTRUCTION;
+ memcpy(insn_buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+ text_poke_bp(op->kp.addr, insn_buf, RELATIVEJUMP_SIZE,
+ op->optinsn.insn);
+}
+
+/*
+ * Recover original instructions and breakpoints from relative jumps.
+ * Caller must call with locking kprobe_mutex.
+ */
+extern void arch_unoptimize_kprobes(struct list_head *oplist,
+ struct list_head *done_list)
+{
+ struct optimized_kprobe *op, *tmp;
+
+ list_for_each_entry_safe(op, tmp, oplist, list) {
+ arch_unoptimize_kprobe(op);
+ list_move(&op->list, done_list);
+ }
+}
+
+int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter)
+{
+ struct optimized_kprobe *op;
+
+ if (p->flags & KPROBE_FLAG_OPTIMIZED) {
+ /* This kprobe is really able to run optimized path. */
+ op = container_of(p, struct optimized_kprobe, kp);
+ /* Detour through copied instructions */
+ regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX;
+ if (!reenter)
+ reset_current_kprobe();
+ return 1;
+ }
+ return 0;
+}
+NOKPROBE_SYMBOL(setup_detour_execution);