kprobes/x86: Move kprobes stuff under arch/x86/kernel/kprobes/

Move arch-dep kprobes stuff under arch/x86/kernel/kprobes.

Link: http://lkml.kernel.org/r/20120928081522.3560.75469.stgit@ltc138.sdl.hitachi.co.jp

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
[ fixed whitespace and s/__attribute__((packed))/__packed/ ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 512 insertions, 0 deletions

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
new file mode 100644
index 000000000000..76dc6f095724
--- /dev/null
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -0,0 +1,512 @@
+/*
+ *  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/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"
+
+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.
+         */
+        memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+        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 __kprobes 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;
+}
+
+static void __used __kprobes kprobes_optinsn_template_holder(void)
+{
+        asm volatile (
+                        ".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");
+}
+
+#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 __kprobes optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
+{
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+        unsigned long flags;
+
+        /* This is possible if op is under delayed unoptimizing */
+        if (kprobe_disabled(&op->kp))
+                return;
+
+        local_irq_save(flags);
+        if (kprobe_running()) {
+                kprobes_inc_nmissed_count(&op->kp);
+        } else {
+                /* 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);
+        }
+        local_irq_restore(flags);
+}
+
+static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src)
+{
+        int len = 0, ret;
+
+        while (len < RELATIVEJUMP_SIZE) {
+                ret = __copy_instruction(dest + len, src + len);
+                if (!ret || !can_boost(dest + 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 __kprobes 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);
+}
+
+/* Decode whole function to ensure any instructions don't jump into target */
+static int __kprobes 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.
+         */
+        if ((paddr >= (unsigned long)__entry_text_start) &&
+            (paddr <  (unsigned long)__entry_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 */
+                if (search_exception_tables(addr))
+                        /*
+                         * Since some fixup code will jumps into this function,
+                         * we can't optimize kprobe in this function.
+                         */
+                        return 0;
+                kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, addr));
+                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 __kprobes 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 __kprobes
+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 __kprobes
+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 __kprobes 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 __kprobes arch_prepare_optimized_kprobe(struct optimized_kprobe *op)
+{
+        u8 *buf;
+        int ret;
+        long rel;
+
+        if (!can_optimize((unsigned long)op->kp.addr))
+                return -EILSEQ;
+
+        op->optinsn.insn = get_optinsn_slot();
+        if (!op->optinsn.insn)
+                return -ENOMEM;
+
+        /*
+         * Verify if the address gap is in 2GB range, because this uses
+         * a relative jump.
+         */
+        rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE;
+        if (abs(rel) > 0x7fffffff)
+                return -ERANGE;
+
+        buf = (u8 *)op->optinsn.insn;
+
+        /* Copy instructions into the out-of-line buffer */
+        ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr);
+        if (ret < 0) {
+                __arch_remove_optimized_kprobe(op, 0);
+                return ret;
+        }
+        op->optinsn.size = ret;
+
+        /* Copy arch-dep-instance from template */
+        memcpy(buf, &optprobe_template_entry, TMPL_END_IDX);
+
+        /* Set probe information */
+        synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op);
+
+        /* Set probe function call */
+        synthesize_relcall(buf + TMPL_CALL_IDX, optimized_callback);
+
+        /* Set returning jmp instruction at the tail of out-of-line buffer */
+        synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size,
+                           (u8 *)op->kp.addr + op->optinsn.size);
+
+        flush_icache_range((unsigned long) buf,
+                           (unsigned long) buf + TMPL_END_IDX +
+                           op->optinsn.size + RELATIVEJUMP_SIZE);
+        return 0;
+}
+
+#define MAX_OPTIMIZE_PROBES 256
+static struct text_poke_param *jump_poke_params;
+static struct jump_poke_buffer {
+        u8 buf[RELATIVEJUMP_SIZE];
+} *jump_poke_bufs;
+
+static void __kprobes setup_optimize_kprobe(struct text_poke_param *tprm,
+                                            u8 *insn_buf,
+                                            struct optimized_kprobe *op)
+{
+        s32 rel = (s32)((long)op->optinsn.insn -
+                        ((long)op->kp.addr + RELATIVEJUMP_SIZE));
+
+        /* 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;
+
+        tprm->addr = op->kp.addr;
+        tprm->opcode = insn_buf;
+        tprm->len = RELATIVEJUMP_SIZE;
+}
+
+/*
+ * Replace breakpoints (int3) with relative jumps.
+ * Caller must call with locking kprobe_mutex and text_mutex.
+ */
+void __kprobes arch_optimize_kprobes(struct list_head *oplist)
+{
+        struct optimized_kprobe *op, *tmp;
+        int c = 0;
+
+        list_for_each_entry_safe(op, tmp, oplist, list) {
+                WARN_ON(kprobe_disabled(&op->kp));
+                /* Setup param */
+                setup_optimize_kprobe(&jump_poke_params[c],
+                                      jump_poke_bufs[c].buf, op);
+                list_del_init(&op->list);
+                if (++c >= MAX_OPTIMIZE_PROBES)
+                        break;
+        }
+
+        /*
+         * text_poke_smp doesn't support NMI/MCE code modifying.
+         * However, since kprobes itself also doesn't support NMI/MCE
+         * code probing, it's not a problem.
+         */
+        text_poke_smp_batch(jump_poke_params, c);
+}
+
+static void __kprobes setup_unoptimize_kprobe(struct text_poke_param *tprm,
+                                              u8 *insn_buf,
+                                              struct optimized_kprobe *op)
+{
+        /* Set int3 to first byte for kprobes */
+        insn_buf[0] = BREAKPOINT_INSTRUCTION;
+        memcpy(insn_buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+
+        tprm->addr = op->kp.addr;
+        tprm->opcode = insn_buf;
+        tprm->len = RELATIVEJUMP_SIZE;
+}
+
+/*
+ * 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;
+        int c = 0;
+
+        list_for_each_entry_safe(op, tmp, oplist, list) {
+                /* Setup param */
+                setup_unoptimize_kprobe(&jump_poke_params[c],
+                                        jump_poke_bufs[c].buf, op);
+                list_move(&op->list, done_list);
+                if (++c >= MAX_OPTIMIZE_PROBES)
+                        break;
+        }
+
+        /*
+         * text_poke_smp doesn't support NMI/MCE code modifying.
+         * However, since kprobes itself also doesn't support NMI/MCE
+         * code probing, it's not a problem.
+         */
+        text_poke_smp_batch(jump_poke_params, c);
+}
+
+/* Replace a relative jump with a breakpoint (int3).  */
+void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op)
+{
+        u8 buf[RELATIVEJUMP_SIZE];
+
+        /* Set int3 to first byte for kprobes */
+        buf[0] = BREAKPOINT_INSTRUCTION;
+        memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+        text_poke_smp(op->kp.addr, buf, RELATIVEJUMP_SIZE);
+}
+
+int  __kprobes
+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();
+                preempt_enable_no_resched();
+                return 1;
+        }
+        return 0;
+}
+
+int __kprobes arch_init_optprobes(void)
+{
+        /* Allocate code buffer and parameter array */
+        jump_poke_bufs = kmalloc(sizeof(struct jump_poke_buffer) *
+                                 MAX_OPTIMIZE_PROBES, GFP_KERNEL);
+        if (!jump_poke_bufs)
+                return -ENOMEM;
+
+        jump_poke_params = kmalloc(sizeof(struct text_poke_param) *
+                                   MAX_OPTIMIZE_PROBES, GFP_KERNEL);
+        if (!jump_poke_params) {
+                kfree(jump_poke_bufs);
+                jump_poke_bufs = NULL;
+                return -ENOMEM;
+        }
+
+        return 0;
+}