1 files changed, 584 insertions, 0 deletions

diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
new file mode 100644
index 000000000000..c96850b061fb
--- /dev/null
+++ b/arch/sh/kernel/kprobes.c
@@ -0,0 +1,584 @@
+/*
+ * Kernel probes (kprobes) for SuperH
+ *
+ * Copyright (C) 2007 Chris Smith <chris.smith@st.com>
+ * Copyright (C) 2006 Lineo Solutions, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/ptrace.h>
+#include <linux/preempt.h>
+#include <linux/kdebug.h>
+#include <asm/cacheflush.h>
+#include <asm/uaccess.h>
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+static struct kprobe saved_current_opcode;
+static struct kprobe saved_next_opcode;
+static struct kprobe saved_next_opcode2;
+
+#define OPCODE_JMP(x)   (((x) & 0xF0FF) == 0x402b)
+#define OPCODE_JSR(x)   (((x) & 0xF0FF) == 0x400b)
+#define OPCODE_BRA(x)   (((x) & 0xF000) == 0xa000)
+#define OPCODE_BRAF(x)  (((x) & 0xF0FF) == 0x0023)
+#define OPCODE_BSR(x)   (((x) & 0xF000) == 0xb000)
+#define OPCODE_BSRF(x)  (((x) & 0xF0FF) == 0x0003)
+
+#define OPCODE_BF_S(x)  (((x) & 0xFF00) == 0x8f00)
+#define OPCODE_BT_S(x)  (((x) & 0xFF00) == 0x8d00)
+
+#define OPCODE_BF(x)    (((x) & 0xFF00) == 0x8b00)
+#define OPCODE_BT(x)    (((x) & 0xFF00) == 0x8900)
+
+#define OPCODE_RTS(x)   (((x) & 0x000F) == 0x000b)
+#define OPCODE_RTE(x)   (((x) & 0xFFFF) == 0x002b)
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+        kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
+
+        if (OPCODE_RTE(opcode))
+                return -EFAULT; /* Bad breakpoint */
+
+        p->opcode = opcode;
+
+        return 0;
+}
+
+void __kprobes arch_copy_kprobe(struct kprobe *p)
+{
+        memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+        p->opcode = *p->addr;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+        *p->addr = BREAKPOINT_INSTRUCTION;
+        flush_icache_range((unsigned long)p->addr,
+                           (unsigned long)p->addr + sizeof(kprobe_opcode_t));
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+        *p->addr = p->opcode;
+        flush_icache_range((unsigned long)p->addr,
+                           (unsigned long)p->addr + sizeof(kprobe_opcode_t));
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+        if (*p->addr == BREAKPOINT_INSTRUCTION)
+                return 1;
+
+        return 0;
+}
+
+/**
+ * If an illegal slot instruction exception occurs for an address
+ * containing a kprobe, remove the probe.
+ *
+ * Returns 0 if the exception was handled successfully, 1 otherwise.
+ */
+int __kprobes kprobe_handle_illslot(unsigned long pc)
+{
+        struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
+
+        if (p != NULL) {
+                printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
+                       (unsigned int)pc + 2);
+                unregister_kprobe(p);
+                return 0;
+        }
+
+        return 1;
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+        if (saved_next_opcode.addr != 0x0) {
+                arch_disarm_kprobe(p);
+                arch_disarm_kprobe(&saved_next_opcode);
+                saved_next_opcode.addr = 0x0;
+                saved_next_opcode.opcode = 0x0;
+
+                if (saved_next_opcode2.addr != 0x0) {
+                        arch_disarm_kprobe(&saved_next_opcode2);
+                        saved_next_opcode2.addr = 0x0;
+                        saved_next_opcode2.opcode = 0x0;
+                }
+        }
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+        kcb->prev_kprobe.kp = kprobe_running();
+        kcb->prev_kprobe.status = kcb->kprobe_status;
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+        __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+        kcb->kprobe_status = kcb->prev_kprobe.status;
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+                                         struct kprobe_ctlblk *kcb)
+{
+        __get_cpu_var(current_kprobe) = p;
+}
+
+/*
+ * Singlestep is implemented by disabling the current kprobe and setting one
+ * on the next instruction, following branches. Two probes are set if the
+ * branch is conditional.
+ */
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+        kprobe_opcode_t *addr = NULL;
+        saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc);
+        addr = saved_current_opcode.addr;
+
+        if (p != NULL) {
+                arch_disarm_kprobe(p);
+
+                if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
+                        unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
+                        saved_next_opcode.addr =
+                            (kprobe_opcode_t *) regs->regs[reg_nr];
+                } else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
+                        unsigned long disp = (p->opcode & 0x0FFF);
+                        saved_next_opcode.addr =
+                            (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
+
+                } else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
+                        unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
+                        saved_next_opcode.addr =
+                            (kprobe_opcode_t *) (regs->pc + 4 +
+                                                 regs->regs[reg_nr]);
+
+                } else if (OPCODE_RTS(p->opcode)) {
+                        saved_next_opcode.addr = (kprobe_opcode_t *) regs->pr;
+
+                } else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
+                        unsigned long disp = (p->opcode & 0x00FF);
+                        /* case 1 */
+                        saved_next_opcode.addr = p->addr + 1;
+                        /* case 2 */
+                        saved_next_opcode2.addr =
+                            (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
+                        saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
+                        arch_arm_kprobe(&saved_next_opcode2);
+
+                } else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
+                        unsigned long disp = (p->opcode & 0x00FF);
+                        /* case 1 */
+                        saved_next_opcode.addr = p->addr + 2;
+                        /* case 2 */
+                        saved_next_opcode2.addr =
+                            (kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
+                        saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
+                        arch_arm_kprobe(&saved_next_opcode2);
+
+                } else {
+                        saved_next_opcode.addr = p->addr + 1;
+                }
+
+                saved_next_opcode.opcode = *(saved_next_opcode.addr);
+                arch_arm_kprobe(&saved_next_opcode);
+        }
+}
+
+/* Called with kretprobe_lock held */
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+                                      struct pt_regs *regs)
+{
+        ri->ret_addr = (kprobe_opcode_t *) regs->pr;
+
+        /* Replace the return addr with trampoline addr */
+        regs->pr = (unsigned long)kretprobe_trampoline;
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+        struct kprobe *p;
+        int ret = 0;
+        kprobe_opcode_t *addr = NULL;
+        struct kprobe_ctlblk *kcb;
+
+        /*
+         * We don't want to be preempted for the entire
+         * duration of kprobe processing
+         */
+        preempt_disable();
+        kcb = get_kprobe_ctlblk();
+
+        addr = (kprobe_opcode_t *) (regs->pc);
+
+        /* Check we're not actually recursing */
+        if (kprobe_running()) {
+                p = get_kprobe(addr);
+                if (p) {
+                        if (kcb->kprobe_status == KPROBE_HIT_SS &&
+                            *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
+                                goto no_kprobe;
+                        }
+                        /* We have reentered the kprobe_handler(), since
+                         * another probe was hit while within the handler.
+                         * We here save the original kprobes variables and
+                         * just single step on the instruction of the new probe
+                         * without calling any user handlers.
+                         */
+                        save_previous_kprobe(kcb);
+                        set_current_kprobe(p, regs, kcb);
+                        kprobes_inc_nmissed_count(p);
+                        prepare_singlestep(p, regs);
+                        kcb->kprobe_status = KPROBE_REENTER;
+                        return 1;
+                } else {
+                        p = __get_cpu_var(current_kprobe);
+                        if (p->break_handler && p->break_handler(p, regs)) {
+                                goto ss_probe;
+                        }
+                }
+                goto no_kprobe;
+        }
+
+        p = get_kprobe(addr);
+        if (!p) {
+                /* Not one of ours: let kernel handle it */
+                if (*(kprobe_opcode_t *)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.
+                         */
+                        ret = 1;
+                }
+
+                goto no_kprobe;
+        }
+
+        set_current_kprobe(p, regs, kcb);
+        kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+        if (p->pre_handler && p->pre_handler(p, regs))
+                /* handler has already set things up, so skip ss setup */
+                return 1;
+
+ss_probe:
+        prepare_singlestep(p, regs);
+        kcb->kprobe_status = KPROBE_HIT_SS;
+        return 1;
+
+no_kprobe:
+        preempt_enable_no_resched();
+        return ret;
+}
+
+/*
+ * For function-return probes, init_kprobes() establishes a probepoint
+ * here. When a retprobed function returns, this probe is hit and
+ * trampoline_probe_handler() runs, calling the kretprobe's handler.
+ */
+static void __used kretprobe_trampoline_holder(void)
+{
+        asm volatile (".globl kretprobe_trampoline\n"
+                      "kretprobe_trampoline:\n\t"
+                      "nop\n");
+}
+
+/*
+ * Called when we hit the probe point at kretprobe_trampoline
+ */
+int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+{
+        struct kretprobe_instance *ri = NULL;
+        struct hlist_head *head, empty_rp;
+        struct hlist_node *node, *tmp;
+        unsigned long flags, orig_ret_address = 0;
+        unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+
+        INIT_HLIST_HEAD(&empty_rp);
+        kretprobe_hash_lock(current, &head, &flags);
+
+        /*
+         * It is possible to have multiple instances associated with a given
+         * task either because an multiple functions in the call path
+         * have a return probe installed on them, and/or more then one return
+         * return probe was registered for a target function.
+         *
+         * We can handle this because:
+         *     - instances are always inserted at the head of the list
+         *     - when multiple return probes are registered for the same
+         *       function, the first instance's ret_addr will point to the
+         *       real return address, and all the rest will point to
+         *       kretprobe_trampoline
+         */
+        hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+                if (ri->task != current)
+                        /* another task is sharing our hash bucket */
+                        continue;
+
+                if (ri->rp && ri->rp->handler) {
+                        __get_cpu_var(current_kprobe) = &ri->rp->kp;
+                        ri->rp->handler(ri, regs);
+                        __get_cpu_var(current_kprobe) = NULL;
+                }
+
+                orig_ret_address = (unsigned long)ri->ret_addr;
+                recycle_rp_inst(ri, &empty_rp);
+
+                if (orig_ret_address != trampoline_address)
+                        /*
+                         * This is the real return address. Any other
+                         * instances associated with this task are for
+                         * other calls deeper on the call stack
+                         */
+                        break;
+        }
+
+        kretprobe_assert(ri, orig_ret_address, trampoline_address);
+
+        regs->pc = orig_ret_address;
+        kretprobe_hash_unlock(current, &flags);
+
+        preempt_enable_no_resched();
+
+        hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+                hlist_del(&ri->hlist);
+                kfree(ri);
+        }
+
+        return orig_ret_address;
+}
+
+static int __kprobes post_kprobe_handler(struct pt_regs *regs)
+{
+        struct kprobe *cur = kprobe_running();
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+        kprobe_opcode_t *addr = NULL;
+        struct kprobe *p = NULL;
+
+        if (!cur)
+                return 0;
+
+        if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+                kcb->kprobe_status = KPROBE_HIT_SSDONE;
+                cur->post_handler(cur, regs, 0);
+        }
+
+        if (saved_next_opcode.addr != 0x0) {
+                arch_disarm_kprobe(&saved_next_opcode);
+                saved_next_opcode.addr = 0x0;
+                saved_next_opcode.opcode = 0x0;
+
+                addr = saved_current_opcode.addr;
+                saved_current_opcode.addr = 0x0;
+
+                p = get_kprobe(addr);
+                arch_arm_kprobe(p);
+
+                if (saved_next_opcode2.addr != 0x0) {
+                        arch_disarm_kprobe(&saved_next_opcode2);
+                        saved_next_opcode2.addr = 0x0;
+                        saved_next_opcode2.opcode = 0x0;
+                }
+        }
+
+        /* Restore back the original saved kprobes variables and continue. */
+        if (kcb->kprobe_status == KPROBE_REENTER) {
+                restore_previous_kprobe(kcb);
+                goto out;
+        }
+
+        reset_current_kprobe();
+
+out:
+        preempt_enable_no_resched();
+
+        return 1;
+}
+
+int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+        struct kprobe *cur = kprobe_running();
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+        const struct exception_table_entry *entry;
+
+        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, point the pc back to the probe address
+                 * and allow the page fault handler to continue as a
+                 * normal page fault.
+                 */
+                regs->pc = (unsigned long)cur->addr;
+                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 ((entry = search_exception_tables(regs->pc)) != NULL) {
+                        regs->pc = entry->fixup;
+                        return 1;
+                }
+
+                /*
+                 * fixup_exception() could not handle it,
+                 * Let do_page_fault() fix it.
+                 */
+                break;
+        default:
+                break;
+        }
+
+        return 0;
+}
+
+/*
+ * Wrapper routine to for handling exceptions.
+ */
+int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+                                       unsigned long val, void *data)
+{
+        struct kprobe *p = NULL;
+        struct die_args *args = (struct die_args *)data;
+        int ret = NOTIFY_DONE;
+        kprobe_opcode_t *addr = NULL;
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+        addr = (kprobe_opcode_t *) (args->regs->pc);
+        if (val == DIE_TRAP) {
+                if (!kprobe_running()) {
+                        if (kprobe_handler(args->regs)) {
+                                ret = NOTIFY_STOP;
+                        } else {
+                                /* Not a kprobe trap */
+                                ret = NOTIFY_DONE;
+                        }
+                } else {
+                        p = get_kprobe(addr);
+                        if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
+                            (kcb->kprobe_status == KPROBE_REENTER)) {
+                                if (post_kprobe_handler(args->regs))
+                                        ret = NOTIFY_STOP;
+                        } else {
+                                if (kprobe_handler(args->regs)) {
+                                        ret = NOTIFY_STOP;
+                                } else {
+                                        p = __get_cpu_var(current_kprobe);
+                                        if (p->break_handler &&
+                                            p->break_handler(p, args->regs))
+                                                ret = NOTIFY_STOP;
+                                }
+                        }
+                }
+        }
+
+        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_r15 = regs->regs[15];
+        addr = kcb->jprobe_saved_r15;
+
+        /*
+         * TBD: 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->pc = (unsigned long)(jp->entry);
+
+        return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+        asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t");
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+        unsigned long stack_addr = kcb->jprobe_saved_r15;
+        u8 *addr = (u8 *)regs->pc;
+
+        if ((addr >= (u8 *)jprobe_return) &&
+            (addr <= (u8 *)jprobe_return_end)) {
+                *regs = kcb->jprobe_saved_regs;
+
+                memcpy((kprobe_opcode_t *)stack_addr, kcb->jprobes_stack,
+                       MIN_STACK_SIZE(stack_addr));
+
+                kcb->kprobe_status = KPROBE_HIT_SS;
+                preempt_enable_no_resched();
+                return 1;
+        }
+
+        return 0;
+}
+
+static struct kprobe trampoline_p = {
+        .addr = (kprobe_opcode_t *)&kretprobe_trampoline,
+        .pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+        saved_next_opcode.addr = 0x0;
+        saved_next_opcode.opcode = 0x0;
+
+        saved_current_opcode.addr = 0x0;
+        saved_current_opcode.opcode = 0x0;
+
+        saved_next_opcode2.addr = 0x0;
+        saved_next_opcode2.opcode = 0x0;
+
+        return register_kprobe(&trampoline_p);
+}