--- /dev/null
+/* arch/sparc64/kernel/kprobes.c
+ *
+ * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
+ */
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/kdebug.h>
+#include <linux/slab.h>
+#include <linux/context_tracking.h>
+#include <asm/signal.h>
+#include <asm/cacheflush.h>
+#include <asm/uaccess.h>
+
+/* We do not have hardware single-stepping on sparc64.
+ * So we implement software single-stepping with breakpoint
+ * traps. The top-level scheme is similar to that used
+ * in the x86 kprobes implementation.
+ *
+ * In the kprobe->ainsn.insn[] array we store the original
+ * instruction at index zero and a break instruction at
+ * index one.
+ *
+ * When we hit a kprobe we:
+ * - Run the pre-handler
+ * - Remember "regs->tnpc" and interrupt level stored in
+ * "regs->tstate" so we can restore them later
+ * - Disable PIL interrupts
+ * - Set regs->tpc to point to kprobe->ainsn.insn[0]
+ * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
+ * - Mark that we are actively in a kprobe
+ *
+ * At this point we wait for the second breakpoint at
+ * kprobe->ainsn.insn[1] to hit. When it does we:
+ * - Run the post-handler
+ * - Set regs->tpc to "remembered" regs->tnpc stored above,
+ * restore the PIL interrupt level in "regs->tstate" as well
+ * - Make any adjustments necessary to regs->tnpc in order
+ * to handle relative branches correctly. See below.
+ * - Mark that we are no longer actively in a kprobe.
+ */
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+ if ((unsigned long) p->addr & 0x3UL)
+ return -EILSEQ;
+
+ p->ainsn.insn[0] = *p->addr;
+ flushi(&p->ainsn.insn[0]);
+
+ p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
+ flushi(&p->ainsn.insn[1]);
+
+ p->opcode = *p->addr;
+ return 0;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+ *p->addr = BREAKPOINT_INSTRUCTION;
+ flushi(p->addr);
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+ *p->addr = p->opcode;
+ flushi(p->addr);
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ kcb->prev_kprobe.kp = kprobe_running();
+ kcb->prev_kprobe.status = kcb->kprobe_status;
+ kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
+ kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+ kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
+ kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ __this_cpu_write(current_kprobe, p);
+ kcb->kprobe_orig_tnpc = regs->tnpc;
+ kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
+}
+
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ regs->tstate |= TSTATE_PIL;
+
+ /*single step inline, if it a breakpoint instruction*/
+ if (p->opcode == BREAKPOINT_INSTRUCTION) {
+ regs->tpc = (unsigned long) p->addr;
+ regs->tnpc = kcb->kprobe_orig_tnpc;
+ } else {
+ regs->tpc = (unsigned long) &p->ainsn.insn[0];
+ regs->tnpc = (unsigned long) &p->ainsn.insn[1];
+ }
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *p;
+ void *addr = (void *) regs->tpc;
+ int ret = 0;
+ struct kprobe_ctlblk *kcb;
+
+ /*
+ * We don't want to be preempted for the entire
+ * duration of kprobe processing
+ */
+ preempt_disable();
+ kcb = get_kprobe_ctlblk();
+
+ if (kprobe_running()) {
+ p = get_kprobe(addr);
+ if (p) {
+ if (kcb->kprobe_status == KPROBE_HIT_SS) {
+ regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
+ kcb->kprobe_orig_tstate_pil);
+ 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);
+ kcb->kprobe_status = KPROBE_REENTER;
+ prepare_singlestep(p, regs, kcb);
+ return 1;
+ } else {
+ if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
+ /* The breakpoint instruction was removed by
+ * another cpu right after we hit, no further
+ * handling of this interrupt is appropriate
+ */
+ ret = 1;
+ goto no_kprobe;
+ }
+ p = __this_cpu_read(current_kprobe);
+ if (p->break_handler && p->break_handler(p, regs))
+ goto ss_probe;
+ }
+ goto no_kprobe;
+ }
+
+ p = get_kprobe(addr);
+ if (!p) {
+ if (*(u32 *)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;
+ }
+ /* Not one of ours: let kernel handle it */
+ goto no_kprobe;
+ }
+
+ set_current_kprobe(p, regs, kcb);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ if (p->pre_handler && p->pre_handler(p, regs))
+ return 1;
+
+ss_probe:
+ prepare_singlestep(p, regs, kcb);
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ return 1;
+
+no_kprobe:
+ preempt_enable_no_resched();
+ return ret;
+}
+
+/* If INSN is a relative control transfer instruction,
+ * return the corrected branch destination value.
+ *
+ * regs->tpc and regs->tnpc still hold the values of the
+ * program counters at the time of trap due to the execution
+ * of the BREAKPOINT_INSTRUCTION_2 at p->ainsn.insn[1]
+ *
+ */
+static unsigned long __kprobes relbranch_fixup(u32 insn, struct kprobe *p,
+ struct pt_regs *regs)
+{
+ unsigned long real_pc = (unsigned long) p->addr;
+
+ /* Branch not taken, no mods necessary. */
+ if (regs->tnpc == regs->tpc + 0x4UL)
+ return real_pc + 0x8UL;
+
+ /* The three cases are call, branch w/prediction,
+ * and traditional branch.
+ */
+ if ((insn & 0xc0000000) == 0x40000000 ||
+ (insn & 0xc1c00000) == 0x00400000 ||
+ (insn & 0xc1c00000) == 0x00800000) {
+ unsigned long ainsn_addr;
+
+ ainsn_addr = (unsigned long) &p->ainsn.insn[0];
+
+ /* The instruction did all the work for us
+ * already, just apply the offset to the correct
+ * instruction location.
+ */
+ return (real_pc + (regs->tnpc - ainsn_addr));
+ }
+
+ /* It is jmpl or some other absolute PC modification instruction,
+ * leave NPC as-is.
+ */
+ return regs->tnpc;
+}
+
+/* If INSN is an instruction which writes it's PC location
+ * into a destination register, fix that up.
+ */
+static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
+ unsigned long real_pc)
+{
+ unsigned long *slot = NULL;
+
+ /* Simplest case is 'call', which always uses %o7 */
+ if ((insn & 0xc0000000) == 0x40000000) {
+ slot = ®s->u_regs[UREG_I7];
+ }
+
+ /* 'jmpl' encodes the register inside of the opcode */
+ if ((insn & 0xc1f80000) == 0x81c00000) {
+ unsigned long rd = ((insn >> 25) & 0x1f);
+
+ if (rd <= 15) {
+ slot = ®s->u_regs[rd];
+ } else {
+ /* Hard case, it goes onto the stack. */
+ flushw_all();
+
+ rd -= 16;
+ slot = (unsigned long *)
+ (regs->u_regs[UREG_FP] + STACK_BIAS);
+ slot += rd;
+ }
+ }
+ if (slot != NULL)
+ *slot = real_pc;
+}
+
+/*
+ * Called after single-stepping. p->addr is the address of the
+ * instruction which has been replaced by the breakpoint
+ * 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[0].
+ *
+ * This function prepares to return from the post-single-step
+ * breakpoint trap.
+ */
+static void __kprobes resume_execution(struct kprobe *p,
+ struct pt_regs *regs, struct kprobe_ctlblk *kcb)
+{
+ u32 insn = p->ainsn.insn[0];
+
+ regs->tnpc = relbranch_fixup(insn, p, regs);
+
+ /* This assignment must occur after relbranch_fixup() */
+ regs->tpc = kcb->kprobe_orig_tnpc;
+
+ retpc_fixup(regs, insn, (unsigned long) p->addr);
+
+ regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
+ kcb->kprobe_orig_tstate_pil);
+}
+
+static int __kprobes post_kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (!cur)
+ return 0;
+
+ if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ cur->post_handler(cur, regs, 0);
+ }
+
+ resume_execution(cur, regs, kcb);
+
+ /*Restore back the original saved kprobes variables and continue. */
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ restore_previous_kprobe(kcb);
+ goto out;
+ }
+ reset_current_kprobe();
+out:
+ preempt_enable_no_resched();
+
+ return 1;
+}
+
+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 and the tpc points back to the probe address
+ * and allow the page fault handler to continue as a
+ * normal page fault.
+ */
+ regs->tpc = (unsigned long)cur->addr;
+ regs->tnpc = kcb->kprobe_orig_tnpc;
+ regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
+ kcb->kprobe_orig_tstate_pil);
+ 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.
+ */
+
+ entry = search_exception_tables(regs->tpc);
+ if (entry) {
+ regs->tpc = entry->fixup;
+ regs->tnpc = regs->tpc + 4;
+ 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 die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ if (args->regs && user_mode(args->regs))
+ return ret;
+
+ switch (val) {
+ case DIE_DEBUG:
+ if (kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_DEBUG_2:
+ if (post_kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
+asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
+ struct pt_regs *regs)
+{
+ enum ctx_state prev_state = exception_enter();
+
+ BUG_ON(trap_level != 0x170 && trap_level != 0x171);
+
+ if (user_mode(regs)) {
+ local_irq_enable();
+ bad_trap(regs, trap_level);
+ goto out;
+ }
+
+ /* trap_level == 0x170 --> ta 0x70
+ * trap_level == 0x171 --> ta 0x71
+ */
+ if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
+ (trap_level == 0x170) ? "debug" : "debug_2",
+ regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
+ bad_trap(regs, trap_level);
+out:
+ exception_exit(prev_state);
+}
+
+/* Jprobes support. */
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct jprobe *jp = container_of(p, struct jprobe, kp);
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
+
+ regs->tpc = (unsigned long) jp->entry;
+ regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
+ regs->tstate |= TSTATE_PIL;
+
+ return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ register unsigned long orig_fp asm("g1");
+
+ orig_fp = kcb->jprobe_saved_regs.u_regs[UREG_FP];
+ __asm__ __volatile__("\n"
+"1: cmp %%sp, %0\n\t"
+ "blu,a,pt %%xcc, 1b\n\t"
+ " restore\n\t"
+ ".globl jprobe_return_trap_instruction\n"
+"jprobe_return_trap_instruction:\n\t"
+ "ta 0x70"
+ : /* no outputs */
+ : "r" (orig_fp));
+}
+
+extern void jprobe_return_trap_instruction(void);
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ u32 *addr = (u32 *) regs->tpc;
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (addr == (u32 *) jprobe_return_trap_instruction) {
+ memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
+ preempt_enable_no_resched();
+ return 1;
+ }
+ return 0;
+}
+
+/* The value stored in the return address register is actually 2
+ * instructions before where the callee will return to.
+ * Sequences usually look something like this
+ *
+ * call some_function <--- return register points here
+ * nop <--- call delay slot
+ * whatever <--- where callee returns to
+ *
+ * To keep trampoline_probe_handler logic simpler, we normalize the
+ * value kept in ri->ret_addr so we don't need to keep adjusting it
+ * back and forth.
+ */
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+ struct pt_regs *regs)
+{
+ ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8);
+
+ /* Replace the return addr with trampoline addr */
+ regs->u_regs[UREG_RETPC] =
+ ((unsigned long)kretprobe_trampoline) - 8;
+}
+
+/*
+ * Called when the probe at kretprobe trampoline is hit
+ */
+static int __kprobes trampoline_probe_handler(struct kprobe *p,
+ struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri = NULL;
+ struct hlist_head *head, empty_rp;
+ struct hlist_node *tmp;
+ unsigned long flags, orig_ret_address = 0;
+ unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
+
+ INIT_HLIST_HEAD(&empty_rp);
+ kretprobe_hash_lock(current, &head, &flags);
+
+ /*
+ * It is possible to have multiple instances associated with a given
+ * task either because an multiple functions in the call path
+ * have a return probe installed on them, and/or more than one return
+ * return probe was registered for a target function.
+ *
+ * We can handle this because:
+ * - instances are always inserted at the head of the list
+ * - when multiple return probes are registered for the same
+ * function, the first instance's ret_addr will point to the
+ * real return address, and all the rest will point to
+ * kretprobe_trampoline
+ */
+ hlist_for_each_entry_safe(ri, tmp, head, hlist) {
+ if (ri->task != current)
+ /* another task is sharing our hash bucket */
+ continue;
+
+ if (ri->rp && ri->rp->handler)
+ ri->rp->handler(ri, regs);
+
+ orig_ret_address = (unsigned long)ri->ret_addr;
+ recycle_rp_inst(ri, &empty_rp);
+
+ if (orig_ret_address != trampoline_address)
+ /*
+ * This is the real return address. Any other
+ * instances associated with this task are for
+ * other calls deeper on the call stack
+ */
+ break;
+ }
+
+ kretprobe_assert(ri, orig_ret_address, trampoline_address);
+ regs->tpc = orig_ret_address;
+ regs->tnpc = orig_ret_address + 4;
+
+ reset_current_kprobe();
+ kretprobe_hash_unlock(current, &flags);
+ preempt_enable_no_resched();
+
+ hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
+ hlist_del(&ri->hlist);
+ kfree(ri);
+ }
+ /*
+ * By returning a non-zero value, we are telling
+ * kprobe_handler() that we don't want the post_handler
+ * to run (and have re-enabled preemption)
+ */
+ return 1;
+}
+
+static void __used kretprobe_trampoline_holder(void)
+{
+ asm volatile(".global kretprobe_trampoline\n"
+ "kretprobe_trampoline:\n"
+ "\tnop\n"
+ "\tnop\n");
+}
+static struct kprobe trampoline_p = {
+ .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
+ .pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+ return register_kprobe(&trampoline_p);
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+ if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
+ return 1;
+
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff