1 files changed, 551 insertions, 0 deletions

diff --git a/arch/sparc/kernel/kprobes.c b/arch/sparc/kernel/kprobes.c
new file mode 100644
index 000000000..dfbca2470
--- /dev/null
+++ b/arch/sparc/kernel/kprobes.c
@@ -0,0 +1,551 @@
+// SPDX-License-Identifier: GPL-2.0
+/* arch/sparc64/kernel/kprobes.c
+ *
+ * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
+ */
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/extable.h>
+#include <linux/kdebug.h>
+#include <linux/slab.h>
+#include <linux/context_tracking.h>
+#include <asm/signal.h>
+#include <asm/cacheflush.h>
+#include <linux/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 = 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)) {
+		reset_current_kprobe();
+		preempt_enable_no_resched();
+		return 1;
+	}
+
+	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 = &regs->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 = &regs->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);
+}
+
+/* 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;
+
+	kretprobe_hash_unlock(current, &flags);
+
+	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;
+}