1 files changed, 394 insertions, 0 deletions

diff --git a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c
new file mode 100644
index 000000000000..7066d7ba667a
--- /dev/null
+++ b/arch/sparc64/kernel/kprobes.c
@@ -0,0 +1,394 @@
+/* arch/sparc64/kernel/kprobes.c
+ *
+ * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+
+#include <asm/kdebug.h>
+#include <asm/signal.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.
+ */
+
+int arch_prepare_kprobe(struct kprobe *p)
+{
+	return 0;
+}
+
+void arch_copy_kprobe(struct kprobe *p)
+{
+	p->ainsn.insn[0] = *p->addr;
+	p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
+}
+
+void arch_remove_kprobe(struct kprobe *p)
+{
+}
+
+/* kprobe_status settings */
+#define KPROBE_HIT_ACTIVE	0x00000001
+#define KPROBE_HIT_SS		0x00000002
+
+static struct kprobe *current_kprobe;
+static unsigned long current_kprobe_orig_tnpc;
+static unsigned long current_kprobe_orig_tstate_pil;
+static unsigned int kprobe_status;
+
+static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+	current_kprobe_orig_tnpc = regs->tnpc;
+	current_kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
+	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 = current_kprobe_orig_tnpc;
+	} else {
+		regs->tpc = (unsigned long) &p->ainsn.insn[0];
+		regs->tnpc = (unsigned long) &p->ainsn.insn[1];
+	}
+}
+
+static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs)
+{
+	*p->addr = p->opcode;
+	flushi(p->addr);
+
+	regs->tpc = (unsigned long) p->addr;
+	regs->tnpc = current_kprobe_orig_tnpc;
+	regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
+			current_kprobe_orig_tstate_pil);
+}
+
+static int kprobe_handler(struct pt_regs *regs)
+{
+	struct kprobe *p;
+	void *addr = (void *) regs->tpc;
+	int ret = 0;
+
+	preempt_disable();
+
+	if (kprobe_running()) {
+		/* We *are* holding lock here, so this is safe.
+		 * Disarm the probe we just hit, and ignore it.
+		 */
+		p = get_kprobe(addr);
+		if (p) {
+			if (kprobe_status == KPROBE_HIT_SS) {
+				regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
+					current_kprobe_orig_tstate_pil);
+				unlock_kprobes();
+				goto no_kprobe;
+			}
+			disarm_kprobe(p, regs);
+			ret = 1;
+		} else {
+			p = current_kprobe;
+			if (p->break_handler && p->break_handler(p, regs))
+				goto ss_probe;
+		}
+		/* If it's not ours, can't be delete race, (we hold lock). */
+		goto no_kprobe;
+	}
+
+	lock_kprobes();
+	p = get_kprobe(addr);
+	if (!p) {
+		unlock_kprobes();
+		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;
+	}
+
+	kprobe_status = KPROBE_HIT_ACTIVE;
+	current_kprobe = p;
+	if (p->pre_handler && p->pre_handler(p, regs))
+		return 1;
+
+ss_probe:
+	prepare_singlestep(p, regs);
+	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.
+ *
+ * The original INSN location was REAL_PC, it actually
+ * executed at PC and produced destination address NPC.
+ */
+static unsigned long relbranch_fixup(u32 insn, unsigned long real_pc,
+				     unsigned long pc, unsigned long npc)
+{
+	/* Branch not taken, no mods necessary.  */
+	if (npc == pc + 0x4UL)
+		return real_pc + 0x4UL;
+
+	/* The three cases are call, branch w/prediction,
+	 * and traditional branch.
+	 */
+	if ((insn & 0xc0000000) == 0x40000000 ||
+	    (insn & 0xc1c00000) == 0x00400000 ||
+	    (insn & 0xc1c00000) == 0x00800000) {
+		/* The instruction did all the work for us
+		 * already, just apply the offset to the correct
+		 * instruction location.
+		 */
+		return (real_pc + (npc - pc));
+	}
+
+	return real_pc + 0x4UL;
+}
+
+/* If INSN is an instruction which writes it's PC location
+ * into a destination register, fix that up.
+ */
+static void retpc_fixup(struct pt_regs *regs, u32 insn, unsigned long real_pc)
+{
+	unsigned long *slot = NULL;
+
+	/* Simplest cast 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 whose first byte 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.
+ *
+ * This function prepares to return from the post-single-step
+ * breakpoint trap.
+ */
+static void resume_execution(struct kprobe *p, struct pt_regs *regs)
+{
+	u32 insn = p->ainsn.insn[0];
+
+	regs->tpc = current_kprobe_orig_tnpc;
+	regs->tnpc = relbranch_fixup(insn,
+				     (unsigned long) p->addr,
+				     (unsigned long) &p->ainsn.insn[0],
+				     regs->tnpc);
+	retpc_fixup(regs, insn, (unsigned long) p->addr);
+
+	regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
+			current_kprobe_orig_tstate_pil);
+}
+
+static inline int post_kprobe_handler(struct pt_regs *regs)
+{
+	if (!kprobe_running())
+		return 0;
+
+	if (current_kprobe->post_handler)
+		current_kprobe->post_handler(current_kprobe, regs, 0);
+
+	resume_execution(current_kprobe, regs);
+
+	unlock_kprobes();
+	preempt_enable_no_resched();
+
+	return 1;
+}
+
+/* Interrupts disabled, kprobe_lock held. */
+static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+	if (current_kprobe->fault_handler
+	    && current_kprobe->fault_handler(current_kprobe, regs, trapnr))
+		return 1;
+
+	if (kprobe_status & KPROBE_HIT_SS) {
+		resume_execution(current_kprobe, regs);
+
+		unlock_kprobes();
+		preempt_enable_no_resched();
+	}
+	return 0;
+}
+
+/*
+ * Wrapper routine to for handling exceptions.
+ */
+int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
+			     void *data)
+{
+	struct die_args *args = (struct die_args *)data;
+	switch (val) {
+	case DIE_DEBUG:
+		if (kprobe_handler(args->regs))
+			return NOTIFY_STOP;
+		break;
+	case DIE_DEBUG_2:
+		if (post_kprobe_handler(args->regs))
+			return NOTIFY_STOP;
+		break;
+	case DIE_GPF:
+		if (kprobe_running() &&
+		    kprobe_fault_handler(args->regs, args->trapnr))
+			return NOTIFY_STOP;
+		break;
+	case DIE_PAGE_FAULT:
+		if (kprobe_running() &&
+		    kprobe_fault_handler(args->regs, args->trapnr))
+			return NOTIFY_STOP;
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+asmlinkage void kprobe_trap(unsigned long trap_level, struct pt_regs *regs)
+{
+	BUG_ON(trap_level != 0x170 && trap_level != 0x171);
+
+	if (user_mode(regs)) {
+		local_irq_enable();
+		bad_trap(regs, trap_level);
+		return;
+	}
+
+	/* 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);
+}
+
+/* Jprobes support.  */
+static struct pt_regs jprobe_saved_regs;
+static struct pt_regs *jprobe_saved_regs_location;
+static struct sparc_stackf jprobe_saved_stack;
+
+int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	struct jprobe *jp = container_of(p, struct jprobe, kp);
+
+	jprobe_saved_regs_location = regs;
+	memcpy(&jprobe_saved_regs, regs, sizeof(*regs));
+
+	/* Save a whole stack frame, this gets arguments
+	 * pushed onto the stack after using up all the
+	 * arg registers.
+	 */
+	memcpy(&jprobe_saved_stack,
+	       (char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
+	       sizeof(jprobe_saved_stack));
+
+	regs->tpc  = (unsigned long) jp->entry;
+	regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
+	regs->tstate |= TSTATE_PIL;
+
+	return 1;
+}
+
+void jprobe_return(void)
+{
+	preempt_enable_no_resched();
+	__asm__ __volatile__(
+		".globl	jprobe_return_trap_instruction\n"
+"jprobe_return_trap_instruction:\n\t"
+		"ta 0x70");
+}
+
+extern void jprobe_return_trap_instruction(void);
+
+extern void __show_regs(struct pt_regs * regs);
+
+int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+	u32 *addr = (u32 *) regs->tpc;
+
+	if (addr == (u32 *) jprobe_return_trap_instruction) {
+		if (jprobe_saved_regs_location != regs) {
+			printk("JPROBE: Current regs (%p) does not match "
+			       "saved regs (%p).\n",
+			       regs, jprobe_saved_regs_location);
+			printk("JPROBE: Saved registers\n");
+			__show_regs(jprobe_saved_regs_location);
+			printk("JPROBE: Current registers\n");
+			__show_regs(regs);
+			BUG();
+		}
+		/* Restore old register state.  Do pt_regs
+		 * first so that UREG_FP is the original one for
+		 * the stack frame restore.
+		 */
+		memcpy(regs, &jprobe_saved_regs, sizeof(*regs));
+
+		memcpy((char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
+		       &jprobe_saved_stack,
+		       sizeof(jprobe_saved_stack));
+
+		return 1;
+	}
+	return 0;
+}