--- /dev/null
+/* 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->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->insn[0]
+ * - Set regs->tnpc to point to kprobe->insn[1]
+ * - Mark that we are actively in a kprobe
+ *
+ * At this point we wait for the second breakpoint at
+ * kprobe->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.
+ */
+
+void arch_prepare_kprobe(struct kprobe *p)
+{
+ p->insn[0] = *p->addr;
+ p->insn[1] = BREAKPOINT_INSTRUCTION_2;
+}
+
+/* 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;
+
+ regs->tpc = (unsigned long) &p->insn[0];
+ regs->tnpc = (unsigned long) &p->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) {
+ 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, 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 = ®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 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->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->insn[0];
+
+ regs->tpc = current_kprobe_orig_tnpc;
+ regs->tnpc = relbranch_fixup(insn,
+ (unsigned long) p->addr,
+ (unsigned long) &p->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;
+}
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