1 /* arch/sparc64/kernel/kprobes.c
3 * Copyright (C) 2004 David S. Miller <davem@davemloft.net>
6 #include <linux/config.h>
7 #include <linux/kernel.h>
8 #include <linux/kprobes.h>
9 #include <asm/kdebug.h>
10 #include <asm/signal.h>
11 #include <asm/cacheflush.h>
13 /* We do not have hardware single-stepping on sparc64.
14 * So we implement software single-stepping with breakpoint
15 * traps. The top-level scheme is similar to that used
16 * in the x86 kprobes implementation.
18 * In the kprobe->ainsn.insn[] array we store the original
19 * instruction at index zero and a break instruction at
22 * When we hit a kprobe we:
23 * - Run the pre-handler
24 * - Remember "regs->tnpc" and interrupt level stored in
25 * "regs->tstate" so we can restore them later
26 * - Disable PIL interrupts
27 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
28 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
29 * - Mark that we are actively in a kprobe
31 * At this point we wait for the second breakpoint at
32 * kprobe->ainsn.insn[1] to hit. When it does we:
33 * - Run the post-handler
34 * - Set regs->tpc to "remembered" regs->tnpc stored above,
35 * restore the PIL interrupt level in "regs->tstate" as well
36 * - Make any adjustments necessary to regs->tnpc in order
37 * to handle relative branches correctly. See below.
38 * - Mark that we are no longer actively in a kprobe.
41 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
42 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
44 int __kprobes arch_prepare_kprobe(struct kprobe *p)
46 p->ainsn.insn[0] = *p->addr;
47 p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
52 void __kprobes arch_arm_kprobe(struct kprobe *p)
54 *p->addr = BREAKPOINT_INSTRUCTION;
58 void __kprobes arch_disarm_kprobe(struct kprobe *p)
64 void __kprobes arch_remove_kprobe(struct kprobe *p)
68 static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
70 kcb->prev_kprobe.kp = kprobe_running();
71 kcb->prev_kprobe.status = kcb->kprobe_status;
72 kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
73 kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
76 static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
78 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
79 kcb->kprobe_status = kcb->prev_kprobe.status;
80 kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
81 kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
84 static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
85 struct kprobe_ctlblk *kcb)
87 __get_cpu_var(current_kprobe) = p;
88 kcb->kprobe_orig_tnpc = regs->tnpc;
89 kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
92 static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
93 struct kprobe_ctlblk *kcb)
95 regs->tstate |= TSTATE_PIL;
97 /*single step inline, if it a breakpoint instruction*/
98 if (p->opcode == BREAKPOINT_INSTRUCTION) {
99 regs->tpc = (unsigned long) p->addr;
100 regs->tnpc = kcb->kprobe_orig_tnpc;
102 regs->tpc = (unsigned long) &p->ainsn.insn[0];
103 regs->tnpc = (unsigned long) &p->ainsn.insn[1];
107 static int __kprobes kprobe_handler(struct pt_regs *regs)
110 void *addr = (void *) regs->tpc;
112 struct kprobe_ctlblk *kcb;
115 * We don't want to be preempted for the entire
116 * duration of kprobe processing
119 kcb = get_kprobe_ctlblk();
121 if (kprobe_running()) {
122 p = get_kprobe(addr);
124 if (kcb->kprobe_status == KPROBE_HIT_SS) {
125 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
126 kcb->kprobe_orig_tstate_pil);
129 /* We have reentered the kprobe_handler(), since
130 * another probe was hit while within the handler.
131 * We here save the original kprobes variables and
132 * just single step on the instruction of the new probe
133 * without calling any user handlers.
135 save_previous_kprobe(kcb);
136 set_current_kprobe(p, regs, kcb);
137 kprobes_inc_nmissed_count(p);
138 kcb->kprobe_status = KPROBE_REENTER;
139 prepare_singlestep(p, regs, kcb);
142 p = __get_cpu_var(current_kprobe);
143 if (p->break_handler && p->break_handler(p, regs))
149 p = get_kprobe(addr);
151 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
153 * The breakpoint instruction was removed right
154 * after we hit it. Another cpu has removed
155 * either a probepoint or a debugger breakpoint
156 * at this address. In either case, no further
157 * handling of this interrupt is appropriate.
161 /* Not one of ours: let kernel handle it */
165 set_current_kprobe(p, regs, kcb);
166 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
167 if (p->pre_handler && p->pre_handler(p, regs))
171 prepare_singlestep(p, regs, kcb);
172 kcb->kprobe_status = KPROBE_HIT_SS;
176 preempt_enable_no_resched();
180 /* If INSN is a relative control transfer instruction,
181 * return the corrected branch destination value.
183 * The original INSN location was REAL_PC, it actually
184 * executed at PC and produced destination address NPC.
186 static unsigned long __kprobes relbranch_fixup(u32 insn, unsigned long real_pc,
190 /* Branch not taken, no mods necessary. */
191 if (npc == pc + 0x4UL)
192 return real_pc + 0x4UL;
194 /* The three cases are call, branch w/prediction,
195 * and traditional branch.
197 if ((insn & 0xc0000000) == 0x40000000 ||
198 (insn & 0xc1c00000) == 0x00400000 ||
199 (insn & 0xc1c00000) == 0x00800000) {
200 /* The instruction did all the work for us
201 * already, just apply the offset to the correct
202 * instruction location.
204 return (real_pc + (npc - pc));
207 return real_pc + 0x4UL;
210 /* If INSN is an instruction which writes it's PC location
211 * into a destination register, fix that up.
213 static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
214 unsigned long real_pc)
216 unsigned long *slot = NULL;
218 /* Simplest cast is call, which always uses %o7 */
219 if ((insn & 0xc0000000) == 0x40000000) {
220 slot = ®s->u_regs[UREG_I7];
223 /* Jmpl encodes the register inside of the opcode */
224 if ((insn & 0xc1f80000) == 0x81c00000) {
225 unsigned long rd = ((insn >> 25) & 0x1f);
228 slot = ®s->u_regs[rd];
230 /* Hard case, it goes onto the stack. */
234 slot = (unsigned long *)
235 (regs->u_regs[UREG_FP] + STACK_BIAS);
244 * Called after single-stepping. p->addr is the address of the
245 * instruction whose first byte has been replaced by the breakpoint
246 * instruction. To avoid the SMP problems that can occur when we
247 * temporarily put back the original opcode to single-step, we
248 * single-stepped a copy of the instruction. The address of this
249 * copy is p->ainsn.insn.
251 * This function prepares to return from the post-single-step
254 static void __kprobes resume_execution(struct kprobe *p,
255 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
257 u32 insn = p->ainsn.insn[0];
259 regs->tpc = kcb->kprobe_orig_tnpc;
260 regs->tnpc = relbranch_fixup(insn,
261 (unsigned long) p->addr,
262 (unsigned long) &p->ainsn.insn[0],
264 retpc_fixup(regs, insn, (unsigned long) p->addr);
266 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
267 kcb->kprobe_orig_tstate_pil);
270 static inline int post_kprobe_handler(struct pt_regs *regs)
272 struct kprobe *cur = kprobe_running();
273 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
278 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
279 kcb->kprobe_status = KPROBE_HIT_SSDONE;
280 cur->post_handler(cur, regs, 0);
283 resume_execution(cur, regs, kcb);
285 /*Restore back the original saved kprobes variables and continue. */
286 if (kcb->kprobe_status == KPROBE_REENTER) {
287 restore_previous_kprobe(kcb);
290 reset_current_kprobe();
292 preempt_enable_no_resched();
297 static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
299 struct kprobe *cur = kprobe_running();
300 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
302 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
305 if (kcb->kprobe_status & KPROBE_HIT_SS) {
306 resume_execution(cur, regs, kcb);
308 reset_current_kprobe();
309 preempt_enable_no_resched();
315 * Wrapper routine to for handling exceptions.
317 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
318 unsigned long val, void *data)
320 struct die_args *args = (struct die_args *)data;
321 int ret = NOTIFY_DONE;
325 if (kprobe_handler(args->regs))
329 if (post_kprobe_handler(args->regs))
334 /* kprobe_running() needs smp_processor_id() */
336 if (kprobe_running() &&
337 kprobe_fault_handler(args->regs, args->trapnr))
347 asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
348 struct pt_regs *regs)
350 BUG_ON(trap_level != 0x170 && trap_level != 0x171);
352 if (user_mode(regs)) {
354 bad_trap(regs, trap_level);
358 /* trap_level == 0x170 --> ta 0x70
359 * trap_level == 0x171 --> ta 0x71
361 if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
362 (trap_level == 0x170) ? "debug" : "debug_2",
363 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
364 bad_trap(regs, trap_level);
367 /* Jprobes support. */
368 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
370 struct jprobe *jp = container_of(p, struct jprobe, kp);
371 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
373 kcb->jprobe_saved_regs_location = regs;
374 memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
376 /* Save a whole stack frame, this gets arguments
377 * pushed onto the stack after using up all the
380 memcpy(&(kcb->jprobe_saved_stack),
381 (char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
382 sizeof(kcb->jprobe_saved_stack));
384 regs->tpc = (unsigned long) jp->entry;
385 regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
386 regs->tstate |= TSTATE_PIL;
391 void __kprobes jprobe_return(void)
393 __asm__ __volatile__(
394 ".globl jprobe_return_trap_instruction\n"
395 "jprobe_return_trap_instruction:\n\t"
399 extern void jprobe_return_trap_instruction(void);
401 extern void __show_regs(struct pt_regs * regs);
403 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
405 u32 *addr = (u32 *) regs->tpc;
406 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
408 if (addr == (u32 *) jprobe_return_trap_instruction) {
409 if (kcb->jprobe_saved_regs_location != regs) {
410 printk("JPROBE: Current regs (%p) does not match "
411 "saved regs (%p).\n",
412 regs, kcb->jprobe_saved_regs_location);
413 printk("JPROBE: Saved registers\n");
414 __show_regs(kcb->jprobe_saved_regs_location);
415 printk("JPROBE: Current registers\n");
419 /* Restore old register state. Do pt_regs
420 * first so that UREG_FP is the original one for
421 * the stack frame restore.
423 memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
425 memcpy((char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
426 &(kcb->jprobe_saved_stack),
427 sizeof(kcb->jprobe_saved_stack));
429 preempt_enable_no_resched();
435 /* architecture specific initialization */
436 int arch_init_kprobes(void)