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 <linux/module.h>
10 #include <asm/kdebug.h>
11 #include <asm/signal.h>
12 #include <asm/cacheflush.h>
13 #include <asm/uaccess.h>
15 /* We do not have hardware single-stepping on sparc64.
16 * So we implement software single-stepping with breakpoint
17 * traps. The top-level scheme is similar to that used
18 * in the x86 kprobes implementation.
20 * In the kprobe->ainsn.insn[] array we store the original
21 * instruction at index zero and a break instruction at
24 * When we hit a kprobe we:
25 * - Run the pre-handler
26 * - Remember "regs->tnpc" and interrupt level stored in
27 * "regs->tstate" so we can restore them later
28 * - Disable PIL interrupts
29 * - Set regs->tpc to point to kprobe->ainsn.insn[0]
30 * - Set regs->tnpc to point to kprobe->ainsn.insn[1]
31 * - Mark that we are actively in a kprobe
33 * At this point we wait for the second breakpoint at
34 * kprobe->ainsn.insn[1] to hit. When it does we:
35 * - Run the post-handler
36 * - Set regs->tpc to "remembered" regs->tnpc stored above,
37 * restore the PIL interrupt level in "regs->tstate" as well
38 * - Make any adjustments necessary to regs->tnpc in order
39 * to handle relative branches correctly. See below.
40 * - Mark that we are no longer actively in a kprobe.
43 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
44 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
46 int __kprobes arch_prepare_kprobe(struct kprobe *p)
48 p->ainsn.insn[0] = *p->addr;
49 p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
54 void __kprobes arch_arm_kprobe(struct kprobe *p)
56 *p->addr = BREAKPOINT_INSTRUCTION;
60 void __kprobes arch_disarm_kprobe(struct kprobe *p)
66 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
68 kcb->prev_kprobe.kp = kprobe_running();
69 kcb->prev_kprobe.status = kcb->kprobe_status;
70 kcb->prev_kprobe.orig_tnpc = kcb->kprobe_orig_tnpc;
71 kcb->prev_kprobe.orig_tstate_pil = kcb->kprobe_orig_tstate_pil;
74 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
76 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
77 kcb->kprobe_status = kcb->prev_kprobe.status;
78 kcb->kprobe_orig_tnpc = kcb->prev_kprobe.orig_tnpc;
79 kcb->kprobe_orig_tstate_pil = kcb->prev_kprobe.orig_tstate_pil;
82 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
83 struct kprobe_ctlblk *kcb)
85 __get_cpu_var(current_kprobe) = p;
86 kcb->kprobe_orig_tnpc = regs->tnpc;
87 kcb->kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL);
90 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
91 struct kprobe_ctlblk *kcb)
93 regs->tstate |= TSTATE_PIL;
95 /*single step inline, if it a breakpoint instruction*/
96 if (p->opcode == BREAKPOINT_INSTRUCTION) {
97 regs->tpc = (unsigned long) p->addr;
98 regs->tnpc = kcb->kprobe_orig_tnpc;
100 regs->tpc = (unsigned long) &p->ainsn.insn[0];
101 regs->tnpc = (unsigned long) &p->ainsn.insn[1];
105 static int __kprobes kprobe_handler(struct pt_regs *regs)
108 void *addr = (void *) regs->tpc;
110 struct kprobe_ctlblk *kcb;
113 * We don't want to be preempted for the entire
114 * duration of kprobe processing
117 kcb = get_kprobe_ctlblk();
119 if (kprobe_running()) {
120 p = get_kprobe(addr);
122 if (kcb->kprobe_status == KPROBE_HIT_SS) {
123 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
124 kcb->kprobe_orig_tstate_pil);
127 /* We have reentered the kprobe_handler(), since
128 * another probe was hit while within the handler.
129 * We here save the original kprobes variables and
130 * just single step on the instruction of the new probe
131 * without calling any user handlers.
133 save_previous_kprobe(kcb);
134 set_current_kprobe(p, regs, kcb);
135 kprobes_inc_nmissed_count(p);
136 kcb->kprobe_status = KPROBE_REENTER;
137 prepare_singlestep(p, regs, kcb);
140 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
141 /* The breakpoint instruction was removed by
142 * another cpu right after we hit, no further
143 * handling of this interrupt is appropriate
148 p = __get_cpu_var(current_kprobe);
149 if (p->break_handler && p->break_handler(p, regs))
155 p = get_kprobe(addr);
157 if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) {
159 * The breakpoint instruction was removed right
160 * after we hit it. Another cpu has removed
161 * either a probepoint or a debugger breakpoint
162 * at this address. In either case, no further
163 * handling of this interrupt is appropriate.
167 /* Not one of ours: let kernel handle it */
171 set_current_kprobe(p, regs, kcb);
172 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
173 if (p->pre_handler && p->pre_handler(p, regs))
177 prepare_singlestep(p, regs, kcb);
178 kcb->kprobe_status = KPROBE_HIT_SS;
182 preempt_enable_no_resched();
186 /* If INSN is a relative control transfer instruction,
187 * return the corrected branch destination value.
189 * The original INSN location was REAL_PC, it actually
190 * executed at PC and produced destination address NPC.
192 static unsigned long __kprobes relbranch_fixup(u32 insn, unsigned long real_pc,
196 /* Branch not taken, no mods necessary. */
197 if (npc == pc + 0x4UL)
198 return real_pc + 0x4UL;
200 /* The three cases are call, branch w/prediction,
201 * and traditional branch.
203 if ((insn & 0xc0000000) == 0x40000000 ||
204 (insn & 0xc1c00000) == 0x00400000 ||
205 (insn & 0xc1c00000) == 0x00800000) {
206 /* The instruction did all the work for us
207 * already, just apply the offset to the correct
208 * instruction location.
210 return (real_pc + (npc - pc));
213 return real_pc + 0x4UL;
216 /* If INSN is an instruction which writes it's PC location
217 * into a destination register, fix that up.
219 static void __kprobes retpc_fixup(struct pt_regs *regs, u32 insn,
220 unsigned long real_pc)
222 unsigned long *slot = NULL;
224 /* Simplest cast is call, which always uses %o7 */
225 if ((insn & 0xc0000000) == 0x40000000) {
226 slot = ®s->u_regs[UREG_I7];
229 /* Jmpl encodes the register inside of the opcode */
230 if ((insn & 0xc1f80000) == 0x81c00000) {
231 unsigned long rd = ((insn >> 25) & 0x1f);
234 slot = ®s->u_regs[rd];
236 /* Hard case, it goes onto the stack. */
240 slot = (unsigned long *)
241 (regs->u_regs[UREG_FP] + STACK_BIAS);
250 * Called after single-stepping. p->addr is the address of the
251 * instruction whose first byte has been replaced by the breakpoint
252 * instruction. To avoid the SMP problems that can occur when we
253 * temporarily put back the original opcode to single-step, we
254 * single-stepped a copy of the instruction. The address of this
255 * copy is p->ainsn.insn.
257 * This function prepares to return from the post-single-step
260 static void __kprobes resume_execution(struct kprobe *p,
261 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
263 u32 insn = p->ainsn.insn[0];
265 regs->tpc = kcb->kprobe_orig_tnpc;
266 regs->tnpc = relbranch_fixup(insn,
267 (unsigned long) p->addr,
268 (unsigned long) &p->ainsn.insn[0],
270 retpc_fixup(regs, insn, (unsigned long) p->addr);
272 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
273 kcb->kprobe_orig_tstate_pil);
276 static int __kprobes post_kprobe_handler(struct pt_regs *regs)
278 struct kprobe *cur = kprobe_running();
279 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
284 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
285 kcb->kprobe_status = KPROBE_HIT_SSDONE;
286 cur->post_handler(cur, regs, 0);
289 resume_execution(cur, regs, kcb);
291 /*Restore back the original saved kprobes variables and continue. */
292 if (kcb->kprobe_status == KPROBE_REENTER) {
293 restore_previous_kprobe(kcb);
296 reset_current_kprobe();
298 preempt_enable_no_resched();
303 static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
305 struct kprobe *cur = kprobe_running();
306 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
307 const struct exception_table_entry *entry;
309 switch(kcb->kprobe_status) {
313 * We are here because the instruction being single
314 * stepped caused a page fault. We reset the current
315 * kprobe and the tpc points back to the probe address
316 * and allow the page fault handler to continue as a
319 regs->tpc = (unsigned long)cur->addr;
320 regs->tnpc = kcb->kprobe_orig_tnpc;
321 regs->tstate = ((regs->tstate & ~TSTATE_PIL) |
322 kcb->kprobe_orig_tstate_pil);
323 if (kcb->kprobe_status == KPROBE_REENTER)
324 restore_previous_kprobe(kcb);
326 reset_current_kprobe();
327 preempt_enable_no_resched();
329 case KPROBE_HIT_ACTIVE:
330 case KPROBE_HIT_SSDONE:
332 * We increment the nmissed count for accounting,
333 * we can also use npre/npostfault count for accouting
334 * these specific fault cases.
336 kprobes_inc_nmissed_count(cur);
339 * We come here because instructions in the pre/post
340 * handler caused the page_fault, this could happen
341 * if handler tries to access user space by
342 * copy_from_user(), get_user() etc. Let the
343 * user-specified handler try to fix it first.
345 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
349 * In case the user-specified fault handler returned
350 * zero, try to fix up.
353 entry = search_exception_tables(regs->tpc);
355 regs->tpc = entry->fixup;
356 regs->tnpc = regs->tpc + 4;
361 * fixup_exception() could not handle it,
362 * Let do_page_fault() fix it.
373 * Wrapper routine to for handling exceptions.
375 int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
376 unsigned long val, void *data)
378 struct die_args *args = (struct die_args *)data;
379 int ret = NOTIFY_DONE;
381 if (args->regs && user_mode(args->regs))
386 if (kprobe_handler(args->regs))
390 if (post_kprobe_handler(args->regs))
395 /* kprobe_running() needs smp_processor_id() */
397 if (kprobe_running() &&
398 kprobe_fault_handler(args->regs, args->trapnr))
408 asmlinkage void __kprobes kprobe_trap(unsigned long trap_level,
409 struct pt_regs *regs)
411 BUG_ON(trap_level != 0x170 && trap_level != 0x171);
413 if (user_mode(regs)) {
415 bad_trap(regs, trap_level);
419 /* trap_level == 0x170 --> ta 0x70
420 * trap_level == 0x171 --> ta 0x71
422 if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2,
423 (trap_level == 0x170) ? "debug" : "debug_2",
424 regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP)
425 bad_trap(regs, trap_level);
428 /* Jprobes support. */
429 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
431 struct jprobe *jp = container_of(p, struct jprobe, kp);
432 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
434 kcb->jprobe_saved_regs_location = regs;
435 memcpy(&(kcb->jprobe_saved_regs), regs, sizeof(*regs));
437 /* Save a whole stack frame, this gets arguments
438 * pushed onto the stack after using up all the
441 memcpy(&(kcb->jprobe_saved_stack),
442 (char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
443 sizeof(kcb->jprobe_saved_stack));
445 regs->tpc = (unsigned long) jp->entry;
446 regs->tnpc = ((unsigned long) jp->entry) + 0x4UL;
447 regs->tstate |= TSTATE_PIL;
452 void __kprobes jprobe_return(void)
454 __asm__ __volatile__(
455 ".globl jprobe_return_trap_instruction\n"
456 "jprobe_return_trap_instruction:\n\t"
460 extern void jprobe_return_trap_instruction(void);
462 extern void __show_regs(struct pt_regs * regs);
464 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
466 u32 *addr = (u32 *) regs->tpc;
467 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
469 if (addr == (u32 *) jprobe_return_trap_instruction) {
470 if (kcb->jprobe_saved_regs_location != regs) {
471 printk("JPROBE: Current regs (%p) does not match "
472 "saved regs (%p).\n",
473 regs, kcb->jprobe_saved_regs_location);
474 printk("JPROBE: Saved registers\n");
475 __show_regs(kcb->jprobe_saved_regs_location);
476 printk("JPROBE: Current registers\n");
480 /* Restore old register state. Do pt_regs
481 * first so that UREG_FP is the original one for
482 * the stack frame restore.
484 memcpy(regs, &(kcb->jprobe_saved_regs), sizeof(*regs));
486 memcpy((char *) (regs->u_regs[UREG_FP] + STACK_BIAS),
487 &(kcb->jprobe_saved_stack),
488 sizeof(kcb->jprobe_saved_stack));
490 preempt_enable_no_resched();
496 /* architecture specific initialization */
497 int arch_init_kprobes(void)