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authorRusty Lynch <rusty.lynch@intel.com>2005-06-27 18:17:09 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-27 18:23:53 -0400
commit4bdbd37f6d01abc4c002bb8de90ea2c3bc7abe7e (patch)
tree91e6506a091cfaeabd6d2ff81ed628b607189a71 /arch/i386/kernel/kprobes.c
parent802eae7c800fb7f583e6c06afa363585af2bef00 (diff)
[PATCH] Return probe redesign: i386 specific changes
The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386/kernel/kprobes.c')
-rw-r--r--arch/i386/kernel/kprobes.c133
1 files changed, 70 insertions, 63 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index 3762f6b35ab2..fc8b17521761 100644
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -127,48 +127,23 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
127 regs->eip = (unsigned long)&p->ainsn.insn; 127 regs->eip = (unsigned long)&p->ainsn.insn;
128} 128}
129 129
130struct task_struct *arch_get_kprobe_task(void *ptr)
131{
132 return ((struct thread_info *) (((unsigned long) ptr) &
133 (~(THREAD_SIZE -1))))->task;
134}
135
136void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs) 130void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs)
137{ 131{
138 unsigned long *sara = (unsigned long *)&regs->esp; 132 unsigned long *sara = (unsigned long *)&regs->esp;
139 struct kretprobe_instance *ri; 133 struct kretprobe_instance *ri;
140 static void *orig_ret_addr; 134
135 if ((ri = get_free_rp_inst(rp)) != NULL) {
136 ri->rp = rp;
137 ri->task = current;
138 ri->ret_addr = (kprobe_opcode_t *) *sara;
141 139
142 /*
143 * Save the return address when the return probe hits
144 * the first time, and use it to populate the (krprobe
145 * instance)->ret_addr for subsequent return probes at
146 * the same addrress since stack address would have
147 * the kretprobe_trampoline by then.
148 */
149 if (((void*) *sara) != kretprobe_trampoline)
150 orig_ret_addr = (void*) *sara;
151
152 if ((ri = get_free_rp_inst(rp)) != NULL) {
153 ri->rp = rp;
154 ri->stack_addr = sara;
155 ri->ret_addr = orig_ret_addr;
156 add_rp_inst(ri);
157 /* Replace the return addr with trampoline addr */ 140 /* Replace the return addr with trampoline addr */
158 *sara = (unsigned long) &kretprobe_trampoline; 141 *sara = (unsigned long) &kretprobe_trampoline;
159 } else {
160 rp->nmissed++;
161 }
162}
163 142
164void arch_kprobe_flush_task(struct task_struct *tk) 143 add_rp_inst(ri);
165{ 144 } else {
166 struct kretprobe_instance *ri; 145 rp->nmissed++;
167 while ((ri = get_rp_inst_tsk(tk)) != NULL) { 146 }
168 *((unsigned long *)(ri->stack_addr)) =
169 (unsigned long) ri->ret_addr;
170 recycle_rp_inst(ri);
171 }
172} 147}
173 148
174/* 149/*
@@ -286,36 +261,59 @@ no_kprobe:
286 */ 261 */
287int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) 262int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
288{ 263{
289 struct task_struct *tsk; 264 struct kretprobe_instance *ri = NULL;
290 struct kretprobe_instance *ri; 265 struct hlist_head *head;
291 struct hlist_head *head; 266 struct hlist_node *node, *tmp;
292 struct hlist_node *node; 267 unsigned long orig_ret_address = 0;
293 unsigned long *sara = ((unsigned long *) &regs->esp) - 1; 268 unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
294
295 tsk = arch_get_kprobe_task(sara);
296 head = kretprobe_inst_table_head(tsk);
297
298 hlist_for_each_entry(ri, node, head, hlist) {
299 if (ri->stack_addr == sara && ri->rp) {
300 if (ri->rp->handler)
301 ri->rp->handler(ri, regs);
302 }
303 }
304 return 0;
305}
306 269
307void trampoline_post_handler(struct kprobe *p, struct pt_regs *regs, 270 head = kretprobe_inst_table_head(current);
308 unsigned long flags)
309{
310 struct kretprobe_instance *ri;
311 /* RA already popped */
312 unsigned long *sara = ((unsigned long *)&regs->esp) - 1;
313 271
314 while ((ri = get_rp_inst(sara))) { 272 /*
315 regs->eip = (unsigned long)ri->ret_addr; 273 * It is possible to have multiple instances associated with a given
274 * task either because an multiple functions in the call path
275 * have a return probe installed on them, and/or more then one return
276 * return probe was registered for a target function.
277 *
278 * We can handle this because:
279 * - instances are always inserted at the head of the list
280 * - when multiple return probes are registered for the same
281 * function, the first instance's ret_addr will point to the
282 * real return address, and all the rest will point to
283 * kretprobe_trampoline
284 */
285 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
286 if (ri->task != current)
287 /* another task is sharing our hash bucket */
288 continue;
289
290 if (ri->rp && ri->rp->handler)
291 ri->rp->handler(ri, regs);
292
293 orig_ret_address = (unsigned long)ri->ret_addr;
316 recycle_rp_inst(ri); 294 recycle_rp_inst(ri);
295
296 if (orig_ret_address != trampoline_address)
297 /*
298 * This is the real return address. Any other
299 * instances associated with this task are for
300 * other calls deeper on the call stack
301 */
302 break;
317 } 303 }
318 regs->eflags &= ~TF_MASK; 304
305 BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
306 regs->eip = orig_ret_address;
307
308 unlock_kprobes();
309 preempt_enable_no_resched();
310
311 /*
312 * By returning a non-zero value, we are telling
313 * kprobe_handler() that we have handled unlocking
314 * and re-enabling preemption.
315 */
316 return 1;
319} 317}
320 318
321/* 319/*
@@ -403,8 +401,7 @@ static inline int post_kprobe_handler(struct pt_regs *regs)
403 current_kprobe->post_handler(current_kprobe, regs, 0); 401 current_kprobe->post_handler(current_kprobe, regs, 0);
404 } 402 }
405 403
406 if (current_kprobe->post_handler != trampoline_post_handler) 404 resume_execution(current_kprobe, regs);
407 resume_execution(current_kprobe, regs);
408 regs->eflags |= kprobe_saved_eflags; 405 regs->eflags |= kprobe_saved_eflags;
409 406
410 /*Restore back the original saved kprobes variables and continue. */ 407 /*Restore back the original saved kprobes variables and continue. */
@@ -534,3 +531,13 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
534 } 531 }
535 return 0; 532 return 0;
536} 533}
534
535static struct kprobe trampoline_p = {
536 .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
537 .pre_handler = trampoline_probe_handler
538};
539
540int __init arch_init(void)
541{
542 return register_kprobe(&trampoline_p);
543}