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SubjectRe: [PATCH 5.4.y] Revert "ia64: kprobes: Use generic kretprobe trampoline handler"
Hi Masami,

I love your patch! Perhaps something to improve:

[auto build test WARNING on stable/linux-5.4.y]

url: https://github.com/0day-ci/linux/commits/Masami-Hiramatsu/Revert-ia64-kprobes-Use-generic-kretprobe-trampoline-handler/20220114-182111
base: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-5.4.y
config: ia64-allmodconfig (https://download.01.org/0day-ci/archive/20220115/202201151231.g2sW8oWt-lkp@intel.com/config)
compiler: ia64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/514059de80b018e0edcf434519ff6bf41b4a519b
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Masami-Hiramatsu/Revert-ia64-kprobes-Use-generic-kretprobe-trampoline-handler/20220114-182111
git checkout 514059de80b018e0edcf434519ff6bf41b4a519b
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=ia64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

arch/ia64/kernel/kprobes.c: In function 'get_kprobe_inst':
arch/ia64/kernel/kprobes.c:325:22: warning: variable 'template' set but not used [-Wunused-but-set-variable]
325 | unsigned int template;
| ^~~~~~~~
arch/ia64/kernel/kprobes.c: At top level:
arch/ia64/kernel/kprobes.c:407:15: warning: no previous prototype for 'trampoline_probe_handler' [-Wmissing-prototypes]
407 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
| ^~~~~~~~~~~~~~~~~~~~~~~~
arch/ia64/kernel/kprobes.c: In function 'trampoline_probe_handler':
>> arch/ia64/kernel/kprobes.c:414:17: warning: initialization of 'long unsigned int' from 'void *' makes integer from pointer without a cast [-Wint-conversion]
414 | dereference_function_descriptor(kretprobe_trampoline);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Kconfig warnings: (for reference only)
WARNING: unmet direct dependencies detected for FRAME_POINTER
Depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
Selected by
- FAULT_INJECTION_STACKTRACE_FILTER && FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT && !X86_64 && !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86


vim +414 arch/ia64/kernel/kprobes.c

320
321 static void __kprobes get_kprobe_inst(bundle_t *bundle, uint slot,
322 unsigned long *kprobe_inst, uint *major_opcode)
323 {
324 unsigned long kprobe_inst_p0, kprobe_inst_p1;
> 325 unsigned int template;
326
327 template = bundle->quad0.template;
328
329 switch (slot) {
330 case 0:
331 *major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
332 *kprobe_inst = bundle->quad0.slot0;
333 break;
334 case 1:
335 *major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
336 kprobe_inst_p0 = bundle->quad0.slot1_p0;
337 kprobe_inst_p1 = bundle->quad1.slot1_p1;
338 *kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
339 break;
340 case 2:
341 *major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
342 *kprobe_inst = bundle->quad1.slot2;
343 break;
344 }
345 }
346
347 /* Returns non-zero if the addr is in the Interrupt Vector Table */
348 static int __kprobes in_ivt_functions(unsigned long addr)
349 {
350 return (addr >= (unsigned long)__start_ivt_text
351 && addr < (unsigned long)__end_ivt_text);
352 }
353
354 static int __kprobes valid_kprobe_addr(int template, int slot,
355 unsigned long addr)
356 {
357 if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
358 printk(KERN_WARNING "Attempting to insert unaligned kprobe "
359 "at 0x%lx\n", addr);
360 return -EINVAL;
361 }
362
363 if (in_ivt_functions(addr)) {
364 printk(KERN_WARNING "Kprobes can't be inserted inside "
365 "IVT functions at 0x%lx\n", addr);
366 return -EINVAL;
367 }
368
369 return 0;
370 }
371
372 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
373 {
374 unsigned int i;
375 i = atomic_add_return(1, &kcb->prev_kprobe_index);
376 kcb->prev_kprobe[i-1].kp = kprobe_running();
377 kcb->prev_kprobe[i-1].status = kcb->kprobe_status;
378 }
379
380 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
381 {
382 unsigned int i;
383 i = atomic_read(&kcb->prev_kprobe_index);
384 __this_cpu_write(current_kprobe, kcb->prev_kprobe[i-1].kp);
385 kcb->kprobe_status = kcb->prev_kprobe[i-1].status;
386 atomic_sub(1, &kcb->prev_kprobe_index);
387 }
388
389 static void __kprobes set_current_kprobe(struct kprobe *p,
390 struct kprobe_ctlblk *kcb)
391 {
392 __this_cpu_write(current_kprobe, p);
393 }
394
395 static void kretprobe_trampoline(void)
396 {
397 }
398
399 /*
400 * At this point the target function has been tricked into
401 * returning into our trampoline. Lookup the associated instance
402 * and then:
403 * - call the handler function
404 * - cleanup by marking the instance as unused
405 * - long jump back to the original return address
406 */
407 int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
408 {
409 struct kretprobe_instance *ri = NULL;
410 struct hlist_head *head, empty_rp;
411 struct hlist_node *tmp;
412 unsigned long flags, orig_ret_address = 0;
413 unsigned long trampoline_address =
> 414 dereference_function_descriptor(kretprobe_trampoline);
415
416 INIT_HLIST_HEAD(&empty_rp);
417 kretprobe_hash_lock(current, &head, &flags);
418
419 /*
420 * It is possible to have multiple instances associated with a given
421 * task either because an multiple functions in the call path
422 * have a return probe installed on them, and/or more than one return
423 * return probe was registered for a target function.
424 *
425 * We can handle this because:
426 * - instances are always inserted at the head of the list
427 * - when multiple return probes are registered for the same
428 * function, the first instance's ret_addr will point to the
429 * real return address, and all the rest will point to
430 * kretprobe_trampoline
431 */
432 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
433 if (ri->task != current)
434 /* another task is sharing our hash bucket */
435 continue;
436
437 orig_ret_address = (unsigned long)ri->ret_addr;
438 if (orig_ret_address != trampoline_address)
439 /*
440 * This is the real return address. Any other
441 * instances associated with this task are for
442 * other calls deeper on the call stack
443 */
444 break;
445 }
446
447 regs->cr_iip = orig_ret_address;
448
449 hlist_for_each_entry_safe(ri, tmp, head, hlist) {
450 if (ri->task != current)
451 /* another task is sharing our hash bucket */
452 continue;
453
454 if (ri->rp && ri->rp->handler)
455 ri->rp->handler(ri, regs);
456
457 orig_ret_address = (unsigned long)ri->ret_addr;
458 recycle_rp_inst(ri, &empty_rp);
459
460 if (orig_ret_address != trampoline_address)
461 /*
462 * This is the real return address. Any other
463 * instances associated with this task are for
464 * other calls deeper on the call stack
465 */
466 break;
467 }
468 kretprobe_assert(ri, orig_ret_address, trampoline_address);
469
470 kretprobe_hash_unlock(current, &flags);
471
472 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
473 hlist_del(&ri->hlist);
474 kfree(ri);
475 }
476 /*
477 * By returning a non-zero value, we are telling
478 * kprobe_handler() that we don't want the post_handler
479 * to run (and have re-enabled preemption)
480 */
481 return 1;
482 }
483

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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