From d81b4253b0f0f1e7b7e03b0cd0f80cab18bc4d7b Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 17 Jul 2014 11:44:11 +0000 Subject: kprobes: Fix "Failed to find blacklist" probing errors on ia64 and ppc64 On ia64 and ppc64, function pointers do not point to the entry address of the function, but to the address of a function descriptor (which contains the entry address and misc data). Since the kprobes code passes the function pointer stored by NOKPROBE_SYMBOL() to kallsyms_lookup_size_offset() for initalizing its blacklist, it fails and reports many errors, such as: Failed to find blacklist 0001013168300000 Failed to find blacklist 0001013000f0a000 [...] To fix this bug, use arch_deref_entry_point() to get the function entry address for kallsyms_lookup_size_offset() instead of the raw function pointer. Suzuki also pointed out that blacklist entries should also be updated as well. Reported-by: Tony Luck Fixed-by: Suzuki K. Poulose Tested-by: Tony Luck Tested-by: Michael Ellerman Signed-off-by: Masami Hiramatsu Acked-by: Michael Ellerman (for powerpc) Acked-by: Benjamin Herrenschmidt Cc: Jeremy Fitzhardinge Cc: sparse@chrisli.org Cc: Paul Mackerras Cc: akataria@vmware.com Cc: anil.s.keshavamurthy@intel.com Cc: Fenghua Yu Cc: Arnd Bergmann Cc: Rusty Russell Cc: Chris Wright Cc: yrl.pp-manager.tt@hitachi.com Cc: Kevin Hao Cc: Ananth N Mavinakayanahalli Cc: rdunlap@infradead.org Cc: dl9pf@gmx.de Cc: Linus Torvalds Cc: David S. Miller Cc: linux-ia64@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20140717114411.13401.2632.stgit@kbuild-fedora.novalocal Signed-off-by: Ingo Molnar --- kernel/kprobes.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3214289df5a7..734e9a7d280b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2037,19 +2037,23 @@ static int __init populate_kprobe_blacklist(unsigned long *start, { unsigned long *iter; struct kprobe_blacklist_entry *ent; - unsigned long offset = 0, size = 0; + unsigned long entry, offset = 0, size = 0; for (iter = start; iter < end; iter++) { - if (!kallsyms_lookup_size_offset(*iter, &size, &offset)) { - pr_err("Failed to find blacklist %p\n", (void *)*iter); + entry = arch_deref_entry_point((void *)*iter); + + if (!kernel_text_address(entry) || + !kallsyms_lookup_size_offset(entry, &size, &offset)) { + pr_err("Failed to find blacklist at %p\n", + (void *)entry); continue; } ent = kmalloc(sizeof(*ent), GFP_KERNEL); if (!ent) return -ENOMEM; - ent->start_addr = *iter; - ent->end_addr = *iter + size; + ent->start_addr = entry; + ent->end_addr = entry + size; INIT_LIST_HEAD(&ent->list); list_add_tail(&ent->list, &kprobe_blacklist); } -- cgit v1.2.3