From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755761AbaE2TNx (ORCPT ); Thu, 29 May 2014 15:13:53 -0400 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:58467 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932537AbaE2TNu (ORCPT ); Thu, 29 May 2014 15:13:50 -0400 Message-ID: <538786D8.1070303@in.ibm.com> Date: Fri, 30 May 2014 00:43:28 +0530 From: "Suzuki K. Poulose" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Masami Hiramatsu , Benjamin Herrenschmidt , Paul Mackerras , Tony Luck CC: Jeremy Fitzhardinge , linux-ia64@vger.kernel.org, sparse@chrisli.org, "H. Peter Anvin" , akataria@vmware.com, linux-tip-commits@vger.kernel.org, anil.s.keshavamurthy@intel.com, Ingo Molnar , Fenghua Yu , Arnd Bergmann , Rusty Russell , Chris Wright , yrl.pp-manager.tt@hitachi.com, Thomas Gleixner , Tony Luck , Kevin Hao , Linus Torvalds , rdunlap@infradead.org, Linux Kernel Mailing List , dl9pf@gmx.de, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Subject: Re: [RFT PATCH -next v2] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64 References: <5383249A.6060407@in.ibm.com> <20140527063121.4399.38014.stgit@ltc230.yrl.intra.hitachi.co.jp> In-Reply-To: <20140527063121.4399.38014.stgit@ltc230.yrl.intra.hitachi.co.jp> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14052919-1618-0000-0000-000000518F8A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/27/2014 12:01 PM, Masami Hiramatsu wrote: > On ia64 and ppc64, the function pointer does not point the > entry address of the function, but the address of function > discriptor (which contains the entry address and misc > data.) Since the kprobes passes the function pointer stored > by NOKPROBE_SYMBOL() to kallsyms_lookup_size_offset() for > initalizing its blacklist, it fails and reports many errors > as below. > > Failed to find blacklist 0001013168300000 > Failed to find blacklist 0001013000f0a000 > Failed to find blacklist 000101315f70a000 > Failed to find blacklist 000101324c80a000 > Failed to find blacklist 0001013063f0a000 > Failed to find blacklist 000101327800a000 > Failed to find blacklist 0001013277f0a000 > Failed to find blacklist 000101315a70a000 > Failed to find blacklist 0001013277e0a000 > Failed to find blacklist 000101305a20a000 > Failed to find blacklist 0001013277d0a000 > Failed to find blacklist 00010130bdc0a000 > Failed to find blacklist 00010130dc20a000 > Failed to find blacklist 000101309a00a000 > Failed to find blacklist 0001013277c0a000 > Failed to find blacklist 0001013277b0a000 > Failed to find blacklist 0001013277a0a000 > Failed to find blacklist 000101327790a000 > Failed to find blacklist 000101303140a000 > Failed to find blacklist 0001013a3280a000 > > To fix this bug, this introduces function_entry() macro to > retrieve the entry address from the given function pointer, > and uses for kallsyms_lookup_size_offset() while initializing > blacklist. > > Changes in V2: > - Use function_entry() macro when lookin up symbols instead > of storing it. > - Update for the latest -next. > > Signed-off-by: Masami Hiramatsu > Reported-by: Tony Luck > Cc: Suzuki K. Poulose > Cc: Tony Luck > Cc: Fenghua Yu > Cc: Benjamin Herrenschmidt > Cc: Paul Mackerras > Cc: Ananth N Mavinakayanahalli > Cc: Kevin Hao > Cc: linux-ia64@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > --- > arch/ia64/include/asm/types.h | 2 ++ > arch/powerpc/include/asm/types.h | 11 +++++++++++ > include/linux/types.h | 4 ++++ > kernel/kprobes.c | 4 +++- > 4 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/arch/ia64/include/asm/types.h b/arch/ia64/include/asm/types.h > index 4c351b1..95279dd 100644 > --- a/arch/ia64/include/asm/types.h > +++ b/arch/ia64/include/asm/types.h > @@ -27,5 +27,7 @@ struct fnptr { > unsigned long gp; > }; > > +#define function_entry(fn) (((struct fnptr *)(fn))->ip) > + > #endif /* !__ASSEMBLY__ */ > #endif /* _ASM_IA64_TYPES_H */ > diff --git a/arch/powerpc/include/asm/types.h b/arch/powerpc/include/asm/types.h > index bfb6ded..8b89d65 100644 > --- a/arch/powerpc/include/asm/types.h > +++ b/arch/powerpc/include/asm/types.h > @@ -25,6 +25,17 @@ typedef struct { > unsigned long env; > } func_descr_t; > > +#if defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF == 1) > +/* > + * On PPC64 ABIv1 the function pointer actually points to the > + * function's descriptor. The first entry in the descriptor is the > + * address of the function text. > + */ > +#define function_entry(fn) (((func_descr_t *)(fn))->entry) > +#else > +#define function_entry(fn) ((unsigned long)(fn)) > +#endif > + > #endif /* __ASSEMBLY__ */ > > #endif /* _ASM_POWERPC_TYPES_H */ > diff --git a/include/linux/types.h b/include/linux/types.h > index a0bb704..3b95369 100644 > --- a/include/linux/types.h > +++ b/include/linux/types.h > @@ -213,5 +213,9 @@ struct callback_head { > }; > #define rcu_head callback_head > > +#ifndef function_entry > +#define function_entry(fn) ((unsigned long)(fn)) > +#endif > + > #endif /* __ASSEMBLY__ */ > #endif /* _LINUX_TYPES_H */ > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 2ac9f13..3859c88 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -32,6 +32,7 @@ > * added function-return probes. > */ > #include > +#include > #include > #include > #include > @@ -2042,7 +2043,8 @@ static int __init populate_kprobe_blacklist(unsigned long *start, > unsigned long offset = 0, size = 0; > > for (iter = start; iter < end; iter++) { > - if (!kallsyms_lookup_size_offset(*iter, &size, &offset)) { > + if (!kallsyms_lookup_size_offset(function_entry(*iter), > + &size, &offset)) { On powerpc we will be able to resolve the *iter to func_descr and won't get the below error with/without this patch. So we have to actually verify the kprobe_blacklist contents to make sure everything is alright. > pr_err("Failed to find blacklist %p\n", (void *)*iter); > continue; > } > There is a bug here. You need to set the ent->start using the function_entry(*iter) and not *iter. Or else you just avoid the 'Warning' and still have an invalid black list. As shown below : 2e:mon> ls kprobe_blacklist kprobe_blacklist: c00000000104dad0 2e:mon> d c00000000104dad0 10 c00000000104dad0: c0000003aff800a0 c0000003aff809a0 2e:mon> d c0000003aff800a0 20 (struct kprobe_blacklist *) c0000003aff800a0: c0000003aff800c0 c00000000104dad0 c0000003aff800b0: c0000000010ef138 c0000000010ef188 start ^^ end ^^ 2e:mon> la c0000000010ef138 (start) c0000000010ef138: notify_die+0x0/0x10 <- still points to the function descriptor 2e:mon> la c0000000010ef188 (end) c0000000010ef188: __blocking_notifier_call_chain+0x0/0x10 Following patch fixes the issue, with the patch : 1:mon> ls kprobe_blacklist kprobe_blacklist: c00000000104dad0 1:mon> d c00000000104dad0 10 c00000000104dad0: c0000003ae1a00a0 c0000003ae1a09a0 1:mon> d c0000003ae1a00a0 20 (struct kprobe_blacklist *) c0000003ae1a00a0: c0000003ae1a00c0 c00000000104dad0 c0000003ae1a00b0: c0000000000b14d0 c0000000000b1520 start ^^ end ^^ 1:mon> la c0000000000b14d0 c0000000000b14d0: .notify_die+0x0/0x50 1:mon> la c0000000000b1520 c0000000000b1520: .atomic_notifier_chain_register+0x0/0xa0 1:mon> di c0000000000b14d0 10 (.notify_die) c0000000000b14d0 7c0802a6 mflr r0 c0000000000b14d4 7c691b78 mr r9,r3 commit ed51674aca8e0496641f565421ab6691a873e80a Author: Suzuki K. Poulose Date: Fri May 30 00:23:01 2014 +0530 diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3859c88..b81d626 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2043,7 +2043,8 @@ static int __init populate_kprobe_blacklist(unsigned long *start, unsigned long offset = 0, size = 0; for (iter = start; iter < end; iter++) { - if (!kallsyms_lookup_size_offset(function_entry(*iter), + unsigned long entry = function_entry(*iter); + if (!kallsyms_lookup_size_offset(entry, &size, &offset)) { pr_err("Failed to find blacklist %p\n", (void *)*iter); continue; @@ -2052,8 +2053,8 @@ static int __init populate_kprobe_blacklist(unsigned long *start, 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); } Thanks Suzuki