Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750881AbWHGMFl (ORCPT ); Mon, 7 Aug 2006 08:05:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932068AbWHGMFl (ORCPT ); Mon, 7 Aug 2006 08:05:41 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:50119 "EHLO e3.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1750881AbWHGMFk (ORCPT ); Mon, 7 Aug 2006 08:05:40 -0400 Date: Mon, 7 Aug 2006 17:36:58 +0530 From: Ananth N Mavinakayanahalli To: linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] Kprobes: Make kprobe modules more portable Message-ID: <20060807120658.GF15253@in.ibm.com> Reply-To: ananth@in.ibm.com References: <20060807115537.GA15253@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060807115537.GA15253@in.ibm.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3701 Lines: 95 On Mon, Aug 07, 2006 at 05:25:37PM +0530, Ananth N Mavinakayanahalli wrote: > From: Ananth N Mavinakayanahalli > > This patch introduces KPROBE_ADDR, a macro that abstracts out the > architecture-specific artefacts of getting the correct text address > given a symbol. While we are at it, also introduce the symbol_name field > in struct kprobe to allow for users to just specify the address to be > probed in terms of the kernel symbol. In-kernel kprobes infrastructure > decodes the actual text address to probe. The symbol resolution happens > only if the kprobe.addr isn't explicitly specified. This change was first mooted by Dave Boutcher during his kprobes tutorial @ OLS. Thanks Dave! (He had also signed off on the patch) > > --- > Signed-off-by: Ananth N Mavinakayanahalli > Signed-off-by: Prasanna S.P Acked-by: Dave Boutcher > > > --- > include/asm-powerpc/kprobes.h | 2 ++ > include/linux/kprobes.h | 8 ++++++++ > kernel/kprobes.c | 4 ++++ > 3 files changed, 14 insertions(+) > > Index: linux-2.6.18-rc3/include/asm-powerpc/kprobes.h > =================================================================== > --- linux-2.6.18-rc3.orig/include/asm-powerpc/kprobes.h > +++ linux-2.6.18-rc3/include/asm-powerpc/kprobes.h > @@ -44,6 +44,8 @@ typedef unsigned int kprobe_opcode_t; > #define IS_TDI(instr) (((instr) & 0xfc000000) == 0x08000000) > #define IS_TWI(instr) (((instr) & 0xfc000000) == 0x0c000000) > > +#define KPROBE_ADDR(name) *((kprobe_opcode_t **)(kallsyms_lookup_name(name))) > + > #define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry) > > #define is_trap(instr) (IS_TW(instr) || IS_TD(instr) || \ > Index: linux-2.6.18-rc3/include/linux/kprobes.h > =================================================================== > --- linux-2.6.18-rc3.orig/include/linux/kprobes.h > +++ linux-2.6.18-rc3/include/linux/kprobes.h > @@ -36,6 +36,7 @@ > #include > #include > #include > +#include > > #ifdef CONFIG_KPROBES > #include > @@ -49,6 +50,10 @@ > /* Attach to insert probes on any functions which should be ignored*/ > #define __kprobes __attribute__((__section__(".kprobes.text"))) > > +#ifndef KPROBE_ADDR /* powerpc has its own definition */ > +#define KPROBE_ADDR(name) (kprobe_opcode_t *)(kallsyms_lookup_name(name)) > +#endif /* KPROBE_ADDR */ > + > struct kprobe; > struct pt_regs; > struct kretprobe; > @@ -77,6 +82,9 @@ struct kprobe { > /* location of the probe point */ > kprobe_opcode_t *addr; > > + /* Allow user to indicate symbol name of the probe point */ > + char *symbol_name; > + > /* Called before addr is executed. */ > kprobe_pre_handler_t pre_handler; > > Index: linux-2.6.18-rc3/kernel/kprobes.c > =================================================================== > --- linux-2.6.18-rc3.orig/kernel/kprobes.c > +++ linux-2.6.18-rc3/kernel/kprobes.c > @@ -446,6 +446,10 @@ static int __kprobes __register_kprobe(s > struct kprobe *old_p; > struct module *probed_mod; > > + /* Do the kallsyms lookup only if p->addr == NULL */ > + if (!p->addr && (p->symbol_name)) > + p->addr = KPROBE_ADDR(p->symbol_name); > + > if ((!kernel_text_address((unsigned long) p->addr)) || > in_kprobes_functions((unsigned long) p->addr)) > return -EINVAL; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/