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[PATCH] Kprobes: Make kprobe modules more portable

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In an effort to make kprobe modules more portable, here is a patch that:

o Introduces the "symbol_name" field to struct kprobe.
  The symbol->address resolution now happens in the kernel in an
  architecture agnostic manner. 64-bit powerpc users no longer have
  to specify the ".symbols"
o Introduces the "offset" field to struct kprobe to allow a user to
  specify an offset into a symbol.
o The legacy mechanism of specifying the kprobe.addr is still supported.
  However, if both the kprobe.addr and kprobe.symbol_name are specified,
  probe registration fails with an -EINVAL.
o The symbol resolution code uses kallsyms_lookup_name(). So
  CONFIG_KPROBES now depends on CONFIG_KALLSYMS
o Apparantly kprobe modules were the only legitimate out-of-tree user of
  the kallsyms_lookup_name() EXPORT. Now that the symbol resolution
  happens in-kernel, remove the EXPORT as suggested by Christoph Hellwig
o Modify tcp_probe.c that uses the kprobe interface so as to make it
  work on multiple platforms (in its earlier form, the code wouldn't
  work, say, on powerpc)

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ananth N Mavinakayanahalli 2006-10-02 02:17:30 -07:00 committed by Linus Torvalds
parent 782237a241
commit 3a872d89ba
10 changed files with 56 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
arch/i386/Kconfig
View file

@ -1142,7 +1142,7 @@ source "arch/i386/oprofile/Kconfig"
config KPROBES
bool "Kprobes (EXPERIMENTAL)"
depends on EXPERIMENTAL && MODULES
depends on KALLSYMS && EXPERIMENTAL && MODULES
help
Kprobes allows you to trap at almost any kernel address and
execute a callback function. register_kprobe() establishes

2
arch/ia64/Kconfig
View file

@ -516,7 +516,7 @@ source "arch/ia64/oprofile/Kconfig"
config KPROBES
bool "Kprobes (EXPERIMENTAL)"
depends on EXPERIMENTAL && MODULES
depends on KALLSYMS && EXPERIMENTAL && MODULES
help
Kprobes allows you to trap at almost any kernel address and
execute a callback function. register_kprobe() establishes

2
arch/powerpc/Kconfig
View file

@ -1069,7 +1069,7 @@ source "arch/powerpc/oprofile/Kconfig"
config KPROBES
bool "Kprobes (EXPERIMENTAL)"
depends on PPC64 && EXPERIMENTAL && MODULES
depends on PPC64 && KALLSYMS && EXPERIMENTAL && MODULES
help
Kprobes allows you to trap at almost any kernel address and
execute a callback function. register_kprobe() establishes

2
arch/sparc64/Kconfig
View file

@ -420,7 +420,7 @@ source "arch/sparc64/oprofile/Kconfig"
config KPROBES
bool "Kprobes (EXPERIMENTAL)"
depends on EXPERIMENTAL && MODULES
depends on KALLSYMS && EXPERIMENTAL && MODULES
help
Kprobes allows you to trap at almost any kernel address and
execute a callback function. register_kprobe() establishes

2
arch/x86_64/Kconfig
View file

@ -690,7 +690,7 @@ source "arch/x86_64/oprofile/Kconfig"
config KPROBES
bool "Kprobes (EXPERIMENTAL)"
depends on EXPERIMENTAL && MODULES
depends on KALLSYMS && EXPERIMENTAL && MODULES
help
Kprobes allows you to trap at almost any kernel address and
execute a callback function. register_kprobe() establishes

15
include/asm-powerpc/kprobes.h
View file

@ -44,6 +44,21 @@ typedef unsigned int kprobe_opcode_t;
#define IS_TDI(instr) (((instr) & 0xfc000000) == 0x08000000)
#define IS_TWI(instr) (((instr) & 0xfc000000) == 0x0c000000)
/*
* 64bit powerpc uses function descriptors.
* Handle cases where:
* - User passes a <.symbol>
* - User passes a <symbol>
* - User passes a non-existant symbol, kallsyms_lookup_name
* returns 0. Don't deref the NULL pointer in that case
*/
#define kprobe_lookup_name(name, addr) \
{ \
addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \
if (!(name[0] == '.') && addr) \
addr = *(kprobe_opcode_t **)addr; \
}
#define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry)
#define is_trap(instr) (IS_TW(instr) || IS_TD(instr) || \

6
include/linux/kprobes.h
View file

@ -77,6 +77,12 @@ struct kprobe {
/* location of the probe point */
kprobe_opcode_t *addr;
/* Allow user to indicate symbol name of the probe point */
char *symbol_name;
/* Offset into the symbol */
unsigned int offset;
/* Called before addr is executed. */
kprobe_pre_handler_t pre_handler;

1
kernel/kallsyms.c
View file

@ -154,7 +154,6 @@ unsigned long kallsyms_lookup_name(const char *name)
}
return module_kallsyms_lookup_name(name);
}
EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
/*
* Lookup an address

26
kernel/kprobes.c
View file

@ -37,6 +37,7 @@
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/kallsyms.h>
#include <asm-generic/sections.h>
#include <asm/cacheflush.h>
#include <asm/errno.h>
@ -45,6 +46,16 @@
#define KPROBE_HASH_BITS 6
#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
/*
* Some oddball architectures like 64bit powerpc have function descriptors
* so this must be overridable.
*/
#ifndef kprobe_lookup_name
#define kprobe_lookup_name(name, addr) \
addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
#endif
static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
static atomic_t kprobe_count;
@ -447,6 +458,21 @@ static int __kprobes __register_kprobe(struct kprobe *p,
struct kprobe *old_p;
struct module *probed_mod;
/*
* If we have a symbol_name argument look it up,
* and add it to the address. That way the addr
* field can either be global or relative to a symbol.
*/
if (p->symbol_name) {
if (p->addr)
return -EINVAL;
kprobe_lookup_name(p->symbol_name, p->addr);
}
if (!p->addr)
return -EINVAL;
p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset);
if ((!kernel_text_address((unsigned long) p->addr)) ||
in_kprobes_functions((unsigned long) p->addr))
return -EINVAL;

6
net/ipv4/tcp_probe.c
View file

@ -99,8 +99,10 @@ static int jtcp_sendmsg(struct kiocb *iocb, struct sock *sk,
}
static struct jprobe tcp_send_probe = {
.kp = { .addr = (kprobe_opcode_t *) &tcp_sendmsg, },
.entry = (kprobe_opcode_t *) &jtcp_sendmsg,
.kp = {
.symbol_name = "tcp_sendmsg",
},
.entry = JPROBE_ENTRY(jtcp_sendmsg),
};