[PATCH] Kprobes: Make kprobe modules more portable
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>
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3f57dfd..f66b8e6 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -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 @@
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;
