The patch titled
Kprobes: Make kprobe modules more portable (updated)
has been added to the -mm tree. Its filename is
kprobes-make-kprobe-modules-more-portable-update.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Kprobes: Make kprobe modules more portable (updated)
From: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Anil discovered that this patch has a case where, on powerpc, we potentially
end up dereferencing a NULL pointer. I have fixed that part and updated
the patch.
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.
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@xxxxxxxxxx>
Signed-off-by: Prasanna S Panchamukhi <prasanna@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/asm-powerpc/kprobes.h | 16 ++++++++++++++--
kernel/kprobes.c | 6 +++---
2 files changed, 17 insertions(+), 5 deletions(-)
diff -puN include/asm-powerpc/kprobes.h~kprobes-make-kprobe-modules-more-portable-update include/asm-powerpc/kprobes.h
--- a/include/asm-powerpc/kprobes.h~kprobes-make-kprobe-modules-more-portable-update
+++ a/include/asm-powerpc/kprobes.h
@@ -44,8 +44,20 @@ typedef unsigned int kprobe_opcode_t;
#define IS_TDI(instr) (((instr) & 0xfc000000) == 0x08000000)
#define IS_TWI(instr) (((instr) & 0xfc000000) == 0x0c000000)
-#define kprobe_lookup_name(name) \
- (*((kprobe_opcode_t **)kallsyms_lookup_name(name)))
+/*
+ * 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)
diff -puN kernel/kprobes.c~kprobes-make-kprobe-modules-more-portable-update kernel/kprobes.c
--- a/kernel/kprobes.c~kprobes-make-kprobe-modules-more-portable-update
+++ a/kernel/kprobes.c
@@ -52,8 +52,8 @@
* so this must be overridable.
*/
#ifndef kprobe_lookup_name
-#define kprobe_lookup_name(name) \
- ((kprobe_opcode_t *)(kallsyms_lookup_name(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];
@@ -466,7 +466,7 @@ static int __kprobes __register_kprobe(s
if (p->symbol_name) {
if (p->addr)
return -EINVAL;
- p->addr = kprobe_lookup_name(p->symbol_name);
+ kprobe_lookup_name(p->symbol_name, p->addr);
}
if (!p->addr)
_
Patches currently in -mm which might be from ananth@xxxxxxxxxx are
origin.patch
kprobes-make-kprobe-modules-more-portable.patch
kprobes-make-kprobe-modules-more-portable-update.patch
add-regs_return_value-helper.patch
update-documentation-kprobestxt.patch
-
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