Re: [PATCH]kprobe handler discard user space trap
From: bibo mao
Date: Wed Mar 01 2006 - 01:27:53 EST
This patch removes code in kprobe_handler() function which calculates
user space int3 trap address in i386 architecture. And this patch is
based on kprobe-handler-discard-user-space-trap.patch, against
2.6.16-rc5-mm1.
Signed-off-by: bibo mao <bibo.mao@xxxxxxxxx>
--- a/arch/i386/kernel/kprobes.c 2006-03-01 12:48:54.000000000 +0800
+++ b/arch/i386/kernel/kprobes.c 2006-03-01 14:08:12.000000000 +0800
@@ -203,7 +203,7 @@ static int __kprobes kprobe_handler(stru
{
struct kprobe *p;
int ret = 0;
- kprobe_opcode_t *addr = NULL;
+ kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->eip -
sizeof(kprobe_opcode_t));
unsigned long *lp;
struct kprobe_ctlblk *kcb;
#ifdef CONFIG_PREEMPT
@@ -217,17 +217,6 @@ static int __kprobes kprobe_handler(stru
preempt_disable();
kcb = get_kprobe_ctlblk();
- /* Check if the application is using LDT entry for its code segment and
- * calculate the address by reading the base address from the LDT entry.
- */
- if ((regs->xcs & 4) && (current->mm)) {
- lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8)
- + (char *) current->mm->context.ldt);
- addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip -
- sizeof(kprobe_opcode_t));
- } else {
- addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
- }
/* Check we're not actually recursing */
if (kprobe_running()) {
p = get_kprobe(addr);
Prasanna S Panchamukhi wrote:
On Tue, Feb 28, 2006 at 03:23:12PM +0800, bibo,mao wrote:
Currently kprobe handler traps only happen in kernel space, so function
kprobe_exceptions_notify should skip traps which happen in user space.
This patch modifies this, and it is based on 2.6.16-rc4.
You need to remove the code which calculates the
user space address in kprobe_handler() and also you need
to remove the code that checks for VM86 in i386, since
your patch check if user/vm86 at the top level.
Thanks
Prasanna
Signed-off-by: bibo mao <bibo.mao@xxxxxxxxx>
diff -Nruap a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
--- a/arch/i386/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800
+++ b/arch/i386/kernel/kprobes.c 2006-03-01 10:37:50.000000000 +0800
@@ -463,6 +463,9 @@ int __kprobes kprobe_exceptions_notify(s
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
+ if (user_mode(args->regs))
+ return ret;
+
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
diff -Nruap a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
--- a/arch/ia64/kernel/kprobes.c 2006-02-25 17:08:53.000000000 +0800
+++ b/arch/ia64/kernel/kprobes.c 2006-03-01 10:39:15.000000000 +0800
@@ -740,6 +740,9 @@ int __kprobes kprobe_exceptions_notify(s
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
+ if (user_mode(args->regs))
+ return ret;
+
switch(val) {
case DIE_BREAK:
/* err is break number from ia64_bad_break() */
diff -Nruap a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
--- a/arch/powerpc/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800
+++ b/arch/powerpc/kernel/kprobes.c 2006-03-01 10:39:53.000000000 +0800
@@ -397,6 +397,9 @@ int __kprobes kprobe_exceptions_notify(s
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
+ if (user_mode(args->regs))
+ return ret;
+
switch (val) {
case DIE_BPT:
if (kprobe_handler(args->regs))
diff -Nruap a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c
--- a/arch/sparc64/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800
+++ b/arch/sparc64/kernel/kprobes.c 2006-03-01 10:40:16.000000000 +0800
@@ -324,6 +324,9 @@ int __kprobes kprobe_exceptions_notify(s
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
+ if (user_mode(args->regs))
+ return ret;
+
switch (val) {
case DIE_DEBUG:
if (kprobe_handler(args->regs))
diff -Nruap a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
--- a/arch/x86_64/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800
+++ b/arch/x86_64/kernel/kprobes.c 2006-03-01 10:38:48.000000000 +0800
@@ -601,6 +601,9 @@ int __kprobes kprobe_exceptions_notify(s
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
+ if (user_mode(args->regs))
+ return ret;
+
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
-
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