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Subject[patch 3/3] Kprobes IA64 safe register kprobe
The current kprobes does not yet handle register
kprobes on some of the following kind of instruction
which needs to be emulated in a special way.
1) mov r1=ip
2) chk -- Speculation check instruction
This patch attempts to fail register_kprobes() when
user tries to insert kprobes on the above kind of
instruction.

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
===================================================================
arch/ia64/kernel/kprobes.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 45 insertions(+)

Index: linux-2.6.12-rc5/arch/ia64/kernel/kprobes.c
===================================================================
--- linux-2.6.12-rc5.orig/arch/ia64/kernel/kprobes.c
+++ linux-2.6.12-rc5/arch/ia64/kernel/kprobes.c
@@ -98,6 +98,48 @@ static inline void set_current_kprobe(st
current_kprobe = p;
}

+/*
+ * In this function we check to see if the instruction
+ * on which we are inserting kprobe is supported.
+ * Returns 0 if supported
+ * Returns -EINVAL if unsupported
+ */
+static int unsupported_inst(uint template, uint slot, uint major_opcode,
+ unsigned long kprobe_inst, struct kprobe *p)
+{
+ unsigned long addr = (unsigned long)p->addr;
+
+ if (bundle_encoding[template][slot] == I) {
+ switch (major_opcode) {
+ case 0x0: //I_UNIT_MISC_OPCODE:
+ /*
+ * Check for Integer speculation instruction
+ * - Bit 33-35 to be equal to 0x1
+ */
+ if (((kprobe_inst >> 33) & 0x7) == 1) {
+ printk(KERN_WARNING
+ "Kprobes on speculation inst at <0x%lx> not supported\n",
+ addr);
+ return -EINVAL;
+ }
+
+ /*
+ * IP relative mov instruction
+ * - Bit 27-35 to be equal to 0x30
+ */
+ if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
+ printk(KERN_WARNING
+ "Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
+ addr);
+ return -EINVAL;
+
+ }
+ }
+ }
+ return 0;
+}
+
+
/*
* In this function we check to see if the instruction
* is IP relative instruction and update the kprobe
@@ -270,6 +312,9 @@ int arch_prepare_kprobe(struct kprobe *p

/* Get kprobe_inst and major_opcode from the bundle */
get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
+
+ if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
+ return -EINVAL;

prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);

--

-
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