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authorManeesh Soni <manesoni@cisco.com>2011-11-08 17:05:35 +0530
committerRalf Baechle <ralf@linux-mips.org>2011-12-07 22:04:03 +0000
commit9233c1ee71bdd3c8a918c8e17026cf3f7d99c90b (patch)
tree9c653068e63cda169569796ce721af418670db5d /arch/mips/kernel
parent41dde781f50c39cddc8032fc04d6a7d538237737 (diff)
MIPS Kprobes: Deny probes on ll/sc instructions
As ll/sc instruction are for atomic read-modify-write operations, allowing probes on top of these insturctions is a bad idea. Signed-off-by: Victor Kamensky <kamensky@cisco.com> Signed-off-by: Maneesh Soni <manesoni@cisco.com> Cc: David Daney <david.daney@cavium.com> Cc: ananth@in.ibm.com Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/2912/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel')
-rw-r--r--arch/mips/kernel/kprobes.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index 9fb1876cb0b..0ab1a5ff104 100644
--- a/arch/mips/kernel/kprobes.c
+++ b/arch/mips/kernel/kprobes.c
@@ -113,6 +113,30 @@ insn_ok:
return 0;
}
+/*
+ * insn_has_ll_or_sc function checks whether instruction is ll or sc
+ * one; putting breakpoint on top of atomic ll/sc pair is bad idea;
+ * so we need to prevent it and refuse kprobes insertion for such
+ * instructions; cannot do much about breakpoint in the middle of
+ * ll/sc pair; it is upto user to avoid those places
+ */
+static int __kprobes insn_has_ll_or_sc(union mips_instruction insn)
+{
+ int ret = 0;
+
+ switch (insn.i_format.opcode) {
+ case ll_op:
+ case lld_op:
+ case sc_op:
+ case scd_op:
+ ret = 1;
+ break;
+ default:
+ break;
+ }
+ return ret;
+}
+
int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
union mips_instruction insn;
@@ -121,6 +145,13 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
insn = p->addr[0];
+ if (insn_has_ll_or_sc(insn)) {
+ pr_notice("Kprobes for ll and sc instructions are not"
+ "supported\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
if (insn_has_delayslot(insn)) {
pr_notice("Kprobes for branch and jump instructions are not"
"supported\n");