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author | Marcin Nowakowski <marcin.nowakowski@imgtec.com> | 2016-09-30 11:33:46 +0200 |
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committer | Ralf Baechle <ralf@linux-mips.org> | 2016-10-06 17:37:40 +0200 |
commit | d05c513069f15be5de766026a4192998688ffff1 (patch) | |
tree | 7948594b560af72ed535a41cc567de4235562ff8 /arch/mips/kernel/uprobes.c | |
parent | e3031b32840c1bee228c58bb284ebc05f97249c7 (diff) | |
download | linux-stable-d05c513069f15be5de766026a4192998688ffff1.tar.gz linux-stable-d05c513069f15be5de766026a4192998688ffff1.tar.bz2 linux-stable-d05c513069f15be5de766026a4192998688ffff1.zip |
MIPS: tracing: disable uprobe/kprobe on compact branch instructions
Current instruction decoder for uprobe/kprobe handler only handles
branches with delay slots. For compact branches the behaviour is rather
unpredictable - and depending on the encoding of a compact branch
instruction may result in one (or more) of:
- executing an instruction that follows a branch which wasn't in a delay
slot and shouldn't have been executed
- incorrectly emulating a branch leading to a jump to a wrong location
- unexpected branching out of the single-stepped code and never reaching
the breakpoint that should terminate the probe handler
Results of these actions are generally unpredictable, but can end up
with a probed application or kernel crash, so disable placing probes on
compact branches until they are handled properly.
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14336/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/uprobes.c')
-rw-r--r-- | arch/mips/kernel/uprobes.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/mips/kernel/uprobes.c b/arch/mips/kernel/uprobes.c index 1161c93a74cb..dbb917403131 100644 --- a/arch/mips/kernel/uprobes.c +++ b/arch/mips/kernel/uprobes.c @@ -36,6 +36,12 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *aup, return -EINVAL; inst.word = aup->insn[0]; + + if (__insn_is_compact_branch(inst)) { + pr_notice("Uprobes for compact branches are not supported\n"); + return -EINVAL; + } + aup->ixol[0] = aup->insn[insn_has_delay_slot(inst)]; aup->ixol[1] = UPROBE_BRK_UPROBE_XOL; /* NOP */ |