4.4-stable review patch. If anyone has any objections, please let me know.
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From: Marcin Nowakowski marcin.nowakowski@imgtec.com
[ Upstream commit 698b851073ddf5a894910d63ca04605e0473414e ]
When ftrace is used with kprobes, it is possible for a kprobe to contain an invalid location (ie. only initialised to 0 and not to a specific location in the code). Trying to perform a cache flush on such location leads to a crash r4k_flush_icache_range().
Fixes: c1bf207d6ee1 ("MIPS: kprobe: Add support.") Signed-off-by: Marcin Nowakowski marcin.nowakowski@imgtec.com Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16296/ Signed-off-by: Ralf Baechle ralf@linux-mips.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/mips/include/asm/kprobes.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/mips/include/asm/kprobes.h +++ b/arch/mips/include/asm/kprobes.h @@ -40,7 +40,8 @@ typedef union mips_instruction kprobe_op
#define flush_insn_slot(p) \ do { \ - flush_icache_range((unsigned long)p->addr, \ + if (p->addr) \ + flush_icache_range((unsigned long)p->addr, \ (unsigned long)p->addr + \ (MAX_INSN_SIZE * sizeof(kprobe_opcode_t))); \ } while (0)