diff options
| author | Maneesh Soni | 2011-11-08 17:08:26 +0530 |
|---|---|---|
| committer | Ralf Baechle | 2011-12-07 22:04:03 +0000 |
| commit | 6457a396bbc20656009eaf950ca165912a943520 (patch) | |
| tree | 5a940616d2b1b55f182d4022a39c4d37a9cda1e7 /arch/mips/include | |
| parent | d8d4e3ae0b5c179c0bfd3f0af5b352d13bea9cfa (diff) | |
MIPS Kprobes: Support branch instructions probing
This patch provides support for kprobes on branch instructions. The branch
instruction at the probed address is actually emulated and not executed
out-of-line like other normal instructions. Instead the delay-slot instruction
is copied and single stepped out of line.
At the time of probe hit, the original branch instruction is evaluated
and the target cp0_epc is computed similar to compute_retrun_epc(). It
is also checked if the delay slot instruction can be skipped, which is
true if there is a NOP in delay slot or branch is taken in case of
branch likely instructions. Once the delay slot instruction is single
stepped the normal execution resume with the cp0_epc updated the earlier
computed cp0_epc as per the branch instructions.
Signed-off-by: Maneesh Soni <manesoni@cisco.com>
Signed-off-by: Victor Kamensky <kamensky@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/2914/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include')
| -rw-r--r-- | arch/mips/include/asm/kprobes.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/mips/include/asm/kprobes.h b/arch/mips/include/asm/kprobes.h index e6ea4d4d7205..1fbbca01e681 100644 --- a/arch/mips/include/asm/kprobes.h +++ b/arch/mips/include/asm/kprobes.h @@ -74,6 +74,8 @@ struct prev_kprobe { : MAX_JPROBES_STACK_SIZE) +#define SKIP_DELAYSLOT 0x0001 + /* per-cpu kprobe control block */ struct kprobe_ctlblk { unsigned long kprobe_status; @@ -82,6 +84,9 @@ struct kprobe_ctlblk { unsigned long kprobe_saved_epc; unsigned long jprobe_saved_sp; struct pt_regs jprobe_saved_regs; + /* Per-thread fields, used while emulating branches */ + unsigned long flags; + unsigned long target_epc; u8 jprobes_stack[MAX_JPROBES_STACK_SIZE]; struct prev_kprobe prev_kprobe; }; |