On Sun, 26 Mar 2017 12:33:01 +0900 Masami Hiramatsu <[email protected]> wrote:
> Consolidate x86 instruction decoder users on the path of > copying original code for kprobes. > > Kprobes decodes same instruction 3 times in maximum when > preparing instruction buffer. The first time for getting the > length of instruction, the 2nd for adjusting displacement, > and the 3rd for checking whether the instruction is boostable > or not. For each time, actually decoding target address is > slightly different (1st is original address or recovered > instruction buffer, 2nd and 3rd are copied buffer), but > basically those must have same instruction. > Thus, this patch also changes the target address to copied > buffer at first and reuses the decoded "insn" for displacement > adjusting and checking boostable. > > Signed-off-by: Masami Hiramatsu <[email protected]> > --- > arch/x86/kernel/kprobes/common.h | 4 +- > arch/x86/kernel/kprobes/core.c | 62 > +++++++++++++++++--------------------- > arch/x86/kernel/kprobes/opt.c | 5 ++- > 3 files changed, 33 insertions(+), 38 deletions(-) > > diff --git a/arch/x86/kernel/kprobes/common.h > b/arch/x86/kernel/kprobes/common.h > index d688826..db2182d 100644 > --- a/arch/x86/kernel/kprobes/common.h > +++ b/arch/x86/kernel/kprobes/common.h > @@ -67,7 +67,7 @@ > #endif > > /* Ensure if the instruction can be boostable */ > -extern int can_boost(kprobe_opcode_t *instruction, void *addr); > +extern int can_boost(struct insn *insn, void *orig_addr); > /* Recover instruction if given address is probed */ > extern unsigned long recover_probed_instruction(kprobe_opcode_t *buf, > unsigned long addr); > @@ -75,7 +75,7 @@ extern unsigned long > recover_probed_instruction(kprobe_opcode_t *buf, > * Copy an instruction and adjust the displacement if the instruction > * uses the %rip-relative addressing mode. > */ > -extern int __copy_instruction(u8 *dest, u8 *src); > +extern int __copy_instruction(u8 *dest, u8 *src, struct insn *insn); > > /* Generate a relative-jump/call instruction */ > extern void synthesize_reljump(void *from, void *to); > diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c > index a9ae61a..de7475b 100644 > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -164,33 +164,29 @@ static kprobe_opcode_t *skip_prefixes(kprobe_opcode_t > *insn) > NOKPROBE_SYMBOL(skip_prefixes); > > /* > - * Returns non-zero if opcode is boostable. > + * Returns non-zero if INSN is boostable. > * RIP relative instructions are adjusted at copying time in 64 bits mode > */ > -int can_boost(kprobe_opcode_t *opcodes, void *addr) > +int can_boost(struct insn *insn, void *addr) > { > - struct insn insn; > kprobe_opcode_t opcode; > > if (search_exception_tables((unsigned long)addr)) > return 0; /* Page fault may occur on this address. */ > > - kernel_insn_init(&insn, (void *)opcodes, MAX_INSN_SIZE); > - insn_get_opcode(&insn); > - > /* 2nd-byte opcode */ > - if (insn.opcode.nbytes == 2) > - return test_bit(insn.opcode.bytes[1], > + if (insn->opcode.nbytes == 2) > + return test_bit(insn->opcode.bytes[1], > (unsigned long *)twobyte_is_boostable); > > - if (insn.opcode.nbytes != 1) > + if (insn.opcode->nbytes != 1) Oops, here is insn->opcode.nbytes, not insn.opcode->nbytes. -- Masami Hiramatsu <[email protected]>
