Adding support to emulate mov reg to reg instructions, because it's often part of the function prologue.
Signed-off-by: Jiri Olsa <[email protected]> --- arch/x86/include/asm/uprobes.h | 5 +++ arch/x86/kernel/uprobes.c | 61 ++++++++++++++++++++++++++++++++++ 2 files changed, 66 insertions(+) diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 819e35aa61c4..e6fd87a1cbc3 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -44,6 +44,11 @@ struct arch_uprobe_xol { u8 reg_offset; /* to the start of pt_regs */ u8 ilen; } push; + struct { + u16 src; /* to the start of pt_regs */ + u16 dst; /* to the start of pt_regs */ + u8 ilen; + } mov; }; }; diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 7d7a5e677472..5c44c4b84e99 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -19,6 +19,7 @@ #include <asm/insn.h> #include <asm/mmu_context.h> #include <asm/nops.h> +#include <asm/insn-eval.h> /* Post-execution fixups. */ @@ -1414,6 +1415,19 @@ static void branch_clear_offset(struct arch_uprobe *auprobe, struct insn *insn) 0, insn->immediate.nbytes); } +static bool mov_emulate_op(struct arch_uprobe *auprobe, struct arch_uprobe_xol *xol, + struct pt_regs *regs) +{ + unsigned long *dst, *src; + + dst = (void *) regs + xol->mov.dst; + src = (void *) regs + xol->mov.src; + *dst = *src; + + regs->ip += xol->mov.ilen; + return true; +} + static const struct uprobe_xol_ops branch_xol_ops = { .emulate = branch_emulate_op, .post_xol = branch_post_xol_op, @@ -1423,6 +1437,10 @@ static const struct uprobe_xol_ops push_xol_ops = { .emulate = push_emulate_op, }; +static const struct uprobe_xol_ops mov_xol_ops = { + .emulate = mov_emulate_op, +}; + /* Returns -ENOSYS if branch_xol_ops doesn't handle this insn */ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) { @@ -1560,6 +1578,45 @@ static int push_setup_xol_ops(struct arch_uprobe_xol *xol, struct insn *insn) return 0; } +#ifdef CONFIG_X86_64 +/* Returns -ENOSYS if mov_xol_ops doesn't handle this insn */ +static int mov_setup_xol_ops(struct arch_uprobe_xol *xol, struct insn *insn) +{ + u8 opc1 = OPCODE1(insn); + int off_src, off_dst; + + /* validate opcode */ + if (opc1 != 0x89) + return -ENOSYS; + if (insn->rex_prefix.nbytes != 1 || + insn->rex_prefix.bytes[0] != 0x48) + return -ENOSYS; + + /* only register operands */ + if (X86_MODRM_MOD(insn->modrm.value) != 3) + return -ENOSYS; + + /* get registers offset */ + off_src = insn_get_modrm_reg_off(insn); + if (off_src < 0) + return off_src; + off_dst = insn_get_modrm_rm_off(insn); + if (off_dst < 0) + return off_dst; + + xol->mov.src = off_src; + xol->mov.dst = off_dst; + xol->mov.ilen = insn->length; + xol->ops = &mov_xol_ops; + return 0; +} +#else +static int mov_setup_xol_ops(struct arch_uprobe_xol *xol, struct insn *insn) +{ + return -ENOSYS; +} +#endif + /** * arch_uprobe_analyze_insn - instruction analysis including validity and fixups. * @auprobe: the probepoint information. @@ -1588,6 +1645,10 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, if (ret != -ENOSYS) return ret; + ret = mov_setup_xol_ops(&auprobe->xol, &insn); + if (ret != -ENOSYS) + return ret; + /* * Figure out which fixups default_post_xol_op() will need to perform, * and annotate defparam->fixups accordingly. -- 2.51.1
