4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Masami Hiramatsu <mhira...@kernel.org> commit 804dec5bda9b4fcdab5f67fe61db4a0498af5221 upstream. Do not modify singlestep execution buffer (kprobe.ainsn.insn) while resuming from single-stepping, instead, modifies the buffer to add a jump back instruction at preparing buffer. Signed-off-by: Masami Hiramatsu <mhira...@kernel.org> Cc: Ananth N Mavinakayanahalli <ana...@linux.vnet.ibm.com> Cc: Andrey Ryabinin <aryabi...@virtuozzo.com> Cc: Anil S Keshavamurthy <anil.s.keshavamur...@intel.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: David S . Miller <da...@davemloft.net> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Ye Xiaolong <xiaolong...@intel.com> Link: http://lkml.kernel.org/r/149076361560.22469.1610155860343077495.stgit@devbox Signed-off-by: Ingo Molnar <mi...@kernel.org> Reviewed-by: "Steven Rostedt (VMware)" <rost...@goodmis.org> Signed-off-by: Alexey Makhalov <amakha...@vmware.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- arch/x86/kernel/kprobes/core.c | 42 +++++++++++++++++++---------------------- 1 file changed, 20 insertions(+), 22 deletions(-) --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -414,25 +414,38 @@ void free_insn_page(void *page) module_memfree(page); } +/* Prepare reljump right after instruction to boost */ +static void prepare_boost(struct kprobe *p, int length) +{ + if (can_boost(p->ainsn.insn, p->addr) && + MAX_INSN_SIZE - length >= RELATIVEJUMP_SIZE) { + /* + * These instructions can be executed directly if it + * jumps back to correct address. + */ + synthesize_reljump(p->ainsn.insn + length, p->addr + length); + p->ainsn.boostable = 1; + } else { + p->ainsn.boostable = -1; + } +} + static int arch_copy_kprobe(struct kprobe *p) { - int ret; + int len; set_memory_rw((unsigned long)p->ainsn.insn & PAGE_MASK, 1); /* Copy an instruction with recovering if other optprobe modifies it.*/ - ret = __copy_instruction(p->ainsn.insn, p->addr); - if (!ret) + len = __copy_instruction(p->ainsn.insn, p->addr); + if (!len) return -EINVAL; /* * __copy_instruction can modify the displacement of the instruction, * but it doesn't affect boostable check. */ - if (can_boost(p->ainsn.insn, p->addr)) - p->ainsn.boostable = 0; - else - p->ainsn.boostable = -1; + prepare_boost(p, len); set_memory_ro((unsigned long)p->ainsn.insn & PAGE_MASK, 1); @@ -897,21 +910,6 @@ static void resume_execution(struct kpro break; } - if (p->ainsn.boostable == 0) { - if ((regs->ip > copy_ip) && - (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { - /* - * These instructions can be executed directly if it - * jumps back to correct address. - */ - synthesize_reljump((void *)regs->ip, - (void *)orig_ip + (regs->ip - copy_ip)); - p->ainsn.boostable = 1; - } else { - p->ainsn.boostable = -1; - } - } - regs->ip += orig_ip - copy_ip; no_change:
