[PATCH] kprobes: fix broken fault handling for x86_64 (c28f8966) · Commits · 戴 / test

arch/x86_64/kernel/kprobes.c

+55 −7

Original line number	Diff line number	Diff line
		@@ -37,10 +37,12 @@
		#include <linux/string.h>
		#include <linux/slab.h>
		#include <linux/preempt.h>
		#include <linux/module.h>

		#include <asm/cacheflush.h>
		#include <asm/pgtable.h>
		#include <asm/kdebug.h>
		#include <asm/uaccess.h>

		void jprobe_return_end(void);
		static void __kprobes arch_copy_kprobe(struct kprobe *p);
		@@ -578,16 +580,62 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
		{
		struct kprobe *cur = kprobe_running();
		struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
		const struct exception_table_entry *fixup;

		switch(kcb->kprobe_status) {
		case KPROBE_HIT_SS:
		case KPROBE_REENTER:
		/*
		* We are here because the instruction being single
		* stepped caused a page fault. We reset the current
		* kprobe and the rip points back to the probe address
		* and allow the page fault handler to continue as a
		* normal page fault.
		*/
		regs->rip = (unsigned long)cur->addr;
		regs->eflags \|= kcb->kprobe_old_rflags;
		if (kcb->kprobe_status == KPROBE_REENTER)
		restore_previous_kprobe(kcb);
		else
		reset_current_kprobe();
		preempt_enable_no_resched();
		break;
		case KPROBE_HIT_ACTIVE:
		case KPROBE_HIT_SSDONE:
		/*
		* We increment the nmissed count for accounting,
		* we can also use npre/npostfault count for accouting
		* these specific fault cases.
		*/
		kprobes_inc_nmissed_count(cur);

		/*
		* We come here because instructions in the pre/post
		* handler caused the page_fault, this could happen
		* if handler tries to access user space by
		* copy_from_user(), get_user() etc. Let the
		* user-specified handler try to fix it first.
		*/
		if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
		return 1;

		if (kcb->kprobe_status & KPROBE_HIT_SS) {
		resume_execution(cur, regs, kcb);
		regs->eflags \|= kcb->kprobe_old_rflags;
		/*
		* In case the user-specified fault handler returned
		* zero, try to fix up.
		*/
		fixup = search_exception_tables(regs->rip);
		if (fixup) {
		regs->rip = fixup->fixup;
		return 1;
		}

		reset_current_kprobe();
		preempt_enable_no_resched();
		/*
		* fixup() could not handle it,
		* Let do_page_fault() fix it.
		*/
		break;
		default:
		break;
		}
		return 0;
		}

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