Messages in this thread | | | Date | Fri, 08 Aug 2014 20:05:13 +0900 | From | Masami Hiramatsu <> | Subject | Re: (ltc-kernel 9786) [PATCH ftrace/core v4 0/4] ftrace, kprobes: Introduce IPMODIFY flag for ftrace_ops to detect conflicts |
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Ping?
BTW, I'd like to add this testcase if ftracetest is accepted.
Thank you,
(2014/07/28 14:22), Masami Hiramatsu wrote: > Hi, > > Here is the 4th version of the series of patches which introduces > IPMODIFY flag for ftrace_ops to detect conflicts of ftrace users > who can modify regs->ip in their handler. > This version is basically an update of previous version, and > I've splitted a patch which adding IPMODIFY to kprobes from ftrace > IPMODIFY introducing patch. > > Currently, only kprobes can change the regs->ip in the handler, > but recently kpatch is also want to change it. Moreover, since > the ftrace itself exported to modules, it might be considerable > senario. > > Here we talked on github. > https://github.com/dynup/kpatch/issues/47 > > To protect modified regs-ip from each other, this series > introduces FTRACE_OPS_FL_IPMODIFY flag and ftrace now ensures > the flag can be set on each function entry location. If there > is someone who already reserve regs->ip on target function > entry, ftrace_set_filter_ip or register_ftrace_function will > return -EBUSY. Users must handle that. > The ftrace_ops with IPMODIFY flag requires at least one > entry for filter hash, and its notrace_hash must be empty, > because the IPMODIFY action is very address sensitve and > user must consider the ip address. > > The 3rd patch adds a special reservation of IPMODIFY on the > jprobed address, since it is the only user who will change > the regs->ip. Other kprobes do not change it anymore. > > Here is the new testcase. > ------- > #!/bin/bash > > echo "IPMODIFY test" > ADDR=0x`grep do_fork /proc/kallsyms | cut -f 1 -d" "` > > echo "Case1: kprobe->jprobe->ipmodify(fail)" > modprobe kprobe_example > modprobe jprobe_example > insmod ./ipmodify.ko target=$ADDR && echo "Case1: [FAIL]" || echo "Case1: [OK]" > rmmod kprobe_example jprobe_example > > echo "Case2: jprobe->kprobe->ipmodify(fail)" > modprobe jprobe_example > modprobe kprobe_example > insmod ./ipmodify.ko target=$ADDR && echo "Case2: [FAIL]" || echo "Case2: [OK]" > rmmod kprobe_example jprobe_example > > echo "Case3: jprobe->ipmodify(fail)" > modprobe jprobe_example > insmod ./ipmodify.ko target=$ADDR && echo "Case3: [FAIL]" || echo "Case3: [OK]" > rmmod jprobe_example > > echo "Case4: ipmodify->jprobe(fail)" > insmod ./ipmodify.ko target=$ADDR > modprobe jprobe_example && echo "Case4: [FAIL]" || echo "Case4: [OK]" > rmmod ipmodify > > echo "Case5: ipmodify->kprobe->jprobe(fail)" > insmod ./ipmodify.ko target=$ADDR > modprobe kprobe_example > modprobe jprobe_example && echo "Case5: [FAIL]" || echo "Case5: [OK]" > rmmod ipmodify kprobe_example > > echo "Case6: ipmodify with targeting all functions(fail)" > insmod ./ipmodify.ko && echo "Case6: [FAIL]" || echo "Case6: [OK]" > rmmod ipmodify > > echo "Case7: ipmodify with notrace filter (fail)" > insmod ./ipmodify.ko target=$ADDR noexp="do_fork" && echo "Case7: [FAIL]" || echo "Case7: [OK]" > rmmod ipmodify > ------- > > And ipmodify.c > ------- > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/ftrace.h> > > > static void ftrace_ipmodify_handler(unsigned long a0, unsigned long a1, > struct ftrace_ops *op, struct pt_regs *regs) > { > return; > } > > static struct ftrace_ops test_ops __read_mostly = { > .func = ftrace_ipmodify_handler, > .flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY, > }; > > static unsigned long target; > module_param(target, ulong, 0444); > static char *noexp = ""; > module_param(noexp, charp, 0444); > > static int __init ipmodify_init(void) > { > int ret; > unsigned long ip = target; > > if (strlen(noexp) != 0) { > ret = ftrace_set_notrace(&test_ops, noexp, 0, 0); > pr_err("ipmodify_test: set notrace \"%s\", ret = %d\n", > noexp, ret); > } > if (ret < 0) > return ret; > > ret = ftrace_set_filter_ip(&test_ops, ip, 0, 0); > pr_err("ipmodify_test: set filter ip 0x%lx, ret = %d\n", ip, ret); > > if (ret >= 0) { > ret = register_ftrace_function(&test_ops); > pr_err("ipmodify_test: register ftrace on 0x%lx, ret = %d\n", > ip, ret); > } > > return ret; > } > > static void __exit ipmodify_exit(void) > { > int ret; > unsigned long ip = target; > > ret = unregister_ftrace_function(&test_ops); > pr_err("ipmodify_test: unregister ftrace on 0x%lx, ret = %d\n", ip, ret); > if (ret >= 0) { > ret = ftrace_set_filter_ip(&test_ops, ip, 1, 0); > pr_err("ipmodify_test: clear filter ip 0x%lx, ret = %d\n", > ip, ret); > } > } > > module_init(ipmodify_init) > module_exit(ipmodify_exit) > MODULE_LICENSE("GPL"); > ------- > > Thank you, > > --- > > Masami Hiramatsu (4): > kprobes/ftrace: Recover original IP if pre_handler doesn't change it > ftrace, kprobes: Support IPMODIFY flag to find IP modify conflict > kprobes: Add IPMODIFY flag to kprobe_ftrace_ops > kprobes: Set IPMODIFY flag only if the probe can change regs->ip > > > Documentation/kprobes.txt | 12 +-- > Documentation/trace/ftrace.txt | 5 + > arch/x86/kernel/kprobes/ftrace.c | 9 ++ > include/linux/ftrace.h | 16 ++++ > kernel/kprobes.c | 123 +++++++++++++++++++++++++++++---- > kernel/trace/ftrace.c | 143 +++++++++++++++++++++++++++++++++++++- > 6 files changed, 279 insertions(+), 29 deletions(-) > > -- > >
-- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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