Messages in this thread | | | Subject | RE: [PATCH]kprobe handler discard user space trap | Date | Thu, 2 Mar 2006 14:36:56 +0800 | From | "Zhang, Yanmin" <> |
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>>-----Original Message----- >>From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of bibo mao >>Sent: 2006年3月1日 14:23 >>To: prasanna@in.ibm.com >>Cc: Mao, Bibo; Andrew Morton; linux-kernel@vger.kernel.org; Ananth N Mavinakayanahalli; Keshavamurthy, Anil S; >>hiramatu@sdl.hitachi.co.jp >>Subject: Re: [PATCH]kprobe handler discard user space trap >> >>This patch removes code in kprobe_handler() function which calculates >>user space int3 trap address in i386 architecture. And this patch is >>based on kprobe-handler-discard-user-space-trap.patch, against >>2.6.16-rc5-mm1. >> >>Signed-off-by: bibo mao <bibo.mao@intel.com> >> >>--- a/arch/i386/kernel/kprobes.c 2006-03-01 12:48:54.000000000 +0800 >>+++ b/arch/i386/kernel/kprobes.c 2006-03-01 14:08:12.000000000 +0800 >>@@ -203,7 +203,7 @@ static int __kprobes kprobe_handler(stru >> { >> struct kprobe *p; >> int ret = 0; >>- kprobe_opcode_t *addr = NULL; >>+ kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->eip - >>sizeof(kprobe_opcode_t)); >> unsigned long *lp; >> struct kprobe_ctlblk *kcb; >> #ifdef CONFIG_PREEMPT >>@@ -217,17 +217,6 @@ static int __kprobes kprobe_handler(stru >> preempt_disable(); >> kcb = get_kprobe_ctlblk(); >> >>- /* Check if the application is using LDT entry for its code segment and >>- * calculate the address by reading the base address from the LDT entry. >>- */ >>- if ((regs->xcs & 4) && (current->mm)) { >>- lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8) >>- + (char *) current->mm->context.ldt); >>- addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip - >>- sizeof(kprobe_opcode_t)); >>- } else { >>- addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t)); >>- } >> /* Check we're not actually recursing */ >> if (kprobe_running()) { >> p = get_kprobe(addr); >> >>Prasanna S Panchamukhi wrote: >>> On Tue, Feb 28, 2006 at 03:23:12PM +0800, bibo,mao wrote: >>>> Currently kprobe handler traps only happen in kernel space, so function >>>> kprobe_exceptions_notify should skip traps which happen in user space. >>>> This patch modifies this, and it is based on 2.6.16-rc4. >>> >>> You need to remove the code which calculates the >>> user space address in kprobe_handler() and also you need >>> to remove the code that checks for VM86 in i386, since >>> your patch check if user/vm86 at the top level. >>> >>> Thanks >>> Prasanna >>> >>>> Signed-off-by: bibo mao <bibo.mao@intel.com> >>>> >>>> diff -Nruap a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c >>>> --- a/arch/i386/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800 >>>> +++ b/arch/i386/kernel/kprobes.c 2006-03-01 10:37:50.000000000 +0800 >>>> @@ -463,6 +463,9 @@ int __kprobes kprobe_exceptions_notify(s >>>> struct die_args *args = (struct die_args *)data; >>>> int ret = NOTIFY_DONE; >>>> >>>> + if (user_mode(args->regs)) >>>> + return ret; >>>> + >>>> switch (val) { >>>> case DIE_INT3: >>>> if (kprobe_handler(args->regs)) >>>> diff -Nruap a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c >>>> --- a/arch/ia64/kernel/kprobes.c 2006-02-25 17:08:53.000000000 +0800 >>>> +++ b/arch/ia64/kernel/kprobes.c 2006-03-01 10:39:15.000000000 +0800 >>>> @@ -740,6 +740,9 @@ int __kprobes kprobe_exceptions_notify(s >>>> struct die_args *args = (struct die_args *)data; >>>> int ret = NOTIFY_DONE; >>>> >>>> + if (user_mode(args->regs)) >>>> + return ret; >>>> + >>>> switch(val) { >>>> case DIE_BREAK: >>>> /* err is break number from ia64_bad_break() */ >>>> diff -Nruap a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c >>>> --- a/arch/powerpc/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800 >>>> +++ b/arch/powerpc/kernel/kprobes.c 2006-03-01 10:39:53.000000000 +0800 >>>> @@ -397,6 +397,9 @@ int __kprobes kprobe_exceptions_notify(s >>>> struct die_args *args = (struct die_args *)data; >>>> int ret = NOTIFY_DONE; >>>> >>>> + if (user_mode(args->regs)) >>>> + return ret; >>>> + >>>> switch (val) { >>>> case DIE_BPT: >>>> if (kprobe_handler(args->regs)) >>>> diff -Nruap a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c >>>> --- a/arch/sparc64/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800 >>>> +++ b/arch/sparc64/kernel/kprobes.c 2006-03-01 10:40:16.000000000 +0800 >>>> @@ -324,6 +324,9 @@ int __kprobes kprobe_exceptions_notify(s >>>> struct die_args *args = (struct die_args *)data; >>>> int ret = NOTIFY_DONE; >>>> >>>> + if (user_mode(args->regs)) >>>> + return ret; >>>> + >>>> switch (val) { >>>> case DIE_DEBUG: >>>> if (kprobe_handler(args->regs)) >>>> diff -Nruap a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c >>>> --- a/arch/x86_64/kernel/kprobes.c 2006-02-25 17:08:52.000000000 +0800 >>>> +++ b/arch/x86_64/kernel/kprobes.c 2006-03-01 10:38:48.000000000 +0800 >>>> @@ -601,6 +601,9 @@ int __kprobes kprobe_exceptions_notify(s >>>> struct die_args *args = (struct die_args *)data; >>>> int ret = NOTIFY_DONE; >>>> >>>> + if (user_mode(args->regs)) >>>> + return ret; >>>> + >>>> switch (val) { >>>> case DIE_INT3: >>>> if (kprobe_handler(args->regs)) >>> When my ia64 box reboots with kernel 2.6.16-rc5-mm1, kernel hanged in kprobe_exceptions_notify. args->regs doesn't always point to a valid address. It might be NULL. machine_restart calls notify_die with parameter regs=NULL. Pls. check args->regs before using user_mode.
Pls. also check if other archs have the same problem.
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