From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Linux-mm <linux-mm@kvack.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Christoph Hellwig <hch@infradead.org>,
Andi Kleen <andi@firstfloor.org>,
Thomas Gleixner <tglx@linutronix.de>,
Jonathan Corbet <corbet@lwn.net>, Oleg Nesterov <oleg@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jim Keniston <jkenisto@linux.vnet.ibm.com>,
Roland McGrath <roland@hack.frob.com>,
SystemTap <systemtap@sources.redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 2.6.39-rc1-tip 8/26] 8: uprobes: store/restore original instruction.
Date: Mon, 18 Apr 2011 18:12:47 +0200 [thread overview]
Message-ID: <1303143167.32491.866.camel@twins> (raw)
In-Reply-To: <20110401143358.15455.53804.sendpatchset@localhost6.localdomain6>
On Fri, 2011-04-01 at 20:03 +0530, Srikar Dronamraju wrote:
> +static int __copy_insn(struct address_space *mapping, char *insn,
> + unsigned long nbytes, unsigned long offset)
> +{
> + struct page *page;
> + void *vaddr;
> + unsigned long off1;
> + loff_t idx;
> +
> + idx = offset >> PAGE_CACHE_SHIFT;
> + off1 = offset &= ~PAGE_MASK;
> + page = grab_cache_page(mapping, (unsigned long)idx);
What if the page wasn't present due to being swapped out?
> + if (!page)
> + return -ENOMEM;
> +
> + vaddr = kmap_atomic(page, KM_USER0);
> + memcpy(insn, vaddr + off1, nbytes);
> + kunmap_atomic(vaddr, KM_USER0);
> + unlock_page(page);
> + page_cache_release(page);
> + return 0;
> +}
> +
> +static int copy_insn(struct uprobe *uprobe, unsigned long addr)
> +{
> + struct address_space *mapping;
> + int bytes;
> + unsigned long nbytes;
> +
> + addr &= ~PAGE_MASK;
> + nbytes = PAGE_SIZE - addr;
> + mapping = uprobe->inode->i_mapping;
> +
> + /* Instruction at end of binary; copy only available bytes */
> + if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size)
> + bytes = uprobe->inode->i_size - uprobe->offset;
> + else
> + bytes = MAX_UINSN_BYTES;
> +
> + /* Instruction at the page-boundary; copy bytes in second page */
> + if (nbytes < bytes) {
> + if (__copy_insn(mapping, uprobe->insn + nbytes,
> + bytes - nbytes, uprobe->offset + nbytes))
> + return -ENOMEM;
> + bytes = nbytes;
> + }
> + return __copy_insn(mapping, uprobe->insn, bytes, uprobe->offset);
> +}
This all made me think why implement read_opcode() again.. I know its
all slightly different, but still.
> +static struct task_struct *uprobes_get_mm_owner(struct mm_struct *mm)
> +{
> + struct task_struct *tsk;
> +
> + rcu_read_lock();
> + tsk = rcu_dereference(mm->owner);
> + if (tsk)
> + get_task_struct(tsk);
> + rcu_read_unlock();
> + return tsk;
> +}
Naming is somewhat inconsistent, most of your functions have the _uprobe
postfix and now its a uprobes_ prefix all of a sudden.
> static int install_uprobe(struct mm_struct *mm, struct uprobe *uprobe)
> {
> - int ret = 0;
> + struct task_struct *tsk = uprobes_get_mm_owner(mm);
> + int ret;
>
> - /*TODO: install breakpoint */
> - if (!ret)
> + if (!tsk) /* task is probably exiting; bail-out */
> + return -ESRCH;
> +
> + if (!uprobe->copy) {
> + ret = copy_insn(uprobe, mm->uprobes_vaddr);
> + if (ret)
> + goto put_return;
> + if (is_bkpt_insn(uprobe->insn)) {
> + print_insert_fail(tsk, mm->uprobes_vaddr,
> + "breakpoint instruction already exists");
> + ret = -EEXIST;
> + goto put_return;
> + }
> + ret = analyze_insn(tsk, uprobe);
> + if (ret) {
> + print_insert_fail(tsk, mm->uprobes_vaddr,
> + "instruction type cannot be probed");
> + goto put_return;
> + }
If you want to expose this functionality to !root users printing stuff
to dmesg like that isn't a good idea.
> + uprobe->copy = 1;
> + }
> +
> + ret = set_bkpt(tsk, uprobe, mm->uprobes_vaddr);
> + if (ret < 0)
> + print_insert_fail(tsk, mm->uprobes_vaddr,
> + "failed to insert bkpt instruction");
> + else
> atomic_inc(&mm->uprobes_count);
> +
> +put_return:
> + put_task_struct(tsk);
> return ret;
> }
next prev parent reply other threads:[~2011-04-18 16:13 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-01 14:32 [PATCH v3 2.6.39-rc1-tip 0/26] 0: Uprobes patchset with perf probe support Srikar Dronamraju
2011-04-01 14:32 ` [PATCH v3 2.6.39-rc1-tip 1/26] 1: mm: replace_page() loses static attribute Srikar Dronamraju
2011-04-01 14:32 ` [PATCH v3 2.6.39-rc1-tip 2/26] 2: mm: Move replace_page() to mm/memory.c Srikar Dronamraju
2011-04-01 14:33 ` [PATCH v3 2.6.39-rc1-tip 3/26] 3: X86 specific breakpoint definitions Srikar Dronamraju
2011-04-01 14:33 ` [PATCH v3 2.6.39-rc1-tip 4/26] 4: uprobes: Breakground page replacement Srikar Dronamraju
2011-04-18 12:20 ` Peter Zijlstra
2011-04-01 14:33 ` [PATCH v3 2.6.39-rc1-tip 5/26] 5: uprobes: Adding and remove a uprobe in a rb tree Srikar Dronamraju
2011-04-18 12:20 ` Peter Zijlstra
2011-04-01 14:33 ` [PATCH v3 2.6.39-rc1-tip 6/26] 6: Uprobes: register/unregister probes Srikar Dronamraju
2011-04-02 0:26 ` Stephen Wilson
2011-04-02 0:53 ` Srikar Dronamraju
2011-04-02 1:29 ` Stephen Wilson
2011-04-18 12:20 ` Peter Zijlstra
2011-04-01 14:33 ` [PATCH v3 2.6.39-rc1-tip 7/26] 7: x86: analyze instruction and determine fixups Srikar Dronamraju
2011-04-19 13:29 ` Steven Rostedt
2011-04-21 17:31 ` Srikar Dronamraju
2011-04-21 17:52 ` Peter Zijlstra
2011-04-01 14:33 ` [PATCH v3 2.6.39-rc1-tip 8/26] 8: uprobes: store/restore original instruction Srikar Dronamraju
2011-04-18 16:12 ` Peter Zijlstra [this message]
2011-04-01 14:34 ` [PATCH v3 2.6.39-rc1-tip 9/26] 9: uprobes: mmap and fork hooks Srikar Dronamraju
2011-04-18 16:21 ` Peter Zijlstra
2011-04-18 16:29 ` Peter Zijlstra
2011-04-19 6:45 ` Srikar Dronamraju
2011-04-01 14:34 ` [PATCH v3 2.6.39-rc1-tip 10/26] 10: x86: architecture specific task information Srikar Dronamraju
2011-04-01 14:34 ` [PATCH v3 2.6.39-rc1-tip 11/26] 11: uprobes: task specific information Srikar Dronamraju
2011-04-01 14:34 ` [PATCH v3 2.6.39-rc1-tip 12/26] 12: uprobes: slot allocation for uprobes Srikar Dronamraju
2011-04-18 16:46 ` Peter Zijlstra
2011-04-19 6:26 ` Srikar Dronamraju
2011-04-19 9:02 ` Peter Zijlstra
2011-04-19 9:11 ` Peter Zijlstra
2011-04-20 13:40 ` Eric Paris
2011-04-20 14:51 ` Frank Ch. Eigler
2011-04-20 15:16 ` Stephen Smalley
2011-04-21 14:11 ` Srikar Dronamraju
2011-04-21 14:45 ` Eric Paris
2011-04-21 16:14 ` Roland McGrath
2011-04-21 16:59 ` Srikar Dronamraju
2011-04-01 14:35 ` [PATCH v3 2.6.39-rc1-tip 13/26] 13: uprobes: get the breakpoint address Srikar Dronamraju
2011-04-18 16:47 ` Peter Zijlstra
2011-04-01 14:35 ` [PATCH v3 2.6.39-rc1-tip 14/26] 14: x86: x86 specific probe handling Srikar Dronamraju
2011-04-18 16:55 ` Peter Zijlstra
2011-04-19 5:43 ` Srikar Dronamraju
2011-04-18 16:57 ` Peter Zijlstra
2011-04-01 14:35 ` [PATCH v3 2.6.39-rc1-tip 15/26] 15: uprobes: Handing int3 and singlestep exception Srikar Dronamraju
2011-04-19 13:03 ` Peter Zijlstra
2011-04-19 13:12 ` Steven Rostedt
2011-04-21 17:10 ` Srikar Dronamraju
2011-04-21 17:41 ` Peter Zijlstra
2011-04-19 13:39 ` Peter Zijlstra
2011-04-21 17:03 ` Srikar Dronamraju
2011-04-01 14:35 ` [PATCH v3 2.6.39-rc1-tip 16/26] 16: x86: uprobes exception notifier for x86 Srikar Dronamraju
2011-04-01 14:35 ` [PATCH v3 2.6.39-rc1-tip 17/26] 17: uprobes: register a notifier for uprobes Srikar Dronamraju
2011-04-19 13:54 ` Peter Zijlstra
2011-04-01 14:36 ` [PATCH v3 2.6.39-rc1-tip 18/26] 18: uprobes: commonly used filters Srikar Dronamraju
2011-04-05 1:26 ` Masami Hiramatsu
2011-04-19 13:57 ` Peter Zijlstra
2011-04-21 11:09 ` Srikar Dronamraju
2011-04-21 11:37 ` Peter Zijlstra
2011-04-21 11:49 ` Srikar Dronamraju
2011-04-01 14:36 ` [PATCH v3 2.6.39-rc1-tip 19/26] 19: tracing: Extract out common code for kprobes/uprobes traceevents Srikar Dronamraju
2011-04-01 14:36 ` [PATCH v3 2.6.39-rc1-tip 20/26] 20: tracing: uprobes trace_event interface Srikar Dronamraju
2011-04-01 14:36 ` [PATCH v3 2.6.39-rc1-tip 21/26] 21: Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Srikar Dronamraju
2011-04-01 14:47 ` [RESEND] [PATCH v3 2.6.39-rc1-tip 21/26] 21: Uprobe tracer documentation " Srikar Dronamraju
2011-04-01 14:36 ` [PATCH v3 2.6.39-rc1-tip 22/26] 22: perf: rename target_module to target Srikar Dronamraju
2011-04-04 10:06 ` Masami Hiramatsu
2011-04-06 23:46 ` Srikar Dronamraju
2011-04-01 14:37 ` [PATCH v3 2.6.39-rc1-tip 23/26] 23: perf: show possible probes in a given executable file or library Srikar Dronamraju
2011-04-04 10:15 ` Masami Hiramatsu
2011-04-06 22:50 ` Srikar Dronamraju
2011-04-01 14:37 ` [PATCH v3 2.6.39-rc1-tip 24/26] 24: perf: perf interface for uprobes Srikar Dronamraju
2011-04-01 14:37 ` [PATCH v3 2.6.39-rc1-tip 25/26] 25: perf: Documentation for perf uprobes Srikar Dronamraju
2011-04-01 14:37 ` [PATCH v3 2.6.39-rc1-tip 26/26] 26: uprobes: filter chain Srikar Dronamraju
2011-04-05 1:27 ` Masami Hiramatsu
2011-04-06 22:41 ` Srikar Dronamraju
2011-04-07 3:19 ` Masami Hiramatsu
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