lkml.org 
[lkml]   [2010]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC patch] extable and module add object is static
    On Sat, Mar 27, 2010 at 08:02:34PM -0400, Mathieu Desnoyers wrote:
    > * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote:
    > > On Sat, Mar 27, 2010 at 07:20:24PM -0400, Mathieu Desnoyers wrote:
    > [...]
    > > > Something close to "object_is_static()" would be "kernel_text_address()", but it
    > > > only considers the text section addresses. I'd need something that would be
    > > > broader than that, containing all core kernel and module bss and data sections.
    > > >
    > > > Still looking...
    > >
    > > I was actually feeling pretty good about remembering object_is_on_stack()
    > > and finding it again. ;-)
    > >
    > > I am not seeing anything the identifies data or bss, and in any case,
    > > other situations such as per-CPU, __read_mostly, and who knows what all
    > > else would also need to be handled. So in the short term, my guess would
    > > be that it would be best to provide the three functions (possibly renaming
    > > them as noted above), but to leave the responsibility for figuring out
    > > which to invoke with the caller. Always happy to be proven wrong, of
    > > course!
    > >
    > > Thanx, Paul
    >
    > I think I found a neat way to do object_is_static(), which is all we need here.
    > Can you have a look at the following patch ? If you think it's right, I'll add
    > it to the patchset for the next submission.

    Looks plausible to me!

    Rusty, any thoughts?

    Thanx, Paul

    > extable and module add object is static
    >
    > Adds an API to extable.c to check if an object is statically defined. This
    > permits, along with object_is_on_stack(), to figure out is an object is either
    > statically defined (object_is_static()) or allocated on the stack
    > (object_is_on_stack()).
    >
    > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
    > CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
    > CC: David S. Miller <davem@davemloft.net>
    > CC: akpm@linux-foundation.org
    > CC: mingo@elte.hu
    > CC: laijs@cn.fujitsu.com
    > CC: dipankar@in.ibm.com
    > CC: josh@joshtriplett.org
    > CC: dvhltc@us.ibm.com
    > CC: niv@us.ibm.com
    > CC: tglx@linutronix.de
    > CC: peterz@infradead.org
    > CC: rostedt@goodmis.org
    > CC: Valdis.Kletnieks@vt.edu
    > CC: dhowells@redhat.com
    > CC: eric.dumazet@gmail.com
    > CC: Alexey Dobriyan <adobriyan@gmail.com>
    > ---
    > include/linux/kernel.h | 2 +
    > kernel/extable.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++
    > 2 files changed, 54 insertions(+)
    >
    > Index: linux.trees.git/include/linux/kernel.h
    > ===================================================================
    > --- linux.trees.git.orig/include/linux/kernel.h 2010-03-27 19:27:02.000000000 -0400
    > +++ linux.trees.git/include/linux/kernel.h 2010-03-27 19:28:02.000000000 -0400
    > @@ -218,6 +218,8 @@ extern int __kernel_text_address(unsigne
    > extern int kernel_text_address(unsigned long addr);
    > extern int func_ptr_is_kernel_text(void *ptr);
    >
    > +extern int object_is_static(void *obj);
    > +
    > struct pid;
    > extern struct pid *session_of_pgrp(struct pid *pgrp);
    >
    > Index: linux.trees.git/kernel/extable.c
    > ===================================================================
    > --- linux.trees.git.orig/kernel/extable.c 2010-03-27 19:28:06.000000000 -0400
    > +++ linux.trees.git/kernel/extable.c 2010-03-27 19:54:40.000000000 -0400
    > @@ -60,6 +60,14 @@ static inline int init_kernel_text(unsig
    > return 0;
    > }
    >
    > +static inline int init_kernel_text_or_data(unsigned long addr)
    > +{
    > + if (addr >= (unsigned long)__init_begin &&
    > + addr <= (unsigned long)__init_end)
    > + return 1;
    > + return 0;
    > +}
    > +
    > int core_kernel_text(unsigned long addr)
    > {
    > if (addr >= (unsigned long)_stext &&
    > @@ -113,3 +121,47 @@ int func_ptr_is_kernel_text(void *ptr)
    > return 1;
    > return is_module_text_address(addr);
    > }
    > +
    > +/*
    > + * Taking the safe approach to refer to each section individually rather than
    > + * just taking a range between _stext and _end, just in case an architecture
    > + * would decide to override the standard linker scripts and put a section
    > + * outside of this range.
    > + *
    > + * Should be kept in sync with linux/section.h and asm-generic/vmlinux.lds.h.
    > + */
    > +static int core_object_is_static(void *obj)
    > +{
    > + unsigned long addr = (unsigned long) obj;
    > +
    > + if (addr >= (unsigned long)_sdata &&
    > + addr <= (unsigned long)_edata)
    > + return 1;
    > + if (addr >= (unsigned long)__bss_start &&
    > + addr <= (unsigned long)__bss_stop)
    > + return 1;
    > + if (addr >= (unsigned long)__per_cpu_start &&
    > + addr <= (unsigned long)__per_cpu_end)
    > + return 1;
    > + if (addr >= (unsigned long)__start_rodata &&
    > + addr <= (unsigned long)__end_rodata)
    > + return 1;
    > + if (system_state == SYSTEM_BOOTING &&
    > + init_kernel_text_or_data(addr))
    > + return 1;
    > + if (core_kernel_text(addr))
    > + return 1;
    > + return 0;
    > +}
    > +
    > +/*
    > + * object_is_static - returns true is an object is statically defined
    > + */
    > +int object_is_static(void *obj)
    > +{
    > + if (core_object_is_static(obj))
    > + return 1;
    > + if (is_module_address((unsigned long) obj))
    > + return 1;
    > + return 0;
    > +}
    >
    >
    > --
    > Mathieu Desnoyers
    > Operating System Efficiency R&D Consultant
    > EfficiOS Inc.
    > http://www.efficios.com


    \
     
     \ /
      Last update: 2010-03-28 01:29    [W:0.053 / U:0.056 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site