svn commit: r203696 - in head: lib/libc/sys sys/kern sys/sys

[Kostik Belousov]

On Tue, Feb 09, 2010 at 04:11:43PM -0800, Marcel Moolenaar wrote:
> 
> On Feb 9, 2010, at 11:17 AM, Marcel Moolenaar wrote:
> 
> > Action items:
> > 
> >>>> - vmspace should be referenced by vmspace_acquire_ref()
> >>>> - vm_map should be read-locked before iterating the map entries.
> > 
> > I'll implement it and send a patch for review to avoid unnecessary
> > repository churn...
> 
> Please review attached patch. I have a sample session of how
> a debugger can use the information (see XXX lines):
> 
> hob% /usr/obj/nfs/bsddbg/trunk/bdb/bdb images/abort/abort
> [cursor=0x2000000000000560:0]
> bdb> run
> process 1539 created
> process 1539 stopped with signal 5
> XXX: 1: 0x2000000000000000-0x2000000000001fff, 5, 0 37 `/nfs/bsddbg/trunk/images/abort/abort`
> XXX: 2: 0x2000000000010000-0x2000000000011fff, 3, 0 0 ``
> XXX: 3: 0x2000000040010000-0x2000000040077fff, 5, 0 21 `/libexec/ld-elf.so.1`
> XXX: 4: 0x2000000040086000-0x2000000040089fff, 3, 0x66000 21 `/libexec/ld-elf.so.1`
> XXX: 5: 0x200000004008a000-0x2000000040091fff, 3, 0 0 ``
> XXX: 6: 0x8000000000000000-0x800000000001ffff, 3, 0 0 ``
> XXX: 7: 0x9ffffffffffe0000-0x9fffffffffffffff, 3, 0 0 ``
>   0x200000004001c560: { // MFB;
> >         alloc   r2 = ar.pfs, 0x0, 0x3, 0x3, 0x0
>           nop.f   0x0
>           nop.b   0x0 ;;
>   }
> [cursor=0x200000004001c560:0]
> bdb> step
> process 1575 stopped with signal 5
>   0x200000004001c560: { // MFB;
>           alloc   r2 = ar.pfs, 0x0, 0x3, 0x3, 0x0
> >         nop.f   0x0
>           nop.b   0x0 ;;
>   }
> [cursor=0x200000004001c560:1]
> bdb> continue
> process 1539 stopped with signal 6
> XXX: 1: 0x2000000000000000-0x2000000000001fff, 5, 0 37 `/nfs/bsddbg/trunk/images/abort/abort`
> XXX: 2: 0x2000000000010000-0x2000000000011fff, 3, 0 0 ``
> XXX: 3: 0x2000000040010000-0x2000000040077fff, 5, 0 21 `/libexec/ld-elf.so.1`
> XXX: 4: 0x200000004007e000-0x2000000040085fff, 3, 0x6000 0 ``
> XXX: 5: 0x2000000040086000-0x2000000040089fff, 3, 0x66000 21 `/libexec/ld-elf.so.1`
> XXX: 6: 0x200000004008a000-0x2000000040099fff, 3, 0 0 ``
> XXX: 7: 0x200000004009c000-0x20000000402e1fff, 5, 0 15 `/lib/libc.so.7`
> XXX: 8: 0x20000000402e2000-0x20000000402effff, 0, 0x246000 0 ``
> XXX: 9: 0x20000000402f0000-0x20000000402fdfff, 3, 0x244000 15 `/lib/libc.so.7`
> XXX: 10: 0x20000000402fe000-0x2000000040319fff, 3, 0x262000 0 ``
> XXX: 11: 0x2000000040328000-0x2000000040339fff, 3, 0xe000 0 ``
> XXX: 12: 0x8000000000000000-0x800000000001ffff, 3, 0 0 ``
> XXX: 13: 0x9ffffffffffe0000-0x9fffffffffffffff, 3, 0 0 ``
>   0x20000000402a0c40: { // MBB;
> >         cmp.eq  p0, p6 = r0, r10
>   (p6)    br.sptk.few 20000000400ded00
>           br.ret.sptk.few rp ;;
>   }
> [cursor=0x20000000402a0c40:0]
> bdb> 

Vnode locks are before vm map locks in global lock order. vn_fullpath()
may need to lock vnodes to call VOP_VPTOCNP(). I think you should (and
can) drop both vm map lock and vmspace reference much earlier.

Would it be cleaner to use explicitely sized types for compat32
structure members ?

Comparing ptrace_vm_entry with kinfo_vmentry, I think that it might
be good idea to add fsid and inode number to ptrace_vm_entry, to
give at least some information when vn_fullpath failed.
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