Eric Lee / smarc-fsl-linux-kernel

01 May, 2013

2 commits

  • a43cb95d5   dump_stack: unify debug information printed by show_regs() ... Browse Code »

    show_regs() is inherently arch-dependent but it does make sense to print
    generic debug information and some archs already do albeit in slightly
    different forms. This patch introduces a generic function to print debug
    information from show_regs() so that different archs print out the same
    information and it's much easier to modify what's printed.

    show_regs_print_info() prints out the same debug info as dump_stack()
    does plus task and thread_info pointers.

    * Archs which didn't print debug info now do.

    alpha, arc, blackfin, c6x, cris, frv, h8300, hexagon, ia64, m32r,
    metag, microblaze, mn10300, openrisc, parisc, score, sh64, sparc,
    um, xtensa

    * Already prints debug info. Replaced with show_regs_print_info().
    The printed information is superset of what used to be there.

    arm, arm64, avr32, mips, powerpc, sh32, tile, unicore32, x86

    * s390 is special in that it used to print arch-specific information
    along with generic debug info. Heiko and Martin think that the
    arch-specific extra isn't worth keeping s390 specfic implementation.
    Converted to use the generic version.

    Note that now all archs print the debug info before actual register
    dumps.

    An example BUG() dump follows.

    kernel BUG at /work/os/work/kernel/workqueue.c:4841!
    invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
    Modules linked in:
    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ #7
    Hardware name: empty empty/S3992, BIOS 080011 10/26/2007
    task: ffff88007c85e040 ti: ffff88007c860000 task.ti: ffff88007c860000
    RIP: 0010:[] [] init_workqueues+0x4/0x6
    RSP: 0000:ffff88007c861ec8 EFLAGS: 00010246
    RAX: ffff88007c861fd8 RBX: ffffffff824466a8 RCX: 0000000000000001
    RDX: 0000000000000046 RSI: 0000000000000001 RDI: ffffffff8234a07a
    RBP: ffff88007c861ec8 R08: 0000000000000000 R09: 0000000000000000
    R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8234a07a
    R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
    FS: 0000000000000000(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000
    CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
    CR2: ffff88015f7ff000 CR3: 00000000021f1000 CR4: 00000000000007f0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    Stack:
    ffff88007c861ef8 ffffffff81000312 ffffffff824466a8 ffff88007c85e650
    0000000000000003 0000000000000000 ffff88007c861f38 ffffffff82335e5d
    ffff88007c862080 ffffffff8223d8c0 ffff88007c862080 ffffffff81c47760
    Call Trace:
    [] do_one_initcall+0x122/0x170
    [] kernel_init_freeable+0x9b/0x1c8
    [] ? rest_init+0x140/0x140
    [] kernel_init+0xe/0xf0
    [] ret_from_fork+0x7c/0xb0
    [] ? rest_init+0x140/0x140
    ...

    v2: Typo fix in x86-32.

    v3: CPU number dropped from show_regs_print_info() as
    dump_stack_print_info() has been updated to print it. s390
    specific implementation dropped as requested by s390 maintainers.

    Signed-off-by: Tejun Heo
    Acked-by: David S. Miller
    Acked-by: Jesper Nilsson
    Cc: Heiko Carstens
    Cc: Martin Schwidefsky
    Cc: Bjorn Helgaas
    Cc: Fengguang Wu
    Cc: Mike Frysinger
    Cc: Vineet Gupta
    Cc: Sam Ravnborg
    Acked-by: Chris Metcalf [tile bits]
    Acked-by: Richard Kuo [hexagon bits]
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Tejun Heo
     
  • 196779b9b   dump_stack: consolidate dump_stack() implementations and unify their behaviors ... Browse Code »

    Both dump_stack() and show_stack() are currently implemented by each
    architecture. show_stack(NULL, NULL) dumps the backtrace for the
    current task as does dump_stack(). On some archs, dump_stack() prints
    extra information - pid, utsname and so on - in addition to the
    backtrace while the two are identical on other archs.

    The usages in arch-independent code of the two functions indicate
    show_stack(NULL, NULL) should print out bare backtrace while
    dump_stack() is used for debugging purposes when something went wrong,
    so it does make sense to print additional information on the task which
    triggered dump_stack().

    There's no reason to require archs to implement two separate but mostly
    identical functions. It leads to unnecessary subtle information.

    This patch expands the dummy fallback dump_stack() implementation in
    lib/dump_stack.c such that it prints out debug information (taken from
    x86) and invokes show_stack(NULL, NULL) and drops arch-specific
    dump_stack() implementations in all archs except blackfin. Blackfin's
    dump_stack() does something wonky that I don't understand.

    Debug information can be printed separately by calling
    dump_stack_print_info() so that arch-specific dump_stack()
    implementation can still emit the same debug information. This is used
    in blackfin.

    This patch brings the following behavior changes.

    * On some archs, an extra level in backtrace for show_stack() could be
    printed. This is because the top frame was determined in
    dump_stack() on those archs while generic dump_stack() can't do that
    reliably. It can be compensated by inlining dump_stack() but not
    sure whether that'd be necessary.

    * Most archs didn't use to print debug info on dump_stack(). They do
    now.

    An example WARN dump follows.

    WARNING: at kernel/workqueue.c:4841 init_workqueues+0x35/0x505()
    Hardware name: empty
    Modules linked in:
    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ #9
    0000000000000009 ffff88007c861e08 ffffffff81c614dc ffff88007c861e48
    ffffffff8108f50f ffffffff82228240 0000000000000040 ffffffff8234a03c
    0000000000000000 0000000000000000 0000000000000000 ffff88007c861e58
    Call Trace:
    [] dump_stack+0x19/0x1b
    [] warn_slowpath_common+0x7f/0xc0
    [] warn_slowpath_null+0x1a/0x20
    [] init_workqueues+0x35/0x505
    ...

    v2: CPU number added to the generic debug info as requested by s390
    folks and dropped the s390 specific dump_stack(). This loses %ksp
    from the debug message which the maintainers think isn't important
    enough to keep the s390-specific dump_stack() implementation.

    dump_stack_print_info() is moved to kernel/printk.c from
    lib/dump_stack.c. Because linkage is per objecct file,
    dump_stack_print_info() living in the same lib file as generic
    dump_stack() means that archs which implement custom dump_stack()
    - at this point, only blackfin - can't use dump_stack_print_info()
    as that will bring in the generic version of dump_stack() too. v1
    The v1 patch broke build on blackfin due to this issue. The build
    breakage was reported by Fengguang Wu.

    Signed-off-by: Tejun Heo
    Acked-by: David S. Miller
    Acked-by: Vineet Gupta
    Acked-by: Jesper Nilsson
    Acked-by: Vineet Gupta
    Acked-by: Martin Schwidefsky [s390 bits]
    Cc: Heiko Carstens
    Cc: Mike Frysinger
    Cc: Fengguang Wu
    Cc: Bjorn Helgaas
    Cc: Sam Ravnborg
    Acked-by: Richard Kuo [hexagon bits]
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Tejun Heo
     

29 Mar, 2012

1 commit

07 Oct, 2011

1 commit