Eric Lee / smarc-fsl-linux-kernel

17 Jun, 2009

1 commit

  • 0d9c25dde   headers: move module_bug_finalize()/module_bug_cleanup() definitions into module.h ... Browse Code »

    They're in linux/bug.h at present, which causes include order tangles. In
    particular, linux/bug.h cannot be used by linux/atomic.h because,
    according to Nikanth:

    linux/bug.h pulls in linux/module.h => linux/spinlock.h => asm/spinlock.h
    (which uses atomic_inc) => asm/atomic.h.

    bug.h is a pretty low-level thing and module.h is a higher-level thing,
    IMO.

    Cc: Nikanth Karthikesan
    Cc: Rusty Russell
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrew Morton
     

17 Jul, 2007

1 commit

  • 608e26196   generic bug: use show_regs() instead of dump_stack() ... Browse Code »

    The current generic bug implementation has a call to dump_stack() in case a
    WARN_ON(whatever) gets hit. Since report_bug(), which calls dump_stack(),
    gets called from an exception handler we can do better: just pass the
    pt_regs structure to report_bug() and pass it to show_regs() in case of a
    warning. This will give more debug informations like register contents,
    etc... In addition this avoids some pointless lines that dump_stack()
    emits, since it includes a stack backtrace of the exception handler which
    is of no interest in case of a warning. E.g. on s390 the following lines
    are currently always present in a stack backtrace if dump_stack() gets
    called from report_bug():

    [] show_trace+0x92/0xe8)
    [] show_stack+0xa0/0xd0
    [] dump_stack+0x2e/0x3c
    [] report_bug+0x98/0xf8
    [] illegal_op+0x1fc/0x21c
    [] sysc_return+0x0/0x10

    Acked-by: Jeremy Fitzhardinge
    Acked-by: Haavard Skinnemoen
    Cc: Andi Kleen
    Cc: Kyle McMartin
    Cc: Paul Mackerras
    Cc: Paul Mundt
    Cc: Martin Schwidefsky
    Signed-off-by: Heiko Carstens
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Heiko Carstens
     

09 Dec, 2006

1 commit

  • 7664c5a1d   [PATCH] Generic BUG implementation ... Browse Code »

    This patch adds common handling for kernel BUGs, for use by architectures as
    they wish. The code is derived from arch/powerpc.

    The advantages of having common BUG handling are:
    - consistent BUG reporting across architectures
    - shared implementation of out-of-line file/line data
    - implement CONFIG_DEBUG_BUGVERBOSE consistently

    This means that in inline impact of BUG is just the illegal instruction
    itself, which is an improvement for i386 and x86-64.

    A BUG is represented in the instruction stream as an illegal instruction,
    which has file/line information associated with it. This extra information is
    stored in the __bug_table section in the ELF file.

    When the kernel gets an illegal instruction, it first confirms it might
    possibly be from a BUG (ie, in kernel mode, the right illegal instruction).
    It then calls report_bug(). This searches __bug_table for a matching
    instruction pointer, and if found, prints the corresponding file/line
    information. If report_bug() determines that it wasn't a BUG which caused the
    trap, it returns BUG_TRAP_TYPE_NONE.

    Some architectures (powerpc) implement WARN using the same mechanism; if the
    illegal instruction was the result of a WARN, then report_bug(Q) returns
    CONFIG_DEBUG_BUGVERBOSE; otherwise it returns BUG_TRAP_TYPE_BUG.

    lib/bug.c keeps a list of loaded modules which can be searched for __bug_table
    entries. The architecture must call
    module_bug_finalize()/module_bug_cleanup() from its corresponding
    module_finalize/cleanup functions.

    Unsetting CONFIG_DEBUG_BUGVERBOSE will reduce the kernel size by some amount.
    At the very least, filename and line information will not be recorded for each
    but, but architectures may decide to store no extra information per BUG at
    all.

    Unfortunately, gcc doesn't have a general way to mark an asm() as noreturn, so
    architectures will generally have to include an infinite loop (or similar) in
    the BUG code, so that gcc knows execution won't continue beyond that point.
    gcc does have a __builtin_trap() operator which may be useful to achieve the
    same effect, unfortunately it cannot be used to actually implement the BUG
    itself, because there's no way to get the instruction's address for use in
    generating the __bug_table entry.

    [randy.dunlap@oracle.com: Handle BUG=n, GENERIC_BUG=n to prevent build errors]
    [bunk@stusta.de: include/linux/bug.h must always #include
    Cc: Andi Kleen
    Cc: Hugh Dickens
    Cc: Michael Ellerman
    Cc: Paul Mackerras
    Cc: Benjamin Herrenschmidt
    Cc: Rusty Russell
    Signed-off-by: Adrian Bunk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Jeremy Fitzhardinge