Commit Graph

5 Commits

Author SHA1 Message Date
Paul Mundt
e115f2c17c sh: unwinder: Use a special bug flag for unwinder traps.
This simplifies the unwinder trap handling, dropping the use of the
special trapa vector and simply piggybacking on top of the BUG support. A
new BUGFLAG_UNWINDER is added for flagging the unwinder fault, before
continuing on with regular BUG dispatch.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-08-22 05:28:25 +09:00
Paul Mundt
c153a58e71 Merge branch 'sh/dwarf-unwinder' of git://github.com/mfleming/linux-2.6 into sh/dwarf-unwinder 2009-08-22 03:49:58 +09:00
Paul Mundt
4ab8f241f6 sh: Export unwind_stack() to satisfy modular oprofile.
If the oprofile code is built as a module, unwind_stack() as used by the
oprofile backtrace code is not available, causing build breakage.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-08-22 03:43:15 +09:00
Matt Fleming
b344e24a8e sh: unwinder: Introduce UNWINDER_BUG() and UNWINDER_BUG_ON()
We can't assume that if we execute the unwinder code and the unwinder
was already running that it has faulted. Clearly two kernel threads can
invoke the unwinder at the same time and may be running simultaneously.

The previous approach used BUG() and BUG_ON() in the unwinder code to
detect whether the unwinder was incapable of unwinding the stack, and
that the next available unwinder should be used instead. A better
approach is to explicitly invoke a trap handler to switch unwinders when
the current unwinder cannot continue.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
2009-08-21 13:02:44 +01:00
Matt Fleming
bf61ad1f87 sh: Allow multiple stack unwinders to be setup
Provide an interface for registering stack unwinders, where each
unwinder is given a rating that describes its accuracy and
complexity. The more accurate an unwinder is, the more complex it is.

If a the current stack unwinder faults, then the stack unwinder with the
next highest accuracy will be used in its place (provided one is
available). For example, this allows unwinders, such as the DWARF
unwinder, to liberally sprinkle BUG()s to catch badly formed DWARF debug
info.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-08-13 19:49:03 +09:00