On Fri, 30 Aug 2013 08:36:58 -0700 "H. Peter Anvin" <h...@zytor.com> wrote:
> On 08/23/2013 09:40 AM, Jan Kiszka wrote: > > Hi all, > > > > 32-bit kernels currently crash/reboot in early microcode loading when > > non-dynamic function tracing is enabled. Several functions in that path > > get instrumented with mcount, but its non-dynamic implementation does > > not work before paging is enabled (it accesses global variables at wrong > > addresses). > > > > Below some hunks to get it working again - at least in the absence of > > any microcode in the initrd. Marking all involved functions as __init is > > another option (as __init implies notrace). But I bet there is more > > hidden. I see e.g. a pr_warn() in find_cpio_init that should trigger the > > issue as well if we hit the error it reports (btw. printing at this > > point of the boot should not work anyway, should it?). > > > > Better ideas? > > > > Jan > > > > A better idea would be for the mcount/__fentry__ function to simply > return until the function tracing stuff is actually ready. > It does when dynamic tracing is enabled. But this issue is with static tracing, there's no code modification, thus all functions call mcount/__fentry__ and we need to look at a variable to determine if we should trace or not. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
