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__get_kernel_nofault() does copy data in supervisor mode when forcing a task backtrace log through /proc/sysrq_trigger. This is expected cause a bus error exception on e.g. NULL pointer dereferencing when logging a kernel task has no workqueue associated. This bus error ought to be ignored. Our 030 bus error handler is ill equipped to deal with this: Whenever ssw indicates a kernel mode access on a data fault, we don't even attempt to handle the fault and instead always send a SEGV signal (or panic). As a result, the check for exception handling at the fault PC (buried in send_sig_fault() which gets called from do_page_fault() eventually) is never used. In contrast, both 040 and 060 access error handlers do not care whether a fault happened on supervisor mode access, and will call do_page_fault() on those, ultimately honoring the exception table. Add a check in bus_error030 to call do_page_fault() in case we do have an entry for the fault PC in our exception table. I had attempted a fix for this earlier in 2019 that did rely on testing pagefault_disabled() (see link below) to achieve the same thing, but this patch should be more generic. Tested on 030 Atari Falcon. Reported-by: Eero Tamminen <oak@helsinkinet.fi> Link: https://lore.kernel.org/r/alpine.LNX.2.21.1904091023540.25@nippy.intranet Link: https://lore.kernel.org/r/63130691-1984-c423-c1f2-73bfd8d3dcd3@gmail.com Signed-off-by: Michael Schmitz <schmitzmic@gmail.com> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Link: https://lore.kernel.org/r/20230301021107.26307-1-schmitzmic@gmail.com Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> |
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| .. | ||
| 68000 | ||
| amiga | ||
| apollo | ||
| atari | ||
| bvme6000 | ||
| coldfire | ||
| configs | ||
| emu | ||
| fpsp040 | ||
| hp300 | ||
| ifpsp060 | ||
| include | ||
| kernel | ||
| lib | ||
| mac | ||
| math-emu | ||
| mm | ||
| mvme16x | ||
| mvme147 | ||
| q40 | ||
| sun3 | ||
| sun3x | ||
| tools/amiga | ||
| virt | ||
| install.sh | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.bus | ||
| Kconfig.cpu | ||
| Kconfig.debug | ||
| Kconfig.devices | ||
| Kconfig.machine | ||
| Makefile | ||