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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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| syscalls | ||
| .gitignore | ||
| asm-offsets.c | ||
| bootinfo_proc.c | ||
| dma.c | ||
| early_printk.c | ||
| entry.S | ||
| head.S | ||
| ints.c | ||
| irq.c | ||
| machine_kexec.c | ||
| Makefile | ||
| module.c | ||
| pcibios.c | ||
| process.c | ||
| ptrace.c | ||
| relocate_kernel.S | ||
| setup_mm.c | ||
| setup_no.c | ||
| setup.c | ||
| signal.c | ||
| sun3-head.S | ||
| sys_m68k.c | ||
| syscalltable.S | ||
| time.c | ||
| traps.c | ||
| uboot.c | ||
| vectors.c | ||
| vmlinux-nommu.lds | ||
| vmlinux-std.lds | ||
| vmlinux-sun3.lds | ||
| vmlinux.lds.S | ||