linux/arch/m68k
Michael Schmitz e36a82bebb m68k: Only force 030 bus error if PC not in exception table
__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>
2023-03-06 14:09:42 +01:00
..
68000 m68knommu: updates and fixes for v6.3 2023-02-27 09:31:02 -08:00
amiga m68k: Add asm/config.h 2022-02-21 12:00:20 +01:00
apollo m68k: Add asm/config.h 2022-02-21 12:00:20 +01:00
atari for-5.18/block-2022-03-18 2022-03-21 16:48:55 -07:00
bvme6000 for-5.18/block-2022-03-18 2022-03-21 16:48:55 -07:00
coldfire m68k: Check syscall_trace_enter() return code 2023-01-30 16:40:15 +01:00
configs m68k: defconfig: Update defconfigs for v6.2-rc3 2023-01-30 16:40:15 +01:00
emu tty: nfcon: use console_is_registered() 2022-12-02 11:25:01 +01:00
fpsp040
hp300 m68k: removed unused "mach_get_ss" 2022-05-25 00:04:11 +10:00
ifpsp060
include - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
kernel m68k: Only force 030 bus error if PC not in exception table 2023-03-06 14:09:42 +01:00
lib net: unexport csum_and_copy_{from,to}_user 2022-04-29 14:37:59 -07:00
mac m68k: mac: Reword comment using double "in" 2022-11-01 12:17:56 +01:00
math-emu m68k: math-emu: Fix typos in comments 2022-05-09 13:13:59 +02:00
mm m68k: mm: Fix systems with memory at end of 32-bit address space 2023-03-06 14:09:42 +01:00
mvme16x for-5.18/block-2022-03-18 2022-03-21 16:48:55 -07:00
mvme147 for-5.18/block-2022-03-18 2022-03-21 16:48:55 -07:00
q40 m68k: q40: Do not initialise statics to 0 2023-01-30 16:39:43 +01:00
sun3 m68k: sun3: Use __func__ to get function's name in an output message 2022-06-20 14:16:43 +02:00
sun3x m68k: Remove set_fs() 2021-09-24 13:35:07 +02:00
tools/amiga
virt m68k: Rework BI_VIRT_RNG_SEED as BI_RNG_SEED 2022-09-28 22:16:44 +02:00
install.sh kbuild: factor out the common installation code into scripts/install.sh 2022-05-11 21:45:53 +09:00
Kbuild m68k: Introduce a virtual m68k machine 2022-04-11 11:48:01 +02:00
Kconfig m68k: Add kernel seccomp support 2023-01-30 16:40:15 +01:00
Kconfig.bus m68k: coldfire: drop ISA_DMA_API support 2022-05-16 13:18:30 +10:00
Kconfig.cpu - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
Kconfig.debug m68k: Kconfig.debug: Replace single quotes 2022-07-06 14:07:04 +02:00
Kconfig.devices m68k: /proc/hardware should depend on PROC_FS 2023-02-13 11:34:49 +01:00
Kconfig.machine m68k: nommu: Fix misspellings of "DragonEngine" 2023-02-13 08:56:39 +10:00
Makefile kbuild: remove head-y syntax 2022-10-02 18:06:03 +09:00