Patch "m68k: Only force 030 bus error if PC not in exception table" has been added to the 6.2-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



This is a note to let you know that I've just added the patch titled

    m68k: Only force 030 bus error if PC not in exception table

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     m68k-only-force-030-bus-error-if-pc-not-in-exception.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3ac10fd9421bc62ab8ca25248c840b6d33062210
Author: Michael Schmitz <schmitzmic@xxxxxxxxx>
Date:   Wed Mar 1 15:11:07 2023 +1300

    m68k: Only force 030 bus error if PC not in exception table
    
    [ Upstream commit e36a82bebbf7da814530d5a179bef9df5934b717 ]
    
    __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@xxxxxxxxxxxxxx>
    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@xxxxxxxxx
    Signed-off-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
    Reviewed-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230301021107.26307-1-schmitzmic@xxxxxxxxx
    Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 5c8cba0efc63e..a700807c9b6d9 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -30,6 +30,7 @@
 #include <linux/init.h>
 #include <linux/ptrace.h>
 #include <linux/kallsyms.h>
+#include <linux/extable.h>
 
 #include <asm/setup.h>
 #include <asm/fpu.h>
@@ -545,7 +546,8 @@ static inline void bus_error030 (struct frame *fp)
 			errorcode |= 2;
 
 		if (mmusr & (MMU_I | MMU_WP)) {
-			if (ssw & 4) {
+			/* We might have an exception table for this PC */
+			if (ssw & 4 && !search_exception_tables(fp->ptregs.pc)) {
 				pr_err("Data %s fault at %#010lx in %s (pc=%#lx)\n",
 				       ssw & RW ? "read" : "write",
 				       fp->un.fmtb.daddr,



[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux