linux-stable.git/arch/s390/kernel/dumpstack.c, branch linux-rolling-stable

s390/fault: Print unmodified PSW address on protection exception

2025-11-14T10:34:28+00:00

In case of a kernel crash caused by a protection exception, print the
unmodified PSW address as reported by the CPU. The protection exception
handler modifies the PSW address in order to keep fault handling easy,
however that leads to misleading call traces.

Therefore restore the original PSW address before printing it.

Before this change the output in case of a protection exception looks like
this:

 Oops: 0004 ilc:2 [#1]SMP
 Krnl PSW : 0704c00180000000 000003ffe0b40d78 (sysrq_handle_crash+0x28/0x40)
            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
...
 Krnl Code: 000003ffe0b40d66: e3e0f0980024        stg     %r14,152(%r15)
            000003ffe0b40d6c: c010fffffff2        larl    %r1,000003ffe0b40d50
           #000003ffe0b40d72: c0200046b6bc        larl    %r2,000003ffe1417aea
           >000003ffe0b40d78: 92021000            mvi     0(%r1),2
            000003ffe0b40d7c: c0e5ffae03d6        brasl   %r14,000003ffe0101528

With this change it looks like this:

 Oops: 0004 ilc:2 [#1]SMP
 Krnl PSW : 0704c00180000000 000003ffe0b40dfc (sysrq_handle_crash+0x2c/0x40)
            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
...
 Krnl Code: 000003ffe0b40dec: c010fffffff2        larl    %r1,000003ffe0b40dd0
            000003ffe0b40df2: c0200046b67c        larl    %r2,000003ffe1417aea
           *000003ffe0b40df8: 92021000            mvi     0(%r1),2
           >000003ffe0b40dfc: c0e5ffae03b6        brasl   %r14,000003ffe0101568
            000003ffe0b40e02: 0707                bcr     0,%r7

Note that with this change the PSW address points to the instruction behind
the instruction which caused the exception like it is expected for
protection exceptions.

This also replaces the '#' marker in the disassembly with '*', which allows
to distinguish between new and old behavior.

Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens

s390/asm-offsets: Remove ASM_OFFSETS_C

2025-03-31T10:20:39+00:00

Remove ASM_OFFSETS_C which is used as guard in thread_info.h to decide if
asm-offsets can be included or not.

There is no reason to include asm-offsets.h in thread_info.h anymore.
Remove the define and the not needed include. Explicitly include
asm-offsets.h in all header files which require it, and where it used
to be included implicitly via thread_info.h.

This reduces header dependencies.

Acked-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: Rely on generic printing of preemption model

2025-03-17T10:23:40+00:00

die() invokes later show_regs() -> show_regs_print_info() which prints
the current preemption model.
Remove it from the initial line.

Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Heiko Carstens 
Link: https://lore.kernel.org/r/20250314160810.2373416-7-bigeasy@linutronix.de

s390: Replace S390_lowcore by get_lowcore()

2024-06-18T15:01:33+00:00

Replace all S390_lowcore usages in arch/s390/ by get_lowcore().

Acked-by: Heiko Carstens 
Signed-off-by: Sven Schnelle 
Signed-off-by: Vasily Gorbik

s390/dumpstack: simplify in stack logic code

2023-04-04T16:34:55+00:00

The pattern for all in__stack() functions is the same; especially
also the size of all stacks is the same. Simplify the code by passing only
the stack address to the generic in_stack() helper, which then can assume a
THREAD_SIZE sized stack.

Reviewed-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/dumpstack: resolve userspace last_break

2023-03-20T09:56:49+00:00

report_user_fault() currently does not show which library last_break
points to. Call print_vma_addr() to find out; the output now looks
like this:

    Last Breaking-Event-Address:
     [<000003ffaa2a56e4>] libc.so.6[3ffaa180000+251000]

For kernel it's unchanged:

    Last Breaking-Event-Address:
     [<000000000030fd06>] trace_hardirqs_on+0x56/0xc8

Signed-off-by: Ilya Leoshkevich 
Acked-by: Heiko Carstens 
Signed-off-by: Heiko Carstens

exit: Add and use make_task_dead.

2021-12-13T18:04:45+00:00

There are two big uses of do_exit.  The first is it's design use to be
the guts of the exit(2) system call.  The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure.  In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman"

Merge branch 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2021-11-11T00:15:54+00:00

Pull exit cleanups from Eric Biederman:
 "While looking at some issues related to the exit path in the kernel I
  found several instances where the code is not using the existing
  abstractions properly.

  This set of changes introduces force_fatal_sig a way of sending a
  signal and not allowing it to be caught, and corrects the misuse of
  the existing abstractions that I found.

  A lot of the misuse of the existing abstractions are silly things such
  as doing something after calling a no return function, rolling BUG by
  hand, doing more work than necessary to terminate a kernel thread, or
  calling do_exit(SIGKILL) instead of calling force_sig(SIGKILL).

  In the review a deficiency in force_fatal_sig and force_sig_seccomp
  where ptrace or sigaction could prevent the delivery of the signal was
  found. I have added a change that adds SA_IMMUTABLE to change that
  makes it impossible to interrupt the delivery of those signals, and
  allows backporting to fix force_sig_seccomp

  And Arnd found an issue where a function passed to kthread_run had the
  wrong prototype, and after my cleanup was failing to build."

* 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (23 commits)
  soc: ti: fix wkup_m3_rproc_boot_thread return type
  signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed
  signal: Replace force_sigsegv(SIGSEGV) with force_fatal_sig(SIGSEGV)
  exit/r8188eu: Replace the macro thread_exit with a simple return 0
  exit/rtl8712: Replace the macro thread_exit with a simple return 0
  exit/rtl8723bs: Replace the macro thread_exit with a simple return 0
  signal/x86: In emulate_vsyscall force a signal instead of calling do_exit
  signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig
  signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails
  exit/syscall_user_dispatch: Send ordinary signals on failure
  signal: Implement force_fatal_sig
  exit/kthread: Have kernel threads return instead of calling do_exit
  signal/s390: Use force_sigsegv in default_trap_handler
  signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.
  signal/vm86_32: Replace open coded BUG_ON with an actual BUG_ON
  signal/sparc: In setup_tsb_params convert open coded BUG into BUG
  signal/powerpc: On swapcontext failure force SIGSEGV
  signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL)
  signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT
  signal/sparc32: Remove unreachable do_exit in do_sparc_fault
  ...

s390/ptrace: add last_break member to pt_regs

2021-10-26T13:21:28+00:00

Instead of using args[0] for the value of the last breaking event
address register, add a member to make things more obvious.

Signed-off-by: Sven Schnelle 
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

exit: Remove calls of do_exit after noreturn versions of die

2021-10-20T18:09:47+00:00

On nds32, openrisc, s390, sh, and xtensa the function die never
returns.  Mark die __noreturn so that no one expects die to return.
Remove the do_exit calls after die as they will never be reached.

Cc: Jonas Bonn 
Cc: Stefan Kristiansson 
Cc: Stafford Horne 
Cc: openrisc@lists.librecores.org
Cc: Nick Hu 
Cc: Greentime Hu 
Cc: Vincent Chen 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: linux-s390@vger.kernel.org
Cc: Yoshinori Sato 
Cc: Rich Felker 
Cc: linux-sh@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: Chris Zankel 
Cc: Max Filippov 
Fixes: 2.3.16
Fixes: 2.3.99-pre8
Fixes: 3f65ce4d141e ("[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 5")
Fixes: 664eec400bf8 ("nds32: MMU fault handling and page table management")
Fixes: 61e85e367535 ("OpenRISC: Memory management")
Link: https://lkml.kernel.org/r/20211020174406.17889-2-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman