lkml.org 
[lkml]   [2021]   [Sep]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.14 068/100] s390/unwind: use current_frame_address() to unwind current task
    Date
    From: Vasily Gorbik <gor@linux.ibm.com>

    [ Upstream commit 88b604263f3d6eedae0b1c2c3bbd602d1e2e8775 ]

    current_stack_pointer() simply returns current value of %r15. If
    current_stack_pointer() caller allocates stack (which is the case in
    unwind code) %r15 points to a stack frame allocated for callees, meaning
    current_stack_pointer() caller (e.g. stack_trace_save) will end up in
    the stacktrace. This is not expected by stack_trace_save*() callers and
    causes problems.

    current_frame_address() on the other hand returns function stack frame
    address, which matches %r15 upon function invocation. Using it in
    get_stack_pointer() makes it more aligned with x86 implementation
    (according to BACKTRACE_SELF_TEST output) and meets stack_trace_save*()
    caller's expectations, notably KCSAN.

    Also make sure unwind_start is always inlined.

    Reported-by: Nathan Chancellor <nathan@kernel.org>
    Suggested-by: Marco Elver <elver@google.com>
    Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
    Tested-by: Marco Elver <elver@google.com>
    Tested-by: Nathan Chancellor <nathan@kernel.org>
    Link: https://lore.kernel.org/r/patch.git-04dd26be3043.your-ad-here.call-01630504868-ext-6188@work.hours
    Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/s390/include/asm/stacktrace.h | 20 ++++++++++----------
    arch/s390/include/asm/unwind.h | 8 ++++----
    2 files changed, 14 insertions(+), 14 deletions(-)

    diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
    index 3d8a4b94c620..dd00d98804ec 100644
    --- a/arch/s390/include/asm/stacktrace.h
    +++ b/arch/s390/include/asm/stacktrace.h
    @@ -34,16 +34,6 @@ static inline bool on_stack(struct stack_info *info,
    return addr >= info->begin && addr + len <= info->end;
    }

    -static __always_inline unsigned long get_stack_pointer(struct task_struct *task,
    - struct pt_regs *regs)
    -{
    - if (regs)
    - return (unsigned long) kernel_stack_pointer(regs);
    - if (task == current)
    - return current_stack_pointer();
    - return (unsigned long) task->thread.ksp;
    -}
    -
    /*
    * Stack layout of a C stack frame.
    */
    @@ -74,6 +64,16 @@ struct stack_frame {
    ((unsigned long)__builtin_frame_address(0) - \
    offsetof(struct stack_frame, back_chain))

    +static __always_inline unsigned long get_stack_pointer(struct task_struct *task,
    + struct pt_regs *regs)
    +{
    + if (regs)
    + return (unsigned long)kernel_stack_pointer(regs);
    + if (task == current)
    + return current_frame_address();
    + return (unsigned long)task->thread.ksp;
    +}
    +
    /*
    * To keep this simple mark register 2-6 as being changed (volatile)
    * by the called function, even though register 6 is saved/nonvolatile.
    diff --git a/arch/s390/include/asm/unwind.h b/arch/s390/include/asm/unwind.h
    index de9006b0cfeb..5ebf534ef753 100644
    --- a/arch/s390/include/asm/unwind.h
    +++ b/arch/s390/include/asm/unwind.h
    @@ -55,10 +55,10 @@ static inline bool unwind_error(struct unwind_state *state)
    return state->error;
    }

    -static inline void unwind_start(struct unwind_state *state,
    - struct task_struct *task,
    - struct pt_regs *regs,
    - unsigned long first_frame)
    +static __always_inline void unwind_start(struct unwind_state *state,
    + struct task_struct *task,
    + struct pt_regs *regs,
    + unsigned long first_frame)
    {
    task = task ?: current;
    first_frame = first_frame ?: get_stack_pointer(task, regs);
    --
    2.33.0


    \
     
     \ /
      Last update: 2021-09-24 15:07    [W:4.108 / U:0.044 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site