Re: [PATCH] x86, 32-bit: Fix invalid stack address while in softirq

[wyang1]

On 09/06/2012 11:54 PM, Steven Rostedt wrote:
On Thu, 2012-09-06 at 17:36 +0200, Robert Richter wrote:
I meant:

unsigned long kernel_stack_pointer(struct pt_regs *regs)
{
        unsigned long context = (unsigned long)regs&  ~(THREAD_SIZE - 1);
        unsigned long sp = (unsigned long)&regs->sp;
        struct thread_info *tinfo;

        if (context == (sp&  ~(THREAD_SIZE - 1)))
                return sp;
        
        tinfo = (struct thread_info *)context;
        if (tinfo->previous_esp)
                return tinfo->previous_esp;

        return (unsigned long)regs;
}

-Robert

Maybe this is even better.


Stevent & Robert,

Actually, we also can revert the following commit:

commit 7b6c6c77732ca1d2498eda7eabb64f9648896e96
Author: Masami Hiramatsu <mhira...@redhat.com>
Date:   Mon May 11 17:03:00 2009 -0400

    x86, 32-bit: fix kernel_trap_sp()

    Use &regs->sp instead of regs for getting the top of stack in 
kernel mode.
    (on x86-64, regs->sp always points the top of stack)


I meant:

static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
{
    #ifdef CONFIG_X86_32
       return (unsigned long)regs;
    #else
       return regs->sp;
    #endif
}


What do you think of it?

Thanks
Wei

Yeah, this is probably the safest.

Thanks,

-- Steve




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