Re: [PATCH 15/20] objtool: Add --backtrace support

[Josh Poimboeuf]

On Thu, Mar 07, 2019 at 12:45:26PM +0100, Peter Zijlstra wrote:
> For when you want to know the path that reached your fail state.
> 
> $ ./objtool check --no-fp --backtrace arch/x86/lib/usercopy_64.o
> arch/x86/lib/usercopy_64.o: warning: objtool: .altinstr_replacement+0x3: UACCESS disable without MEMOPs: __clear_user()
> arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x3a: (alt)
> arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x2e: (branch)
> arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x18: (branch)
> arch/x86/lib/usercopy_64.o: warning: objtool:   .altinstr_replacement+0xffffffffffffffff: (branch)
> arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x5: (alt)
> arch/x86/lib/usercopy_64.o: warning: objtool:   __clear_user()+0x0: <=== (func)

We should have done this a long time ago.  Thank you for this!

-- 
Josh