Re: [PATCH] fix compilation of 64-bit kernel with 32-bit compiler

[Peter Zijlstra]

On Thu, Mar 08, 2018 at 04:09:30AM -0500, Mikulas Patocka wrote:
> 
> 
> On Thu, 8 Mar 2018, Peter Zijlstra wrote:
> 
> > On Thu, Mar 08, 2018 at 01:11:26AM -0500, Mikulas Patocka wrote:
> > > The patch b5bc2231b8ad4387c9641f235ca0ad8cd300b6df ("objtool: Add 
> > > retpoline validation") broke compiling 64-bit kernel with 32-bit compiler.
> > > 
> > > This patch fixes the following error and a large number of "can't find
> > > rela for retpoline_safe" errors that occur when using x32 or i386 gcc.
> > > 
> > > You shouldn't use the type 'unsigned long' in objtool at all - because its
> > > size depends on the compiler and not on the kernel you are compiling.
> > 
> > Your patch is wrong because the data field is actually a long. A correct
> > patch is already in merged in tip.
> 
> I'm wondering, why is objtool using 'unsigned long' at all? Why not 
> uint32_t and uint64_t? The size of 'unsigned long' is dependent on the 
> compiler, so it will lead to different behavior.

Because pointers... As Josh said, I should've used the right ELF methods
which use the object's ABI.