Re: [Xen-devel] [PATCH v3 04/23] elf: Add relocation types to elfstructs.h

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.02.16 at 22:05, <konrad.wilk@xxxxxxxxxx> wrote:
> On Mon, Feb 15, 2016 at 01:34:42AM -0700, Jan Beulich wrote:
>> >>> On 12.02.16 at 19:05, <konrad.wilk@xxxxxxxxxx> wrote:
>> > --- a/xen/include/xen/elfstructs.h
>> > +++ b/xen/include/xen/elfstructs.h
>> > @@ -348,6 +348,14 @@ typedef struct {
>> >  #define   ELF64_R_TYPE(info)      ((info) & 0xFFFFFFFF)
>> >  #define ELF64_R_INFO(s,t)         (((s) << 32) + (u_int32_t)(t))
>> >  
>> > +/* x86-64 relocation types. We list only the ones we implement. */
>> 
>> "we implement" is too vague for my taste: This comment should
>> have some kind of reference to xSplice.
> 
> 
> /* x86-64 relocation types. We list only the ones xSplice implements. */
> 
> ?
> 
>> 
>> > +#define R_X86_64_NONE             0       /* No reloc */
>> > +#define R_X86_64_64               1       /* Direct 64 bit  */
>> > +#define R_X86_64_PC32             2       /* PC relative 32 bit signed */
>> > +#define R_X86_64_PLT32            4       /* 32 bit PLT address */
>> > +#define R_X86_64_32               10      /* Direct 32 bit zero extended 
>> > */
>> > +#define R_X86_64_32S              11      /* Direct 32 bit sign extended 
>> > */
>> 
>> Is there really a use case for the last two in the hypervisor
>> (which doesn't live in the top 2G of address space)? (If the
> 
> No. But they are there to catch tools (and developers) by accident
> building the payloads with wacky linker options (like I did).

Since you will need to refuse any unknown ones anyway, I don't
see a reason to name some unsupported one but not others.

Jan


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