On Tue 2016-01-26 11:50:25, Miroslav Benes wrote:

[ added Petr to CC list ]

On Mon, 25 Jan 2016, Torsten Duwe wrote:

quoted

  * create the appropriate files+functions
    arch/powerpc/include/asm/livepatch.h
        klp_check_compiler_support,
        klp_arch_set_pc
    arch/powerpc/kernel/livepatch.c with a stub for
        klp_write_module_reloc
    This is architecture-independent work in progress.
  * introduce a fixup in arch/powerpc/kernel/entry_64.S
    for local calls that are becoming global due to live patching.
    And of course do the main KLP thing: return to a maybe different
    address, possibly altered by the live patching ftrace op.

Signed-off-by: Torsten Duwe <redacted>

Hi,

I have a few questions...

We still need Petr's patch from [1] to make livepatch work, right? Could 
you, please, add it to this patch set to make it self-sufficient?

Second, what is the situation with mcount prologue between gcc < 6 and 
gcc-6? Are there only 12 bytes in gcc-6 prologue? If yes, we need to 
change Petr's patch to make it more general and to be able to cope with 
different prologues. This is unfortunate. Either way, please mention it 
somewhere in a changelog.

I am going to update the extra patch. There is an idea to detect the
offset during build by scrips/recordmcount. This tool looks for the
ftrace locations. The offset should always be a constant that depends
on the used architecture, compiler, and compiler flags.

The tool is called post build. We might need to pass the constant
as a symbol added to the binary. The tool already adds some symbols.


Best Regards,
Petr