Re: [PATCH v4 8/9] Implement kernel live patching for ppc64le (ABIv2)

From: Petr Mladek
Date: Thu Dec 03 2015 - 11:24:52 EST


On Wed 2015-11-25 17:48:36, Torsten Duwe wrote:
> * 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.
>
> --- /dev/null
> +++ b/arch/powerpc/include/asm/livepatch.h
> @@ -0,0 +1,45 @@
[...]
> +#include <linux/module.h>
> +#include <linux/ftrace.h>
> +
> +#ifdef CONFIG_LIVEPATCH
> +static inline int klp_check_compiler_support(void)
> +{
> +#if !defined(_CALL_ELF) || _CALL_ELF != 2

I am just curious why we do not check CC_USING_MPROFILE_KERNEL
like in the other similar locations. It would look less cryptic.
But I am not sure if it is precise enough.

Best Regards,
Petr

> + return 1;
> +#endif
> + return 0;
> +}
> +
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