Re: [PATCH v1 04/10] asm-generic: Use HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR to define associated stub

Helge Deller
2021-10-12T06:02:53Z

On 10/11/21 17:25, Christophe Leroy wrote:
> Use HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR instead of 'dereference_function_descriptor'
> to know whether arch has function descriptors.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> arch/ia64/include/asm/sections.h | 4 ++--
> arch/parisc/include/asm/sections.h | 6 ++++--
> arch/powerpc/include/asm/sections.h | 6 ++++--
> include/asm-generic/sections.h | 3 ++-
> 4 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/arch/ia64/include/asm/sections.h b/arch/ia64/include/asm/sections.h
> index 35f24e52149a..80f5868afb06 100644
> --- a/arch/ia64/include/asm/sections.h
> +++ b/arch/ia64/include/asm/sections.h
> @@ -7,6 +7,8 @@
> * David Mosberger-Tang <davidm@hpl.hp.com>
> */
>
> +#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
> +
> #include <linux/elf.h>
> #include <linux/uaccess.h>
> #include <asm-generic/sections.h>
> @@ -27,8 +29,6 @@ extern char __start_gate_brl_fsys_bubble_down_patchlist[], __end_gate_brl_fsys_b
> extern char __start_unwind[], __end_unwind[];
> extern char __start_ivt_text[], __end_ivt_text[];
>
> -#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
> -
> #undef dereference_function_descriptor
> static inline void *dereference_function_descriptor(void *ptr)
> {
> diff --git a/arch/parisc/include/asm/sections.h b/arch/parisc/include/asm/sections.h
> index bb52aea0cb21..2e781ee19b66 100644
> --- a/arch/parisc/include/asm/sections.h
> +++ b/arch/parisc/include/asm/sections.h
> @@ -2,6 +2,10 @@
> #ifndef _PARISC_SECTIONS_H
> #define _PARISC_SECTIONS_H
>
> +#ifdef CONFIG_64BIT
> +#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
> +#endif
> +
> /* nothing to see, move along */
> #include <asm-generic/sections.h>
>
> @@ -9,8 +13,6 @@ extern char __alt_instructions[], __alt_instructions_end[];
>
> #ifdef CONFIG_64BIT
>
> -#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
> -
> #undef dereference_function_descriptor
> void *dereference_function_descriptor(void *);
>
> diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
> index 32e7035863ac..b7f1ba04e756 100644
> --- a/arch/powerpc/include/asm/sections.h
> +++ b/arch/powerpc/include/asm/sections.h
> @@ -8,6 +8,10 @@
>
> #define arch_is_kernel_initmem_freed arch_is_kernel_initmem_freed
>
> +#ifdef PPC64_ELF_ABI_v1
> +#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
> +#endif
> +
> #include <asm-generic/sections.h>
>
> extern bool init_mem_is_free;
> @@ -69,8 +73,6 @@ static inline int overlaps_kernel_text(unsigned long start, unsigned long end)
>
> #ifdef PPC64_ELF_ABI_v1
>
> -#define HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR 1
> -
> #undef dereference_function_descriptor
> static inline void *dereference_function_descriptor(void *ptr)
> {
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index d16302d3eb59..1db5cfd69817 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -59,7 +59,8 @@ extern char __noinstr_text_start[], __noinstr_text_end[];
> extern __visible const void __nosave_begin, __nosave_end;
>
> /* Function descriptor handling (if any). Override in asm/sections.h */
> -#ifndef dereference_function_descriptor
> +#ifdef HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR
> +#else

why not
#ifndef HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR
instead of #if/#else ?

> #define dereference_function_descriptor(p) ((void *)(p))
> #define dereference_kernel_function_descriptor(p) ((void *)(p))
> #endif
>