linux-kernel - Re: [PATCH V2 1/3] powerpc/jump_label: adjust inline asm to be consistent

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Message-ID: <306b01a2-caba-4c15-89d4-849c3f4848cb@kernel.org>
Date: Thu, 5 Feb 2026 09:09:41 +0100
From: "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
To: "Mukesh Kumar Chaurasiya (IBM)" <mkchauras@...il.com>,
 linkmauve@...kmauve.fr, ojeda@...nel.org, boqun.feng@...il.com,
 gary@...yguo.net, bjorn3_gh@...tonmail.com, lossin@...nel.org,
 a.hindborg@...nel.org, aliceryhl@...gle.com, tmgross@...ch.edu,
 dakr@...nel.org, corbet@....net, maddy@...ux.ibm.com, mpe@...erman.id.au,
 npiggin@...il.com, peterz@...radead.org, jpoimboe@...nel.org,
 jbaron@...mai.com, rostedt@...dmis.org, ardb@...nel.org,
 rust-for-linux@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH V2 1/3] powerpc/jump_label: adjust inline asm to be
 consistent



Le 04/02/2026 à 22:01, Mukesh Kumar Chaurasiya (IBM) a écrit :
> [Vous ne recevez pas souvent de courriers de mkchauras@...il.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> Added support for a new macro ARCH_STATIC_BRANCH_ASM in powerpc
> to avoid duplication of inline asm between C and Rust. This is
> inline with commit aecaf181651c '("jump_label: adjust inline asm to be consistent")'
> 
> Signed-off-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
> Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@...il.com>

Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@...nel.org>

> ---
>   arch/powerpc/include/asm/jump_label.h | 23 +++++++++++++----------
>   1 file changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
> index d4eaba459a0e..a6b211502bfe 100644
> --- a/arch/powerpc/include/asm/jump_label.h
> +++ b/arch/powerpc/include/asm/jump_label.h
> @@ -15,14 +15,20 @@
>   #define JUMP_ENTRY_TYPE                stringify_in_c(FTR_ENTRY_LONG)
>   #define JUMP_LABEL_NOP_SIZE    4
> 
> +#define JUMP_TABLE_ENTRY(key, label)                   \
> +       ".pushsection __jump_table,  \"aw\"     \n\t"   \
> +       ".long 1b - ., " label " - .            \n\t"   \
> +       JUMP_ENTRY_TYPE key " - .               \n\t"   \
> +       ".popsection                            \n\t"
> +
> +#define ARCH_STATIC_BRANCH_ASM(key, label)             \
> +       "1:     nop                             \n\t"   \
> +       JUMP_TABLE_ENTRY(key,label)
> +
>   static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
>   {
> -       asm goto("1:\n\t"
> -                "nop # arch_static_branch\n\t"
> -                ".pushsection __jump_table,  \"aw\"\n\t"
> -                ".long 1b - ., %l[l_yes] - .\n\t"
> -                JUMP_ENTRY_TYPE "%c0 - .\n\t"
> -                ".popsection \n\t"
> +       asm goto(
> +                ARCH_STATIC_BRANCH_ASM("%c0", "%l[l_yes]")
>                   : :  "i" (&((char *)key)[branch]) : : l_yes);
> 
>          return false;
> @@ -34,10 +40,7 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
>   {
>          asm goto("1:\n\t"
>                   "b %l[l_yes] # arch_static_branch_jump\n\t"
> -                ".pushsection __jump_table,  \"aw\"\n\t"
> -                ".long 1b - ., %l[l_yes] - .\n\t"
> -                JUMP_ENTRY_TYPE "%c0 - .\n\t"
> -                ".popsection \n\t"
> +                JUMP_TABLE_ENTRY("%c0", "%l[l_yes]")
>                   : :  "i" (&((char *)key)[branch]) : : l_yes);
> 
>          return false;
> --
> 2.52.0
>