linux-kernel - Re: [PATCH v9 1/2] riscv: Move nop definition to insn-def.h

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Message-ID: <CAHVXubjbfVmU4PFD8s-uRF03KjtVKyyUsCHxhKQ6vXJfFhsVzA@mail.gmail.com>
Date: Wed, 19 Mar 2025 13:06:48 +0100
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Charlie Jenkins <charlie@...osinc.com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Ard Biesheuvel <ardb@...nel.org>, Ben Dooks <ben.dooks@...ethink.co.uk>, 
	Pasha Bouzarjomehri <pasha@...osinc.com>, 
	Emil Renner Berthing <emil.renner.berthing@...onical.com>, Steven Rostedt <rostedt@...dmis.org>, 
	Masami Hiramatsu <mhiramat@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Albert Ou <aou@...s.berkeley.edu>, Peter Zijlstra <peterz@...radead.org>, 
	Josh Poimboeuf <jpoimboe@...nel.org>, Jason Baron <jbaron@...mai.com>, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH v9 1/2] riscv: Move nop definition to insn-def.h

Hi Charlie,

On Wed, Mar 19, 2025 at 1:39 AM Charlie Jenkins <charlie@...osinc.com> wrote:
>
> We have duplicated the definition of the nop instruction in ftrace.h and
> in jump_label.c. Move this definition into the generic file insn-def.h
> so that they can share the definition with each other and with future
> files.
>
> Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
> ---
>  arch/riscv/include/asm/ftrace.h   | 1 -
>  arch/riscv/include/asm/insn-def.h | 2 ++
>  arch/riscv/kernel/ftrace.c        | 6 +++---
>  arch/riscv/kernel/jump_label.c    | 4 ++--
>  4 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
> index c4721ce44ca474654b37b3d51bc0a63d46bc1eff..b7f361a50f6445d02a0d88eef5547ee27c1fb52e 100644
> --- a/arch/riscv/include/asm/ftrace.h
> +++ b/arch/riscv/include/asm/ftrace.h
> @@ -79,7 +79,6 @@ struct dyn_arch_ftrace {
>  #define AUIPC_RA               (0x00000097)
>  #define JALR_T0                        (0x000282e7)
>  #define AUIPC_T0               (0x00000297)
> -#define NOP4                   (0x00000013)
>
>  #define to_jalr_t0(offset)                                             \
>         (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_T0)
> diff --git a/arch/riscv/include/asm/insn-def.h b/arch/riscv/include/asm/insn-def.h
> index 9a913010cdd93cdfdd93f467e7880e20cce0dd2b..0a1fc5134f29da190554c59f8cee3b5374c9aa2d 100644
> --- a/arch/riscv/include/asm/insn-def.h
> +++ b/arch/riscv/include/asm/insn-def.h
> @@ -200,4 +200,6 @@
>  #define ZAWRS_WRS_NTO  ".4byte 0x00d00073"
>  #define ZAWRS_WRS_STO  ".4byte 0x01d00073"
>
> +#define RISCV_INSN_NOP4        0x00000013U
> +
>  #endif /* __ASM_INSN_DEF_H */
> diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
> index 3524db5e4fa014a4594465f849d898a030bfb7b8..674dcdfae7a149c339f1e791adb450535f22991b 100644
> --- a/arch/riscv/kernel/ftrace.c
> +++ b/arch/riscv/kernel/ftrace.c
> @@ -36,7 +36,7 @@ static int ftrace_check_current_call(unsigned long hook_pos,
>                                      unsigned int *expected)
>  {
>         unsigned int replaced[2];
> -       unsigned int nops[2] = {NOP4, NOP4};
> +       unsigned int nops[2] = {RISCV_INSN_NOP4, RISCV_INSN_NOP4};
>
>         /* we expect nops at the hook position */
>         if (!expected)
> @@ -68,7 +68,7 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
>                                 bool enable, bool ra)
>  {
>         unsigned int call[2];
> -       unsigned int nops[2] = {NOP4, NOP4};
> +       unsigned int nops[2] = {RISCV_INSN_NOP4, RISCV_INSN_NOP4};
>
>         if (ra)
>                 make_call_ra(hook_pos, target, call);
> @@ -97,7 +97,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
>  int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
>                     unsigned long addr)
>  {
> -       unsigned int nops[2] = {NOP4, NOP4};
> +       unsigned int nops[2] = {RISCV_INSN_NOP4, RISCV_INSN_NOP4};
>
>         if (patch_insn_write((void *)rec->ip, nops, MCOUNT_INSN_SIZE))
>                 return -EPERM;
> diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> index 654ed159c830b3d5e34ac58bf367107066eb73a1..b4c1a6a3fbd28533552036194f27ed206bea305d 100644
> --- a/arch/riscv/kernel/jump_label.c
> +++ b/arch/riscv/kernel/jump_label.c
> @@ -11,8 +11,8 @@
>  #include <asm/bug.h>
>  #include <asm/cacheflush.h>
>  #include <asm/text-patching.h>
> +#include <asm/insn-def.h>
>
> -#define RISCV_INSN_NOP 0x00000013U
>  #define RISCV_INSN_JAL 0x0000006fU
>
>  bool arch_jump_label_transform_queue(struct jump_entry *entry,
> @@ -33,7 +33,7 @@ bool arch_jump_label_transform_queue(struct jump_entry *entry,
>                         (((u32)offset & GENMASK(10,  1)) << (21 -  1)) |
>                         (((u32)offset & GENMASK(20, 20)) << (31 - 20));
>         } else {
> -               insn = RISCV_INSN_NOP;
> +               insn = RISCV_INSN_NOP4;
>         }
>
>         if (early_boot_irqs_disabled) {
>
> --
> 2.43.0
>

Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>
Tested-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks,

Alex