linux-kernel - Re: [PATCH v2 4/7] riscv: Simplify text patching loops

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Message-ID: <20240424-cranial-punch-27b38726d3f7@spud>
Date: Wed, 24 Apr 2024 11:44:17 +0100
From: Conor Dooley <conor@...nel.org>
To: Samuel Holland <samuel.holland@...ive.com>
Cc: Palmer Dabbelt <palmer@...belt.com>,
	Björn Töpel <bjorn@...osinc.com>,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/7] riscv: Simplify text patching loops

On Wed, Mar 27, 2024 at 09:04:43AM -0700, Samuel Holland wrote:
> This reduces the number of variables and makes the code easier to parse.
> 
> Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
> ---
> 
> Changes in v2:
>  - Further simplify patch_insn_set()/patch_insn_write() loop conditions
>  - Use min() instead of min_t() since both sides are unsigned long
> 
>  arch/riscv/kernel/patch.c | 37 +++++++++++++++++++++----------------
>  1 file changed, 21 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
> index 9a1bce1adf5a..0d1700d1934c 100644
> --- a/arch/riscv/kernel/patch.c
> +++ b/arch/riscv/kernel/patch.c
> @@ -155,22 +155,24 @@ NOKPROBE_SYMBOL(__patch_insn_write);
>  
>  static int patch_insn_set(void *addr, u8 c, size_t len)
>  {
> -	size_t patched = 0;
>  	size_t size;
> -	int ret = 0;
>  
>  	/*
>  	 * __patch_insn_set() can only work on 2 pages at a time so call it in a
>  	 * loop with len <= 2 * PAGE_SIZE.
>  	 */
> -	while (patched < len && !ret) {
> -		size = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(addr + patched), len - patched);
> -		ret = __patch_insn_set(addr + patched, c, size);
> -
> -		patched += size;
>  	}
>  
> -	return ret;
>  }

Weren't these actively wrong before, if a non-ultimate
__patch_insn_set() failed we'd just ignore the error?

Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>

Thanks,
Conor.

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