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

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Message-ID: <20240424-gallows-resilient-c46a69705a0c@spud>
Date: Wed, 24 Apr 2024 11:47:45 +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, Apr 24, 2024 at 11:44:17AM +0100, Conor Dooley wrote:
> 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?

nvm, failure to read on my part..

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