linux-kernel - Re: [PATCH v4 1/2] riscv: Safely remove entries from relocation list

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Date:   Wed, 29 Nov 2023 08:29:31 +0100
From:   Björn Töpel <bjorn@...nel.org>
To:     Charlie Jenkins <charlie@...osinc.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>, Ron Economos <re@...z.net>,
        Samuel Holland <samuel.holland@...ive.com>,
        Andreas Schwab <schwab@...ux-m68k.org>
Cc:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Charlie Jenkins <charlie@...osinc.com>
Subject: Re: [PATCH v4 1/2] riscv: Safely remove entries from relocation list

Charlie Jenkins <charlie@...osinc.com> writes:

> Use the safe versions of list and hlist iteration to safely remove
> entries from the module relocation lists. To allow mutliple threads to
> load modules concurrently, move relocation list pointers onto the stack
> rather than using global variables.
>
> Fixes: 8fd6c5142395 ("riscv: Add remaining module relocations")
> Reported-by: Ron Economos <re@...z.net>
> Closes: https://lore.kernel.org/linux-riscv/444de86a-7e7c-4de7-5d1d-c1c40eefa4ba@w6rz.net
> Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
> ---
>  arch/riscv/kernel/module.c | 110 +++++++++++++++++++++++++++++++++------------
>  1 file changed, 82 insertions(+), 28 deletions(-)
>
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 56a8c78e9e21..53593fe58cd8 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -40,15 +40,6 @@ struct relocation_handlers {
>  				  long buffer);
>  };
>  
> -unsigned int initialize_relocation_hashtable(unsigned int num_relocations);
> -void process_accumulated_relocations(struct module *me);
> -int add_relocation_to_accumulate(struct module *me, int type, void *location,
> -				 unsigned int hashtable_bits, Elf_Addr v);
> -
> -struct hlist_head *relocation_hashtable;
> -
> -struct list_head used_buckets_list;
> -
>  /*
>   * The auipc+jalr instruction pair can reach any PC-relative offset
>   * in the range [-2^31 - 2^11, 2^31 - 2^11)
> @@ -604,7 +595,10 @@ static const struct relocation_handlers reloc_handlers[] = {
>  	/* 192-255 nonstandard ABI extensions  */
>  };
>  
> -void process_accumulated_relocations(struct module *me)
> +static void
> +process_accumulated_relocations(struct module *me,

Nit/breaks my workflow ;-): Don't bother if you're not respinning for
other reasons. The linebreak after return type makes it harder to grep
the code (and also is not in line with the layout with rest of this).


Björn