netdev - Re: [PATCH 01/13] nios2: define virtual address space for modules

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Date: Tue, 13 Jun 2023 17:16:18 -0500
From: Dinh Nguyen <dinguyen@...nel.org>
To: Mike Rapoport <rppt@...nel.org>, linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Catalin Marinas <catalin.marinas@....com>,
 Christophe Leroy <christophe.leroy@...roup.eu>,
 "David S. Miller" <davem@...emloft.net>, Heiko Carstens <hca@...ux.ibm.com>,
 Helge Deller <deller@....de>, Huacai Chen <chenhuacai@...nel.org>,
 Kent Overstreet <kent.overstreet@...ux.dev>,
 Luis Chamberlain <mcgrof@...nel.org>, Michael Ellerman <mpe@...erman.id.au>,
 "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
 Palmer Dabbelt <palmer@...belt.com>, Russell King <linux@...linux.org.uk>,
 Song Liu <song@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
 Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
 Thomas Gleixner <tglx@...utronix.de>, Will Deacon <will@...nel.org>,
 bpf@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mips@...r.kernel.org, linux-mm@...ck.org,
 linux-modules@...r.kernel.org, linux-parisc@...r.kernel.org,
 linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
 loongarch@...ts.linux.dev, netdev@...r.kernel.org,
 sparclinux@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 01/13] nios2: define virtual address space for modules

On 6/1/23 05:12, Mike Rapoport wrote:
> From: "Mike Rapoport (IBM)" <rppt@...nel.org>
> 
> nios2 uses kmalloc() to implement module_alloc() because CALL26/PCREL26
> cannot reach all of vmalloc address space.
> 
> Define module space as 32MiB below the kernel base and switch nios2 to
> use vmalloc for module allocations.
> 
> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Mike Rapoport (IBM) <rppt@...nel.org>
> ---
>   arch/nios2/include/asm/pgtable.h |  5 ++++-
>   arch/nios2/kernel/module.c       | 19 ++++---------------
>   2 files changed, 8 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/pgtable.h
> index 0f5c2564e9f5..0073b289c6a4 100644
> --- a/arch/nios2/include/asm/pgtable.h
> +++ b/arch/nios2/include/asm/pgtable.h
> @@ -25,7 +25,10 @@
>   #include <asm-generic/pgtable-nopmd.h>
>   
>   #define VMALLOC_START		CONFIG_NIOS2_KERNEL_MMU_REGION_BASE
> -#define VMALLOC_END		(CONFIG_NIOS2_KERNEL_REGION_BASE - 1)
> +#define VMALLOC_END		(CONFIG_NIOS2_KERNEL_REGION_BASE - SZ_32M - 1)
> +
> +#define MODULES_VADDR		(CONFIG_NIOS2_KERNEL_REGION_BASE - SZ_32M)
> +#define MODULES_END		(CONFIG_NIOS2_KERNEL_REGION_BASE - 1)
>   
>   struct mm_struct;
>   
> diff --git a/arch/nios2/kernel/module.c b/arch/nios2/kernel/module.c
> index 76e0a42d6e36..9c97b7513853 100644
> --- a/arch/nios2/kernel/module.c
> +++ b/arch/nios2/kernel/module.c
> @@ -21,23 +21,12 @@
>   
>   #include <asm/cacheflush.h>
>   
> -/*
> - * Modules should NOT be allocated with kmalloc for (obvious) reasons.
> - * But we do it for now to avoid relocation issues. CALL26/PCREL26 cannot reach
> - * from 0x80000000 (vmalloc area) to 0xc00000000 (kernel) (kmalloc returns
> - * addresses in 0xc0000000)
> - */
>   void *module_alloc(unsigned long size)
>   {
> -	if (size == 0)
> -		return NULL;
> -	return kmalloc(size, GFP_KERNEL);
> -}
> -
> -/* Free memory returned from module_alloc */
> -void module_memfree(void *module_region)
> -{
> -	kfree(module_region);
> +	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
> +				    GFP_KERNEL, PAGE_KERNEL_EXEC,
> +				    VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
> +				    __builtin_return_address(0));
>   }
>   
>   int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,

Acked-by: Dinh Nguyen <dinguyen@...nel.org>