linux-kernel - Re: [PATCH v3 07/13] arm64, execmem: extend execmem

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Message-ID: <20231023172059.GB4041@willie-the-truck>
Date:   Mon, 23 Oct 2023 18:21:00 +0100
From:   Will Deacon <will@...nel.org>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Björn Töpel <bjorn@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        "David S. Miller" <davem@...emloft.net>,
        Dinh Nguyen <dinguyen@...nel.org>,
        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>,
        Mark Rutland <mark.rutland@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nadav Amit <nadav.amit@...il.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Puranjay Mohan <puranjay12@...il.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.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>, 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 v3 07/13] arm64, execmem: extend execmem_params for
 generated code allocations

On Mon, Sep 18, 2023 at 10:29:49AM +0300, Mike Rapoport wrote:
> From: "Mike Rapoport (IBM)" <rppt@...nel.org>
> 
> The memory allocations for kprobes and BPF on arm64 can be placed
> anywhere in vmalloc address space and currently this is implemented with
> overrides of alloc_insn_page() and bpf_jit_alloc_exec() in arm64.
> 
> Define EXECMEM_KPROBES and EXECMEM_BPF ranges in arm64::execmem_params and
> drop overrides of alloc_insn_page() and bpf_jit_alloc_exec().
> 
> Signed-off-by: Mike Rapoport (IBM) <rppt@...nel.org>
> ---
>  arch/arm64/kernel/module.c         | 13 +++++++++++++
>  arch/arm64/kernel/probes/kprobes.c |  7 -------
>  arch/arm64/net/bpf_jit_comp.c      | 11 -----------
>  3 files changed, 13 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
> index cd6320de1c54..d27db168d2a2 100644
> --- a/arch/arm64/kernel/module.c
> +++ b/arch/arm64/kernel/module.c
> @@ -116,6 +116,16 @@ static struct execmem_params execmem_params __ro_after_init = {
>  			.flags = EXECMEM_KASAN_SHADOW,
>  			.alignment = MODULE_ALIGN,
>  		},
> +		[EXECMEM_KPROBES] = {
> +			.start = VMALLOC_START,
> +			.end = VMALLOC_END,
> +			.alignment = 1,
> +		},
> +		[EXECMEM_BPF] = {
> +			.start = VMALLOC_START,
> +			.end = VMALLOC_END,
> +			.alignment = 1,
> +		},
>  	},
>  };
>  
> @@ -140,6 +150,9 @@ struct execmem_params __init *execmem_arch_params(void)
>  		r->end = module_plt_base + SZ_2G;
>  	}
>  
> +	execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_ROX;
> +	execmem_params.ranges[EXECMEM_BPF].pgprot = PAGE_KERNEL;
> +
>  	return &execmem_params;
>  }
>  
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index 70b91a8c6bb3..6fccedd02b2a 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -129,13 +129,6 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
>  	return 0;
>  }
>  
> -void *alloc_insn_page(void)
> -{
> -	return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END,
> -			GFP_KERNEL, PAGE_KERNEL_ROX, VM_FLUSH_RESET_PERMS,
> -			NUMA_NO_NODE, __builtin_return_address(0));
> -}

It's slightly curious that we didn't clear the tag here, so it's nice that
it all happens magically with your series:

Acked-by: Will Deacon <will@...nel.org>

Will