Re: [PATCH v3 08/13] riscv: extend execmem_params for generated code allocations

[Alexandre Ghiti]

Hi Mike,

On 18/09/2023 09:29, Mike Rapoport wrote:
> From: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx>
>
> The memory allocations for kprobes and BPF on RISC-V are not placed in
> the modules area and these custom allocations are implemented with
> overrides of alloc_insn_page() and  bpf_jit_alloc_exec().
>
> Slightly reorder execmem_params initialization to support both 32 and 64
> bit variants, define EXECMEM_KPROBES and EXECMEM_BPF ranges in
> riscv::execmem_params and drop overrides of alloc_insn_page() and
> bpf_jit_alloc_exec().
>
> Signed-off-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
> ---
>   arch/riscv/kernel/module.c         | 21 ++++++++++++++++++++-
>   arch/riscv/kernel/probes/kprobes.c | 10 ----------
>   arch/riscv/net/bpf_jit_core.c      | 13 -------------
>   3 files changed, 20 insertions(+), 24 deletions(-)
>
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 343a0edfb6dd..31505ecb5c72 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -436,20 +436,39 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>   	return 0;
>   }
>   
> -#if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
> +#ifdef CONFIG_MMU
>   static struct execmem_params execmem_params __ro_after_init = {
>   	.ranges = {
>   		[EXECMEM_DEFAULT] = {
>   			.pgprot = PAGE_KERNEL,
>   			.alignment = 1,
>   		},
> +		[EXECMEM_KPROBES] = {
> +			.pgprot = PAGE_KERNEL_READ_EXEC,
> +			.alignment = 1,
> +		},
> +		[EXECMEM_BPF] = {
> +			.pgprot = PAGE_KERNEL,
> +			.alignment = 1,


Not entirely sure it is the same alignment (sorry did not go through the 
entire series), but if it is, the alignment above ^ is not the same that 
is requested by our current bpf_jit_alloc_exec() implementation which is 
PAGE_SIZE.


> +		},
>   	},
>   };
>   
>   struct execmem_params __init *execmem_arch_params(void)
>   {
> +#ifdef CONFIG_64BIT
>   	execmem_params.ranges[EXECMEM_DEFAULT].start = MODULES_VADDR;
>   	execmem_params.ranges[EXECMEM_DEFAULT].end = MODULES_END;
> +#else
> +	execmem_params.ranges[EXECMEM_DEFAULT].start = VMALLOC_START;
> +	execmem_params.ranges[EXECMEM_DEFAULT].end = VMALLOC_END;
> +#endif
> +
> +	execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_START;
> +	execmem_params.ranges[EXECMEM_KPROBES].end = VMALLOC_END;
> +
> +	execmem_params.ranges[EXECMEM_BPF].start = BPF_JIT_REGION_START;
> +	execmem_params.ranges[EXECMEM_BPF].end = BPF_JIT_REGION_END;
>   
>   	return &execmem_params;
>   }
> diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
> index 2f08c14a933d..e64f2f3064eb 100644
> --- a/arch/riscv/kernel/probes/kprobes.c
> +++ b/arch/riscv/kernel/probes/kprobes.c
> @@ -104,16 +104,6 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
>   	return 0;
>   }
>   
> -#ifdef CONFIG_MMU
> -void *alloc_insn_page(void)
> -{
> -	return  __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END,
> -				     GFP_KERNEL, PAGE_KERNEL_READ_EXEC,
> -				     VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
> -				     __builtin_return_address(0));
> -}
> -#endif
> -
>   /* install breakpoint in text */
>   void __kprobes arch_arm_kprobe(struct kprobe *p)
>   {
> diff --git a/arch/riscv/net/bpf_jit_core.c b/arch/riscv/net/bpf_jit_core.c
> index 7b70ccb7fec3..c8a758f0882b 100644
> --- a/arch/riscv/net/bpf_jit_core.c
> +++ b/arch/riscv/net/bpf_jit_core.c
> @@ -218,19 +218,6 @@ u64 bpf_jit_alloc_exec_limit(void)
>   	return BPF_JIT_REGION_SIZE;
>   }
>   
> -void *bpf_jit_alloc_exec(unsigned long size)
> -{
> -	return __vmalloc_node_range(size, PAGE_SIZE, BPF_JIT_REGION_START,
> -				    BPF_JIT_REGION_END, GFP_KERNEL,
> -				    PAGE_KERNEL, 0, NUMA_NO_NODE,
> -				    __builtin_return_address(0));
> -}
> -
> -void bpf_jit_free_exec(void *addr)
> -{
> -	return vfree(addr);
> -}
> -
>   void *bpf_arch_text_copy(void *dst, void *src, size_t len)
>   {
>   	int ret;


Otherwise, you can add:

Reviewed-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>

Thanks,

Alex