[PATCH] RISC-V: Load modules within relative jump range of the kernel text.

[shea@shealevy.com (Shea Levy)]

Hi Palmer,

Shea Levy <shea@shealevy.com> writes:

> Signed-off-by: Shea Levy <shea@shealevy.com>
> ---
>
> Note that this patch worked in my old modules patchset and seems to be
> working now, but my kernel boot locks up on top of
> riscv-for-linus-4.17-mw0 and I don't know if it's due to this patch or
> something else that's changed in the mean time.
>
> ---
>  arch/riscv/include/asm/pgtable.h |  9 +++++++++
>  arch/riscv/kernel/module.c       | 11 +++++++++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 16301966d65b..b08ded13364a 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -25,6 +25,7 @@
>  #include <asm/page.h>
>  #include <asm/tlbflush.h>
>  #include <linux/mm_types.h>
> +#include <linux/sizes.h>
>  
>  #ifdef CONFIG_64BIT
>  #include <asm/pgtable-64.h>
> @@ -425,6 +426,14 @@ static inline void pgtable_cache_init(void)
>  #define TASK_SIZE VMALLOC_START
>  #endif
>  
> +/*
> + * The module space lives between the addresses given by TASK_SIZE
> + * and PAGE_OFFSET - it must be within 2G of the kernel text.
> + */
> +#define MODULES_SIZE		(SZ_128M)
> +#define MODULES_VADDR		(PAGE_OFFSET - MODULES_SIZE)
> +#define MODULES_END		(VMALLOC_END)
> +
>  #include <asm-generic/pgtable.h>
>  
>  #endif /* !__ASSEMBLY__ */
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 5dddba301d0a..1b382c7de095 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -16,6 +16,8 @@
>  #include <linux/err.h>
>  #include <linux/errno.h>
>  #include <linux/moduleloader.h>
> +#include <linux/vmalloc.h>
> +#include <asm/pgtable.h>
>  
>  static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
>  {
> @@ -382,3 +384,12 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
>  
>  	return 0;
>  }
> +
> +void *module_alloc(unsigned long size)
> +{
> +	return __vmalloc_node_range(size, 1, MODULES_VADDR,
> +				    MODULES_END, GFP_KERNEL,
> +				    PAGE_KERNEL_EXEC, 0,
> +				    NUMA_NO_NODE,
> +				    __builtin_return_address(0));
> +}
> -- 
> 2.16.2

Any thoughts on this?

Thanks,
Shea
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