Messages in this thread | | | From | Shea Levy <> | Subject | Re: [PATCH] RISC-V: Load modules within relative jump range of the kernel text. | Date | Tue, 24 Apr 2018 07:54:18 -0400 |
| |
Hi Palmer,
Palmer Dabbelt <palmer@sifive.com> writes:
> On Sun, 22 Apr 2018 05:53:56 PDT (-0700), shea@shealevy.com wrote: >> 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? > > The concept looks good, but does this actually keep the modules within 2GiB of > the text if PAGE_OFFSET is large?
It's been some time since I wrote this, but I thought PAGE_OFFSET was where the kernel text *started*? So unless the text itself is bigger than 2G - 128 M, in which case we're SOL anyway, it seems like this should work. Is there something better we can do, without a large memory model?
Thanks, Shea [unhandled content-type:application/pgp-signature] | |