From 0cff8bff7af886af0923d5c91776cd51603e531f Mon Sep 17 00:00:00 2001 From: Vincent Chen Date: Fri, 21 Feb 2020 10:47:54 +0800 Subject: [PATCH] riscv: avoid the PIC offset of static percpu data in module beyond 2G limits The compiler uses the PIC-relative method to access static variables instead of GOT when the code model is PIC. Therefore, the limitation of the access range from the instruction to the symbol address is +-2GB. Under this circumstance, the kernel cannot load a kernel module if this module has static per-CPU symbols declared by DEFINE_PER_CPU(). The reason is that kernel relocates the .data..percpu section of the kernel module to the end of kernel's .data..percpu. Hence, the distance between the per-CPU symbols and the instruction will exceed the 2GB limits. To solve this problem, the kernel should place the loaded module in the memory area [&_end-2G, VMALLOC_END]. Signed-off-by: Vincent Chen Suggested-by: Alexandre Ghiti Suggested-by: Anup Patel Tested-by: Alexandre Ghiti Tested-by: Carlos de Paula Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/module.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c index b7401858d872..8bbe5dbe1341 100644 --- a/arch/riscv/kernel/module.c +++ b/arch/riscv/kernel/module.c @@ -8,6 +8,10 @@ #include #include #include +#include +#include +#include +#include static int apply_r_riscv_32_rela(struct module *me, u32 *location, Elf_Addr v) { @@ -386,3 +390,15 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, return 0; } + +#if defined(CONFIG_MMU) && defined(CONFIG_64BIT) +#define VMALLOC_MODULE_START \ + max(PFN_ALIGN((unsigned long)&_end - SZ_2G), VMALLOC_START) +void *module_alloc(unsigned long size) +{ + return __vmalloc_node_range(size, 1, VMALLOC_MODULE_START, + VMALLOC_END, GFP_KERNEL, + PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, + __builtin_return_address(0)); +} +#endif -- 2.34.1