From: Vincent Chen vincent.chen@sifive.com
[ Upstream commit 0cff8bff7af886af0923d5c91776cd51603e531f ]
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 vincent.chen@sifive.com Suggested-by: Alexandre Ghiti alex@ghiti.fr Suggested-by: Anup Patel anup@brainfault.org Tested-by: Alexandre Ghiti alex@ghiti.fr Tested-by: Carlos de Paula me@carlosedp.com Signed-off-by: Palmer Dabbelt palmerdabbelt@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 7dd308129b40f..7c012ad1d7ede 100644 --- a/arch/riscv/kernel/module.c +++ b/arch/riscv/kernel/module.c @@ -16,6 +16,10 @@ #include <linux/err.h> #include <linux/errno.h> #include <linux/moduleloader.h> +#include <linux/vmalloc.h> +#include <linux/sizes.h> +#include <asm/pgtable.h> +#include <asm/sections.h>
static int apply_r_riscv_32_rela(struct module *me, u32 *location, Elf_Addr v) { @@ -394,3 +398,15 @@ 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