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| author |   Vincent Chen <vincent.chen@sifive.com> | 2020-02-21 10:47:54 +0800 |
|---|---|---|
| committer |   Palmer Dabbelt <palmerdabbelt@google.com> | 2020-03-03 10:27:45 -0800 |
| commit | 0cff8bff7af886af0923d5c91776cd51603e531f (patch) | |
| tree | c357d85caec49d5de84a84d7398a30e7a5d3c375 /arch/riscv/kernel/module.c | |
| parent | Linux 5.6-rc4 (diff) | |
| download | linux-dev-0cff8bff7af886af0923d5c91776cd51603e531f.tar.xz linux-dev-0cff8bff7af886af0923d5c91776cd51603e531f.zip | |
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 <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>
Diffstat (limited to '')
| -rw-r--r-- | arch/riscv/kernel/module.c | 16 |
1 files changed, 16 insertions, 0 deletions
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 <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) { @@ -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 |