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authorVincent Chen <vincent.chen@sifive.com>2020-02-21 10:47:54 +0800
committerPalmer Dabbelt <palmerdabbelt@google.com>2020-03-03 10:27:45 -0800
commit0cff8bff7af886af0923d5c91776cd51603e531f (patch)
treec357d85caec49d5de84a84d7398a30e7a5d3c375 /arch
parent98d54f81e36ba3bf92172791eba5ca5bd813989b (diff)
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 'arch')
-rw-r--r--arch/riscv/kernel/module.c16
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