riscv: kprobes: Implement alloc_insn_page()

Allocate PAGE_KERNEL_READ_EXEC(read only, executable) page for kprobes
insn page. This is to prepare for STRICT_MODULE_RWX.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
index a2ec186..0b451ff 100644 (file)
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -84,6 +84,14 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
        return 0;
 }
 
+void *alloc_insn_page(void)
+{
+       return  __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END,
+                                    GFP_KERNEL, PAGE_KERNEL_READ_EXEC,
+                                    VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
+                                    __builtin_return_address(0));
+}
+
 /* install breakpoint in text */
 void __kprobes arch_arm_kprobe(struct kprobe *p)
 {