riscv, bpf: Provide RISC-V specific JIT image alloc/free

This commit makes sure that the JIT images is kept close to the kernel
text, so BPF calls can use relative calling with auipc/jalr or jal
instead of loading the full 64-bit address and jalr.

The BPF JIT image region is 128 MB before the kernel text.

Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191216091343.23260-7-bjorn.topel@gmail.com

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 7ff0ed4..cc3f494 100644 (file)
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -404,6 +404,10 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 #define VMALLOC_END      (PAGE_OFFSET - 1)
 #define VMALLOC_START    (PAGE_OFFSET - VMALLOC_SIZE)
 
+#define BPF_JIT_REGION_SIZE    (SZ_128M)
+#define BPF_JIT_REGION_START   (PAGE_OFFSET - BPF_JIT_REGION_SIZE)
+#define BPF_JIT_REGION_END     (VMALLOC_END)
+
 /*
  * Roughly size the vmemmap space to be large enough to fit enough
  * struct pages to map half the virtual address space. Then

diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
index 8aa19c8..46cff09 100644 (file)
--- a/arch/riscv/net/bpf_jit_comp.c
+++ b/arch/riscv/net/bpf_jit_comp.c
@@ -1656,3 +1656,16 @@ out:
                                           tmp : orig_prog);
        return prog;
 }
+
+void *bpf_jit_alloc_exec(unsigned long size)
+{
+       return __vmalloc_node_range(size, PAGE_SIZE, BPF_JIT_REGION_START,
+                                   BPF_JIT_REGION_END, GFP_KERNEL,
+                                   PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
+                                   __builtin_return_address(0));
+}
+
+void bpf_jit_free_exec(void *addr)
+{
+       return vfree(addr);
+}