From 7f3631e88ee6fb13beac333a0e9e605d2414d17f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= <bjorn.topel@gmail.com>
Date: Mon, 16 Dec 2019 10:13:40 +0100
Subject: [PATCH] riscv, bpf: Provide RISC-V specific JIT image alloc/free
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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
---
arch/riscv/include/asm/pgtable.h | 4 ++++
arch/riscv/net/bpf_jit_comp.c | 13 +++++++++++++
2 files changed, 17 insertions(+)
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 7ff0ed4f292e4..cc3f49415620e 100644
--- 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 8aa19c846881c..46cff093f526c 100644
--- a/arch/riscv/net/bpf_jit_comp.c
+++ b/arch/riscv/net/bpf_jit_comp.c
@@ -1656,3 +1656,16 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
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);
+}
--
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