On 05/26/2017 08:14 AM, Daniel Borkmann wrote:
On 05/26/2017 02:38 AM, David Daney wrote:
Since the eBPF machine has 64-bit registers, we only support this in
64-bit kernels. As of the writing of this commit log test-bpf is
showing:
test_bpf: Summary: 316 PASSED, 0 FAILED, [308/308 JIT'ed]
All current test cases are successfully compiled.
Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
Awesome work!
Did you also manage to run tools/testing/selftests/bpf/ fine with
the JIT enabled?
I haven't done that yet, I will before the next revision.
[...]
+struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
+{
+ struct jit_ctx ctx;
+ unsigned int alloc_size;
+
+ /* Only 64-bit kernel supports eBPF */
+ if (!IS_ENABLED(CONFIG_64BIT) || !bpf_jit_enable)
Isn't this already reflected by the following?
select HAVE_EBPF_JIT if (64BIT && !CPU_MICROMIPS)
Not exactly. The eBPF JIT is in the same file as the classic-BPF JIT,
so when HAVE_EBPF_JIT is false this will indeed never be called. But
the kernel would otherwise contain all the JIT code.
By putting in !IS_ENABLED(CONFIG_64BIT) we allow gcc to eliminate all
the dead code when compiling the JITs.
+ return prog;
+
+ memset(&ctx, 0, sizeof(ctx));
+
+ ctx.offsets = kcalloc(prog->len + 1, sizeof(*ctx.offsets),
GFP_KERNEL);
+ if (ctx.offsets == NULL)
+ goto out;
+
+ ctx.reg_val_types = kcalloc(prog->len + 1,
sizeof(*ctx.reg_val_types), GFP_KERNEL);
+ if (ctx.reg_val_types == NULL)
+ goto out;
+
+ ctx.skf = prog;
+
+ if (reg_val_propagate(&ctx))
+ goto out;
+
+ /* First pass discovers used resources */
+ if (build_int_body(&ctx))
+ goto out;
+
+ /* Second pass generates offsets */
+ ctx.idx = 0;
+ if (gen_int_prologue(&ctx))
+ goto out;
+ if (build_int_body(&ctx))
+ goto out;
+ if (build_int_epilogue(&ctx))
+ goto out;
+
+ alloc_size = 4 * ctx.idx;
+
+ ctx.target = module_alloc(alloc_size);
You would need to use bpf_jit_binary_alloc() like all other
eBPF JITs do, otherwise kallsyms of the JITed progs would
break.
OK, I was just copying code from the classic-BPF JIT in the same file.
I will fix this.
+ if (ctx.target == NULL)
+ goto out;
+
+ /* Clean it */
+ memset(ctx.target, 0, alloc_size);
+
+ /* Third pass generates the code */
+ ctx.idx = 0;
+ if (gen_int_prologue(&ctx))
+ goto out;
+ if (build_int_body(&ctx))
+ goto out;
+ if (build_int_epilogue(&ctx))
+ goto out;
+ /* Update the icache */
+ flush_icache_range((ptr)ctx.target, (ptr)(ctx.target + ctx.idx));
+
+ if (bpf_jit_enable > 1)
+ /* Dump JIT code */
+ bpf_jit_dump(prog->len, alloc_size, 2, ctx.target);
+
+ prog->bpf_func = (void *)ctx.target;
+ prog->jited = 1;
+
+out:
+ kfree(ctx.offsets);
+ kfree(ctx.reg_val_types);
+
+ return prog;
+}
