Re: [PATCH v3] bpf: s390: add JIT support for multi-function programs

[Daniel Borkmann <daniel@iogearbox.net>]

On 8/28/19 8:28 PM, Yauheni Kaliuta wrote:
> This adds support for bpf-to-bpf function calls in the s390 JIT
> compiler. The JIT compiler converts the bpf call instructions to
> native branch instructions. After a round of the usual passes, the
> start addresses of the JITed images for the callee functions are
> known. Finally, to fixup the branch target addresses, we need to
> perform an extra pass.
> 
> Because of the address range in which JITed images are allocated on
> s390, the offsets of the start addresses of these images from
> __bpf_call_base are as large as 64 bits. So, for a function call,
> the imm field of the instruction cannot be used to determine the
> callee's address. Use bpf_jit_get_func_addr() helper instead.
> 
> The patch borrows a lot from:
> 
> commit 8c11ea5ce13d ("bpf, arm64: fix getting subprog addr from aux
> for calls")
> 
> commit e2c95a61656d ("bpf, ppc64: generalize fetching subprog into
> bpf_jit_get_func_addr")
> 
> commit 8484ce8306f9 ("bpf: powerpc64: add JIT support for
> multi-function programs")
> 
> (including the commit message).
> 
> test_verifier (5.3-rc6 with CONFIG_BPF_JIT_ALWAYS_ON=y):
> 
> without patch:
> Summary: 1501 PASSED, 0 SKIPPED, 47 FAILED
> 
> with patch:
> Summary: 1540 PASSED, 0 SKIPPED, 8 FAILED
> 
> Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>

Applied, thanks!