[bpf-next,v3,1/3] bpf, arm64: enable kfunc call

Commit Message

Hou Tao Jan. 30, 2022, 9:29 a.m. UTC

From: Hou Tao <[e-mail]>

Since commit b2eed9b58811 ("arm64/kernel: kaslr: reduce module
randomization range to 2 GB"), for arm64 whether KASLR is enabled
or not, the module is placed within 2GB of the kernel region, so
s32 in bpf_kfunc_desc is sufficient to represente the offset of
module function relative to __bpf_call_base. The only thing needed
is to override bpf_jit_supports_kfunc_call().

Signed-off-by: Hou Tao <[e-mail]>
---
 arch/arm64/net/bpf_jit_comp.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Daniel Borkmann Feb. 4, 2022, 3:42 p.m. UTC | #1

On 1/30/22 10:29 AM, Hou Tao wrote:
> From: Hou Tao <[e-mail]>
> 
> Since commit b2eed9b58811 ("arm64/kernel: kaslr: reduce module
> randomization range to 2 GB"), for arm64 whether KASLR is enabled
> or not, the module is placed within 2GB of the kernel region, so
> s32 in bpf_kfunc_desc is sufficient to represente the offset of
> module function relative to __bpf_call_base. The only thing needed
> is to override bpf_jit_supports_kfunc_call().
> 
> Signed-off-by: Hou Tao <[e-mail]>

Could you rebase patch 2 & 3 and resend as they don't apply to bpf-next
right now. Meanwhile, applied this one, thanks a lot!

Patch

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index e96d4d87291f..74f9a9b6a053 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -1143,6 +1143,11 @@  struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 	return prog;
 }
 
+bool bpf_jit_supports_kfunc_call(void)
+{
+	return true;
+}
+
 u64 bpf_jit_alloc_exec_limit(void)
 {
 	return VMALLOC_END - VMALLOC_START;