On 8/28/24 6:46 PM, Alexei Starovoitov wrote:
On Wed, Aug 28, 2024 at 5:41 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
On Tue, 2024-08-27 at 12:48 -0700, Martin KaFai Lau wrote:
From: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
This patch moves the 'struct bpf_insn insn_buf[16]' stack usage
to the bpf_verifier_env. A '#define INSN_BUF_SIZE 16' is also added
to replace the ARRAY_SIZE(insn_buf) usages.
Both convert_ctx_accesses() and do_misc_fixup() are changed
to use the env->insn_buf.
It is a prep work for adding the epilogue_buf[16] in a later patch.
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
---
Not sure if this refactoring is worth it but code looks correct.
Note that there is also inline_bpf_loop()
(it needs a slightly bigger buffer).
Probably worth it in the follow up, since people complain that
this or that function in verifier.c reaches stack size limit
when compiled with sanitizers.
These buffers on stack are the biggest consumers.
ok. I will drop this patch for now. Redo it again as a followup and will
consider inline_bpf_loop() together at that time.
Regarding the stack size, I did notice the compilation warning difference on the
stack size which I should have put in the commit message.
Before:
./kernel/bpf/verifier.c:22133:5: warning: stack frame size (2584) exceeds limit
(2048) in 'bpf_check' [-Wframe-larger-than]
After:
./kernel/bpf/verifier.c:22184:5: warning: stack frame size (2264) exceeds limit
(2048) in 'bpf_check' [-Wframe-larger-than]
