On Thu, Aug 29, 2024 at 8:20 AM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote: > > 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. why? Keep it. It's an improvement already. > 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] Exactly. It's a step forward.
