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Wed, 17 Dec 2025 00:40:18 -0800 (PST) Received: from krava ([176.74.159.170]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4310adacfbbsm3637780f8f.12.2025.12.17.00.40.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 00:40:18 -0800 (PST) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Wed, 17 Dec 2025 09:40:15 +0100 To: bot+bpf-ci@kernel.org Cc: rostedt@kernel.org, revest@google.com, mark.rutland@arm.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, menglong8.dong@gmail.com, song@kernel.org, martin.lau@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, clm@meta.com, ihor.solodrai@linux.dev Subject: Re: [PATCHv5 bpf-next 1/9] ftrace,bpf: Remove FTRACE_OPS_FL_JMP ftrace_ops flag Message-ID: References: <20251215211402.353056-2-jolsa@kernel.org> <95c13c0b793604796037ca67c191e1bfce22770dd020107c7179a698c5d49b91@mail.kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <95c13c0b793604796037ca67c191e1bfce22770dd020107c7179a698c5d49b91@mail.kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251217_004021_243222_AA13D26B X-CRM114-Status: GOOD ( 23.47 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Dec 15, 2025 at 09:31:51PM +0000, bot+bpf-ci@kernel.org wrote: > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > > index 015dd1049bea..505b7d3f5641 100644 > > --- a/include/linux/ftrace.h > > +++ b/include/linux/ftrace.h > > [ ... ] > > > diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c > > index 976d89011b15..b9a358d7a78f 100644 > > --- a/kernel/bpf/trampoline.c > > +++ b/kernel/bpf/trampoline.c > > @@ -214,10 +214,15 @@ static int modify_fentry(struct bpf_trampoline *tr, u32 orig_flags, > > int ret; > > > > if (tr->func.ftrace_managed) { > > + unsigned long addr = (unsigned long) new_addr; > > + > > + if (bpf_trampoline_use_jmp(tr->flags)) > > + addr = ftrace_jmp_set(addr); > > + > > if (lock_direct_mutex) > > - ret = modify_ftrace_direct(tr->fops, (long)new_addr); > > + ret = modify_ftrace_direct(tr->fops, addr); > > else > > - ret = modify_ftrace_direct_nolock(tr->fops, (long)new_addr); > > + ret = modify_ftrace_direct_nolock(tr->fops, addr); > > } else { > > ret = bpf_trampoline_update_fentry(tr, orig_flags, old_addr, > > new_addr); > > @@ -240,10 +245,15 @@ static int register_fentry(struct bpf_trampoline *tr, void *new_addr) > > } > > > > if (tr->func.ftrace_managed) { > > + unsigned long addr = (unsigned long) new_addr; > > + > > + if (bpf_trampoline_use_jmp(tr->flags)) > > + addr = ftrace_jmp_set(addr); > > + > > ret = ftrace_set_filter_ip(tr->fops, (unsigned long)ip, 0, 1); > > if (ret) > > return ret; > > - ret = register_ftrace_direct(tr->fops, (long)new_addr); > > + ret = register_ftrace_direct(tr->fops, addr); > > } else { > > ret = bpf_trampoline_update_fentry(tr, 0, NULL, new_addr); > > } > > After this change, register_ftrace_direct() receives an address with > the LSB bit already set (via ftrace_jmp_set) and stores it as-is in > entry->direct. This address then flows through to ftrace_find_rec_direct() > which returns entry->direct unchanged. > > In available_filter_functions_show(): hum, there's no such function.. AFAICS it's t_show called through ftrace_avail_fops->ftrace_avail_open->show_ftrace_seq_ops > > direct = ftrace_find_rec_direct(rec->ip); > if (direct) > seq_printf(m, "\n\tdirect-->%pS", (void *)direct); > but yep, it's related problem, that Menglong said he will address in separate patch thanks, jirka > Can the debug output show misleading symbol offsets? When the LSB is > set, %pS will resolve addresses like "function+0x1" instead of just > "function". This makes ftrace debug output harder to read for users > trying to understand direct call attachments. > > The fix would be to strip the LSB bit before printing: > seq_printf(m, "\n\tdirect-->%pS", (void *)ftrace_jmp_get(direct)); > > [ ... ] > > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > > index bbb37c0f8c6c..b0dc911411f1 100644 > > --- a/kernel/trace/ftrace.c > > +++ b/kernel/trace/ftrace.c > > @@ -6017,15 +6017,8 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > > if (ftrace_hash_empty(hash)) > > return -EINVAL; > > > > - /* This is a "raw" address, and this should never happen. */ > > - if (WARN_ON_ONCE(ftrace_is_jmp(addr))) > > - return -EINVAL; > > - > > mutex_lock(&direct_mutex); > > > > - if (ops->flags & FTRACE_OPS_FL_JMP) > > - addr = ftrace_jmp_set(addr); > > - > > /* Make sure requested entries are not already registered.. */ > > size = 1 << hash->size_bits; > > for (i = 0; i < size; i++) { > > [ ... ] > > > @@ -6146,13 +6139,6 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > > > > lockdep_assert_held_once(&direct_mutex); > > > > - /* This is a "raw" address, and this should never happen. */ > > - if (WARN_ON_ONCE(ftrace_is_jmp(addr))) > > - return -EINVAL; > > - > > - if (ops->flags & FTRACE_OPS_FL_JMP) > > - addr = ftrace_jmp_set(addr); > > - > > /* Enable the tmp_ops to have the same functions as the direct ops */ > > ftrace_ops_init(&tmp_ops); > > tmp_ops.func_hash = ops->func_hash; > > [ ... ] > > > --- > AI reviewed your patch. Please fix the bug or email reply why it's not a bug. > See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md > > CI run summary: https://github.com/kernel-patches/bpf/actions/runs/20247816064