From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-187.mta1.migadu.com (out-187.mta1.migadu.com [95.215.58.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6CB6740D592 for ; Wed, 24 Jun 2026 01:45:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782265533; cv=none; b=pMO4F2l48KHJsjbfcNR84pe9Fs44yq557QAapm8TtxtLuHt+lmJ0LeStz1perKDma4DNzEqnNZioa3Kl6xhUbMeYieGktEyKXRCqNKnF5egWHRptcXsw4JY2qBBqElT5cqGvEd+CzkrtdrLHPyoksjWLb1SWAGitst0i7TU5+M0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782265533; c=relaxed/simple; bh=CngTVle8YDcuOTJdYITzR0b8sLOqOysx2B7lKtSiKkg=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=abc9CY2gaP6QtninDa2dI7ILauUC8ZEEX6aoHaO5Ckem9dxeApMePk80Wo099RHoy3jwZH4cCFyCMrFhCoTAW1+KL+HjuXdBnyTLcawtwvPRooPX7mPQO+8x8SaPu0D1z5gXfI4TRDCcYVDdlKz4JCzi/OfnnfpluB0acNRG/Lc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=FsJjBbmp; arc=none smtp.client-ip=95.215.58.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="FsJjBbmp" Message-ID: <5d332838-8f41-43f7-9509-ec97dcbb0578@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782265529; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7quBymQv6qig28yFts2+yXJkHxS0N3Z7ODbIG7Vxt8Y=; b=FsJjBbmpxqDSJl59dI8pzd4XeKDt9Dbva3CIHnOy8e4tJihSRaQOVd+XlbK/umYfsBCGvk DWBybJPRyTla+vOmtqGe2Wm+j1w5aVvKr4pdZemokvQpx7DZyVJkwkHgwmMOk4VmP5Hyf3 1MgqY6YC1x6w7lO8zN6GGVoB8X+v2Os= Date: Tue, 23 Jun 2026 18:45:17 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH dwarves v8 4/5] btf_encoder: Emit true function signatures Content-Language: en-GB X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song To: Alan Maguire , Arnaldo Carvalho de Melo , dwarves@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , bpf@vger.kernel.org, kernel-team@fb.com References: <20260623222850.3290612-1-yonghong.song@linux.dev> <20260623222911.3294083-1-yonghong.song@linux.dev> In-Reply-To: <20260623222911.3294083-1-yonghong.song@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 6/23/26 3:29 PM, Yonghong Song wrote: > When true_signature is enabled, consume the per-parameter analysis the > DWARF loader recorded while saving a function's BTF: > - Drop parameters that were optimized out of a signature-changed function > (cu->producer_clang && param->optimized), adjusting the saved > parameter count accordingly. > - When a parameter was reduced to a single aggregate member > (param->true_sig_member_name is set), emit it under the synthesized name > "__" so the BTF reflects the value actually passed in > the register. > > Signed-off-by: Yonghong Song > --- > btf_encoder.c | 26 +++++++++++++++++++++++++- > 1 file changed, 25 insertions(+), 1 deletion(-) > > diff --git a/btf_encoder.c b/btf_encoder.c > index d5af706..eb6ccaa 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -1297,14 +1297,38 @@ static int32_t btf_encoder__save_func(struct btf_encoder *encoder, struct functi > state->reordered_parm = ftype->reordered_parm; > ftype__for_each_parameter(ftype, param) { > const char *name; > + char *final_name = NULL; > > /* No location info/optimized + reordered means optimized out. */ > if (ftype->reordered_parm && (!param->has_loc || param->optimized)) { > state->nr_parms--; > continue; > } > - name = parameter__name(param) ?: ""; > + if (encoder->true_signature && encoder->cu->producer_clang && param->optimized) { > + state->nr_parms--; > + continue; > + } > + > + name = parameter__name(param); > + if (!name) { > + name = ""; > + } else if (encoder->true_signature && > + encoder->cu->producer_clang && > + param->true_sig_member_name) { > + /* Non-null param->true_sig_member_name indicates that the parameter > + * name is __. > + */ > + if (asprintf(&final_name, "%s__%s", name, param->true_sig_member_name) == -1) { > + err = -ENOMEM; > + goto out; > + } > + name = final_name; > + } > + > str_off = btf__add_str(btf, name); > + if (final_name) > + free(final_name); > + > if (str_off < 0) { > err = str_off; > goto out; Find another issue in this file, not related to the above. Just give a simple example for static inline void io_file_bitmap_set(struct io_file_table *table, int bit) { WARN_ON_ONCE(test_bit(bit, table->bitmap)); __set_bit(bit, table->bitmap); table->alloc_hint = bit + 1; } It is in a header file io_uring/filetable.h. We have inlined subprogram: 0x04fb6857: DW_TAG_subprogram DW_AT_name ("io_file_bitmap_set") DW_AT_decl_file ("/home/yhs/work/bpf-next/io_uring/filetable.h") DW_AT_decl_line (29) DW_AT_prototyped (true) DW_AT_inline (DW_INL_inlined) 0x04fb685c: DW_TAG_formal_parameter DW_AT_name ("table") DW_AT_decl_file ("/home/yhs/work/bpf-next/io_uring/filetable.h") DW_AT_decl_line (29) DW_AT_type (0x04fb6885 "io_file_table *") 0x04fb6865: DW_TAG_formal_parameter DW_AT_name ("bit") DW_AT_decl_file ("/home/yhs/work/bpf-next/io_uring/filetable.h") DW_AT_decl_line (29) DW_AT_type (0x04fa5103 "int") and 0x04fb77d8: DW_TAG_subprogram DW_AT_low_pc (0xffffffff8273d430) DW_AT_high_pc (0xffffffff8273d50c) DW_AT_frame_base (DW_OP_reg7 RSP) DW_AT_call_all_calls (true) DW_AT_abstract_origin (0x04fb6857 "io_file_bitmap_set") 0x04fb77e5: DW_TAG_formal_parameter DW_AT_location (indexed (0x11f) loclist = 0x00d4bcf7: [0xffffffff8273d430, 0xffffffff8273d45c): DW_OP_reg5 RDI [0xffffffff8273d45c, 0xffffffff8273d4c3): DW_OP_reg3 RBX [0xffffffff8273d4c3, 0xffffffff8273d4e6): DW_OP_entry_value(DW_OP_reg5 RDI), DW_OP_stack_value [0xffffffff8273d4e6, 0xffffffff8273d4f6): DW_OP_reg3 RBX [0xffffffff8273d4f6, 0xffffffff8273d50c): DW_OP_entry_value(DW_OP_reg5 RDI), DW_OP_stack_value) DW_AT_abstract_origin (0x04fb685c "table") 0x04fb77ec: DW_TAG_formal_parameter DW_AT_location (indexed (0x120) loclist = 0x00d4bd23: [0xffffffff8273d430, 0xffffffff8273d464): DW_OP_reg4 RSI [0xffffffff8273d464, 0xffffffff8273d50c): DW_OP_entry_value(DW_OP_reg4 RSI), DW_OP_stack_value) DW_AT_abstract_origin (0x04fb6865 "bit") 0x04ff5f5e: DW_TAG_subprogram DW_AT_name ("io_file_bitmap_set") DW_AT_decl_file ("/home/yhs/work/bpf-next/io_uring/filetable.h") DW_AT_decl_line (29) DW_AT_prototyped (true) DW_AT_inline (DW_INL_inlined) 0x04ff5f63: DW_TAG_formal_parameter DW_AT_name ("table") DW_AT_decl_file ("/home/yhs/work/bpf-next/io_uring/filetable.h") DW_AT_decl_line (29) DW_AT_type (0x04ff5f59 "io_file_table *") 0x04ff5f6c: DW_TAG_formal_parameter DW_AT_name ("bit") DW_AT_decl_file ("/home/yhs/work/bpf-next/io_uring/filetable.h") DW_AT_decl_line (29) DW_AT_type (0x04fe77c6 "int") I get the following error: +io_file_bitmap_set : skipping BTF encoding of function due to param count mismatch; 2 params != 0 params +io_file_bitmap_set : skipping BTF encoding of function due to inconsistet prototype How do we resolve the issue like this? If this is hard, we can try to resolve as a follow-up.