On 17/10/2024 23:03, Arnaldo Carvalho de Melo wrote: > Hi, > > While testing the latest patches on a fedora 40 system I > noticed: > > Compilation Unit @ offset 0x77fda3d: > Length: 0xd527 (32-bit) > Version: 5 > Unit Type: DW_UT_compile (1) > Abbrev Offset: 0x38012d > Pointer Size: 8 > <0><77fda49>: Abbrev Number: 6 (DW_TAG_compile_unit) > <77fda4a> DW_AT_producer : (indirect string, offset: 0x4ec527): GNU C11 14.2.1 20240912 (Red Hat 14.2.1-3) -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mno-fp-ret > -in-387 -mpreferred-stack-boundary=3 -mskip-rax-setup -mtune=generic -mno-red-zone -mcmodel=kernel -mindirect-branch=thunk-extern -mindirect-branch-register -mindirect-branch-cs-prefix -mfunc > tion-return=thunk-extern -mharden-sls=all -mrecord-mcount -mfentry -march=x86-64 -g -O2 -std=gnu11 -p -fshort-wchar -funsigned-char -fno-common -fno-PIE -fno-strict-aliasing -fcf-protection=b > ranch -falign-jumps=1 -falign-loops=1 -fno-asynchronous-unwind-tables -fno-jump-tables -fpatchable-function-entry=16,16 -fno-delete-null-pointer-checks -fno-allow-store-data-races -fstack-pro > tector-strong -ftrivial-auto-var-init=zero -fno-stack-clash-protection -fmin-function-alignment=16 -fstrict-flex-arrays=3 -fno-strict-overflow -fstack-check=no -fconserve-stack -fsanitize=bou > nds-strict -fsanitize=shift > <77fda4e> DW_AT_language : 29 (C11) > <77fda4f> DW_AT_name : (indirect line string, offset: 0xfa3e): rust/exports.c > <77fda53> DW_AT_comp_dir : (indirect line string, offset: 0x4db): /usr/src/debug/kernel-6.11.3/linux-6.11.3-200.fc40.x86_64 > <SNIP> > <78078ce> DW_AT_name : (indirect string, offset: 0x5310d): __UNIQUE_ID___addressable__RNvXshK_NtCshatLywNUlpX_8bindings12bindings_rawNtB6_28mei_connect_client_data_vtagNtNtCs2vSfyxKMEZc_4core7default7Default7default1222 > <78078d2> DW_AT_decl_file : 4 > <78078d3> DW_AT_decl_line : 740 > <78078d5> DW_AT_decl_column : 1 > <78078d5> DW_AT_type : <0x77fdac9> > <78078d9> DW_AT_location : 9 byte block: 3 0 0 0 0 0 0 0 0 (DW_OP_addr: 0) > <1><78078e3>: Abbrev Number: 1 (DW_TAG_variable) > <78078e4> DW_AT_name : (indirect string, offset: 0x51af69): _RNvXshL_NtCshatLywNUlpX_8bindings12bindings_rawNtB6_13hda_device_idNtNtCs2vSfyxKMEZc_4core7default7Default7default > <78078e8> DW_AT_decl_file : 4 > <78078e9> DW_AT_decl_line : 741 > <78078eb> DW_AT_decl_column : 1 > <78078eb> DW_AT_type : <0x77fda8c> > <78078ef> DW_AT_external : 1 > <78078ef> DW_AT_declaration : 1 > <1><78078ef>: Abbrev Number: 2 (DW_TAG_variable) > <78078f0> DW_AT_name : (indirect string, offset: 0x83a79): __UNIQUE_ID___addressable__RNvXshL_NtCshatLywNUlpX_8bindings12bindings_rawNtB6_13hda_device_idNtNtCs2vSfyxKMEZc_4core7default7Default7default1223 > > That caused: > > acme@number:~/git/pahole$ tests/btf_functions.sh > Validation of BTF encoding of functions; this may take some time: PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXsa_NtCs2vSfyxKMEZc_4core4charNtB5_11EscapeDebugNtNtNtNtB7_4iter6traits10exact_size17ExactSizeIterator3len57'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXse_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits8iterator8Iterator4next59'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXse_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits8iterator8Iterator9size_hint60'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXse_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits8iterator8Iterator5count61'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXse_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits8iterator8Iterator4last62'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXse_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits8iterator8Iterator10advance_by63'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXsf_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits12double_ended19DoubleEndedIterator9next_back64'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXsf_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits12double_ended19DoubleEndedIterator15advance_back_by65'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXsg_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits10exact_size17ExactSizeIterator3len66'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXsg_NtCs2vSfyxKMEZc_4core4charNtB5_15CaseMappingIterNtNtNtNtB7_4iter6traits10exact_size17ExactSizeIterator8is_empty67'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXs0_NtNtCs2vSfyxKMEZc_4core3net6parserNtNtB7_7ip_addr6IpAddrNtNtNtB9_3str6traits7FromStr8from_str95'). > PAHOLE: Warning: Found invalid variable name when encoding btf, ignored (sym: '__UNIQUE_ID___addressable__RNvXs2_NtNtCs2vSfyxKMEZc_4core3net6parserNtNtB7_7ip_addr8Ipv4AddrNtNtNtB9_3str6traits7FromStr8from_str97'). > > > At first I thought that was from Rust source code, but nope, its things > in C to connect to Rust, have you guys thought about this? The warning > is not that good, invalid why? Lenght of the symbol name? > > Its the end of my work day, so I have yet to think this through, so just > reporting it here to initiate a discussion. > > acme@number:~/git/pahole$ grep RUST /boot/config-6.11.3-200.fc40.x86_64 > CONFIG_RUST_IS_AVAILABLE=y > CONFIG_RUST=y > CONFIG_RUSTC_VERSION_TEXT="rustc 1.81.0 (eeb90cda1 2024-09-04) (Fedora 1.81.0-1.fc40)" > CONFIG_HAVE_RUST=y > CONFIG_RUST_FW_LOADER_ABSTRACTIONS=y > CONFIG_BLK_DEV_RUST_NULL=m > CONFIG_RUST_PHYLIB_ABSTRACTIONS=y > CONFIG_AX88796B_RUST_PHY=y > CONFIG_HID_THRUSTMASTER=m > CONFIG_THRUSTMASTER_FF=y > CONFIG_TRUSTED_KEYS=y > CONFIG_HAVE_TRUSTED_KEYS=y > CONFIG_TRUSTED_KEYS_TPM=y > CONFIG_INTEGRITY_TRUSTED_KEYRING=y > CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT=y > CONFIG_SYSTEM_TRUSTED_KEYRING=y > # CONFIG_SYSTEM_TRUSTED_KEYS="certs/rhel.pem" > CONFIG_SYSTEM_TRUSTED_KEYS="" > CONFIG_SECONDARY_TRUSTED_KEYRING=y > # CONFIG_SECONDARY_TRUSTED_KEYRING_SIGNED_BY_BUILTIN is not set > # CONFIG_RUST_DEBUG_ASSERTIONS is not set > CONFIG_RUST_OVERFLOW_CHECKS=y > # CONFIG_RUST_BUILD_ASSERT_ALLOW is not set > acme@number:~/git/pahole$ > hi Arnaldo, thanks for the report! This is as you suspected due to the name being longer than KSYM_NAME_LEN as checked by btf_name_valid(), but we should skip it anyway as __UNIQUE_ID is one of the filter prefixes we skip in encoding. If we just reorder the checks we can avoid these warnings I think. I've sent a patch for that [1]; if you could test it (or can point me at a vmlinux with the symbols I can do so) that would be great. Thanks! Alan [1] https://lore.kernel.org/dwarves/20241018094301.1550149-1-alan.maguire@xxxxxxxxxx/
