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kallsyms: Fix kallsyms_selftest failure
Kernel test robot reported a kallsyms_test failure when clang lto is enabled (thin or full) and CONFIG_KALLSYMS_SELFTEST is also enabled. I can reproduce in my local environment with the following error message with thin lto: [ 1.877897] kallsyms_selftest: Test for 1750th symbol failed: (tsc_cs_mark_unstable) addr=ffffffff81038090 [ 1.877901] kallsyms_selftest: abort It appears that commit8cc32a9bbf
("kallsyms: strip LTO-only suffixes from promoted global functions") caused the failure. Commit8cc32a9bbf
changed cleanup_symbol_name() based on ".llvm." instead of '.' where ".llvm." is appended to a before-lto-optimization local symbol name. We need to propagate such knowledge in kallsyms_selftest.c as well. Further more, compare_symbol_name() in kallsyms.c needs change as well. In scripts/kallsyms.c, kallsyms_names and kallsyms_seqs_of_names are used to record symbol names themselves and index to symbol names respectively. For example: kallsyms_names: ... __amd_smn_rw._entry <== seq 1000 __amd_smn_rw._entry.5 <== seq 1001 __amd_smn_rw.llvm.<hash> <== seq 1002 ... kallsyms_seqs_of_names are sorted based on cleanup_symbol_name() through, so the order in kallsyms_seqs_of_names actually has index 1000: seq 1002 <== __amd_smn_rw.llvm.<hash> (actual symbol comparison using '__amd_smn_rw') index 1001: seq 1000 <== __amd_smn_rw._entry index 1002: seq 1001 <== __amd_smn_rw._entry.5 Let us say at a particular point, at index 1000, symbol '__amd_smn_rw.llvm.<hash>' is comparing to '__amd_smn_rw._entry' where '__amd_smn_rw._entry' is the one to search e.g., with function kallsyms_on_each_match_symbol(). The current implementation will find out '__amd_smn_rw._entry' is less than '__amd_smn_rw.llvm.<hash>' and then continue to search e.g., index 999 and never found a match although the actual index 1001 is a match. To fix this issue, let us do cleanup_symbol_name() first and then do comparison. In the above case, comparing '__amd_smn_rw' vs '__amd_smn_rw._entry' and '__amd_smn_rw._entry' being greater than '__amd_smn_rw', the next comparison will be > index 1000 and eventually index 1001 will be hit an a match is found. For any symbols not having '.llvm.' substr, there is no functionality change for compare_symbol_name(). Fixes:8cc32a9bbf
("kallsyms: strip LTO-only suffixes from promoted global functions") Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202308232200.1c932a90-oliver.sang@intel.com Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Reviewed-by: Song Liu <song@kernel.org> Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com> Link: https://lore.kernel.org/r/20230825034659.1037627-1-yonghong.song@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org>
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parent
2ddd3cac1f
commit
33f0467fe0
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@ -188,16 +188,13 @@ static bool cleanup_symbol_name(char *s)
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static int compare_symbol_name(const char *name, char *namebuf)
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static int compare_symbol_name(const char *name, char *namebuf)
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{
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{
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int ret;
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/* The kallsyms_seqs_of_names is sorted based on names after
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* cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled.
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ret = strcmp(name, namebuf);
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* To ensure correct bisection in kallsyms_lookup_names(), do
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if (!ret)
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* cleanup_symbol_name(namebuf) before comparing name and namebuf.
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return ret;
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*/
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cleanup_symbol_name(namebuf);
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if (cleanup_symbol_name(namebuf) && !strcmp(name, namebuf))
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return strcmp(name, namebuf);
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return 0;
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return ret;
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}
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}
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static unsigned int get_symbol_seq(int index)
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static unsigned int get_symbol_seq(int index)
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@ -196,7 +196,7 @@ static bool match_cleanup_name(const char *s, const char *name)
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if (!IS_ENABLED(CONFIG_LTO_CLANG))
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if (!IS_ENABLED(CONFIG_LTO_CLANG))
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return false;
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return false;
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p = strchr(s, '.');
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p = strstr(s, ".llvm.");
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if (!p)
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if (!p)
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return false;
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return false;
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@ -344,27 +344,6 @@ static int test_kallsyms_basic_function(void)
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goto failed;
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goto failed;
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}
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}
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/*
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* The first '.' may be the initial letter, in which case the
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* entire symbol name will be truncated to an empty string in
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* cleanup_symbol_name(). Do not test these symbols.
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*
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* For example:
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* cat /proc/kallsyms | awk '{print $3}' | grep -E "^\." | head
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* .E_read_words
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* .E_leading_bytes
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* .E_trailing_bytes
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* .E_write_words
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* .E_copy
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* .str.292.llvm.12122243386960820698
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* .str.24.llvm.12122243386960820698
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* .str.29.llvm.12122243386960820698
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* .str.75.llvm.12122243386960820698
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* .str.99.llvm.12122243386960820698
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*/
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if (IS_ENABLED(CONFIG_LTO_CLANG) && !namebuf[0])
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continue;
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lookup_addr = kallsyms_lookup_name(namebuf);
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lookup_addr = kallsyms_lookup_name(namebuf);
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memset(stat, 0, sizeof(*stat));
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memset(stat, 0, sizeof(*stat));
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