--- /dev/null
+From 33f0467fe06934d5e4ea6e24ce2b9c65ce618e26 Mon Sep 17 00:00:00 2001
+From: Yonghong Song <yonghong.song@linux.dev>
+Date: Thu, 24 Aug 2023 20:46:59 -0700
+Subject: kallsyms: Fix kallsyms_selftest failure
+
+From: Yonghong Song <yonghong.song@linux.dev>
+
+commit 33f0467fe06934d5e4ea6e24ce2b9c65ce618e26 upstream.
+
+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 commit 8cc32a9bbf29 ("kallsyms: strip LTO-only suffixes
+from promoted global functions") caused the failure. Commit 8cc32a9bbf29
+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: 8cc32a9bbf29 ("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>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/kallsyms.c | 17 +++++++----------
+ kernel/kallsyms_selftest.c | 23 +----------------------
+ 2 files changed, 8 insertions(+), 32 deletions(-)
+
+--- a/kernel/kallsyms.c
++++ b/kernel/kallsyms.c
+@@ -188,16 +188,13 @@ static bool cleanup_symbol_name(char *s)
+
+ static int compare_symbol_name(const char *name, char *namebuf)
+ {
+- int ret;
+-
+- ret = strcmp(name, namebuf);
+- if (!ret)
+- return ret;
+-
+- if (cleanup_symbol_name(namebuf) && !strcmp(name, namebuf))
+- return 0;
+-
+- return ret;
++ /* The kallsyms_seqs_of_names is sorted based on names after
++ * cleanup_symbol_name() (see scripts/kallsyms.c) if clang lto is enabled.
++ * To ensure correct bisection in kallsyms_lookup_names(), do
++ * cleanup_symbol_name(namebuf) before comparing name and namebuf.
++ */
++ cleanup_symbol_name(namebuf);
++ return strcmp(name, namebuf);
+ }
+
+ static unsigned int get_symbol_seq(int index)
+--- a/kernel/kallsyms_selftest.c
++++ b/kernel/kallsyms_selftest.c
+@@ -196,7 +196,7 @@ static bool match_cleanup_name(const cha
+ if (!IS_ENABLED(CONFIG_LTO_CLANG))
+ return false;
+
+- p = strchr(s, '.');
++ p = strstr(s, ".llvm.");
+ if (!p)
+ return false;
+
+@@ -344,27 +344,6 @@ static int test_kallsyms_basic_function(
+ goto failed;
+ }
+
+- /*
+- * The first '.' may be the initial letter, in which case the
+- * entire symbol name will be truncated to an empty string in
+- * cleanup_symbol_name(). Do not test these symbols.
+- *
+- * For example:
+- * cat /proc/kallsyms | awk '{print $3}' | grep -E "^\." | head
+- * .E_read_words
+- * .E_leading_bytes
+- * .E_trailing_bytes
+- * .E_write_words
+- * .E_copy
+- * .str.292.llvm.12122243386960820698
+- * .str.24.llvm.12122243386960820698
+- * .str.29.llvm.12122243386960820698
+- * .str.75.llvm.12122243386960820698
+- * .str.99.llvm.12122243386960820698
+- */
+- if (IS_ENABLED(CONFIG_LTO_CLANG) && !namebuf[0])
+- continue;
+-
+ lookup_addr = kallsyms_lookup_name(namebuf);
+
+ memset(stat, 0, sizeof(*stat));
projects / thirdparty / kernel / stable-queue.git / commitdiff
