From: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>
To: jeyu@kernel.org, keescook@chromium.org, nathan@kernel.org,
ndesaulniers@google.com, samitolvanen@google.com
Cc: treasure4paddy@gmail.com, Miroslav Benes <mbenes@suse.cz>,
Stephen Boyd <swboyd@chromium.org>, Joe Perches <joe@perches.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: [PATCH v5] kallsyms: strip CLANG CFI postfix ".cfi_jt"
Date: Sat, 14 Aug 2021 14:42:19 +0200 [thread overview]
Message-ID: <20210814124224.8551-1-treasure4paddy@gmail.com> (raw)
In-Reply-To: <CABCJKue6dYBYTJtyX6oE8Lq1LVHcS+vq+Z4cRE2-Tut8GRHjPQ@mail.gmail.com>
Clang CFI adds a postfix ".cfi_jt" to a symbols of extern functions.
For e.g. this breaks syscall tracer that doesn't expect such postfix,
so strip out the postfix from the expanded symbol.
Signed-off-by: Padmanabha Srinivasaiah <treasure4paddy@gmail.com>
---
Change in v5:
- Also remove explcit config check for postfix ".llvm." as LLVM
renames even in full LTO case
Change in v4:
- Remove redundant check; irrespective of LTO type (THIN/FULL),
LTO_CLANG will be always enabled. Hence will be used as entry flag
to check various postfix patterns.
- And prior to stripping postfix ".cfi_jt", added a comment to
justify why we are doing so.
Change in v3:
- Modified commit message to indicate fix is for Clang CFI postfix
- Rebased on recent patch from ndesaulniers@google.com.
https://lore.kernel.org/lkml/
20210707181814.365496-1-ndesaulniers@google.com/#t
- Fix is enabled even for CONFIG_LTO_CLANG
Change in v2:
- Use existing routine in kallsyms to strip postfix ".cfi_jt" from
extern function name.
- Modified the commit message accordingly
kernel/kallsyms.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 5cabe4dd3ff4..c8ef618e2a71 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -174,7 +174,7 @@ static bool cleanup_symbol_name(char *s)
* foo.llvm.974640843467629774. This can break hooking of static
* functions with kprobes.
*/
- if (!IS_ENABLED(CONFIG_LTO_CLANG_THIN))
+ if (!IS_ENABLED(CONFIG_LTO_CLANG))
return false;
res = strstr(s, ".llvm.");
@@ -194,6 +194,17 @@ static bool cleanup_symbol_name(char *s)
return false;
res = strrchr(s, '$');
+ if (!res) {
+ /*
+ * In case of non static function symbol <funcsym>,
+ * the local jump table will have entry as <funcsym>.cfi_jt.
+ *
+ * Such expansion breaks some built-in components,
+ * e.g. syscall tracer. Hence remove postfix ".cfi_jt".
+ */
+ res = strstr(s, ".cfi_jt");
+ }
+
if (res) {
*res = '\0';
return true;
--
2.17.1
next prev parent reply other threads:[~2021-08-14 12:43 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210727131853.GA18032@pswork>
2021-07-27 14:06 ` [PATCH v2] kallsyms: strip ThinLTO postfix ".cfi_jt" Padmanabha Srinivasaiah
2021-07-28 20:57 ` Sami Tolvanen
2021-07-29 15:29 ` Padmanabha Srinivasaiah
2021-07-29 20:53 ` [PATCH v3] kallsyms: strip CLANG CFI " Padmanabha Srinivasaiah
2021-08-03 16:28 ` Sami Tolvanen
2021-08-04 17:17 ` Padmanabha Srinivasaiah
2021-08-05 23:27 ` [PATCH v4] " Padmanabha Srinivasaiah
2021-08-12 23:05 ` Sami Tolvanen
2021-08-14 12:15 ` Padmanabha Srinivasaiah
2021-08-14 12:42 ` Padmanabha Srinivasaiah [this message]
2021-10-01 18:29 ` [PATCH v5] " Nick Desaulniers
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