linux-kernel - [PATCH] samples/ftrace: mark my

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Message-Id: <20201113183414.1446671-1-samitolvanen@google.com>
Date:   Fri, 13 Nov 2020 10:34:14 -0800
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Colin Ian King <colin.king@...onical.com>,
        linux-kernel@...r.kernel.org,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH] samples/ftrace: mark my_tramp[12]? global

my_tramp[12]? are declared as global functions in C, but they are not
marked global in the inline assembly definition. This mismatch confuses
Clang's Control-Flow Integrity checking. Fix the definitions by adding
.globl.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
 samples/ftrace/ftrace-direct-modify.c | 2 ++
 samples/ftrace/ftrace-direct-too.c    | 1 +
 samples/ftrace/ftrace-direct.c        | 1 +
 3 files changed, 4 insertions(+)

diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
index c13a5bc5095b..5b9a09957c6e 100644
--- a/samples/ftrace/ftrace-direct-modify.c
+++ b/samples/ftrace/ftrace-direct-modify.c
@@ -21,6 +21,7 @@ static unsigned long my_ip = (unsigned long)schedule;
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"
 "	.type		my_tramp1, @function\n"
+"	.globl		my_tramp1\n"
 "   my_tramp1:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"
@@ -29,6 +30,7 @@ asm (
 "	.size		my_tramp1, .-my_tramp1\n"
 "	ret\n"
 "	.type		my_tramp2, @function\n"
+"	.globl		my_tramp2\n"
 "   my_tramp2:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"
diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
index d5c5022be664..3f0079c9bd6f 100644
--- a/samples/ftrace/ftrace-direct-too.c
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -16,6 +16,7 @@ extern void my_tramp(void *);
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"
 "	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
 "   my_tramp:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"
diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
index 63ca06d42c80..a2729d1ef17f 100644
--- a/samples/ftrace/ftrace-direct.c
+++ b/samples/ftrace/ftrace-direct.c
@@ -14,6 +14,7 @@ extern void my_tramp(void *);
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"
 "	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
 "   my_tramp:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"

base-commit: 585e5b17b92dead8a3aca4e3c9876fbca5f7e0ba
-- 
2.29.2.299.gdc1121823c-goog