x86/kprobes: Move trampoline code into RODATA [Linux 5.1]

x86/kprobes: Move trampoline code into RODATA [Linux 5.1]

This Linux kernel change "x86/kprobes: Move trampoline code into RODATA" is included in the Linux 5.1 release. This change is authored by Masami Hiramatsu <mhiramat [at] kernel.org> on Wed Feb 13 01:11:47 2019 +0900. The commit for this change in Linux stable tree is 877b145 (patch).

x86/kprobes: Move trampoline code into RODATA

Move optprobe trampoline code into RODATA since it is
not executed, but copied and modified to be used on
a trampoline buffer.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/154998790744.31052.3016106262944915510.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>

There are 9 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/x86/kernel/kprobes/opt.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 544bd41..f142629 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -97,6 +97,7 @@ static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
 }

 asm (
+           ".pushsection .rodata\n"
            "optprobe_template_func:\n"
            ".global optprobe_template_entry\n"
            "optprobe_template_entry:\n"
@@ -136,16 +137,10 @@ static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
 #endif
            ".global optprobe_template_end\n"
            "optprobe_template_end:\n"
-           ".type optprobe_template_func, @function\n"
-           ".size optprobe_template_func, .-optprobe_template_func\n");
+           ".popsection\n");

 void optprobe_template_func(void);
 STACK_FRAME_NON_STANDARD(optprobe_template_func);
-NOKPROBE_SYMBOL(optprobe_template_func);
-NOKPROBE_SYMBOL(optprobe_template_entry);
-NOKPROBE_SYMBOL(optprobe_template_val);
-NOKPROBE_SYMBOL(optprobe_template_call);
-NOKPROBE_SYMBOL(optprobe_template_end);

 #define TMPL_MOVE_IDX \
    ((long)optprobe_template_val - (long)optprobe_template_entry)

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