From b8a94bfb33952bb17fbc65f8903d242a721c533d Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Mon, 5 Apr 2021 05:03:50 +0200
Subject: kallsyms: increase maximum kernel symbol length to 512

Rust symbols can become quite long due to namespacing introduced
by modules, types, traits, generics, etc. For instance,
the following code:

    pub mod my_module {
        pub struct MyType;
        pub struct MyGenericType<T>(T);

        pub trait MyTrait {
            fn my_method() -> u32;
        }

        impl MyTrait for MyGenericType<MyType> {
            fn my_method() -> u32 {
                42
            }
        }
    }

generates a symbol of length 96 when using the upcoming v0 mangling scheme:

    _RNvXNtCshGpAVYOtgW1_7example9my_moduleINtB2_13MyGenericTypeNtB2_6MyTypeENtB2_7MyTrait9my_method

At the moment, Rust symbols may reach up to 300 in length.
Setting 512 as the maximum seems like a reasonable choice to
keep some headroom.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
Co-developed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 tools/lib/perf/include/perf/event.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'tools/lib/perf/include')

diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h
index 93bf93a59c99..d8ae4e944467 100644
--- a/tools/lib/perf/include/perf/event.h
+++ b/tools/lib/perf/include/perf/event.h
@@ -97,7 +97,7 @@ struct perf_record_throttle {
 };
 
 #ifndef KSYM_NAME_LEN
-#define KSYM_NAME_LEN 256
+#define KSYM_NAME_LEN 512
 #endif
 
 struct perf_record_ksymbol {
-- 
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