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 <[e-mail]>
Reviewed-by: Petr Mladek <[e-mail]>
Reviewed-by: Greg Kroah-Hartman <[e-mail]>
Co-developed-by: Alex Gaynor <[e-mail]>
Signed-off-by: Alex Gaynor <[e-mail]>
Co-developed-by: Wedson Almeida Filho <[e-mail]>
Signed-off-by: Wedson Almeida Filho <[e-mail]>
Co-developed-by: Gary Guo <[e-mail]>
Signed-off-by: Gary Guo <[e-mail]>
Co-developed-by: Boqun Feng <[e-mail]>
Signed-off-by: Boqun Feng <[e-mail]>
Signed-off-by: Miguel Ojeda <[e-mail]>

include/linux/kallsyms.h

···
 
 #include <asm/sections.h>
 
-#define KSYM_NAME_LEN 128
+#define KSYM_NAME_LEN 512
 #define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s %s]") + \
 			(KSYM_NAME_LEN - 1) + \
 			2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + \

kernel/livepatch/core.c

···
 	 * we use the smallest/strictest upper bound possible (56, based on
 	 * the current definition of MODULE_NAME_LEN) to prevent overflows.
 	 */
-	BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128);
+	BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512);
 
 	relas = (Elf_Rela *) relasec->sh_addr;
 	/* For each rela in this klp relocation section */
···
 
 		/* Format: .klp.sym.sym_objname.sym_name,sympos */
 		cnt = sscanf(strtab + sym->st_name,
-			     ".klp.sym.%55[^.].%127[^,],%lu",
+			     ".klp.sym.%55[^.].%511[^,],%lu",
 			     sym_objname, sym_name, &sympos);
 		if (cnt != 3) {
 			pr_err("symbol %s has an incorrectly formatted name\n",

scripts/kallsyms.c

···
 #define _stringify_1(x)	#x
 #define _stringify(x)	_stringify_1(x)
 
-#define KSYM_NAME_LEN		128
+#define KSYM_NAME_LEN		512
 
 /*
  * A substantially bigger size than the current maximum.
···
  * for the fscanf() format string. Therefore, a _Static_assert() is
  * used instead to maintain the relationship with KSYM_NAME_LEN.
  */
-#define KSYM_NAME_LEN_BUFFER	512
+#define KSYM_NAME_LEN_BUFFER	2048
 _Static_assert(
 	KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,
 	"Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN"

tools/include/linux/kallsyms.h

···
 #include <stdio.h>
 #include <unistd.h>
 
-#define KSYM_NAME_LEN 128
+#define KSYM_NAME_LEN 512
 
 struct module;
 

tools/lib/perf/include/perf/event.h

···
 };
 
 #ifndef KSYM_NAME_LEN
-#define KSYM_NAME_LEN 256
+#define KSYM_NAME_LEN 512
 #endif
 
 struct perf_record_ksymbol {

tools/lib/symbol/kallsyms.h

···
 #include <linux/types.h>
 
 #ifndef KSYM_NAME_LEN
-#define KSYM_NAME_LEN 256
+#define KSYM_NAME_LEN 512
 #endif
 
 static inline u8 kallsyms2elf_binding(char type)