Commit b8a94bfb authored by Miguel Ojeda's avatar Miguel Ojeda
Browse files

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: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Co-developed-by: default avatarAlex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: default avatarAlex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: default avatarWedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: default avatarWedson Almeida Filho <wedsonaf@google.com>
Co-developed-by: default avatarGary Guo <gary@garyguo.net>
Signed-off-by: default avatarGary Guo <gary@garyguo.net>
Co-developed-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 73bbb944

include/linux/kallsyms.h

+1 −1
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ 


#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

+2 −2
Original line number Diff line number Diff line
@@ -213,7 +213,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, 
	 * 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 */
@@ -227,7 +227,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, 


		/* 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

+2 −2
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ 
#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.
@@ -39,7 +39,7 @@ 
 * 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

+1 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 
#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

+1 −1
Original line number Diff line number Diff line
@@ -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 {