Subject: + kernel-modulec-compare-symbol-values-when-marking-symbols-as-exported-in-proc-kallsyms.patch added to -mm tree Date: Tue, 18 Nov 2008 15:06:09 -0800 From: Tim Abbott The patch titled kernel/module.c: compare symbol values when marking symbols as exported in /proc/kallsyms. has been added to the -mm tree. Its filename is kernel-modulec-compare-symbol-values-when-marking-symbols-as-exported-in-proc-kallsyms.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: kernel/module.c: compare symbol values when marking symbols as exported in /proc/kallsyms. From: Tim Abbott When there are two symbols in a module with the same name, one of which is exported, both will be marked as exported in /proc/kallsyms. There aren't any instances of this in the current kernel, but it is easy to construct a simple module with two compilation units that exhibits the problem. $ objdump -j .text -t testmod.ko | grep foo 00000000 l F .text 00000032 foo 00000080 g F .text 00000001 foo $ sudo insmod testmod.ko $ grep "T foo" /proc/kallsyms c28e8000 T foo [testmod] c28e8080 T foo [testmod] Fix this by comparing the symbol values once we've found the exported symbol table entry matching the symbol name. Tested using Ksplice: $ ksplice-create --patch=this_commit.patch --id=bar . $ sudo ksplice-apply ksplice-bar.tar.gz Done! $ grep "T foo" /proc/kallsyms c28e8080 T foo [testmod] Signed-off-by: Tim Abbott Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Rusty Russell --- kernel/module.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff -puN kernel/module.c~kernel-modulec-compare-symbol-values-when-marking-symbols-as-exported-in-proc-kallsyms kernel/module.c --- a/kernel/module.c~kernel-modulec-compare-symbol-values-when-marking-symbols-as-exported-in-proc-kallsyms +++ a/kernel/module.c @@ -1569,15 +1569,15 @@ static const struct kernel_symbol *looku return NULL; } -static int is_exported(const char *name, const struct module *mod) +static int is_exported(const char *name, unsigned long value, + const struct module *mod) { - if (!mod && lookup_symbol(name, __start___ksymtab, __stop___ksymtab)) - return 1; + const struct kernel_symbol *ks; + if (!mod) + ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab); else - if (mod && lookup_symbol(name, mod->syms, mod->syms + mod->num_syms)) - return 1; - else - return 0; + ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms); + return ks != NULL && ks->value == value; } /* As per nm */ @@ -2363,7 +2363,7 @@ int module_get_kallsym(unsigned int symn strlcpy(name, mod->strtab + mod->symtab[symnum].st_name, KSYM_NAME_LEN); strlcpy(module_name, mod->name, MODULE_NAME_LEN); - *exported = is_exported(name, mod); + *exported = is_exported(name, *value, mod); preempt_enable(); return 0; } _ Patches currently in -mm which might be from tabbott@MIT.EDU are kernel-modulec-compare-symbol-values-when-marking-symbols-as-exported-in-proc-kallsyms.patch