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ANDROID: kallsyms: strip hashes from static functions with ThinLTO and CFI

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With CONFIG_THINLTO and CFI both enabled, LLVM appends a hash to the
names of all static functions. This breaks userspace tools, so strip
out the hash from output.

Bug: 147422318
Change-Id: Ie19a59d9d0681298be54e73064badc361c0f7014
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Sami Tolvanen 2018-02-14 10:26:35 -08:00
parent 383f53ee18
commit f683c8dc7f
1 changed files with 44 additions and 5 deletions
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49
kernel/kallsyms.c
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@ -271,6 +271,24 @@ int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
!!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
}
#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_THINLTO)
/*
* LLVM appends a hash to static function names when ThinLTO and CFI are
* both enabled, which causes confusion and potentially breaks user space
* tools, so we will strip the postfix from expanded symbol names.
*/
static inline void cleanup_symbol_name(char *s)
{
char *res;
res = strrchr(s, '$');
if (res)
*res = '\0';
}
#else
static inline void cleanup_symbol_name(char *s) {}
#endif
/*
* Lookup an address
* - modname is set to NULL if it's in the kernel.
@ -297,7 +315,9 @@ const char *kallsyms_lookup(unsigned long addr,
namebuf, KSYM_NAME_LEN);
if (modname)
*modname = NULL;
return namebuf;
ret = namebuf;
goto found;
}
/* See if it's in a module or a BPF JITed image. */
@ -310,11 +330,16 @@ const char *kallsyms_lookup(unsigned long addr,
if (!ret)
ret = ftrace_mod_address_lookup(addr, symbolsize,
offset, modname, namebuf);
found:
cleanup_symbol_name(namebuf);
return ret;
}
int lookup_symbol_name(unsigned long addr, char *symname)
{
int res;
symname[0] = '\0';
symname[KSYM_NAME_LEN - 1] = '\0';
@ -325,15 +350,23 @@ int lookup_symbol_name(unsigned long addr, char *symname)
/* Grab name */
kallsyms_expand_symbol(get_symbol_offset(pos),
symname, KSYM_NAME_LEN);
return 0;
goto found;
}
/* See if it's in a module. */
return lookup_module_symbol_name(addr, symname);
res = lookup_module_symbol_name(addr, symname);
if (res)
return res;
found:
cleanup_symbol_name(symname);
return 0;
}
int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
unsigned long *offset, char *modname, char *name)
{
int res;
name[0] = '\0';
name[KSYM_NAME_LEN - 1] = '\0';
@ -345,10 +378,16 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
kallsyms_expand_symbol(get_symbol_offset(pos),
name, KSYM_NAME_LEN);
modname[0] = '\0';
return 0;
goto found;
}
/* See if it's in a module. */
return lookup_module_symbol_attrs(addr, size, offset, modname, name);
res = lookup_module_symbol_attrs(addr, size, offset, modname, name);
if (res)
return res;
found:
cleanup_symbol_name(name);
return 0;
}
/* Look up a kernel symbol and return it in a text buffer. */