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kbuild: whitelist false section mismatch warnings

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In several cases the section mismatch check triggered false warnings.
Following patch introduce a whitelist to 'false positives' are not warned of.
Two types of patterns are recognised:
1) Typical case when a module parameter is _initdata
2) When a function pointer is assigned to a driver structure

In both patterns we rely on the actual name of the variable assigned

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
This commit is contained in:
Sam Ravnborg 2006-02-26 22:18:11 +01:00
parent cc006288fb
commit 4c8fbca583
1 changed files with 89 additions and 0 deletions
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89
scripts/mod/modpost.c
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@ -451,6 +451,89 @@ static char *get_modinfo(void *modinfo, unsigned long modinfo_len,
return NULL;
}
/**
* Test if string s ends in string sub
* return 0 if match
**/
static int strrcmp(const char *s, const char *sub)
{
int slen, sublen;
if (!s || !sub)
return 1;
slen = strlen(s);
sublen = strlen(sub);
if ((slen == 0) || (sublen == 0))
return 1;
if (sublen > slen)
return 1;
return memcmp(s + slen - sublen, sub, sublen);
}
/**
* Whitelist to allow certain references to pass with no warning.
* Pattern 1:
* If a module parameter is declared __initdata and permissions=0
* then this is legal despite the warning generated.
* We cannot see value of permissions here, so just ignore
* this pattern.
* The pattern is identified by:
* tosec = .init.data
* fromsec = .data
* atsym =__param*
*
* Pattern 2:
* Many drivers utilise a *_driver container with references to
* add, remove, probe functions etc.
* These functions may often be marked __init and we do not want to
* warn here.
* the pattern is identified by:
* tosec = .init.text | .exit.text
* fromsec = .data
* atsym = *_driver, *_ops, *_probe, *probe_one
**/
static int secref_whitelist(const char *tosec, const char *fromsec,
const char *atsym)
{
int f1 = 1, f2 = 1;
const char **s;
const char *pat2sym[] = {
"_driver",
"_ops",
"_probe",
"_probe_one",
NULL
};
/* Check for pattern 1 */
if (strcmp(tosec, ".init.data") != 0)
f1 = 0;
if (strcmp(fromsec, ".data") != 0)
f1 = 0;
if (strncmp(atsym, "__param", strlen("__param")) != 0)
f1 = 0;
if (f1)
return f1;
/* Check for pattern 2 */
if ((strcmp(tosec, ".init.text") != 0) &&
(strcmp(tosec, ".exit.text") != 0))
f2 = 0;
if (strcmp(fromsec, ".data") != 0)
f2 = 0;
for (s = pat2sym; *s; s++)
if (strrcmp(atsym, *s) == 0)
f1 = 1;
return f1 && f2;
}
/**
* Find symbol based on relocation record info.
* In some cases the symbol supplied is a valid symbol so
@ -518,6 +601,7 @@ static void find_symbols_between(struct elf_info *elf, Elf_Addr addr,
/**
* Print a warning about a section mismatch.
* Try to find symbols near it so user can find it.
* Check whitelist before warning - it may be a false positive.
**/
static void warn_sec_mismatch(const char *modname, const char *fromsec,
struct elf_info *elf, Elf_Sym *sym, Elf_Rela r)
@ -536,6 +620,11 @@ static void warn_sec_mismatch(const char *modname, const char *fromsec,
refsym = find_elf_symbol(elf, r.r_addend, sym);
if (refsym && strlen(elf->strtab + refsym->st_name))
refsymname = elf->strtab + refsym->st_name;
/* check whitelist - we may ignore it */
if (before &&
secref_whitelist(secname, fromsec, elf->strtab + before->st_name))
return;
if (before && after) {
warn("%s - Section mismatch: reference to %s:%s from %s "