aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorPaul Gortmaker <paul.gortmaker@windriver.com>2015-04-20 10:20:40 +0930
committerRusty Russell <rusty@rustcorp.com.au>2015-04-22 17:31:34 +0930
commit4a3893d069b788f3570c19c12d9e986e8e15870f (patch)
treef2b4c93e1239befe1acc257b683bbba6c1ef8ff1
parent09c20c032b0f753969ae778d9783d946f054d7fe (diff)
downloadlinux-linaro-stable-4a3893d069b788f3570c19c12d9e986e8e15870f.tar.gz
modpost: don't emit section mismatch warnings for compiler optimizations
Currently an allyesconfig build [gcc-4.9.1] can generate the following: WARNING: vmlinux.o(.text.unlikely+0x3864): Section mismatch in reference from the function cpumask_empty.constprop.3() to the variable .init.data:nmi_ipi_mask which comes from the cpumask_empty usage in arch/x86/kernel/nmi_selftest.c. Normally we would not see a symbol entry for cpumask_empty since it is: static inline bool cpumask_empty(const struct cpumask *srcp) however in this case, the variant of the symbol gets emitted when GCC does constant propagation optimization. Fix things up so that any locally optimized constprop variants don't warn when accessing variables that live in the __init sections. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--scripts/mod/modpost.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 1c2101bf63d2..91ee1b2e0f9a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -908,6 +908,9 @@ static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL };
static const char *const init_exit_sections[] =
{ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL };
+/* all text sections */
+static const char *const text_sections[] = { ALL_TEXT_SECTIONS, NULL };
+
/* data section */
static const char *const data_sections[] = { DATA_SECTIONS, NULL };
@@ -926,6 +929,7 @@ static const char *const data_sections[] = { DATA_SECTIONS, NULL };
static const char *const head_sections[] = { ".head.text*", NULL };
static const char *const linker_symbols[] =
{ "__init_begin", "_sinittext", "_einittext", NULL };
+static const char *const optim_symbols[] = { "*.constprop.*", NULL };
enum mismatch {
TEXT_TO_ANY_INIT,
@@ -1136,6 +1140,17 @@ static const struct sectioncheck *section_mismatch(
* This pattern is identified by
* refsymname = __init_begin, _sinittext, _einittext
*
+ * Pattern 5:
+ * GCC may optimize static inlines when fed constant arg(s) resulting
+ * in functions like cpumask_empty() -- generating an associated symbol
+ * cpumask_empty.constprop.3 that appears in the audit. If the const that
+ * is passed in comes from __init, like say nmi_ipi_mask, we get a
+ * meaningless section warning. May need to add isra symbols too...
+ * This pattern is identified by
+ * tosec = init section
+ * fromsec = text section
+ * refsymname = *.constprop.*
+ *
**/
static int secref_whitelist(const struct sectioncheck *mismatch,
const char *fromsec, const char *fromsym,
@@ -1168,6 +1183,12 @@ static int secref_whitelist(const struct sectioncheck *mismatch,
if (match(tosym, linker_symbols))
return 0;
+ /* Check for pattern 5 */
+ if (match(fromsec, text_sections) &&
+ match(tosec, init_sections) &&
+ match(fromsym, optim_symbols))
+ return 0;
+
return 1;
}