kbuild: Avoid inconsistent kallsyms data
Several reports on inconsistent kallsyms data has been caused by the aliased symbols
__sched_text_start and __down to shift places in the output of nm.
The root cause was that on second pass ld aligned __sched_text_start to a 4 byte boundary
which is the function alignment on i386.
sched.text and spinlock.text is now aligned to an 8 byte boundary to make sure they
are aligned to a function alignemnt on most (all?) archs.
Tested by: Paulo Marques <pmarques@grupopie.com>
Tested by: Alexander Stohr <Alexander.Stohr@gmx.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b3bb326..3fa9428 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -6,6 +6,9 @@
#define VMLINUX_SYMBOL(_sym_) _sym_
#endif
+/* Align . to a 8 byte boundary equals to maximum function alignment. */
+#define ALIGN_FUNCTION() . = ALIGN(8)
+
#define RODATA \
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
*(.rodata) *(.rodata.*) \
@@ -79,12 +82,18 @@
VMLINUX_SYMBOL(__security_initcall_end) = .; \
}
+/* sched.text is aling to function alignment to secure we have same
+ * address even at second ld pass when generating System.map */
#define SCHED_TEXT \
+ ALIGN_FUNCTION(); \
VMLINUX_SYMBOL(__sched_text_start) = .; \
*(.sched.text) \
VMLINUX_SYMBOL(__sched_text_end) = .;
+/* spinlock.text is aling to function alignment to secure we have same
+ * address even at second ld pass when generating System.map */
#define LOCK_TEXT \
+ ALIGN_FUNCTION(); \
VMLINUX_SYMBOL(__lock_text_start) = .; \
*(.spinlock.text) \
VMLINUX_SYMBOL(__lock_text_end) = .;