powerpc: Fixup lwsync at runtime

To allow for a single kernel image on e500 v1/v2/mc we need to fixup lwsync
at runtime.  On e500v1/v2 lwsync causes an illop so we need to patch up
the code.  We default to 'sync' since that is always safe and if the cpu
is capable we will replace 'sync' with 'lwsync'.

We introduce CPU_FTR_LWSYNC as a way to determine at runtime if this is
needed.  This flag could be moved elsewhere since we dont really use it
for the normal CPU_FTR purpose.

Finally we only store the relative offset in the fixup section to keep it
as small as possible rather than using a full fixup_entry.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/asm-powerpc/feature-fixups.h b/include/asm-powerpc/feature-fixups.h
index ab30129dced7..a1029967620b 100644
--- a/include/asm-powerpc/feature-fixups.h
+++ b/include/asm-powerpc/feature-fixups.h
@@ -113,4 +113,14 @@ label##5:					       	\
 
 #endif /* __ASSEMBLY__ */
 
+/* LWSYNC feature sections */
+#define START_LWSYNC_SECTION(label)     label##1:
+#define MAKE_LWSYNC_SECTION_ENTRY(label, sect)          \
+label##2:                                               \
+        .pushsection sect,"a";                          \
+        .align 2;                                       \
+label##3:                                               \
+        .long label##1b-label##3b;                      \
+        .popsection;
+
 #endif /* __ASM_POWERPC_FEATURE_FIXUPS_H */