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>

7 files changed, 34 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index 40dd52d..af07003 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -86,6 +86,12 @@ int module_finalize(const Elf_Ehdr *hdr,
 				  (void *)sect->sh_addr + sect->sh_size);
 #endif
 
+	sect = find_section(hdr, sechdrs, "__lwsync_fixup");
+	if (sect != NULL)
+		do_lwsync_fixups(cur_cpu_spec->cpu_features,
+				 (void *)sect->sh_addr,
+				 (void *)sect->sh_addr + sect->sh_size);
+
 	return 0;
 }
 
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 9e83add..0109e7f 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -101,6 +101,10 @@ unsigned long __init early_init(unsigned long dt_ptr)
 			  PTRRELOC(&__start___ftr_fixup),
 			  PTRRELOC(&__stop___ftr_fixup));
 
+	do_lwsync_fixups(spec->cpu_features,
+			 PTRRELOC(&__start___lwsync_fixup),
+			 PTRRELOC(&__stop___lwsync_fixup));
+
 	return KERNELBASE + offset;
 }
 
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 098fd96..04d8de9 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -363,6 +363,8 @@ void __init setup_system(void)
 			  &__start___ftr_fixup, &__stop___ftr_fixup);
 	do_feature_fixups(powerpc_firmware_features,
 			  &__start___fw_ftr_fixup, &__stop___fw_ftr_fixup);
+	do_lwsync_fixups(cur_cpu_spec->cpu_features,
+			 &__start___lwsync_fixup, &__stop___lwsync_fixup);
 
 	/*
 	 * Unflatten the device-tree passed by prom_init or kexec
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index ce245a8..f177c60 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -571,6 +571,11 @@ static __init int vdso_fixup_features(struct lib32_elfinfo *v32,
 	if (start64)
 		do_feature_fixups(powerpc_firmware_features,
 				  start64, start64 + size64);
+
+	start64 = find_section64(v64->hdr, "__lwsync_fixup", &size64);
+	if (start64)
+		do_lwsync_fixups(cur_cpu_spec->cpu_features,
+				 start64, start64 + size64);
 #endif /* CONFIG_PPC64 */
 
 	start32 = find_section32(v32->hdr, "__ftr_fixup", &size32);
@@ -585,6 +590,11 @@ static __init int vdso_fixup_features(struct lib32_elfinfo *v32,
 				  start32, start32 + size32);
 #endif /* CONFIG_PPC64 */
 
+	start32 = find_section32(v32->hdr, "__lwsync_fixup", &size32);
+	if (start32)
+		do_lwsync_fixups(cur_cpu_spec->cpu_features,
+				 start32, start32 + size32);
+
 	return 0;
 }
 
diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S b/arch/powerpc/kernel/vdso32/vdso32.lds.S
index 2717935..be3b6a4 100644
--- a/arch/powerpc/kernel/vdso32/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S
@@ -33,6 +33,9 @@ SECTIONS
 	. = ALIGN(8);
 	__ftr_fixup	: { *(__ftr_fixup) }
 
+	. = ALIGN(8);
+	__lwsync_fixup	: { *(__lwsync_fixup) }
+
 #ifdef CONFIG_PPC64
 	. = ALIGN(8);
 	__fw_ftr_fixup	: { *(__fw_ftr_fixup) }
diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S b/arch/powerpc/kernel/vdso64/vdso64.lds.S
index e608d1b..d0b2526 100644
--- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
@@ -35,6 +35,9 @@ SECTIONS
 	__ftr_fixup	: { *(__ftr_fixup) }
 
 	. = ALIGN(8);
+	__lwsync_fixup	: { *(__lwsync_fixup) }
+
+	. = ALIGN(8);
 	__fw_ftr_fixup	: { *(__fw_ftr_fixup) }
 
 	/*
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 3c07811..6856f6c 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -127,6 +127,12 @@ SECTIONS
 		*(__ftr_fixup)
 		__stop___ftr_fixup = .;
 	}
+	. = ALIGN(8);
+	__lwsync_fixup : AT(ADDR(__lwsync_fixup) - LOAD_OFFSET) {
+		__start___lwsync_fixup = .;
+		*(__lwsync_fixup)
+		__stop___lwsync_fixup = .;
+	}
 #ifdef CONFIG_PPC64
 	. = ALIGN(8);
 	__fw_ftr_fixup : AT(ADDR(__fw_ftr_fixup) - LOAD_OFFSET) {