Re: [PATCH v2] powerpc/64: option to force run-at-load to test relocation

[Balbir Singh]

On 14/10/16 18:31, Nicholas Piggin wrote:
> This adds a config option that can help exercise the case when
> the kernel is not running at PAGE_OFFSET.
> 
> Signed-off-by: Nicholas Piggin 
> ---

Reviewed-by: Balbir Singh 

[PATCH v2] powerpc/64: option to force run-at-load to test relocation

[Nicholas Piggin]

This adds a config option that can help exercise the case when
the kernel is not running at PAGE_OFFSET.

Signed-off-by: Nicholas Piggin 
---
Changes since v1:
- Improved style as suggested by Balbir and Michael

 arch/powerpc/Kconfig  | 9 +
 arch/powerpc/kernel/head_64.S | 8 +++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 65fba4c..5d43cb8 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -478,6 +478,15 @@ config RELOCATABLE
  setting can still be useful to bootwrappers that need to know the
  load address of the kernel (eg. u-boot/mkimage).
 
+config RELOCATABLE_TEST
+   bool "Test relocatable kernel"
+   depends on (PPC64 && RELOCATABLE)
+   default n
+   help
+ This runs the relocatable kernel at the address it was initially
+ loaded at, which tends to be non-zero and therefore test the
+ relocation code.
+
 config CRASH_DUMP
bool "Build a kdump crash kernel"
depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 79da0641..a0aaced 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -107,11 +107,17 @@ __secondary_hold_acknowledge:
 * observing the alignment requirement.
 */
/* Do not move this variable as kexec-tools knows about it. */
+#ifdef CONFIG_RELOCATABLE_TEST
+#define RUN_AT_LOAD_DEFAULT 1  /* Test relocation, do not copy to 0 */
+#else
+#define RUN_AT_LOAD_DEFAULT 0x72756e30  /* "run0" -- relocate to 0 by default 
*/
+#endif
+
. = 0x5c
.globl  __run_at_load
 __run_at_load:
 DEFINE_FIXED_SYMBOL(__run_at_load)
-   .long   0x72756e30  /* "run0" -- relocate to 0 by default */
+   .long   RUN_AT_LOAD_DEFAULT
 #endif
 
. = 0x60
-- 
2.9.3