[U-Boot] [PATCH] Revert "armv8: release slave cores from CPU_RELEASE_ADDR"

[Masahiro Yamada]

This reverts commit 8c36e99f211104fd7dcbf0669a35a47ce5e154f5.

There is misunderstanding in commit 8c36e99f2111 ("armv8: release
slave cores from CPU_RELEASE_ADDR").  How to bring the slave cores
into U-Boot proper is platform-specific.  So, it should be cared
in SoC/board files instead of common/spl/spl.c.  As you see SPL
is the acronym of Secondary Program Loader, there is generally
something that runs before SPL (the First one is usually Boot ROM).

How to wake up slave cores from the Boot ROM is really SoC specific.
So, the intention for the spin table support is to bring the slave
cores into U-Boot proper in an SoC specific manner.  (this must be
done after relocation.  see below.)

If you bring the slaves into SPL, it is SoC own code responsibility
to transfer them to U-Boot proper.  The Spin Table defines the
interface between a boot-loader and Linux kernel.  It is unrelated
to the interface between SPL and U-Boot proper.

One more thing is missing in the commit; spl_image->entry_point
points to the entry address of U-Boot *before* relocation.  U-Boot
relocates itself between board_init_f() and board_init_r().  This
means the master CPU sees the different copy of the spin code than
the slave CPUs enter.  The spin_table_update_dt() protects the code
*after* relocation.  As a result, the slave CPUs spin in unprotected
code, which leads to unstable behavior.

Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
---

 common/spl/spl.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/common/spl/spl.c b/common/spl/spl.c
index 8fb8da4..d3a4ff6 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -167,14 +167,6 @@ __weak void __noreturn jump_to_image_no_args(struct spl_image_info *spl_image)
 		(image_entry_noargs_t)spl_image->entry_point;
 
 	debug("image entry point: 0x%lX\n", spl_image->entry_point);
-#if defined(CONFIG_ARMV8_SPIN_TABLE) && defined(CONFIG_ARMV8_MULTIENTRY)
-	/*
-	 * Release all slave cores from CPU_RELEASE_ADDR so they could
-	 * arrive to the spin-table code in start.S of the u-boot
-	 */
-	*(ulong *)CPU_RELEASE_ADDR = (ulong)spl_image->entry_point;
-#endif
-
 	image_entry();
 }
 
-- 
2.7.4