[U-Boot] [RFC PATCH 07/11] riscv: support SPL stack and global data relocation

[Lukas Auer]

To support relocation of the stack and global data on RISC-V, the
secondary harts must be notified of the change using IPIs. We can reuse
the hart relocation code for this purpose. It uses global data to store
the new stack pointer and global data pointer for the secondary harts.
This means that we cannot update the global data pointer of the main
hart in spl_relocate_stack_gd(), because the secondary harts have not
yet been relocated at this point. It is updated after the secondary
harts have been notified.

Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
---

 arch/riscv/cpu/start.S | 35 ++++++++++++++++++++++++++++++++++-
 common/spl/spl.c       |  2 +-
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
index e053197645..e8c65c887a 100644
--- a/arch/riscv/cpu/start.S
+++ b/arch/riscv/cpu/start.S
@@ -170,13 +170,46 @@ wait_for_gd_init:
 spl_clear_bss:
 	la	t0, __bss_start
 	la	t1, __bss_end
-	beq	t0, t1, spl_call_board_init_r
+	beq	t0, t1, spl_stack_gd_setup
 
 spl_clear_bss_loop:
 	SREG	zero, 0(t0)
 	addi	t0, t0, REGBYTES
 	bne	t0, t1, spl_clear_bss_loop
 
+spl_stack_gd_setup:
+	jal	spl_relocate_stack_gd
+
+	/* skip setup if we did not relocate */
+	beqz	a0, spl_call_board_init_r
+	mv	s0, a0
+
+	/* setup stack on main hart */
+#ifdef CONFIG_SMP
+	/* tp: hart id */
+	slli	t0, tp, CONFIG_STACK_SIZE_SHIFT
+	sub	sp, s0, t0
+#else
+	mv	sp, s0
+#endif
+
+	/* set new stack and global data pointer on secondary harts */
+spl_secondary_hart_stack_gd_setup:
+	la	a0, secondary_hart_relocate
+	mv	a1, s0
+	mv	a2, s0
+	jal	smp_call_function
+
+	/* hang if relocation of secondary harts has failed */
+	beqz	a0, 1f
+	mv	a1, a0
+	la	a0, secondary_harts_relocation_error
+	jal	printf
+	jal	hang
+
+	/* set new global data pointer on main hart */
+1:	mv	gp, s0
+
 spl_call_board_init_r:
 	mv	a0, zero
 	mv	a1, zero
diff --git a/common/spl/spl.c b/common/spl/spl.c
index 1ed4741bdc..834f39908b 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -756,7 +756,7 @@ ulong spl_relocate_stack_gd(void)
 #if CONFIG_IS_ENABLED(DM)
 	dm_fixup_for_gd_move(new_gd);
 #endif
-#if !defined(CONFIG_ARM)
+#if !defined(CONFIG_ARM) && !defined(CONFIG_RISCV)
 	gd = new_gd;
 #endif
 	return ptr;
-- 
2.21.0