[BOOT-WRAPPER v2 08/10] Simplify spin logic

[Mark Rutland]

The logic for initial boot is more complicated than it needs to be,
with both first_spin() having a special case for CPU0 that requires an
additional argument to be passed to spin().

Simplify this by moving the special-case logic for CPU0 into
first_spin(). This removes the need to provide a dummy mailbox for CPU0
to spin on, simplfiies callers of first_spin() and spin(), which no
longer need to pass a dummy mailbox or 'is_entry' for CPU0.

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Acked-by: Marc Zyngier <maz at kernel.org>
Cc: Akos Denke <akos.denke at arm.com>
Cc: Andre Przywara <andre.przywara at arm.com>
Cc: Luca Fancellu <luca.fancellu at arm.com>
---
 arch/aarch64/spin.S | 11 +----------
 common/boot.c       | 20 ++++++++------------
 common/psci.c       |  2 +-
 include/boot.h      |  2 +-
 4 files changed, 11 insertions(+), 24 deletions(-)

diff --git a/arch/aarch64/spin.S b/arch/aarch64/spin.S
index 375f732..a7879d4 100644
--- a/arch/aarch64/spin.S
+++ b/arch/aarch64/spin.S
@@ -23,15 +23,6 @@ ASM_FUNC(start_bootmethod)
 	 * Primary CPU (x0 = 0) jumps to kernel, the other ones wait for an
 	 * address to appear in mbox
 	 */
-	adr	x3, mbox
-	adr	x4, kernel_address
-	cmp	x0, #0
-	csel	x1, x3, x4, ne
+	adr	x1, mbox
 	mov	x2, #0
 	bl	first_spin
-
-	.align 3
-kernel_address:
-	.long 0
-
-	.ltorg
diff --git a/common/boot.c b/common/boot.c
index 29d53a4..4417649 100644
--- a/common/boot.c
+++ b/common/boot.c
@@ -27,7 +27,7 @@ const unsigned long id_table[] = { CPU_IDS };
  * @invalid: value of an invalid address, 0 or -1 depending on the boot method
  * @is_entry: when true, pass boot parameters to the kernel, instead of 0
  */
-void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry)
+void __noreturn spin(unsigned long *mbox, unsigned long invalid)
 {
 	unsigned long addr = invalid;
 
@@ -36,13 +36,6 @@ void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry)
 		addr = *mbox;
 	}
 
-	if (is_entry)
-#ifdef KERNEL_32
-		jump_kernel(addr, 0, ~0, (unsigned long)&dtb, 0);
-#else
-		jump_kernel(addr, (unsigned long)&dtb, 0, 0, 0);
-#endif
-
 	jump_kernel(addr, 0, 0, 0, 0);
 
 	unreachable();
@@ -60,12 +53,15 @@ void __noreturn first_spin(unsigned int cpu, unsigned long *mbox,
 			   unsigned long invalid)
 {
 	if (cpu == 0) {
-		*mbox = (unsigned long)&entrypoint;
-		sevl();
-		spin(mbox, invalid, 1);
+		unsigned long addr = (unsigned long)&entrypoint;
+#ifdef KERNEL_32
+		jump_kernel(addr, 0, ~0, (unsigned long)&dtb, 0);
+#else
+		jump_kernel(addr, (unsigned long)&dtb, 0, 0, 0);
+#endif
 	} else {
 		*mbox = invalid;
-		spin(mbox, invalid, 0);
+		spin(mbox, invalid);
 	}
 
 	unreachable();
diff --git a/common/psci.c b/common/psci.c
index 5ae4255..19cc315 100644
--- a/common/psci.c
+++ b/common/psci.c
@@ -57,7 +57,7 @@ static int psci_cpu_off(void)
 
 	branch_table[cpu] = PSCI_ADDR_INVALID;
 
-	spin(branch_table + cpu, PSCI_ADDR_INVALID, 0);
+	spin(branch_table + cpu, PSCI_ADDR_INVALID);
 
 	unreachable();
 }
diff --git a/include/boot.h b/include/boot.h
index 459d1d5..18b805d 100644
--- a/include/boot.h
+++ b/include/boot.h
@@ -12,7 +12,7 @@
 #include <compiler.h>
 #include <stdbool.h>
 
-void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry);
+void __noreturn spin(unsigned long *mbox, unsigned long invalid);
 
 void __noreturn first_spin(unsigned int cpu, unsigned long *mbox,
 			   unsigned long invalid_addr);
-- 
2.30.2