[PATCH v8 4/8] arm: armv7: save boot arguments

[Raymond Mao]

Save boot arguments r[0-3] into an array for handover of bloblist from
previous boot stage.

Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
Suggested-by: Ard Biesheuvel <ardb at kernel.org>
---
Changes in v2
- New patch file created for v2.
Changes in v3
- Swap value of r0 with r2.
Changes in v4
- Fix a bug when saving the boot args.
Changes in V5
- Drop the dependence on OF_BOARD.
Changes in V7
- Exclude the saved_args when BLOBLIST is disabled.
Changes in V8
- Use PC-relative reference for saved_args.
- Add 4-byte alignment for saved_args.

 arch/arm/cpu/armv7/start.S | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 69e281b086..7730a16e51 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -152,9 +152,38 @@ ENDPROC(c_runtime_cpu_setup)
  *
  *************************************************************************/
 WEAK(save_boot_params)
+#if (IS_ENABLED(CONFIG_BLOBLIST))
+	/* Calculate the PC-relative address of saved_args */
+	adr	r12, saved_args_offset
+	ldr	r13, saved_args_offset
+	add	r12, r12, r13
+
+	/*
+	 * Intentionally swapping r0 with r2 in order to simplify the C
+	 * function we use later.
+	 */
+	str	r2, [r12]
+	str	r1, [r12, #4]
+	str	r0, [r12, #8]
+	str	r3, [r12, #12]
+#endif
 	b	save_boot_params_ret		@ back to my caller
 ENDPROC(save_boot_params)
 
+#if (IS_ENABLED(CONFIG_BLOBLIST))
+saved_args_offset:
+	.long	saved_args - .	/* offset from current code to save_args */
+
+	.section .data
+	.align 2
+	.global saved_args
+saved_args:
+	.rept 4
+	.word 0
+	.endr
+END(saved_args)
+#endif
+
 #ifdef CONFIG_ARMV7_LPAE
 WEAK(switch_to_hypervisor)
 	b	switch_to_hypervisor_ret
-- 
2.25.1