[PATCH v2 11/15] arm: riscv: efi: Export _start symbol from crt0_*_efi stubs

[Sam Edwards <cfsworks@gmail.com>]

While the _start label is only intended for use locally to populate the
(hand-written) PE header, the linker script includes ENTRY(_start) which
designates it as the entry point in the output ELF, resulting in linker
warnings under some linkers (e.g. LLVM's lld) due to _start not being a
globally-visible symbol. Since  ELF is only an intermediary build
format, and the aforementioned PE header correctly points to _start, the
ENTRY(_start) directive could easily be removed to silence this warning.

However, since some developers who are debugging EFI by analyzing the
intermediary ELF may appreciate having correct entry-point information,
this patch instead promotes the _start labels to global symbols,
silencing the linker warning and making the intermediary ELF reflect the
true entry point.

This patch doesn't affect the final output binaries in any way.

Signed-off-by: Sam Edwards <CFSworks@gmail.com>
---
 arch/arm/lib/crt0_aarch64_efi.S | 1 +
 arch/arm/lib/crt0_arm_efi.S     | 1 +
 arch/riscv/lib/crt0_riscv_efi.S | 1 +
 3 files changed, 3 insertions(+)

diff --git a/arch/arm/lib/crt0_aarch64_efi.S b/arch/arm/lib/crt0_aarch64_efi.S
index e21b54fdbcb..003d5f83041 100644
--- a/arch/arm/lib/crt0_aarch64_efi.S
+++ b/arch/arm/lib/crt0_aarch64_efi.S
@@ -144,6 +144,7 @@ section_table:
 		 IMAGE_SCN_CNT_INITIALIZED_DATA)
 
 	.align		12
+	.globl		_start
 _start:
 	stp		x29, x30, [sp, #-32]!
 	mov		x29, sp
diff --git a/arch/arm/lib/crt0_arm_efi.S b/arch/arm/lib/crt0_arm_efi.S
index 235b3a0c48f..593ee1e194a 100644
--- a/arch/arm/lib/crt0_arm_efi.S
+++ b/arch/arm/lib/crt0_arm_efi.S
@@ -143,6 +143,7 @@ section_table:
 		 IMAGE_SCN_CNT_INITIALIZED_DATA)
 
 	.align		12
+	.globl		_start
 _start:
 	stmfd		sp!, {r0-r2, lr}
 
diff --git a/arch/riscv/lib/crt0_riscv_efi.S b/arch/riscv/lib/crt0_riscv_efi.S
index 9eacbe4a859..f170e4b26d6 100644
--- a/arch/riscv/lib/crt0_riscv_efi.S
+++ b/arch/riscv/lib/crt0_riscv_efi.S
@@ -179,6 +179,7 @@ section_table:
 		 IMAGE_SCN_CNT_INITIALIZED_DATA)
 
 	.align		12
+	.globl		_start
 _start:
 	addi		sp, sp, -(SIZE_LONG * 3)
 	SAVE_LONG(a0, 0)
-- 
2.48.1