[RFC PATCH v2 2/8] tools/nolibc: Remove .global _start from the entry point code

Ammar Faizi
2022-03-22T10:21:41Z

Building with clang yields the following error:
```
<inline asm>:3:1: error: _start changed binding to STB_GLOBAL
.global _start
^
1 error generated.
```
Make sure only specify one between `.global _start` and `.weak _start`.
Removing `.global _start`.

Cc: llvm@lists.linux.dev
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---

@@ Changelog:

Link RFC v1: https://lore.kernel.org/llvm/20220320093750.159991-3-ammarfaizi2@gnuweeb.org
RFC v1 -> RFC v2:
- Remove all `.global _start` for all build (GCC and Clang) instead of
removing all `.weak _start` for clang build (Comment from Willy).
---
tools/include/nolibc/arch-aarch64.h | 1 -
tools/include/nolibc/arch-arm.h | 1 -
tools/include/nolibc/arch-i386.h | 1 -
tools/include/nolibc/arch-mips.h | 1 -
tools/include/nolibc/arch-riscv.h | 1 -
tools/include/nolibc/arch-x86_64.h | 1 -
6 files changed, 6 deletions(-)

diff --git a/tools/include/nolibc/arch-aarch64.h b/tools/include/nolibc/arch-aarch64.h
index 87d9e434820c..2dbd80d633cb 100644
--- a/tools/include/nolibc/arch-aarch64.h
+++ b/tools/include/nolibc/arch-aarch64.h
@@ -184,7 +184,6 @@ struct sys_stat_struct {
/* startup code */
asm(".section .text\n"
".weak _start\n"
- ".global _start\n"
"_start:\n"
"ldr x0, [sp]\n" // argc (x0) was in the stack
"add x1, sp, 8\n" // argv (x1) = sp
diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-arm.h
index 001a3c8c9ad5..1191395b5acd 100644
--- a/tools/include/nolibc/arch-arm.h
+++ b/tools/include/nolibc/arch-arm.h
@@ -177,7 +177,6 @@ struct sys_stat_struct {
/* startup code */
asm(".section .text\n"
".weak _start\n"
- ".global _start\n"
"_start:\n"
#if defined(__THUMBEB__) || defined(__THUMBEL__)
/* We enter here in 32-bit mode but if some previous functions were in
diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i386.h
index d7e4d53325a3..125a691fc631 100644
--- a/tools/include/nolibc/arch-i386.h
+++ b/tools/include/nolibc/arch-i386.h
@@ -176,7 +176,6 @@ struct sys_stat_struct {
*/
asm(".section .text\n"
".weak _start\n"
- ".global _start\n"
"_start:\n"
"pop %eax\n" // argc (first arg, %eax)
"mov %esp, %ebx\n" // argv[] (second arg, %ebx)
diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h
index c9a6aac87c6d..1a124790c99f 100644
--- a/tools/include/nolibc/arch-mips.h
+++ b/tools/include/nolibc/arch-mips.h
@@ -192,7 +192,6 @@ struct sys_stat_struct {
asm(".section .text\n"
".weak __start\n"
".set nomips16\n"
- ".global __start\n"
".set noreorder\n"
".option pic0\n"
".ent __start\n"
diff --git a/tools/include/nolibc/arch-riscv.h b/tools/include/nolibc/arch-riscv.h
index bc10b7b5706d..511d67fc534e 100644
--- a/tools/include/nolibc/arch-riscv.h
+++ b/tools/include/nolibc/arch-riscv.h
@@ -185,7 +185,6 @@ struct sys_stat_struct {
/* startup code */
asm(".section .text\n"
".weak _start\n"
- ".global _start\n"
"_start:\n"
".option push\n"
".option norelax\n"
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index a7b70ea51b68..84c174181425 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -199,7 +199,6 @@ struct sys_stat_struct {
*/
asm(".section .text\n"
".weak _start\n"
- ".global _start\n"
"_start:\n"
"pop %rdi\n" // argc (first arg, %rdi)
"mov %rsp, %rsi\n" // argv[] (second arg, %rsi)
--
Ammar Faizi