From: Zhangjin Wu <falcon@tinylab.org>
To: w@1wt.eu
Cc: falcon@tinylab.org, arnd@arndb.de, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, thomas@t-8ch.de
Subject: [PATCH v3 06/11] tools/nolibc: x86_64: shrink _start with _start_c
Date: Wed, 12 Jul 2023 17:22:00 +0800 [thread overview]
Message-ID: <8bdc96799300a5c5a40320d4f66ad54e97b4b9de.1689150149.git.falcon@tinylab.org> (raw)
In-Reply-To: <cover.1689150149.git.falcon@tinylab.org>
move most of the _start operations to _start_c().
Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
---
tools/include/nolibc/arch-x86_64.h | 28 +++++++---------------------
1 file changed, 7 insertions(+), 21 deletions(-)
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index e980ca5417d0..0048adf6b11f 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -8,6 +8,7 @@
#define _NOLIBC_ARCH_X86_64_H
#include "compiler.h"
+#include "crt.h"
/* Syscalls for x86_64 :
* - registers are 64-bit
@@ -153,9 +154,6 @@
_ret; \
})
-char **environ __attribute__((weak));
-const unsigned long *_auxv __attribute__((weak));
-
/* startup code */
/*
* x86-64 System V ABI mandates:
@@ -167,25 +165,13 @@ void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __no_stack_pr
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
- "call __stack_chk_init\n" /* initialize stack protector */
+ "call __stack_chk_init\n" /* initialize stack protector */
#endif
- "pop %rdi\n" /* argc (first arg, %rdi) */
- "mov %rsp, %rsi\n" /* argv[] (second arg, %rsi) */
- "lea 8(%rsi,%rdi,8),%rdx\n" /* then a NULL then envp (third arg, %rdx) */
- "mov %rdx, environ\n" /* save environ */
- "xor %ebp, %ebp\n" /* zero the stack frame */
- "mov %rdx, %rax\n" /* search for auxv (follows NULL after last env) */
- "0:\n"
- "add $8, %rax\n" /* search for auxv using rax, it follows the */
- "cmp -8(%rax), %rbp\n" /* ... NULL after last env (rbp is zero here) */
- "jnz 0b\n"
- "mov %rax, _auxv\n" /* save it into _auxv */
- "and $-16, %rsp\n" /* x86 ABI : esp must be 16-byte aligned before call */
- "call main\n" /* main() returns the status code, we'll exit with it. */
- "mov %eax, %edi\n" /* retrieve exit code (32 bit) */
- "mov $60, %eax\n" /* NR_exit == 60 */
- "syscall\n" /* really exit */
- "hlt\n" /* ensure it does not return */
+ "xor %ebp, %ebp\n" /* zero the stack frame */
+ "mov %rsp, %rdi\n" /* save stack pointer to %rdi, as arg1 of _start_c */
+ "and $-16, %rsp\n" /* %rsp must be 16-byte aligned before call */
+ "call _start_c\n" /* transfer to c runtime */
+ "hlt\n" /* ensure it does not return */
);
__builtin_unreachable();
}
--
2.25.1
next prev parent reply other threads:[~2023-07-12 9:28 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-12 9:15 [PATCH v3 00/11] tools/nolibc: shrink arch support Zhangjin Wu
2023-07-12 9:16 ` [PATCH v3 01/11] tools/nolibc: remove the old sys_stat support Zhangjin Wu
2023-07-15 8:59 ` Willy Tarreau
2023-07-15 10:39 ` Zhangjin Wu
2023-07-15 11:45 ` Willy Tarreau
2023-07-12 9:17 ` [PATCH v3 02/11] tools/nolibc: add new crt.h with _start_c Zhangjin Wu
2023-07-12 20:39 ` Thomas Weißschuh
2023-07-13 6:12 ` Zhangjin Wu
2023-07-13 6:23 ` Zhangjin Wu
2023-07-13 6:24 ` Thomas Weißschuh
2023-07-13 6:34 ` Willy Tarreau
2023-07-14 5:58 ` Zhangjin Wu
2023-07-14 6:34 ` Thomas Weißschuh
2023-07-14 9:47 ` Zhangjin Wu
2023-07-15 7:24 ` Thomas Weißschuh
2023-07-15 9:23 ` Zhangjin Wu
2023-07-15 9:57 ` Willy Tarreau
2023-07-12 9:18 ` [PATCH v3 03/11] tools/nolibc: arm: shrink _start " Zhangjin Wu
2023-07-12 9:19 ` [PATCH v3 04/11] tools/nolibc: aarch64: " Zhangjin Wu
2023-07-12 9:20 ` [PATCH v3 05/11] tools/nolibc: i386: " Zhangjin Wu
2023-07-12 9:22 ` Zhangjin Wu [this message]
2023-07-12 9:23 ` [PATCH v3 07/11] tools/nolibc: mips: " Zhangjin Wu
2023-07-12 9:24 ` [PATCH v3 08/11] tools/nolibc: loongarch: " Zhangjin Wu
2023-07-12 9:25 ` [PATCH v3 09/11] tools/nolibc: riscv: " Zhangjin Wu
2023-07-12 9:26 ` [PATCH v3 10/11] tools/nolibc: s390: " Zhangjin Wu
2023-07-12 9:27 ` [PATCH v3 11/11] tools/nolibc: arch-*.h: add missing space after ',' Zhangjin Wu
2023-07-15 10:01 ` [PATCH v3 00/11] tools/nolibc: shrink arch support Willy Tarreau
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