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Message-ID: <38183c29-9b7f-4960-8702-d71ce816cf80@p183>
Date: Sat, 2 Dec 2023 15:45:13 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: Willy Tarreau <w@....eu>,
Thomas Weißschuh <linux@...ssschuh.net>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] nolibc: optimise _start() on x86_64
Just jump into _start_c, it is not going to return anyway.
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
Also, kernel clears all registers before starting process,
I'm not sure why
xor ebp, ebp
was added.
tools/include/nolibc/arch-x86_64.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -167,8 +167,7 @@ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_
"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 */
+ "jmp _start_c\n" /* transfer to c runtime */
);
__builtin_unreachable();
}
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