mirror of https://lore.kernel.org/lkml/
 help / color / mirror / Atom feed
From: Alexey Dobriyan <adobriyan@gmail.com>
To: "Willy Tarreau" <w@1wt.eu>, "Thomas Weißschuh" <linux@weissschuh.net>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] nolibc: optimise _start() on x86_64
Date: Sat, 2 Dec 2023 15:45:13 +0300	[thread overview]
Message-ID: <38183c29-9b7f-4960-8702-d71ce816cf80@p183> (raw)

Just jump into _start_c, it is not going to return anyway.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.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();
 }

             reply	other threads:[~2023-12-02 12:45 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-02 12:45 Alexey Dobriyan [this message]
2023-12-02 13:23 ` Willy Tarreau
2023-12-03 12:00   ` Alexey Dobriyan
2023-12-03 21:37     ` Willy Tarreau

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=38183c29-9b7f-4960-8702-d71ce816cf80@p183 \
    --to=adobriyan@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@weissschuh.net \
    --cc=w@1wt.eu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox

all inboxes | Powered by JetHome®