lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-Id: <20211024174323.18338-3-w@1wt.eu> Date: Sun, 24 Oct 2021 19:43:22 +0200 From: Willy Tarreau <w@....eu> To: "Paul E . McKenney" <paulmck@...nel.org> Cc: Ammar Faizi <ammar.faizi@...dents.amikom.ac.id>, linux-kernel@...r.kernel.org Subject: [PATCH 2/3] tools/nolibc: x86-64: Use `mov $60,%eax` instead of `mov $60,%rax` From: Ammar Faizi <ammar.faizi@...dents.amikom.ac.id> Note that mov to 32-bit register will zero extend to 64-bit register. Thus `mov $60,%eax` has the same effect with `mov $60,%rax`. Use the shorter opcode to achieve the same thing. ``` b8 3c 00 00 00 mov $60,%eax (5 bytes) [1] 48 c7 c0 3c 00 00 00 mov $60,%rax (7 bytes) [2] ``` Currently, we use [2]. Change it to [1] for shorter code. Signed-off-by: Ammar Faizi <ammar.faizi@...dents.amikom.ac.id> Signed-off-by: Willy Tarreau <w@....eu> --- tools/include/nolibc/nolibc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h index f9afe89ec6f2..4988866af0b5 100644 --- a/tools/include/nolibc/nolibc.h +++ b/tools/include/nolibc/nolibc.h @@ -420,7 +420,7 @@ asm(".section .text\n" "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, %rax\n" // NR_exit == 60 + "mov $60, %eax\n" // NR_exit == 60 "syscall\n" // really exit "hlt\n" // ensure it does not return ""); -- 2.17.5
Powered by blists - more mailing lists