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Date: Sat, 21 May 2016 12:04:48 -0400 From: Brian Gerst <brgerst@...il.com> To: x86@...nel.org, linux-kernel@...r.kernel.org Cc: Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>, Denys Vlasenko <dvlasenk@...hat.com>, Andy Lutomirski <luto@...capital.net>, Borislav Petkov <bp@...e.de>, Thomas Gleixner <tglx@...utronix.de> Subject: [PATCH 1/4] x86: Save return value from kernel_thread Kernel threads should always return zero on success after calling do_execve(). The two existing cases in the kernel (kernel_init() and call_usermodehelper_exec_async()) correctly do this. Save a few bytes by storing EAX/RAX instead of an immediate zero. Also fix the 64-bit case which should save the full 64-bits. Signed-off-by: Brian Gerst <brgerst@...il.com> --- arch/x86/entry/entry_32.S | 2 +- arch/x86/entry/entry_64.S | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 983e5d3..ee6fea0 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -221,7 +221,7 @@ ENTRY(ret_from_kernel_thread) popl %eax movl PT_EBP(%esp), %eax call *PT_EBX(%esp) - movl $0, PT_EAX(%esp) + movl %eax, PT_EAX(%esp) /* * Kernel threads return to userspace as if returning from a syscall. diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 9ee0da1..ab9f8c8 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -387,7 +387,7 @@ ENTRY(ret_from_fork) */ movq RBP(%rsp), %rdi call *RBX(%rsp) - movl $0, RAX(%rsp) + movq %rax, RAX(%rsp) /* * Fall through as though we're exiting a syscall. This makes a -- 2.5.5
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