linux-kernel - Re: [PATCH 4/5] x86/syscall/x32: Move x32 syscall table

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Message-ID: <a30872ce-3acf-4d6a-8d96-c073c6f33895@intel.com>
Date: Thu, 13 Mar 2025 16:47:51 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: Brian Gerst <brgerst@...il.com>, <linux-kernel@...r.kernel.org>,
	<x86@...nel.org>
CC: Ingo Molnar <mingo@...nel.org>, "H . Peter Anvin" <hpa@...or.com>, "Thomas
 Gleixner" <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>, "Andy
 Lutomirski" <luto@...nel.org>, Juergen Gross <jgross@...e.com>, "Boris
 Ostrovsky" <boris.ostrovsky@...cle.com>
Subject: Re: [PATCH 4/5] x86/syscall/x32: Move x32 syscall table

On 3/13/2025 11:22 AM, Brian Gerst wrote:
> Since commit:
> 
>   2e958a8a510d ("x86/entry/x32: Rename __x32_compat_sys_* to
> 		 __x64_compat_sys_*"),
> 
> the ABI prefix for x32 syscalls is the same as native 64-bit
> syscalls.  Move the x32 syscall table to syscall_64.c
> 
> No functional changes.
> 
> Signed-off-by: Brian Gerst <brgerst@...il.com>
> ---
>  arch/x86/entry/Makefile      |  1 -
>  arch/x86/entry/syscall_64.c  | 13 +++++++++++++
>  arch/x86/entry/syscall_x32.c | 25 -------------------------
>  3 files changed, 13 insertions(+), 26 deletions(-)
>  delete mode 100644 arch/x86/entry/syscall_x32.c
> 
> diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile
> index 5fd28abfd5a0..e870f8aa936c 100644
> --- a/arch/x86/entry/Makefile
> +++ b/arch/x86/entry/Makefile
> @@ -27,4 +27,3 @@ CFLAGS_REMOVE_entry_fred.o	+= -pg $(CC_FLAGS_FTRACE)
>  obj-$(CONFIG_X86_FRED)		+= entry_64_fred.o entry_fred.o
>  
>  obj-$(CONFIG_IA32_EMULATION)	+= entry_64_compat.o syscall_32.o
> -obj-$(CONFIG_X86_X32_ABI)	+= syscall_x32.o
> diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
> index 9e0ba339013c..b96f5621a2aa 100644
> --- a/arch/x86/entry/syscall_64.c
> +++ b/arch/x86/entry/syscall_64.c
> @@ -19,6 +19,9 @@
>  #define __SYSCALL(nr, sym) extern long __x64_##sym(const struct pt_regs *);
>  #define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __x64_##sym(const struct pt_regs *);
>  #include <asm/syscalls_64.h>
> +#ifdef CONFIG_X86_X32_ABI
> +#include <asm/syscalls_x32.h>
> +#endif
>  #undef  __SYSCALL
>  
>  #undef  __SYSCALL_NORETURN
> @@ -44,6 +47,16 @@ long x64_sys_call(const struct pt_regs *regs, unsigned int nr)
>  	}
>  };
>  
> +#ifdef CONFIG_X86_X32_ABI
> +long x32_sys_call(const struct pt_regs *regs, unsigned int nr)
> +{
> +	switch (nr) {
> +	#include <asm/syscalls_x32.h>
> +	default: return __x64_sys_ni_syscall(regs);
> +	}
> +};

There seems to be a stray semicolon here. The original code also has it
but it doesn't seem necessary.

> +#endif
> +
>  static __always_inline bool do_syscall_x64(struct pt_regs *regs, int nr)
>  {
>  	/*
> diff --git a/arch/x86/entry/syscall_x32.c b/arch/x86/entry/syscall_x32.c
> deleted file mode 100644
> index fb77908f44f3..000000000000
> --- a/arch/x86/entry/syscall_x32.c
> +++ /dev/null
> @@ -1,25 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -/* System call table for x32 ABI. */
> -
> -#include <linux/linkage.h>
> -#include <linux/sys.h>
> -#include <linux/cache.h>
> -#include <linux/syscalls.h>
> -#include <asm/syscall.h>
> -
> -#define __SYSCALL(nr, sym) extern long __x64_##sym(const struct pt_regs *);
> -#define __SYSCALL_NORETURN(nr, sym) extern long __noreturn __x64_##sym(const struct pt_regs *);
> -#include <asm/syscalls_x32.h>
> -#undef  __SYSCALL
> -
> -#undef  __SYSCALL_NORETURN
> -#define __SYSCALL_NORETURN __SYSCALL
> -
> -#define __SYSCALL(nr, sym) case nr: return __x64_##sym(regs);
> -long x32_sys_call(const struct pt_regs *regs, unsigned int nr)
> -{
> -	switch (nr) {
> -	#include <asm/syscalls_x32.h>
> -	default: return __x64_sys_ni_syscall(regs);
> -	}
> -};