linux-kernel - [PATCH] x86/syscalls: shrink entry/syscall

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Date: Thu, 04 Jan 2024 00:13:29 +0000
From: Tanzir Hasan <tanzirh@...gle.com>
To: Andy Lutomirski <luto@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>
Cc: linux-kernel@...r.kernel.org, Nick Desaulniers <nnn@...gle.com>, 
	Al Viro <viro@...iv.linux.org.uk>, Tanzir Hasan <tanzirh@...gle.com>
Subject: [PATCH] x86/syscalls: shrink entry/syscall_64.i via IWYU

This diff uses an open source tool include-what-you-use (IWYU) to modify
the include list, changing indirect includes to direct includes. IWYU is
implemented using the IWYUScripts github repository which is a tool that
is currently undergoing development. These changes seek to improve build
times.

This change to entry/syscall_64.c resulted in a preprocessed size of
entry/syscall_64.i from 64003 lines to 24509 lines (-62%) for the x86
defconfig.

Suggested-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Tanzir Hasan <tanzirh@...gle.com>
---
 arch/x86/entry/syscall_64.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
index be120eec1fc9..9e4a3d8957f3 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -1,12 +1,22 @@
 // SPDX-License-Identifier: GPL-2.0
 /* System call table for x86-64. */
 
-#include <linux/linkage.h>
-#include <linux/sys.h>
-#include <linux/cache.h>
-#include <linux/syscalls.h>
 #include <asm/syscall.h>
 
+struct pt_regs;
+typedef long (*sys_call_ptr_t)(const struct pt_regs *);
+extern const sys_call_ptr_t sys_call_table[];
+#if defined(CONFIG_X86_32)
+#define ia32_sys_call_table sys_call_table
+#else
+/*
+ * These may not exist, but still put the prototypes in so we
+ * can use IS_ENABLED().
+ */
+extern const sys_call_ptr_t ia32_sys_call_table[];
+extern const sys_call_ptr_t x32_sys_call_table[];
+#endif
+
 #define __SYSCALL(nr, sym) extern long __x64_##sym(const struct pt_regs *);
 #include <asm/syscalls_64.h>
 #undef __SYSCALL

---
base-commit: f5837722ffecbbedf1b1dbab072a063565f0dad1
change-id: 20231228-syscall_64-30ba68440a85

Best regards,
-- 
Tanzir Hasan <tanzirh@...gle.com>