linux-kernel - [PATCH 5/5] x86: Drop asmlinkage from syscalls

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Date:   Fri, 21 Feb 2020 00:09:34 -0500
From:   Brian Gerst <brgerst@...il.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Brian Gerst <brgerst@...il.com>
Subject: [PATCH 5/5] x86: Drop asmlinkage from syscalls

asmlinkage is no longer required since the syscall ABI is now fully under
x86 architecture control.  This makes the 32-bit native syscalls a bit more
effecient by passing in regs via EAX instead of on the stack.

Signed-off-by: Brian Gerst <brgerst@...il.com>
---
 arch/x86/entry/syscall_32.c            |  2 +-
 arch/x86/entry/syscall_64.c            |  2 +-
 arch/x86/include/asm/syscall.h         |  2 +-
 arch/x86/include/asm/syscall_wrapper.h | 20 ++++++++++----------
 4 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/x86/entry/syscall_32.c b/arch/x86/entry/syscall_32.c
index 7af944b686ef..4e0113f3d4e8 100644
--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -8,7 +8,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/syscall.h>
 
-#define __SYSCALL_I386(nr, sym, qual) extern asmlinkage long sym(const struct pt_regs *);
+#define __SYSCALL_I386(nr, sym, qual) extern long sym(const struct pt_regs *);
 
 #include <asm/syscalls_32.h>
 #undef __SYSCALL_I386
diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
index 058dc1b73e96..3331a71eec77 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -8,7 +8,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/syscall.h>
 
-#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(const struct pt_regs *);
+#define __SYSCALL_64(nr, sym, qual) extern long sym(const struct pt_regs *);
 #define __SYSCALL_X32(nr, sym, qual) __SYSCALL_64(nr, sym, qual)
 #include <asm/syscalls_64.h>
 #undef __SYSCALL_64
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index 576178aefa01..a0b189714bac 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -17,7 +17,7 @@
 #include <asm/thread_info.h>	/* for TS_COMPAT */
 #include <asm/unistd.h>
 
-typedef asmlinkage long (*sys_call_ptr_t)(const 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)
diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h
index 9e9259a92020..68d2231bbff0 100644
--- a/arch/x86/include/asm/syscall_wrapper.h
+++ b/arch/x86/include/asm/syscall_wrapper.h
@@ -8,8 +8,8 @@
 
 struct pt_regs;
 
-extern asmlinkage long __x64_sys_ni_syscall(const struct pt_regs *regs);
-extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
+extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
+extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
 
 /*
  * Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes
@@ -59,23 +59,23 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
 	      ,,(unsigned int)regs->di,,(unsigned int)regs->bp)
 
 #define __SYS_STUBx(abi, name, ...)					\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs);	\
+	long __##abi##_##name(const struct pt_regs *regs);		\
 	ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO);			\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs)	\
+	long __##abi##_##name(const struct pt_regs *regs)		\
 	{								\
 		return __se_##name(__VA_ARGS__);			\
 	}
 
 #define __SYS_STUB0(abi, name)						\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs);	\
+	long __##abi##_##name(const struct pt_regs *regs);		\
 	ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO);			\
-	asmlinkage long __##abi##_##name(const struct pt_regs *regs)	\
+	long __##abi##_##name(const struct pt_regs *regs)		\
 	{								\
 		return __do_##name();					\
 	}
 
 #define __COND_SYSCALL(abi, name)					\
-	asmlinkage __weak long						\
+	__weak long							\
 	 __##abi##_##name(const struct pt_regs *regs)			\
 	{								\
 		return sys_ni_syscall();				\
@@ -270,8 +270,8 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
  * For VSYSCALLS, we need to declare these three syscalls with the new
  * pt_regs-based calling convention for in-kernel use.
  */
-asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
-asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
-asmlinkage long __x64_sys_time(const struct pt_regs *regs);
+long __x64_sys_getcpu(const struct pt_regs *regs);
+long __x64_sys_gettimeofday(const struct pt_regs *regs);
+long __x64_sys_time(const struct pt_regs *regs);
 
 #endif /* _ASM_X86_SYSCALL_WRAPPER_H */
-- 
2.24.1