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From:   Brian Gerst <brgerst@gmail.com>
To:     linux-kernel@vger.kernel.org, x86@kernel.org
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@kernel.org>,
        Dominik Brodowski <linux@dominikbrodowski.net>,
        Brian Gerst <brgerst@gmail.com>
Subject: [PATCH v4 17/18] x86: Drop asmlinkage from syscalls
Date:   Fri, 13 Mar 2020 15:51:43 -0400
Message-Id: <20200313195144.164260-18-brgerst@gmail.com>
In-Reply-To: <20200313195144.164260-1-brgerst@gmail.com>
References: <20200313195144.164260-1-brgerst@gmail.com>
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Sender: linux-kernel-owner@vger.kernel.org
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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@gmail.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/syscall_32.c            |  2 +-
 arch/x86/entry/syscall_64.c            |  2 +-
 arch/x86/entry/syscall_x32.c           |  4 ++--
 arch/x86/include/asm/syscall.h         |  2 +-
 arch/x86/include/asm/syscall_wrapper.h | 31 ++++++++++++--------------
 5 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/arch/x86/entry/syscall_32.c b/arch/x86/entry/syscall_32.c
index 097413c705ad..86eb0d89d46f 100644
--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -8,7 +8,7 @@
 #include <asm/unistd.h>
 #include <asm/syscall.h>
 
-#define __SYSCALL_I386(nr, sym) extern asmlinkage long __ia32_##sym(const struct pt_regs *);
+#define __SYSCALL_I386(nr, sym) extern long __ia32_##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 66d3e65e3b6b..1594ec72bcbb 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -11,7 +11,7 @@
 #define __SYSCALL_X32(nr, sym)
 #define __SYSCALL_COMMON(nr, sym) __SYSCALL_64(nr, sym)
 
-#define __SYSCALL_64(nr, sym) extern asmlinkage long __x64_##sym(const struct pt_regs *);
+#define __SYSCALL_64(nr, sym) extern long __x64_##sym(const struct pt_regs *);
 #include <asm/syscalls_64.h>
 #undef __SYSCALL_64
 
diff --git a/arch/x86/entry/syscall_x32.c b/arch/x86/entry/syscall_x32.c
index 2fb09efd7b40..3d8d70d3896c 100644
--- a/arch/x86/entry/syscall_x32.c
+++ b/arch/x86/entry/syscall_x32.c
@@ -10,8 +10,8 @@
 
 #define __SYSCALL_64(nr, sym)
 
-#define __SYSCALL_X32(nr, sym) extern asmlinkage long __x32_##sym(const struct pt_regs *);
-#define __SYSCALL_COMMON(nr, sym) extern asmlinkage long __x64_##sym(const struct pt_regs *);
+#define __SYSCALL_X32(nr, sym) extern long __x32_##sym(const struct pt_regs *);
+#define __SYSCALL_COMMON(nr, sym) extern long __x64_##sym(const struct pt_regs *);
 #include <asm/syscalls_64.h>
 #undef __SYSCALL_X32
 #undef __SYSCALL_COMMON
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index bb427d8cb1ef..7cbf733d11af 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -16,7 +16,7 @@
 #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 5e13e2caf2e4..e10efa1454bc 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, the x86 version takes
@@ -66,22 +66,21 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
 	      ,,(unsigned int)regs->di,,(unsigned int)regs->bp)
 
 #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)		\
 		__alias(__do_##name);
 
 #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 __COND_SYSCALL(abi, name)					\
-	asmlinkage __weak long						\
-	__##abi##_##name(const struct pt_regs *__unused)		\
+	__weak long __##abi##_##name(const struct pt_regs *__unused)	\
 	{								\
 		return sys_ni_syscall();				\
 	}
@@ -192,11 +191,11 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
  * of them.
  */
 #define COMPAT_SYSCALL_DEFINE0(name)					\
-	static asmlinkage long						\
+	static long							\
 	__do_compat_sys_##name(const struct pt_regs *__unused);		\
 	__IA32_COMPAT_SYS_STUB0(name)					\
 	__X32_COMPAT_SYS_STUB0(name)					\
-	static asmlinkage long						\
+	static long							\
 	__do_compat_sys_##name(const struct pt_regs *__unused)
 
 #define COMPAT_SYSCALL_DEFINEx(x, name, ...)					\
@@ -248,12 +247,10 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs);
  */
 #define SYSCALL_DEFINE0(sname)						\
 	SYSCALL_METADATA(_##sname, 0);					\
-	static asmlinkage long						\
-	__do_sys_##sname(const struct pt_regs *__unused);		\
+	static long __do_sys_##sname(const struct pt_regs *__unused);	\
 	__X64_SYS_STUB0(sname)						\
 	__IA32_SYS_STUB0(sname)						\
-	static asmlinkage long						\
-	__do_sys_##sname(const struct pt_regs *__unused)
+	static long __do_sys_##sname(const struct pt_regs *__unused)
 
 #define COND_SYSCALL(name)						\
 	__X64_COND_SYSCALL(name)					\
@@ -268,8 +265,8 @@ 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