[PATCH 6/7] syscalls/x86: unconditionally enable struct pt_regs based syscalls on x86_64

Dominik Brodowski
2018-03-30T09:37:40Z

Remove CONFIG_SYSCALL_PTREGS from arch/x86/Kconfig and simply select
ARCH_HAS_SYSCALL_WRAPPER unconditionally on x86-64 allows us to simplify
several codepaths.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
arch/x86/Kconfig | 6 +-----
arch/x86/entry/common.c | 10 ++--------
arch/x86/entry/syscall_32.c | 6 +++---
arch/x86/entry/syscall_64.c | 5 -----
arch/x86/entry/vsyscall/vsyscall_64.c | 16 ----------------
arch/x86/include/asm/syscall.h | 4 ++--
arch/x86/include/asm/syscalls.h | 20 ++++----------------
7 files changed, 12 insertions(+), 55 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2ad46f7c522c..7c0e135819f1 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -29,6 +29,7 @@ config X86_64
select HAVE_ARCH_SOFT_DIRTY
select MODULES_USE_ELF_RELA
select X86_DEV_DMA_OPS
+ select ARCH_HAS_SYSCALL_WRAPPER

#
# Arch settings
@@ -2957,8 +2958,3 @@ source "crypto/Kconfig"
source "arch/x86/kvm/Kconfig"

source "lib/Kconfig"
-
-config SYSCALL_PTREGS
- def_bool y
- depends on X86_64
- select ARCH_HAS_SYSCALL_WRAPPER
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 425f798b39e3..fbf6a6c3fd2d 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -284,13 +284,7 @@ __visible void do_syscall_64(unsigned long nr, struct pt_regs *regs)
nr &= __SYSCALL_MASK;
if (likely(nr < NR_syscalls)) {
nr = array_index_nospec(nr, NR_syscalls);
-#ifdef CONFIG_SYSCALL_PTREGS
regs->ax = sys_call_table[nr](regs);
-#else
- regs->ax = sys_call_table[nr](
- regs->di, regs->si, regs->dx,
- regs->r10, regs->r8, regs->r9);
-#endif
}

syscall_return_slowpath(regs);
@@ -325,7 +319,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)

if (likely(nr < IA32_NR_syscalls)) {
nr = array_index_nospec(nr, IA32_NR_syscalls);
-#ifdef CONFIG_SYSCALL_PTREGS
+#ifdef CONFIG_IA32_EMULATION
regs->ax = ia32_sys_call_table[nr](regs);
#else
/*
@@ -338,7 +332,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
(unsigned int)regs->bx, (unsigned int)regs->cx,
(unsigned int)regs->dx, (unsigned int)regs->si,
(unsigned int)regs->di, (unsigned int)regs->bp);
-#endif /* CONFIG_SYSCALL_PTREGS */
+#endif /* CONFIG_IA32_EMULATION */
}

syscall_return_slowpath(regs);
diff --git a/arch/x86/entry/syscall_32.c b/arch/x86/entry/syscall_32.c
index bbd8dda36c7d..84901c4ad67b 100644
--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -7,17 +7,17 @@
#include <asm/asm-offsets.h>
#include <asm/syscall.h>

-#ifdef CONFIG_SYSCALL_PTREGS
+#ifdef CONFIG_IA32_EMULATION
/* On X86_64, we use struct pt_regs * to pass parameters to syscalls */
#define __SYSCALL_I386(nr, sym, qual) extern asmlinkage long sym(struct pt_regs *);

/* this is a lie, but it does not hurt as sys_ni_syscall just returns -EINVAL */
extern asmlinkage long sys_ni_syscall(struct pt_regs *);

-#else /* CONFIG_SYSCALL_PTREGS */
+#else /* CONFIG_IA32_EMULATION */
#define __SYSCALL_I386(nr, sym, qual) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
-#endif /* CONFIG_SYSCALL_PTREGS */
+#endif /* CONFIG_IA32_EMULATION */

#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 b4e724777a7d..0ff4de8d9571 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -7,14 +7,9 @@
#include <asm/asm-offsets.h>
#include <asm/syscall.h>

-#ifdef CONFIG_SYSCALL_PTREGS
/* this is a lie, but it does not hurt as sys_ni_syscall just returns -EINVAL */
extern asmlinkage long sys_ni_syscall(struct pt_regs *);
#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(struct pt_regs *);
-#else /* CONFIG_SYSCALL_PTREGS */
-extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
-#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
-#endif /* CONFIG_SYSCALL_PTREGS */
#include <asm/syscalls_64.h>
#undef __SYSCALL_64

diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
index 9fad68899f82..4e08df16d9da 100644
--- a/arch/x86/entry/vsyscall/vsyscall_64.c
+++ b/arch/x86/entry/vsyscall/vsyscall_64.c
@@ -227,35 +227,19 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
ret = -EFAULT;
switch (vsyscall_nr) {
case 0:
-#ifdef CONFIG_SYSCALL_PTREGS
/* this decodes regs->di and regs->si on its own */
ret = sys_gettimeofday(regs);
-#else
- ret = sys_gettimeofday(
- (struct timeval __user *)regs->di,
- (struct timezone __user *)regs->si);
-#endif /* CONFIG_SYSCALL_PTREGS */
break;

case 1:
-#ifdef CONFIG_SYSCALL_PTREGS
/* this decodes regs->di on its own */
ret = sys_time(regs);
-#else
- ret = sys_time((time_t __user *)regs->di);
-#endif /* CONFIG_SYSCALL_PTREGS */
break;

case 2:
-#ifdef CONFIG_SYSCALL_PTREGS
/* this decodes regs->di, regs->si and regs->dx on its own */
regs->dx = 0;
ret = sys_getcpu(regs);
-#else
- ret = sys_getcpu((unsigned __user *)regs->di,
- (unsigned __user *)regs->si,
- NULL);
-#endif /* CONFIG_SYSCALL_PTREGS */
break;
}

diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index 8702c7951bc7..0af95296ace8 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -20,13 +20,13 @@
#include <asm/thread_info.h> /* for TS_COMPAT */
#include <asm/unistd.h>

-#ifdef CONFIG_SYSCALL_PTREGS
+#ifdef CONFIG_X86_64
typedef asmlinkage long (*sys_call_ptr_t)(struct pt_regs *);
#else
typedef asmlinkage long (*sys_call_ptr_t)(unsigned long, unsigned long,
unsigned long, unsigned long,
unsigned long, unsigned long);
-#endif /* CONFIG_SYSCALL_PTREGS */
+#endif /* CONFIG_X86_64 */
extern const sys_call_ptr_t sys_call_table[];

#if defined(CONFIG_X86_32)
diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index e4ad93c05f02..a3aecee89881 100644
--- a/arch/x86/include/asm/syscalls.h
+++ b/arch/x86/include/asm/syscalls.h
@@ -19,10 +19,10 @@
/* kernel/ioport.c */
long ksys_ioperm(unsigned long from, unsigned long num, int turn_on);

-#ifndef CONFIG_SYSCALL_PTREGS
-/*
- * If CONFIG_SYSCALL_PTREGS is enabled, a different syscall calling convention
- * is used. Do not include these -- invalid -- prototypes then
+#ifdef CONFIG_X86_32
+/*
+ * These definitions are only valid on pure 32bit systems; x86-64 uses a
+ * different syscall calling convention
*/
asmlinkage long sys_ioperm(unsigned long, unsigned long, int);
asmlinkage long sys_iopl(unsigned int);
@@ -38,7 +38,6 @@ asmlinkage long sys_set_thread_area(struct user_desc __user *);
asmlinkage long sys_get_thread_area(struct user_desc __user *);

/* X86_32 only */
-#ifdef CONFIG_X86_32

/* kernel/signal.c */
asmlinkage long sys_sigreturn(void);
@@ -48,16 +47,5 @@ struct vm86_struct;
asmlinkage long sys_vm86old(struct vm86_struct __user *);
asmlinkage long sys_vm86(unsigned long, unsigned long);

-#else /* CONFIG_X86_32 */
-
-/* X86_64 only */
-/* kernel/process_64.c */
-asmlinkage long sys_arch_prctl(int, unsigned long);
-
-/* kernel/sys_x86_64.c */
-asmlinkage long sys_mmap(unsigned long, unsigned long, unsigned long,
- unsigned long, unsigned long, unsigned long);
-
#endif /* CONFIG_X86_32 */
-#endif /* CONFIG_SYSCALL_PTREGS */
#endif /* _ASM_X86_SYSCALLS_H */
--
2.16.3