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syscalls/x86: Unconditionally enable 'struct pt_regs' based syscalls on x86_64

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

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180405095307.3730-7-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dominik Brodowski 2018-04-05 11:53:05 +02:00 committed by Ingo Molnar
parent ebeb8c82ff
commit f8781c4a22
7 changed files with 12 additions and 57 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/Kconfig
View File

@ -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
@ -2954,8 +2955,3 @@ 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

10
arch/x86/entry/common.c
View File

@ -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);

6
arch/x86/entry/syscall_32.c
View File

@ -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(const 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(const 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

5
arch/x86/entry/syscall_64.c
View File

@ -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(const struct pt_regs *);
#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(const 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

18
arch/x86/entry/vsyscall/vsyscall_64.c
View File

@ -127,9 +127,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
int vsyscall_nr, syscall_nr, tmp;
int prev_sig_on_uaccess_err;
long ret;
#ifdef CONFIG_SYSCALL_PTREGS
unsigned long orig_dx;
#endif
/*
* No point in checking CS -- the only way to get here is a user mode
@ -230,38 +228,22 @@ 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
/* while we could clobber regs->dx, we didn't in the past... */
orig_dx = regs->dx;
regs->dx = 0;
/* this decodes regs->di, regs->si and regs->dx on its own */
ret = sys_getcpu(regs);
regs->dx = orig_dx;
#else
ret = sys_getcpu((unsigned __user *)regs->di,
(unsigned __user *)regs->si,
NULL);
#endif /* CONFIG_SYSCALL_PTREGS */
break;
}

4
arch/x86/include/asm/syscall.h
View File

@ -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)(const 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)

20
arch/x86/include/asm/syscalls.h
View File

@ -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 32-bit 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 */