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    Subject[PATCH 6/8] syscalls/x86: unconditionally enable struct pt_regs based syscalls on x86_64
    Date
    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.

    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 | 18 ------------------
    arch/x86/include/asm/syscall.h | 4 ++--
    arch/x86/include/asm/syscalls.h | 20 ++++----------------
    7 files changed, 12 insertions(+), 57 deletions(-)

    diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
    index 7bbd6a174722..bcdd3e0e2ef5 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
    @@ -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
    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 47060dd8efb1..aa3336a7cb15 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(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
    diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
    index 6197850adf91..d5252bc1e380 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(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

    diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
    index 05eebbf9b989..20b3d4a88ee4 100644
    --- a/arch/x86/entry/vsyscall/vsyscall_64.c
    +++ b/arch/x86/entry/vsyscall/vsyscall_64.c
    @@ -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;
    }

    diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
    index 17c62373a6f9..d653139857af 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)(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)
    diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
    index e4ad93c05f02..d4d18d94695c 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 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 */
    --
    2.16.3
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