From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 In-Reply-To: <20160915233324.6060-2-khuey@kylehuey.com> References: <20160915233324.6060-1-khuey@kylehuey.com> <20160915233324.6060-2-khuey@kylehuey.com> From: Andy Lutomirski Date: Thu, 15 Sep 2016 16:51:29 -0700 Message-ID: Subject: Re: [PATCH v3 1/3] syscalls,x86 Expose arch_prctl on x86-32. Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org To: Kyle Huey Cc: Robert O'Callahan , "linux-kernel@vger.kernel.org" , Dave Hansen , Dmitry Safonov <0x7f454c46@gmail.com>, Borislav Petkov , Linux API , "xen-devel@lists.xenproject.org" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Jeff Dike , Richard Weinberger , Al Viro , David Howells , Anna Schumaker , Andy Lutomirski , Zach Brown , Eric B Munson , "Dmitry V. Levin" , Peter Zijlstra , Paul Gortmaker , Jiri Slaby , Andrey Ryabinin , "Michael S. Tsirkin" , Borislav Petkov , Dmitry Vyukov , Jan Beulich , Mateusz Guzik , Chuck Ebbert , Oleg Nesterov , Dmitry Safonov , "chengang@emindsoft.com.cn" , Jeff Moyer , Andrew Morton , Jiri Kosina , Milosz Tanski , "open list:USER-MODE LINUX (UML)" , "open list:USER-MODE LINUX (UML)" List-ID: On Thu, Sep 15, 2016 at 4:33 PM, Kyle Huey wrote: > arch_prctl is currently 64-bit only. Wire it up for 32-bits, as a no-op for > now. Rename the second arg to a more generic name. > > Signed-off-by: Kyle Huey > --- > arch/x86/entry/syscalls/syscall_32.tbl | 1 + > arch/x86/include/asm/proto.h | 5 ++++- > arch/x86/kernel/process.c | 10 ++++++++++ > arch/x86/kernel/process_64.c | 33 +++++++++++++++++++++------------ > arch/x86/kernel/ptrace.c | 8 ++++---- > arch/x86/um/Makefile | 2 +- > arch/x86/um/syscalls_32.c | 7 +++++++ > arch/x86/um/syscalls_64.c | 4 ++-- > include/linux/compat.h | 2 ++ > 9 files changed, 52 insertions(+), 20 deletions(-) > create mode 100644 arch/x86/um/syscalls_32.c > > diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl > index f848572..666fa61 100644 > --- a/arch/x86/entry/syscalls/syscall_32.tbl > +++ b/arch/x86/entry/syscalls/syscall_32.tbl > @@ -386,3 +386,4 @@ > 377 i386 copy_file_range sys_copy_file_range > 378 i386 preadv2 sys_preadv2 compat_sys_preadv2 > 379 i386 pwritev2 sys_pwritev2 compat_sys_pwritev2 > +380 i386 arch_prctl compat_sys_arch_prctl compat_sys_arch_prctl Let's call this sys_arch_prctl_32, even if it's unconventional. See below. > diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h > index 9b9b30b..f0e86aa 100644 > --- a/arch/x86/include/asm/proto.h > +++ b/arch/x86/include/asm/proto.h > @@ -30,6 +30,9 @@ void x86_report_nx(void); > > extern int reboot_force; > > -long do_arch_prctl(struct task_struct *task, int code, unsigned long addr); > +long do_arch_prctl_common(struct task_struct *task, int code, unsigned long addr); > +#ifdef CONFIG_X86_64 > +long do_arch_prctl_64(struct task_struct *task, int code, unsigned long addr); > +#endif > > #endif /* _ASM_X86_PROTO_H */ > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index 62c0b0e..1421451 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -567,3 +567,13 @@ unsigned long get_wchan(struct task_struct *p) > } while (count++ < 16 && p->state != TASK_RUNNING); > return 0; > } > + > +long do_arch_prctl_common(struct task_struct *task, int code, unsigned long arg2) > +{ > + return -EINVAL; > +} > + > +asmlinkage long compat_sys_arch_prctl(int code, unsigned long arg2) I believe you mean COMPAT_SYSCALL_DEFINE2 here. But I see what you're doing here. Could you instead do: #if defined(CONFIG_IA32_EMULATION) || defined(CONFIG_X86_32) #ifdef CONFIG_X86_32 COMPAT_SYSCALL_DEFINE2(...) #else SYSCALL_DEFINE2(...) #endif ... body here ... #endif and name the thing do_arch_prctl_32? It's too bad we don't have a SYSCALL_DEFINE_32 macro. But you could add one... > diff --git a/arch/x86/um/syscalls_32.c b/arch/x86/um/syscalls_32.c > new file mode 100644 > index 0000000..c6812c1 > --- /dev/null > +++ b/arch/x86/um/syscalls_32.c > @@ -0,0 +1,7 @@ > +#include > +#include > + > +long compat_sys_arch_prctl(int code, unsigned long arg2) COMPAT_SYSCALL_DEFINE2 Also, does this really need a new file? > -long sys_arch_prctl(int code, unsigned long addr) > +long sys_arch_prctl(int code, unsigned long arg2) SYSCALL_DEFINE2