| Message ID | 20200918132439.1475479-2-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | syscalls: remove compat_alloc_user_space callers | expand |
On Fri, Sep 18, 2020 at 03:24:36PM +0200, Arnd Bergmann wrote: > sys_move_pages() is an optional syscall, and once we remove > the compat version of it in favor of the native one with an > in_compat_syscall() check, the x32 syscall table refers to > a __x32_sys_move_pages symbol that may not exist when the > syscall is disabled. > > Change the COND_SYSCALL() definition on x86 to also include > the redirection for x32. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Adding the x86 maintainers and Brian Gerst. Brian proposed another problem to the mess that most of the compat syscall handlers used by x32 here: https://lkml.org/lkml/2020/6/16/664 hpa didn't particularly like it, but with your and my pending series we'll soon use more native than compat syscalls for x32, so something will need to change.. > --- > arch/x86/include/asm/syscall_wrapper.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h > index a84333adeef2..5eacd35a7f97 100644 > --- a/arch/x86/include/asm/syscall_wrapper.h > +++ b/arch/x86/include/asm/syscall_wrapper.h > @@ -171,12 +171,16 @@ extern long __ia32_sys_ni_syscall(const struct pt_regs *regs); > __SYS_STUBx(x32, compat_sys##name, \ > SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__)) > > +#define __X32_COND_SYSCALL(name) \ > + __COND_SYSCALL(x32, sys_##name) > + > #define __X32_COMPAT_COND_SYSCALL(name) \ > __COND_SYSCALL(x32, compat_sys_##name) > > #define __X32_COMPAT_SYS_NI(name) \ > __SYS_NI(x32, compat_sys_##name) > #else /* CONFIG_X86_X32 */ > +#define __X32_COND_SYSCALL(name) > #define __X32_COMPAT_SYS_STUB0(name) > #define __X32_COMPAT_SYS_STUBx(x, name, ...) > #define __X32_COMPAT_COND_SYSCALL(name) > @@ -253,6 +257,7 @@ extern long __ia32_sys_ni_syscall(const struct pt_regs *regs); > static long __do_sys_##sname(const struct pt_regs *__unused) > > #define COND_SYSCALL(name) \ > + __X32_COND_SYSCALL(name) \ > __X64_COND_SYSCALL(name) \ > __IA32_COND_SYSCALL(name) > > -- > 2.27.0 > ---end quoted text---
On Fri, Sep 18, 2020 at 10:35 PM Christoph Hellwig <hch@infradead.org> wrote: > > On Fri, Sep 18, 2020 at 03:24:36PM +0200, Arnd Bergmann wrote: > > sys_move_pages() is an optional syscall, and once we remove > > the compat version of it in favor of the native one with an > > in_compat_syscall() check, the x32 syscall table refers to > > a __x32_sys_move_pages symbol that may not exist when the > > syscall is disabled. > > > > Change the COND_SYSCALL() definition on x86 to also include > > the redirection for x32. > > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Adding the x86 maintainers and Brian Gerst. Brian proposed another > problem to the mess that most of the compat syscall handlers used by > x32 here: > > https://lkml.org/lkml/2020/6/16/664 > > hpa didn't particularly like it, but with your and my pending series > we'll soon use more native than compat syscalls for x32, so something > will need to change.. I'm fine with either solution.
On September 19, 2020 9:23:22 AM PDT, Andy Lutomirski <luto@kernel.org> wrote: >On Fri, Sep 18, 2020 at 10:35 PM Christoph Hellwig <hch@infradead.org> >wrote: >> >> On Fri, Sep 18, 2020 at 03:24:36PM +0200, Arnd Bergmann wrote: >> > sys_move_pages() is an optional syscall, and once we remove >> > the compat version of it in favor of the native one with an >> > in_compat_syscall() check, the x32 syscall table refers to >> > a __x32_sys_move_pages symbol that may not exist when the >> > syscall is disabled. >> > >> > Change the COND_SYSCALL() definition on x86 to also include >> > the redirection for x32. >> > >> > Signed-off-by: Arnd Bergmann <arnd@arndb.de> >> >> Adding the x86 maintainers and Brian Gerst. Brian proposed another >> problem to the mess that most of the compat syscall handlers used by >> x32 here: >> >> https://lkml.org/lkml/2020/6/16/664 >> >> hpa didn't particularly like it, but with your and my pending series >> we'll soon use more native than compat syscalls for x32, so something >> will need to change.. > >I'm fine with either solution. My main objection was naming. x64 is a widely used synonym for x86-64, and so that is confusing.
> On Sep 19, 2020, at 10:14 AM, hpa@zytor.com wrote: > > On September 19, 2020 9:23:22 AM PDT, Andy Lutomirski <luto@kernel.org> wrote: >>> On Fri, Sep 18, 2020 at 10:35 PM Christoph Hellwig <hch@infradead.org> >>> wrote: >>> >>> On Fri, Sep 18, 2020 at 03:24:36PM +0200, Arnd Bergmann wrote: >>>> sys_move_pages() is an optional syscall, and once we remove >>>> the compat version of it in favor of the native one with an >>>> in_compat_syscall() check, the x32 syscall table refers to >>>> a __x32_sys_move_pages symbol that may not exist when the >>>> syscall is disabled. >>>> >>>> Change the COND_SYSCALL() definition on x86 to also include >>>> the redirection for x32. >>>> >>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de> >>> >>> Adding the x86 maintainers and Brian Gerst. Brian proposed another >>> problem to the mess that most of the compat syscall handlers used by >>> x32 here: >>> >>> https://lkml.org/lkml/2020/6/16/664 >>> >>> hpa didn't particularly like it, but with your and my pending series >>> we'll soon use more native than compat syscalls for x32, so something >>> will need to change.. >> >> I'm fine with either solution. > > My main objection was naming. x64 is a widely used synonym for x86-64, and so that is confusing. > > The way I deal with the syscall wrappers is that I assume the naming makes no sense whatsoever, and I go from there. With this perspective, the patches are neither an improvement nor a worsening of the current situation. (Similarly, the last column of the tables is useless garbage. My last attempt to fix that stalled.)
An alternative to the patch I proposed earlier would be to use aliases with the __x32_ prefix for the common syscalls. -- Brian Gerst On Sat, Sep 19, 2020 at 1:14 PM <hpa@zytor.com> wrote: > > On September 19, 2020 9:23:22 AM PDT, Andy Lutomirski <luto@kernel.org> wrote: > >On Fri, Sep 18, 2020 at 10:35 PM Christoph Hellwig <hch@infradead.org> > >wrote: > >> > >> On Fri, Sep 18, 2020 at 03:24:36PM +0200, Arnd Bergmann wrote: > >> > sys_move_pages() is an optional syscall, and once we remove > >> > the compat version of it in favor of the native one with an > >> > in_compat_syscall() check, the x32 syscall table refers to > >> > a __x32_sys_move_pages symbol that may not exist when the > >> > syscall is disabled. > >> > > >> > Change the COND_SYSCALL() definition on x86 to also include > >> > the redirection for x32. > >> > > >> > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > >> > >> Adding the x86 maintainers and Brian Gerst. Brian proposed another > >> problem to the mess that most of the compat syscall handlers used by > >> x32 here: > >> > >> https://lkml.org/lkml/2020/6/16/664 > >> > >> hpa didn't particularly like it, but with your and my pending series > >> we'll soon use more native than compat syscalls for x32, so something > >> will need to change.. > > > >I'm fine with either solution. > > My main objection was naming. x64 is a widely used synonym for x86-64, and so that is confusing. > > -- > Sent from my Android device with K-9 Mail. Please excuse my brevity.
diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h index a84333adeef2..5eacd35a7f97 100644 --- a/arch/x86/include/asm/syscall_wrapper.h +++ b/arch/x86/include/asm/syscall_wrapper.h @@ -171,12 +171,16 @@ extern long __ia32_sys_ni_syscall(const struct pt_regs *regs); __SYS_STUBx(x32, compat_sys##name, \ SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__)) +#define __X32_COND_SYSCALL(name) \ + __COND_SYSCALL(x32, sys_##name) + #define __X32_COMPAT_COND_SYSCALL(name) \ __COND_SYSCALL(x32, compat_sys_##name) #define __X32_COMPAT_SYS_NI(name) \ __SYS_NI(x32, compat_sys_##name) #else /* CONFIG_X86_X32 */ +#define __X32_COND_SYSCALL(name) #define __X32_COMPAT_SYS_STUB0(name) #define __X32_COMPAT_SYS_STUBx(x, name, ...) #define __X32_COMPAT_COND_SYSCALL(name) @@ -253,6 +257,7 @@ extern long __ia32_sys_ni_syscall(const struct pt_regs *regs); static long __do_sys_##sname(const struct pt_regs *__unused) #define COND_SYSCALL(name) \ + __X32_COND_SYSCALL(name) \ __X64_COND_SYSCALL(name) \ __IA32_COND_SYSCALL(name)
sys_move_pages() is an optional syscall, and once we remove the compat version of it in favor of the native one with an in_compat_syscall() check, the x32 syscall table refers to a __x32_sys_move_pages symbol that may not exist when the syscall is disabled. Change the COND_SYSCALL() definition on x86 to also include the redirection for x32. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- arch/x86/include/asm/syscall_wrapper.h | 5 +++++ 1 file changed, 5 insertions(+)