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SubjectRe: [PATCH 1/4] x86: add __X32_COND_SYSCALL() macro
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---

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