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    Subject[PATCH 5.6 01/43] x86/syscalls: Revert "x86/syscalls: Make __X32_SYSCALL_BIT be unsigned long"
    Date
    From: Andy Lutomirski <luto@kernel.org>

    [ Upstream commit 700d3a5a664df267f01ec8887fd2d8ff98f67e7f ]

    Revert

    45e29d119e99 ("x86/syscalls: Make __X32_SYSCALL_BIT be unsigned long")

    and add a comment to discourage someone else from making the same
    mistake again.

    It turns out that some user code fails to compile if __X32_SYSCALL_BIT
    is unsigned long. See, for example [1] below.

    [ bp: Massage and do the same thing in the respective tools/ header. ]

    Fixes: 45e29d119e99 ("x86/syscalls: Make __X32_SYSCALL_BIT be unsigned long")
    Reported-by: Thorsten Glaser <t.glaser@tarent.de>
    Signed-off-by: Andy Lutomirski <luto@kernel.org>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Cc: stable@kernel.org
    Link: [1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=954294
    Link: https://lkml.kernel.org/r/92e55442b744a5951fdc9cfee10badd0a5f7f828.1588983892.git.luto@kernel.org
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/x86/include/uapi/asm/unistd.h | 11 +++++++++--
    tools/arch/x86/include/uapi/asm/unistd.h | 2 +-
    2 files changed, 10 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/include/uapi/asm/unistd.h b/arch/x86/include/uapi/asm/unistd.h
    index 196fdd02b8b1..be5e2e747f50 100644
    --- a/arch/x86/include/uapi/asm/unistd.h
    +++ b/arch/x86/include/uapi/asm/unistd.h
    @@ -2,8 +2,15 @@
    #ifndef _UAPI_ASM_X86_UNISTD_H
    #define _UAPI_ASM_X86_UNISTD_H

    -/* x32 syscall flag bit */
    -#define __X32_SYSCALL_BIT 0x40000000UL
    +/*
    + * x32 syscall flag bit. Some user programs expect syscall NR macros
    + * and __X32_SYSCALL_BIT to have type int, even though syscall numbers
    + * are, for practical purposes, unsigned long.
    + *
    + * Fortunately, expressions like (nr & ~__X32_SYSCALL_BIT) do the right
    + * thing regardless.
    + */
    +#define __X32_SYSCALL_BIT 0x40000000

    #ifndef __KERNEL__
    # ifdef __i386__
    diff --git a/tools/arch/x86/include/uapi/asm/unistd.h b/tools/arch/x86/include/uapi/asm/unistd.h
    index 196fdd02b8b1..30d7d04d72d6 100644
    --- a/tools/arch/x86/include/uapi/asm/unistd.h
    +++ b/tools/arch/x86/include/uapi/asm/unistd.h
    @@ -3,7 +3,7 @@
    #define _UAPI_ASM_X86_UNISTD_H

    /* x32 syscall flag bit */
    -#define __X32_SYSCALL_BIT 0x40000000UL
    +#define __X32_SYSCALL_BIT 0x40000000

    #ifndef __KERNEL__
    # ifdef __i386__
    --
    2.25.1


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