Am 21.10.24 um 08:48 schrieb Muhammad Usama Anjum:
Hi,
The asm-generic/unistd.h file has wrong __NR_userfaultfd syscall number which doesn't even depend on the architecture. This has caused failure of a selftest which was fixed recently [1].
grep -rnIF "#define __NR_userfaultfd" tools/include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282 arch/x86/include/generated/uapi/asm/unistd_32.h:374:#define __NR_userfaultfd 374 arch/x86/include/generated/uapi/asm/unistd_64.h:327:#define __NR_userfaultfd 323 arch/x86/include/generated/uapi/asm/unistd_x32.h:282:#define __NR_userfaultfd (__X32_SYSCALL_BIT + 323) arch/arm/include/generated/uapi/asm/unistd-eabi.h:347:#define __NR_userfaultfd (__NR_SYSCALL_BASE + 388) arch/arm/include/generated/uapi/asm/unistd-oabi.h:359:#define __NR_userfaultfd (__NR_SYSCALL_BASE + 388) include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282
The number is dependent on the architecture. The above data shows that it is different for different arch: x86 374 x86_64 323 ARM 347/358
It seems include/uapi/asm-generic/unistd has wrong 282 value in it. Maybe I'm missing some context.. Please have a look at it.
The __NR_userfaultfd was added to include/uapi/asm-generic/unistd.h in 09f7298100ea ("Subject: [PATCH] userfaultfd: register uapi generic syscall (aarch64)").
This is not specific to __NR_userfaultfd, just take a look at some of the other syscalls (e.g., __NR_membarrier).
Now, some of the files you list above are "generated". Doing it on a clean tree:
$ grep -rnIF "#define __NR_userfaultfd" arch/arm64/include/asm/unistd32.h:789:#define __NR_userfaultfd 388 tools/include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282 include/uapi/asm-generic/unistd.h:681:#define __NR_userfaultfd 282
But now comes the tricky part: an architecture defines whether it wants to
(a) Use the asm-generic unistd.h (b) Use a custom one
E.g.,
$ cat include/uapi/linux/unistd.h /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ #ifndef _LINUX_UNISTD_H_ #define _LINUX_UNISTD_H_
/* * Include machine specific syscall numbers */ #include <asm/unistd.h>
#endif /* _LINUX_UNISTD_H_ */
For example on riscv arch/riscv/include/asm/unistd.h will include arch/riscv/include/uapi/asm/unistd.h which will include "asm-generic/unistd.h".
If you follow the flow on x86, you'll find that it will not include that asm-generic one as default.
So the asm-generic variant only applies if an arch wants to do it in the generic way.
$ find tools -name unistd.h tools/arch/x86/include/uapi/asm/unistd.h tools/arch/arc/include/uapi/asm/unistd.h tools/arch/riscv/include/uapi/asm/unistd.h tools/arch/hexagon/include/uapi/asm/unistd.h tools/arch/arm64/include/uapi/asm/unistd.h tools/arch/loongarch/include/uapi/asm/unistd.h tools/include/uapi/asm-generic/unistd.h tools/include/nolibc/unistd.h
Consequently, the asm-generic one should never be used directly.