On Tue, 30 Jul 2024 17:43:36 +0200
Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> Despite multiple attempts to get the syscall number assignment right
> for the newly added uretprobe syscall, we ended up with a bit of a mess:
>
> - The number is defined as 467 based on the assumption that the
> xattrat family of syscalls would use 463 through 466, but those
> did not make it into 6.11.
OK... that was not expected.
>
> - The include/uapi/asm-generic/unistd.h file still lists the number
> 463, but the new scripts/syscall.tbl that was supposed to have the
> same data lists 467 instead as the number for arc, arm64, csky,
> hexagon, loongarch, nios2, openrisc and riscv. None of these
> architectures actually provide a uretprobe syscall.
Oops, thanks for finding.
>
> - All the other architectures (powerpc, arm, mips, ...) don't list
> this syscall at all.
OK, so even if it is not supported on those, we need to put it as a
placeholder.
>
> There are two ways to make it consistent again: either list it with
> the same syscall number on all architectures, or only list it on x86
> but not in scripts/syscall.tbl and asm-generic/unistd.h.
>
> Based on the most recent discussion, it seems like we won't need it
> anywhere else, so just remove the inconsistent assignment and instead
> move the x86 number to the next available one in the architecture
> specific range, which is 335.
>
> Fixes: 5c28424e9a34 ("syscalls: Fix to add sys_uretprobe to syscall.tbl")
> Fixes: 190fec72df4a ("uprobe: Wire up uretprobe system call")
> Fixes: 63ded110979b ("uprobe: Change uretprobe syscall scope and number")
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> I think we should fix this as soon as possible. Please let me know if
> you agree on this approach, or prefer one of the alternatives.
OK, I think it is good. But you missed to fix a selftest code which
also needs to be updated.
Could you revert commit 3e301b431b91 ("selftests/bpf: Change uretprobe
syscall number in uprobe_syscall test") too?
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Thank you,
>
> I've queued up this version in the asm-generic tree so I can send a
> pull request in the next few days, but I'm fine with doing this a
> differently if someone has a stronger opinion on what numbers to
> assign for it on earch architecture.
>
> arch/x86/entry/syscalls/syscall_64.tbl | 2 +-
> include/uapi/asm-generic/unistd.h | 5 +----
> scripts/syscall.tbl | 1 -
> 3 files changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
> index 83073fa3c989..7093ee21c0d1 100644
> --- a/arch/x86/entry/syscalls/syscall_64.tbl
> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> @@ -344,6 +344,7 @@
> 332 common statx sys_statx
> 333 common io_pgetevents sys_io_pgetevents
> 334 common rseq sys_rseq
> +335 common uretprobe sys_uretprobe
> # don't use numbers 387 through 423, add new calls after the last
> # 'common' entry
> 424 common pidfd_send_signal sys_pidfd_send_signal
> @@ -385,7 +386,6 @@
> 460 common lsm_set_self_attr sys_lsm_set_self_attr
> 461 common lsm_list_modules sys_lsm_list_modules
> 462 common mseal sys_mseal
> -467 common uretprobe sys_uretprobe
>
> #
> # Due to a historical design error, certain syscalls are numbered differently
> diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> index 985a262d0f9e..5bf6148cac2b 100644
> --- a/include/uapi/asm-generic/unistd.h
> +++ b/include/uapi/asm-generic/unistd.h
> @@ -841,11 +841,8 @@ __SYSCALL(__NR_lsm_list_modules, sys_lsm_list_modules)
> #define __NR_mseal 462
> __SYSCALL(__NR_mseal, sys_mseal)
>
> -#define __NR_uretprobe 463
> -__SYSCALL(__NR_uretprobe, sys_uretprobe)
> -
> #undef __NR_syscalls
> -#define __NR_syscalls 464
> +#define __NR_syscalls 463
>
> /*
> * 32 bit systems traditionally used different
> diff --git a/scripts/syscall.tbl b/scripts/syscall.tbl
> index 591d85e8ca7e..797e20ea99a2 100644
> --- a/scripts/syscall.tbl
> +++ b/scripts/syscall.tbl
> @@ -402,4 +402,3 @@
> 460 common lsm_set_self_attr sys_lsm_set_self_attr
> 461 common lsm_list_modules sys_lsm_list_modules
> 462 common mseal sys_mseal
> -467 common uretprobe sys_uretprobe
> --
> 2.39.2
>
--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
