On Thu, Oct 22 2026 at 16:24, Sebastian Andrzej Siewior wrote:
On 2026-07-07 21:07:01 [+0200], Thomas Gleixner wrote:
quoted
Invoking sys_ni_syscall() from a code path, which already knows that the
syscall number is invalid just to assign -ENOSYS to regs->ax is a pointless
exercise. It's even redundant as the low level entry code already has set
regs->ax to -ENOSYS on entry.
Remove the extra conditionals and the function calls.
Since this patch, tools/testing/selftests/x86/syscall_numbering_64
throws in this:
|[RUN] Running tests under ptrace: modifying the default return
|[RUN] Checking system calls with msb = 0 (0x0)
|[RUN] Checking some common syscalls as 64 bit
|[OK] x64 syscall 0:0 returned 0 as expected
|[OK] x64 syscall 0:1 returned 0 as expected
|[RUN] Checking some 64-bit only syscalls as 64 bit
|[OK] x64 syscall 0:19 returned 0 as expected
|[OK] x64 syscall 0:20 returned 0 as expected
|[RUN] Checking out of range system calls
|[FAIL] x32 syscall 0:-64 returned -9999, but it should have returned -ENOSYS
…
|[FAIL] x32 syscall 0:-2 returned -9999, but it should have returned -ENOSYS
|[FAIL] x32 syscalls 0:-64..-2 had 63 failure
|[OK] x32 syscall 0:-1 returned MODIFIED_BY_PTRACE as expected
|[FAIL] x64 syscall 0:1073741760 returned -9999, but it should have returned -ENOSYS
…
|[FAIL] x64 syscall 0:1073741823 returned -9999, but it should have returned -ENOSYS
|[FAIL] x64 syscalls 0:1073741760..1073741823 had 64 failure
|[FAIL] x64 syscall 0:-64 returned -9999, but it should have returned -ENOSYS
…
|[FAIL] x64 syscall 0:547 returned -9999, but it should have returned -ENOSYS
|[FAIL] x64 syscalls 0:512..547 had 36 failure
|[RUN] Checking some common syscalls as x32
|[OK] x32 syscall 0:0 returned 0 as expected
…
|[RUN] Checking out of range system calls
|[FAIL] x32 syscall 1:-64 returned -9999, but it should have returned -ENOSYS
|[FAIL] x32 syscalls 1:-64..-2 had 63 failure
|[OK] x32 syscall 1:-1 returned MODIFIED_BY_PTRACE as expected
|[FAIL] x64 syscall 1:1073741760 returned -9999, but it should have returned -ENOSYS
…
and so on… The test has
| #define MODIFIED_BY_PTRACE -9999
and the ptracer modifies the return code. However not always. Not sure
if this was indeed a pointless exercise or not.
Hrmm. That's weird. Let me have a look.