Failed to find some gadgets on glibc 2.31

[david942j]

Checked with https://gitlab.com/david942j/libcdb/blob/master/libc/libc6_2.31-0ubuntu10_amd64/lib/x86_64-linux-gnu/libc-2.31.so

Current findings:

0xe6d43 execve("/bin/sh", r10, r12)
constraints:
  [r10] == NULL || r10 == NULL
  [r12] == NULL || r12 == NULL

0xe6d46 execve("/bin/sh", r10, rdx)
constraints:
  [r10] == NULL || r10 == NULL
  [rdx] == NULL || rdx == NULL

0xe6d49 execve("/bin/sh", rsi, rdx)
constraints:
  [rsi] == NULL || rsi == NULL
  [rdx] == NULL || rdx == NULL

Expected more gadgets such as:

   e6b4e:       4c 89 e2                mov    rdx,r12
   e6b51:       4c 89 fe                mov    rsi,r15
   e6b54:       48 8d 3d 4f 0a 0d 00    lea    rdi,[rip+0xd0a4f]        # 1b75aa <_libc_intl_domainname@@GLIBC_2.2.5+0x1a5>
   e6b5b:       e8 60 f6 ff ff          call   e61c0 <execve@@GLIBC_2.2.5>

0xe6b4e execve("/bin/sh", r15, r12)

this pattern is exactly same as the one at 0xe6d43, assuming a bug exists.