I've been working on a rust UEFI operating system, and I'm getting confused about this one callq that seems to be calling to code that doesn't exist.
0x0000000006693fa0 <+0>: push %rbp
0x0000000006693fa1 <+1>: mov %rsp,%rbp
0x0000000006693fa4 <+4>: sub $0x180,%rsp
0x0000000006693fab <+11>: mov %rdi,%rax
0x0000000006693fae <+14>: mov $0x1d,%ecx
0x0000000006693fb3 <+19>: mov $0x8,%edx
0x0000000006693fb8 <+24>: lea -0x130(%rbp),%r8
0x0000000006693fbf <+31>: mov %rdi,-0x158(%rbp)
0x0000000006693fc6 <+38>: mov %r8,%rdi
0x0000000006693fc9 <+41>: mov %rsi,-0x160(%rbp)
0x0000000006693fd0 <+48>: mov %ecx,%esi
0x0000000006693fd2 <+50>: mov %rax,-0x168(%rbp)
0x0000000006693fd9 <+57>: callq 0x66c3700
0x0000000006693fde <+62>: mov -0x160(%rbp),%rax
0x0000000006693fe5 <+69>: mov %rax,-0x8(%rbp)
0x0000000006693fe9 <+73>: callq 0x66941d0 <gnu_efi::mem::size_of<gnu_efi::def::MemoryDescriptors>>
0x0000000006693fee <+78>: lea -0x88(%rbp),%rdi
0x0000000006693ff5 <+85>: mov %rax,-0x10(%rbp)
0x0000000006693ff9 <+89>: callq 0x66941e0 <gnu_efi::mem::uninitialized<gnu_efi::def::MemoryDescriptors>>
0x0000000006693ffe <+94>: callq 0x66941f0 <gnu_efi::mem::uninitialized<usize>>
0x0000000006694003 <+99>: mov %rax,-0x90(%rbp)
0x000000000669400a <+106>: callq 0x66941f0 <gnu_efi::mem::uninitialized<usize>>
0x000000000669400f <+111>: mov %rax,-0x98(%rbp)
0x0000000006694016 <+118>: callq 0x6694200 <gnu_efi::mem::uninitialized<u32>>
0x000000000669401b <+123>: lea -0x88(%rbp),%rdx
0x0000000006694022 <+130>: mov %eax,-0x9c(%rbp)
0x0000000006694028 <+136>: mov -0x8(%rbp),%rdi
0x000000000669402c <+140>: mov 0x38(%rdi),%rdi
0x0000000006694030 <+144>: mov %rdx,-0xc0(%rbp)
0x0000000006694037 <+151>: movq $0x3,-0xb8(%rbp)
0x0000000006694042 <+162>: mov -0xc0(%rbp),%rdx
0x0000000006694049 <+169>: mov -0xb8(%rbp),%rsi
0x0000000006694050 <+176>: mov %rdi,-0x170(%rbp)
0x0000000006694057 <+183>: mov %rdx,%rdi
0x000000000669405a <+186>: callq 0x6694210 <gnu_efi::slice::[T].SliceExt::as_mut_ptr>
0x000000000669405f <+191>: lea -0x10(%rbp),%rdi
0x0000000006694063 <+195>: lea -0x90(%rbp),%rdx
0x000000000669406a <+202>: lea -0x98(%rbp),%rcx
0x0000000006694071 <+209>: lea -0x9c(%rbp),%r8
0x0000000006694078 <+216>: mov %rax,-0xb0(%rbp)
0x000000000669407f <+223>: mov -0xb0(%rbp),%rsi
0x0000000006694086 <+230>: mov -0x170(%rbp),%rax
0x000000000669408d <+237>: callq *%rax
0x000000000669408f <+239>: lea -0xa8(%rbp),%rdi
0x0000000006694096 <+246>: lea 0x31293(%rip),%rsi # 0x66c5330 <_ZN4core3num7flt2dec8strategy5grisu12CACHED_POW1017h66041a01fc2c0e94E+248>
0x000000000669409d <+253>: mov %rax,-0xa8(%rbp)
0x00000000066940a4 <+260>: callq 0x6694230 <gnu_efi::cmp::PartialEq::ne<gnu_efi::err::Status>>
0x00000000066940a9 <+265>: and $0x1,%al
0x00000000066940ab <+267>: mov %al,-0xc1(%rbp)
0x00000000066940b1 <+273>: testb $0x1,-0xc1(%rbp)
0x00000000066940b8 <+280>: je 0x669418d <gnu_efi::api::BootServices::get_memory_map+493>
0x00000000066940be <+286>: lea -0x130(%rbp),%rax
0x00000000066940c5 <+293>: movups 0x3679c(%rip),%xmm0 # 0x66ca868 <panic_bounds_check_loc55659+16>
0x00000000066940cc <+300>: movaps %xmm0,-0x110(%rbp)
0x00000000066940d3 <+307>: mov -0x110(%rbp),%rsi
0x00000000066940da <+314>: mov -0x108(%rbp),%rdx
0x00000000066940e1 <+321>: lea -0xa8(%rbp),%rcx
0x00000000066940e8 <+328>: mov %rcx,-0x128(%rbp)
0x00000000066940ef <+335>: mov %rcx,-0x130(%rbp)
0x00000000066940f6 <+342>: mov %rax,-0x138(%rbp)
0x00000000066940fd <+349>: mov %rdx,-0x178(%rbp)
0x0000000006694104 <+356>: mov %rsi,-0x180(%rbp)
0x000000000669410b <+363>: lea -0x3562(%rip),%rdx # 0x6690bb0 <gnu_efi::err::Status.::core::fmt::Debug::fmt>
0x0000000006694112 <+370>: lea -0x120(%rbp),%rdi
0x0000000006694119 <+377>: mov -0x138(%rbp),%rax
0x0000000006694120 <+384>: mov (%rax),%rax
0x0000000006694123 <+387>: mov %rax,-0x140(%rbp)
0x000000000669412a <+394>: mov -0x140(%rbp),%rsi
0x0000000006694131 <+401>: callq 0x66942c0 <gnu_efi::fmt::ArgumentV1<'a>::new<gnu_efi::err::Status>>
0x0000000006694136 <+406>: lea -0xf8(%rbp),%rdi
0x000000000669413d <+413>: lea -0x120(%rbp),%rax
0x0000000006694144 <+420>: mov %rax,-0x150(%rbp)
0x000000000669414b <+427>: movq $0x1,-0x148(%rbp)
0x0000000006694156 <+438>: mov -0x150(%rbp),%rcx
0x000000000669415d <+445>: mov -0x148(%rbp),%r8
0x0000000006694164 <+452>: mov -0x180(%rbp),%rsi
0x000000000669416b <+459>: mov -0x178(%rbp),%rdx
0x0000000006694172 <+466>: callq 0x6694270 <gnu_efi::fmt::Arguments<'a>::new_v1>
0x0000000006694177 <+471>: lea -0xf8(%rbp),%rdi
0x000000000669417e <+478>: lea 0x3670b(%rip),%rax # 0x66ca890 <panic_bounds_check_loc55661+8>
0x0000000006694185 <+485>: mov %rax,%rsi
0x0000000006694188 <+488>: callq 0x6694cc0 <_ZN4core9panicking9panic_fmt17ha6b3c19493c123b3E>
0x000000000669418d <+493>: mov $0x78,%eax
0x0000000006694192 <+498>: mov %eax,%edx
0x0000000006694194 <+500>: lea -0x88(%rbp),%rcx
0x000000000669419b <+507>: mov -0x158(%rbp),%rsi
0x00000000066941a2 <+514>: mov %rsi,%rdi
0x00000000066941a5 <+517>: mov %rcx,%rsi
0x00000000066941a8 <+520>: callq 0x66c3730
0x00000000066941ad <+525>: mov -0x90(%rbp),%rcx
0x00000000066941b4 <+532>: mov -0x158(%rbp),%rdx
0x00000000066941bb <+539>: mov %rcx,0x78(%rdx)
0x00000000066941bf <+543>: mov -0x168(%rbp),%rax
0x00000000066941c6 <+550>: add $0x180,%rsp
0x00000000066941cd <+557>: pop %rbp
0x00000000066941ce <+558>: retq
Although the code makes sense in general, there is one line that says callq 0x66c3700, and gdb can't find that symbol in my object file. I looked at the MIR generated for this code and couldn't figure out what this function call might be.
Here's the code that this function corresponds to:
pub fn get_memory_map(&self) -> (def::MemoryDescriptors, usize) {
let mut memory_map_size = mem::size_of::<def::MemoryDescriptors>();
unsafe {
let mut memory_map: def::MemoryDescriptors = mem::uninitialized();
let mut map_key = mem::uninitialized();
let mut descriptor_size = mem::uninitialized();
let mut descriptor_version = mem::uninitialized();
let status = (self.GetMemoryMap)(
&mut memory_map_size,
memory_map.descriptors.as_mut_ptr(),
&mut map_key,
&mut descriptor_size,
&mut descriptor_version);
if status != def::Status::Success {
panic!("Unable to get memory map: {:?}", status);
}
(memory_map, map_key)
}
}
Does anyone have any ideas what that callq might be?