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Auto merge of #58235 - jethrogb:jb/sgx-usercall-internals, r=alexcrichton

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SGX target: simplify usercall internals

This moves logic from assembly to Rust and removes the special case for exit/panic handling, merging it with regular usercall handling.

Also, this fixes a bug in the exit usercall introduced in a75ae00. The bug would make regular exits look like panics with high probability. It would also with some probability leak information through uncleared registers.

cc @VardhanThigle

r? @alexcrichton
This commit is contained in:
bors
2019-02-13 07:46:21 +00:00
parent 827a141466 0d2ab0b77d
commit ccd23b95e5
7 changed files with 59 additions and 84 deletions
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55
src/libstd/sys/sgx/abi/entry.S
View File

@@ -69,10 +69,6 @@ IMAGE_BASE:
.asciz "Re-entered aborted enclave!"
.Lreentry_panic_msg_end:
.Lusercall_panic_msg:
.asciz "Invalid usercall#!"
.Lusercall_panic_msg_end:
.org .Lxsave_clear+512
.Lxsave_header:
.int 0, 0 /* XSTATE_BV */
@@ -219,13 +215,21 @@ sgx_entry:
orq $8,%rsp
jmp panic_msg
.Lusercall_panic:
lea .Lusercall_panic_msg(%rip),%rdi
mov $.Lusercall_panic_msg_end-.Lusercall_panic_msg,%esi
orq $8,%rsp
jmp panic_msg
.macro push_callee_saved_registers
/* This *MUST* be called with 6 parameters, otherwise register information */
/* might leak! */
.global usercall
usercall:
test %rcx,%rcx /* check `abort` function argument */
jnz .Lusercall_abort /* abort is set, jump to abort code (unlikely forward conditional) */
jmp .Lusercall_save_state /* non-aborting usercall */
.Lusercall_abort:
/* set aborted bit */
movb $1,.Laborted(%rip)
/* save registers in DEBUG mode, so that debugger can reconstruct the stack */
testb $0xff,DEBUG(%rip)
jz .Lusercall_noreturn
.Lusercall_save_state:
/* save callee-saved state */
push %r15
push %r14
push %r13
@@ -235,33 +239,8 @@ sgx_entry:
sub $8, %rsp
fstcw 4(%rsp)
stmxcsr (%rsp)
.endm
.global usercall_exit
usercall_exit:
/* save registers in DEBUG mode, so that debugger can reconstruct the stack */
testb $0xff,DEBUG(%rip)
jz .Lskip_save_registers
push_callee_saved_registers
movq %rsp,%gs:tcsls_panic_last_rsp
.Lskip_save_registers:
/* set aborted bit */
movb $1,.Laborted(%rip)
/* call usercall exit(true) */
/* NOP: mov %rsi,%rsi */ /* RSI = usercall() argument: panic */
xor %rdx,%rdx /* RDX cleared */
movq $usercall_nr_exit,%rdi /* RDI = usercall exit */
jmp .Lexit
/* This *MUST* be called with 6 parameters, otherwise register information */
/* might leak! */
.global usercall
usercall:
test %rdi,%rdi
jle .Lusercall_panic
/* save callee-saved state */
push_callee_saved_registers
movq %rsp,%gs:tcsls_last_rsp
.Lusercall_noreturn:
/* clear general purpose register state */
/* RAX overwritten by ENCLU */
/* RBX set by sgx_exit */
@@ -281,7 +260,7 @@ usercall:
jmp .Lsgx_exit
.Lusercall_ret:
movq $0,%gs:tcsls_last_rsp
/* restore callee-saved state, cf. push_callee_saved_registers */
/* restore callee-saved state, cf. "save" above */
mov %r11,%rsp
ldmxcsr (%rsp)
fldcw 4(%rsp)

2
src/libstd/sys/sgx/abi/mod.rs
View File

@@ -12,7 +12,7 @@ pub mod tls;
#[macro_use]
pub mod usercalls;
global_asm!(concat!(usercalls_asm!(), include_str!("entry.S")));
global_asm!(include_str!("entry.S"));
#[no_mangle]
unsafe extern "C" fn tcs_init(secondary: bool) {

6
src/libstd/sys/sgx/abi/panic.rs
View File

@@ -1,4 +1,4 @@
use super::usercalls::alloc::UserRef;
use super::usercalls::{alloc::UserRef, self};
use cmp;
use io::{self, Write};
use mem;
@@ -52,7 +52,5 @@ impl Write for SgxPanicOutput {
#[no_mangle]
pub extern "C" fn panic_msg(msg: &str) -> ! {
let _ = SgxPanicOutput::new().map(|mut out| out.write(msg.as_bytes()));
unsafe { usercall_exit(true); }
usercalls::exit(true)
}
extern "C" { pub fn usercall_exit(panic: bool) -> !; }

2
src/libstd/sys/sgx/abi/usercalls/mod.rs
View File

@@ -120,7 +120,7 @@ pub unsafe fn launch_thread() -> IoResult<()> {
/// Usercall `exit`. See the ABI documentation for more information.
#[unstable(feature = "sgx_platform", issue = "56975")]
pub fn exit(panic: bool) -> ! {
unsafe { super::panic::usercall_exit(panic) }
unsafe { raw::exit(panic) }
}
/// Usercall `wait`. See the ABI documentation for more information.

73
src/libstd/sys/sgx/abi/usercalls/raw.rs
View File

@@ -4,12 +4,13 @@
pub use fortanix_sgx_abi::*;
use ptr::NonNull;
use num::NonZeroU64;
#[repr(C)]
struct UsercallReturn(u64, u64);
extern "C" {
fn usercall(nr: u64, p1: u64, p2: u64, _ignore: u64, p3: u64, p4: u64) -> UsercallReturn;
fn usercall(nr: NonZeroU64, p1: u64, p2: u64, abort: u64, p3: u64, p4: u64) -> UsercallReturn;
}
/// Performs the raw usercall operation as defined in the ABI calling convention.
@@ -23,9 +24,11 @@ extern "C" {
///
/// Panics if `nr` is `0`.
#[unstable(feature = "sgx_platform", issue = "56975")]
pub unsafe fn do_usercall(nr: u64, p1: u64, p2: u64, p3: u64, p4: u64) -> (u64, u64) {
if nr==0 { panic!("Invalid usercall number {}",nr) }
let UsercallReturn(a, b) = usercall(nr,p1,p2,0,p3,p4);
#[inline]
pub unsafe fn do_usercall(nr: NonZeroU64, p1: u64, p2: u64, p3: u64, p4: u64, abort: bool)
-> (u64, u64)
{
let UsercallReturn(a, b) = usercall(nr, p1, p2, abort as _, p3, p4);
(a, b)
}
@@ -41,7 +44,6 @@ trait ReturnValue {
}
macro_rules! define_usercalls {
// Using `$r:tt` because `$r:ty` doesn't match ! in `clobber_diverging`
($(fn $f:ident($($n:ident: $t:ty),*) $(-> $r:tt)*; )*) => {
/// Usercall numbers as per the ABI.
#[repr(u64)]
@@ -59,22 +61,6 @@ macro_rules! define_usercalls {
};
}
macro_rules! define_usercalls_asm {
($(fn $f:ident($($n:ident: $t:ty),*) $(-> $r:ty)*; )*) => {
macro_rules! usercalls_asm {
() => {
concat!(
".equ usercall_nr_LAST, 0\n",
$(
".equ usercall_nr_", stringify!($f), ", usercall_nr_LAST+1\n",
".equ usercall_nr_LAST, usercall_nr_", stringify!($f), "\n"
),*
)
}
}
};
}
macro_rules! define_ra {
(< $i:ident > $t:ty) => {
impl<$i> RegisterArgument for $t {
@@ -173,74 +159,90 @@ impl<T: RegisterArgument, U: RegisterArgument> ReturnValue for (T, U) {
}
}
macro_rules! return_type_is_abort {
(!) => { true };
($r:ty) => { false };
}
// In this macro: using `$r:tt` because `$r:ty` doesn't match ! in `return_type_is_abort`
macro_rules! enclave_usercalls_internal_define_usercalls {
(def fn $f:ident($n1:ident: $t1:ty, $n2:ident: $t2:ty,
$n3:ident: $t3:ty, $n4:ident: $t4:ty) -> $r:ty) => (
$n3:ident: $t3:ty, $n4:ident: $t4:ty) -> $r:tt) => (
/// This is the raw function definition, see the ABI documentation for
/// more information.
#[unstable(feature = "sgx_platform", issue = "56975")]
#[inline(always)]
pub unsafe fn $f($n1: $t1, $n2: $t2, $n3: $t3, $n4: $t4) -> $r {
ReturnValue::from_registers(stringify!($f), do_usercall(
Usercalls::$f as Register,
NonZeroU64::new(Usercalls::$f as Register)
.expect("Usercall number must be non-zero"),
RegisterArgument::into_register($n1),
RegisterArgument::into_register($n2),
RegisterArgument::into_register($n3),
RegisterArgument::into_register($n4),
return_type_is_abort!($r)
))
}
);
(def fn $f:ident($n1:ident: $t1:ty, $n2:ident: $t2:ty, $n3:ident: $t3:ty) -> $r:ty) => (
(def fn $f:ident($n1:ident: $t1:ty, $n2:ident: $t2:ty, $n3:ident: $t3:ty) -> $r:tt) => (
/// This is the raw function definition, see the ABI documentation for
/// more information.
#[unstable(feature = "sgx_platform", issue = "56975")]
#[inline(always)]
pub unsafe fn $f($n1: $t1, $n2: $t2, $n3: $t3) -> $r {
ReturnValue::from_registers(stringify!($f), do_usercall(
Usercalls::$f as Register,
NonZeroU64::new(Usercalls::$f as Register)
.expect("Usercall number must be non-zero"),
RegisterArgument::into_register($n1),
RegisterArgument::into_register($n2),
RegisterArgument::into_register($n3),
0
0,
return_type_is_abort!($r)
))
}
);
(def fn $f:ident($n1:ident: $t1:ty, $n2:ident: $t2:ty) -> $r:ty) => (
(def fn $f:ident($n1:ident: $t1:ty, $n2:ident: $t2:ty) -> $r:tt) => (
/// This is the raw function definition, see the ABI documentation for
/// more information.
#[unstable(feature = "sgx_platform", issue = "56975")]
#[inline(always)]
pub unsafe fn $f($n1: $t1, $n2: $t2) -> $r {
ReturnValue::from_registers(stringify!($f), do_usercall(
Usercalls::$f as Register,
NonZeroU64::new(Usercalls::$f as Register)
.expect("Usercall number must be non-zero"),
RegisterArgument::into_register($n1),
RegisterArgument::into_register($n2),
0,0
0,0,
return_type_is_abort!($r)
))
}
);
(def fn $f:ident($n1:ident: $t1:ty) -> $r:ty) => (
(def fn $f:ident($n1:ident: $t1:ty) -> $r:tt) => (
/// This is the raw function definition, see the ABI documentation for
/// more information.
#[unstable(feature = "sgx_platform", issue = "56975")]
#[inline(always)]
pub unsafe fn $f($n1: $t1) -> $r {
ReturnValue::from_registers(stringify!($f), do_usercall(
Usercalls::$f as Register,
NonZeroU64::new(Usercalls::$f as Register)
.expect("Usercall number must be non-zero"),
RegisterArgument::into_register($n1),
0,0,0
0,0,0,
return_type_is_abort!($r)
))
}
);
(def fn $f:ident() -> $r:ty) => (
(def fn $f:ident() -> $r:tt) => (
/// This is the raw function definition, see the ABI documentation for
/// more information.
#[unstable(feature = "sgx_platform", issue = "56975")]
#[inline(always)]
pub unsafe fn $f() -> $r {
ReturnValue::from_registers(stringify!($f), do_usercall(
Usercalls::$f as Register,
0,0,0,0
NonZeroU64::new(Usercalls::$f as Register)
.expect("Usercall number must be non-zero"),
0,0,0,0,
return_type_is_abort!($r)
))
}
);
@@ -250,4 +252,3 @@ macro_rules! enclave_usercalls_internal_define_usercalls {
}
invoke_with_usercalls!(define_usercalls);
invoke_with_usercalls!(define_usercalls_asm);

2
src/libstd/sys/sgx/mod.rs
View File

@@ -125,7 +125,7 @@ pub unsafe fn strlen(mut s: *const c_char) -> usize {
}
pub unsafe fn abort_internal() -> ! {
abi::panic::usercall_exit(true)
abi::usercalls::exit(true)
}
pub fn hashmap_random_keys() -> (u64, u64) {