user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

merge the sgx/fortanix __rust_probestack into the general x86_64 one

Browse source
This commit is contained in:
Folkert de Vries 2025-06-04 01:32:04 +02:00
parent b6eb4f9c3a
commit 45d649e2ea
No known key found for this signature in database
GPG key ID: 1F17F6FFD112B97C
1 changed files with 23 additions and 73 deletions
Download patch file Download diff file Expand all files Collapse all files

96
library/compiler-builtins/compiler-builtins/src/probestack.rs
View file

@ -57,15 +57,31 @@
//
// The ABI here is that the stack frame size is located in `%rax`. Upon
// return we're not supposed to modify `%rsp` or `%rax`.
//
// Any changes to this function should be replicated to the SGX version below.
#[cfg(all(
target_arch = "x86_64",
not(all(target_env = "sgx", target_vendor = "fortanix"))
))]
#[cfg(target_arch = "x86_64")]
#[unsafe(naked)]
#[rustc_std_internal_symbol]
pub unsafe extern "C" fn __rust_probestack() {
#[cfg(not(all(target_env = "sgx", target_vendor = "fortanix")))]
macro_rules! ret {
() => {
"ret"
};
}
#[cfg(all(target_env = "sgx", target_vendor = "fortanix"))]
macro_rules! ret {
// for this target, [manually patch for LVI].
//
// [manually patch for LVI]: https://software.intel.com/security-software-guidance/insights/deep-dive-load-value-injection#specialinstructions
() => {
"
pop %r11
lfence
jmp *%r11
"
};
}
core::arch::naked_asm!(
"
.cfi_startproc
@ -114,75 +130,9 @@ pub unsafe extern "C" fn __rust_probestack() {
leave
.cfi_def_cfa_register %rsp
.cfi_adjust_cfa_offset -8
ret
.cfi_endproc
",
options(att_syntax)
)
}
// This function is the same as above, except that some instructions are
// [manually patched for LVI].
//
// [manually patched for LVI]: https://software.intel.com/security-software-guidance/insights/deep-dive-load-value-injection#specialinstructions
#[cfg(all(
target_arch = "x86_64",
all(target_env = "sgx", target_vendor = "fortanix")
))]
#[unsafe(naked)]
#[no_mangle]
pub unsafe extern "C" fn __rust_probestack() {
core::arch::naked_asm!(
ret!(),
"
.cfi_startproc
pushq %rbp
.cfi_adjust_cfa_offset 8
.cfi_offset %rbp, -16
movq %rsp, %rbp
.cfi_def_cfa_register %rbp
mov %rax,%r11 // duplicate %rax as we're clobbering %r11
// Main loop, taken in one page increments. We're decrementing rsp by
// a page each time until there's less than a page remaining. We're
// guaranteed that this function isn't called unless there's more than a
// page needed.
//
// Note that we're also testing against `8(%rsp)` to account for the 8
// bytes pushed on the stack orginally with our return address. Using
// `8(%rsp)` simulates us testing the stack pointer in the caller's
// context.
// It's usually called when %rax >= 0x1000, but that's not always true.
// Dynamic stack allocation, which is needed to implement unsized
// rvalues, triggers stackprobe even if %rax < 0x1000.
// Thus we have to check %r11 first to avoid segfault.
cmp $0x1000,%r11
jna 3f
2:
sub $0x1000,%rsp
test %rsp,8(%rsp)
sub $0x1000,%r11
cmp $0x1000,%r11
ja 2b
3:
// Finish up the last remaining stack space requested, getting the last
// bits out of r11
sub %r11,%rsp
test %rsp,8(%rsp)
// Restore the stack pointer to what it previously was when entering
// this function. The caller will readjust the stack pointer after we
// return.
add %rax,%rsp
leave
.cfi_def_cfa_register %rsp
.cfi_adjust_cfa_offset -8
pop %r11
lfence
jmp *%r11
.cfi_endproc
",
options(att_syntax)